Comparison: Sigma 400mm f/5.6 HSM vs Sigma 600mm f/8 Mirror

I sold my Sigma 600mm this week, but before I shipped it out I did a head to head comparison between the Sigma 600mm f/8 Mirror (Reflex) and the Sigma 400mm f/5.6 APO Tele-Macro HSM. The result was interesting, but not very surprising.

I tested three lens combinations:

1. Sigma 400mm alone
2. Sigma 400mm with 1.4x Tamron-F teleconverter
3. Sigma 600mm alone (well, using FD-EF adapter without the optical element)

In terms of setup, I shot across my living room and kitchen to a (mostly) flat Costco ad posted on a cupboard door. A single Sunpak 383 at 1/16 power illuminated it to add more light and to avoid any camera shake (the flash effectively makes the shutter speed 1/1000th second or faster). All shots were taken at 1/200 sec, wide open (f/5.6 for the 400mm alone, f/8 for 400mm w/ tele and 600mm), and ISO 100 for f/5.6, ISO 200 for f/8. All shots were manual focus and I took at least five for each, choosing the best to display below to avoid focus issues.

Here are the full frame shots (downsampled, click to see larger... but not full-res):

Overview: Sigma 400mm f/5.6 Telemacro HSM

Overview: Sigma 400mm f/5.6 with 1.4x teleconverter

Overview: Sigma 600mm f/8 Mirror

These shots don't really show anything notable for full frame. Yes, the 600mm has less contrast, but we expect that from a mirror lens. The 600mm seems to have more vignetting too, but again, that's expected.

One thing I noticed was that both lenses performed about the same in terms of focusing -- as in, it was a pain in the a**, but in this static situation I had over 50% accuracy on nailing focus. Obviously, the f/5.6 of the 400mm wide open makes the viewfinder brighter, but in this case I didn't find that a brighter viewfinder made focusing any easier.

Next up, a comparison of 100% crops. All were from the center of the shot. These were converted from RAW with 100% sharpening in Bibble and all other settings off.

100% Crop: Sigma 400mm f/5.6 Telemacro HSM

100% Crop: Sigma 400mm f/5.6 with 1.4x teleconverter

100% Crop: Sigma 600mm f/8 Mirror

As expected, the 400mm alone is the sharpest, followed by the 400mm with TC, and the 600mm decently behind. I'd also say the 400mm alone has the best contrast and color; again, this was expected. So, if you don't need 600mm of reach, the 400mm will definitely be your best option.

But what if you do need 600mm of reach? For instance, if you shoot birds, you pretty much need whatever reach you can get. Which lens combination will give you the best reach if you want to see something really tiny or really far away?

I tested this by taking larger portions of each of the images above and upsampling them to all be at the same resolution as the 600mm image. The image below is the composite of these three images (click to see it at 100% crop):

Comparison: All upsampled to resolution of 600mm
Top: 400mm, Middle: 400mm w/ TC, Bottom: 600mm

This is where things get interesting.

In terms of best reach, the 400mm with 1.4x teleconverter gives the sharpest image. Not by a lot, but you can definitely tell in areas of fine text (like the "invent" in the HP logo). But, on the other hand, the 600mm does slightly outperform the upsampled 400mm. Again, not by a lot, and the 400mm has much better contrast, but I can definitely see more detail on the 600mm image.

Of course, these results are the lower end of 400mm image quality. Although Tamron-Fs aren't that bad, they are a lower-end teleconverter, and a Pro TC should be at least marginally better on a super telephoto. Also, these were shot wide-open; if I could have stopped down the 400mm, it would have sharpened up even more. I'm not exactly sure how much more it would have sharpened up, but I suspect it would be noticeable.

So, in the end, yes, you are much better off with the 400mm lens than the 600mm mirror lens. This was my original hypothesis back when I got the 600mm. Plus, the 400mm lens gives better contrast, bokeh that isn't donut shaped, and autofocus. It seems like the 400mm would be a no-brainer compared to the Sigma 600mm.

Until you look at cost.

The 400mm (without TC) goes for $250+. The 600mm goes for right around $100 if you have to purchase the adapter with it. In fact, mine just sold for $70 including shipping without the adapter. Ultimately, it comes down to how much money you can spend and if you are willing to tolerate the quirks of the 600mm.

Personally, I'm happy to have the 400mm, but the 600mm was a great stepping stone until I could afford it.

Hodgepodge

What's a hodgepodge? It means mishmash!

And that's what this post is...

1. After buying the Sigma 400mm with money I do not have, I'm selling off some of my older equipment that I do not need. In particular, that means my Canon 50mm f/1.8 II is going up along with my Sigma 600mm f/8 mirror lens. If you are interested, my listings are here. The 600mm has already been replaced with the 400mm, and I'm hoping to replace the 50mm f/1.8 II once I get a job with a 1.4.
2. I added another tool on Used Camera Database to include live eBay auctions along with historical data. Check it out if you are interested. It has been quite educational to learn how to make it work, and there is plenty more to do over there.
   
3. I haven't updated here much, and that will likely decrease even more as I'm spawning off a blog on Used Camera Database to hold that sort of stuff. If you are interested, check it out.
4. I'm still planning to post a few things here in the next week or two. One is an anatomy of a photo on a series of shots I did at work for a coworker. I'm pretty happy with how they turned out. The second thing is a Sigma 400mm and Sigma 600mm comparison. Trust me, I can't put that off too much because the 600mm will be in the mail in a week!
5. Microstock is basically dead for me. I've made pocket change for the handful of images I uploaded, but not nearly enough to actually pull any cash out and, while I want to make a post listing my stats, there's very little motivation to do so.
6. Lately I've been doing very little shooting, and I don't really have much planned in the near future. Once I get this dissertation submitted and a real job, that might change (or, I might have even less time!).

Birds at 600mm

This is a photography blog, after all, so I should probably post some photographs. These are from a few weeks ago when I walked around Stanford with my Sigma 600mm and monopod (it was mostly a test of my monopod).

This first guy is an Acorn Woodpecker (Whatbird) I've seen him and his type all over the place on campus drilling holes in palm trees. Since the trees are 50 ft or so high, the 600mm is really necessary for reach (this is approximately half the frame -- he's really high up!).

The next two hummingbirds I found in the Cactus Garden (Arizona Garden) and I don't really have a good enough shot to get an identification. Of course, hummingbirds all look alike to me anyway :)


I just love this one, even though you can't see the bird's head. I just really like the color, composition, and motion. FYI, this is the full frame.

Review: Sigma 600mm f/8 Reflex (Part 2 of 2)

The first half of this review is here with a follow-up here. I recommend reading those first.

This is the second half of my Sigma 600mm f/8 Mirror lens review. In the first, I focused on the physical characteristics and the ideal performance of the lens. In this part, I'll focus on how the lens performs in the field. And, as before, I'll start with my:

Conclusions:

• The Sigma 600mm f/8 does have substantially better image quality than an up -sampled Canon 70-200mm f/4, but only if conditions are perfect.
• The lens has high build quality but it is still a mirror lens with mirror lens limitations.
• It is VERY hard to get decent pictures out of the lens since it has narrow depth of field, is very sensitive to camera shake with an equivalent focal length of 1000mm (even on a tripod), and is relatively slow (f/8). Expect to do a lot of shooting at ISO 400+ and expect to toss a lot of soft images.
  
• If you are strapped for cash but need the reach and you can get a Sigma 600mm for $150 or less (in a mount that fits your camera or can be adapted to your camera), do it.

This lens is really a b**** to use. If you have your shutter speed a little too low, you'll get a crappy image. If you are wobbling a little, you'll get a crappy image. If you miss the focus, you'll get a crappy image.

Yet, oddly enough, I've had a lot of fun using it.

The primary reason for my enjoyment is that I can actually see details through the camera way better than with my naked eye (that may be partially due to my declining vision, but that's another post altogether). With a 1000mm effective focal length, my 20D and Sigma act as a 20x spotting scope. And, yeah, the manual focus takes some getting used to, but once I had more practice with it, I got pretty good at rapidly snapping things into decent focus. The focus wheel has great feel to it making focusing relatively easy.

So, that all said, let me go into some more details. I'll start with mirror lens limitations, which apply to any mirror lens, not just the Sigma 600mm f/8 (arguably one of the better mirror lenses out there). Then, I'll talk about the handling issues and my personal guidelines when I want to get a shot, and sprinkle in a lot of example shots all through the post. As always, click the images to see them larger.


Mirror Lens Limitations:

Mirror lenses are generally shorter, lighter, and less expensive than the equivalent refractive lens. Yet, mirror (or reflex, or catadioptric) lenses suffer from most (if not all) of the following limitations:

• Fixed Aperture: Catadioptric lenses, by their very construction, cannot provide aperture control (to my knowledge; correct me if I'm wrong). The lens works by reflecting light from the outer donut mirror, off the front mirror, and then through a few refractive elements. I've heard of fixed apertures as large as f/4 and as small as f/13, but most fall in the f/5.6-f/8 range for 500mm lenses. Either way, a fixed aperture restricts your photographic options. The standard compromise of f/8 results in a pretty slow lens (using ISO 100 is difficult even in bright sunlight without a excellent tripod) yet a narrow depth of field for longer focal lengths (i.e. 300mm+). And, you have no way of adjusting to changing conditions.
• Donut-shaped Bokeh: Bokeh is the appearance of bright (or dark) artifacts due to out of focus highlights. If a point light source is out of focus, it will appear on the image as a bright circle (or polygon). The bokeh on a catadioptric lens is not circular; it is donut-shaped. Turns out, donuts are very distracting to the eye because they have a lot of edges involved with them. Of all the mirror lens problems, this one annoys me the most.
  
• Low Contrast: Catadioptric lenses tend to have lower contrast because of the path the light takes. In the modern digital age though, this is less of an issue because you can easily clean up the problem in Photoshop later.
  
• No Auto Focus: There are a few reflex lenses that do autofocus, but most don't. In this modern world of auto-everything, lack of auto focus can really make it much harder to shoot images in fast situations. Likewise, newer cameras no longer come with focusing screens suited to manual focus, making the task that much harder.

Now that I've introduced the main problems, I'll give you illustrated examples of how that impacts me when I use my Sigma 600mm f/8.


Fixed Aperture: Keep Your Shutter Speed Up

As mentioned in the previous review, the Sigma 600mm has an effective focal length around 1000mm. By the usual shutter speed = 1/focal length rule, that'd mean I should get a substantial number of keepers at 1/1000sec. I've found in practice that I actually need to go a bit beyond that to get reliable shake-free images (around 1/2000s works pretty well). Even when I look through the viewfinder, it looks like one of those across the field shots in an NFL playoff when one of the team scores: shaking all over the place.



Fixed Aperture and No Auto-focus: Focusing is hard!

Depth of field narrows as your aperture widens, your focal length gets longer, and/or your subject gets closer. On a 600mm lens, an aperture of f/8 turns out to be really, really narrow. For example, in the shot of the bird above, look at the focus on the fence. The reasonable depth of field is only a few centimeters, barely enough room to get the bird's face in focus. Obviously, your focus needs to be right on to get a shot.

If focus is a little off, you get an image like this:

A great shot, except focus is a few centimeters too close. Darn.

This wouldn't be too bad, except you don't even have auto-focus to help you. I've found with my 20D's viewscreen I can nail the focus if I take my time (a few seconds) and take a few shots. The problem is, for fast-moving subjects, you rarely have more than a second to get the focus.



Donut-shaped Bokeh:

Mirror lens bokeh is the number one reason I'll be planning on upgrading as soon as I can.

A great (or really bad) example is the shot of the Great Blue Heron above. He (she?) was backlit and you can see how distracting the ring highlights are. To get any sort of decent image, you need to keep your foreground and background clean and uniform; this is typical for any photography, but a catadioptric lens makes any background clutter super distracting, even if it is just fine textures (like the image below).


Even lines like the branches below get hollowed out and distracting!


In comparison, here is a shot from the Canon 70-200 f/4. Note how the bokeh is there, but not distracting.




Also: Keep Your ISOs Up!

I don't think I've ever taken a shot with the Sigma at ISO 100 except for the testing images where I used a flash. And, while I'm looking into a Better Beamer or the equivalent, even flash isn't very useful when your subject is very far away. Most of my shots are at ISO 400 or ISO 800. Beyond that, noise gets really bad.

The good news is that the noise (which usually decreases the effective resolution of the camera once you've run noise reduction) has less of an effect when the lens already is already on the soft side. The end result is I feel like I can get 2-4MP images out of the 20D + Sigma instead of 8MP, but that's an ok compromise considering the cost.



Handling: Not Bad

During most of my shooting with the Sigma 600mm f/8 Reflex, my camera looked like the image above. I pretty much always keep the hood on it (for protection more than anything else, but also to avoid any image flare). While it looks massive, the lens itself ends where the hood starts, and the overall assembly is easy to carry around and aim.

I've had a lot better luck with the lens on a tripod, mostly because it lets me lower the ISO a stop along with lowering the shutter speed to around 1/500s (about a 2-3 stop difference). I tend to screw the tripod into the camera since the camera is a little too heavy to properly balance when I screw it into the lens. Also, I can't seem to get my tripod plate to attach firmly to the Sigma, but I expect that is probably just my cheap tripod!

When I shoot, I try to snug the camera as firmly as against my face (using the eyecup) as possible and drape my hand over the lens to steady it. That's a little more complicated when I need one hand to operate the camera and a second to focus the lens. But it works out pretty well. I've used the tripod as a monopod with some success; a monopod is on my short list of things to acquire in the near future.

Attaching and detaching it from the camera isn't hard, but it isn't as easy as the EF mount (it is an older FD mount with breech-lock action. For some reason I always try to turn it the wrong way which is probably why the base of the lens got loose.

Also, I should mention I always shoot with the FD/EOS converter without the optical element. It turns out, since the Sigma 600mm f/8 focuses well-past infinity, I can get it to focus almost to infinity without the glass installed. By my estimation, this gives me maximum focus around a kilometer! I've been able to focus on planes traveling overhead with no problem... And why add another element to the optical path?

Once you get to know the lens and it's quirks, it really is a lot of fun to use!


A Few (Good) Images

I'll leave you with some of my better images from the past few weeks that haven't been posted on the blog yet.






If you'd like to see more images, check out Jacob's shots (including a nice shot of a sparrowhawk).

Sigma 600mm f/8 Reflex Performance Addendum

Truthsayer asked the following question in a comment:

Why are you comparing a 200mm lens to the Sigma 600mm?

That's an excellent question, and probably an indicator that I rushed the last post (Part 1 of the Sigma 600mm f/8 Reflex review) before it had all the explanation it needed. So I'll try to fill in some blanks about the performance of the Sigma 600mm in this post.

Before I go on, I need to specify that I'll only be discussing the pure, best-case, performance of the Sigma 600mm. In real-life use, the Sigma 600mm will generally not perform as well as these 'ideal' test shots. So this is more of a theoretical discussion of how well the Sigma 600mm performs rather than what to expect out of it when you use it. In my next post, I'll discuss the real-life use of the lens and its many handling quirks.


So, why compare the Sigma to a Canon 70-200mm f/4 USM?

1. The short version is that I had the Canon 70-200mm handy. It is currently my only telephoto lens.

2. The slightly longer version is that the Canon 70-200mm is similar to the existing lens of someone interested in purchasing a Sigma 600mm (admittedly, the Sigma is a budget lens). A better comparison would probably be one of the 70-300mm consumer zooms, or even the Canon 70-300mm f/4-5.6 IS. Comparing the $100, 20 year old Sigma 600mm to the $7,000 Canon 600mm f/4L IS USM or even the $1,000 Canon 400mm f/4L USM would be just rude.

3. The real reason is that I wanted to validate my purchase. If my tests conclude the same thing as this guy (that a 600mm shot is no better than an upsized, high quality, 200mm shot), then there is zero reason to keep the lens around. I could get shots just as good (and with less struggle) using the 70-200mm. That conclusion would make me very sad.


And what did I learn?

Well, luckily, my tests showed that the Sigma 600mm f/8 Reflex can easily achieve more detail than an upsampled shot from the 200mm end of the Canon 70-200mm f/4 USM, as shown in the comparison shot below:

Left: Upsampled Canon, Right: Sigma 600mm 100% crop

Essentially, for shooting pictures of birds or other far away objects (like the moon) I should be able to achieve a substantially more detailed image using the Sigma. Obviously not super sharp, but better. That makes it worth keeping around until I can get a used 400mm lens.

After I read Truthsayer's comment about getting a 1200mm effective focal length, I started to wonder about the Olympus series of cameras. It turns out Olympus dSLRs use the four-thirds standard, meaning their sensors are smaller than Canon APS-C sensor and use a 4:3 aspect ratio instead of 3:2. The image at right (from Wikipedia) shows the relative sizes of the various digital sensors.

I dug a little further and found that those Olympus photographers have really put a lot of testing into the OM mount version of the Sigma 600mm. For instance, this thread provides a well-done review of the 600mm and concludes that the lens is pretty darn soft. And this thread concludes the same thing, along with a discussion of many of the other reflex lenses that are out there.

Some observations and comments:

• The first review/thread actually gives MTF50 measurements for the lens, which is something I've seen nowhere else.
  
• The second thread has a lot of handling comments that I'll echo in my next post.
• There may be an adjustment method (screws under the center obstruction) to get the lens in better alignment. I'll check this out when I get home.
  
• The second thread has a moon picture which is softer than mine. I think I got a good copy of the lens and it works better on a Canon than an Olympus due to the sensor size (more on this later).
• Sigma lenses are prone to mold (I knew that!).
• The Zuiko 500/8 Reflex is very well respected, but it goes for $300+ on eBay. Not worth it to me since it is still going to suffer from most of the handling drawbacks of the Sigma. Here's a good comparison including the Zuiko.
  

I think the main problem for Olympus/four-thirds owners is that their smaller sensor size (a little more than half the area of the APS-C, and a quarter of the size of a 35mm frame) is exposing the optical deficiencies of the Sigma 600mm mirror lens. I would urge Olympus users (or other 4/3 bodies) to stay away from the 600mm Sigma or at least go in with reasonable expectations.

Luckily, on my 20D, the Sigma performs a bit better just because the pixels aren't as close together!


MTF Discussion (Geeks Only!)

Ultimately, it comes down to spatial resolution, or line pairs per millimeter (lp/mm). In the business, this is called a Modulation Transfer Function (MTF). MTF is a trait of both the lens and the camera. I don't want to describe MTF50 in detail here, but if you are curious, look at Imatest's page on MTF or Bob Atkins' page on MTF.

Imagine what's happening in your camera: light enters the lens, gets refracted/reflected, and then is projected onto the image plane inside the camera. If the lens is good, then the image on this plane will be very sharp (very narrow lines can be distinguished). But to get a sharp image, you also need lots of pixels to resolve the image projection from the lens. MTF is thus a factor of both lens and camera, with the limiting factor (lens or camera) deciding the overall MTF.

So, imagine the Sigma 600mm f/8 projecting an image onto 35mm film. The lens designers did what needed to be done to get decent MTF (lw/mm) on film. Not perfect, of course, but most people who have used the Sigma 600mm f/8 on a film camera have been happy with its performance. Now, take the same lens, and stick it on a 4/3 camera. Since the 4/3 image sensor is half the height of film, even though the lw/mm is the same, we've got less total lines/image on our sensor. And, as a result, the overall image is going to look like it has half the spatial resolution and appear softer than the image on film. In First Light's post, he quotes an MTF50 on his E-1 of 703 lp/ph. But, on 35mm film, that would be around 1400 lp/ph, which is generally considered to be a good resolution.

Note that I switched to lp/ph (line pairs to picture height) for this argument. On my 20D, FL's figure equates to around 800 lp/ph (it is actually a little higher when you consider the difference in aspect ratio). Not great, but only a little on the poor side of good. That pretty much summarizes my experiences: all my images are soft and probably comparable to upsampling an image from a decent 400mm lens.


Conclusion:

It isn't that the Sigma 600mm f/8 is so bad, but it works better on larger sensors. And for my purposes, since it outperforms my other telephoto lens (a Canon 70-200mm f/4), it will sometimes find itself on my camera.

As an example, here's a shot which I could never have gotten with my Canon 70-200mm:

American Tree Sparrow (?), Sigma 600mm F/8, 1/2000s, ISO 800

Ok, well, I could have gotten it, but it wouldn't have as much detail. The image above is nearly full frame; click it to see it at 1600pix!

Review: Sigma 600mm f/8 Reflex (Part 1 of 2)

Finally, the time has come for my full Sigma 600mm f/8 Reflex review. If you aren't a regular reader of my blog and you'd like the know the back story, check out all the posts marked Sigma600mm.

Of course, if you are too lazy to read the previous posts, let me give you a recap. First, I was looking for a long (400mm+) lens for bird photos and did a bunch of searching on eBay (here are some other lenses I considered). On a whim, I bid on and won a Sigma 600mm f/8 for $78 + $14 S/H. The Sigma 600mm is a well-regarded version of those infamous mirror/reflex lenses (or, officially, catadioptric lenses). My Sigma is an FD lens, so I also purchased an FD-EOS converter (review) for $36 including shipping. I've also described the process, advantages, and drawbacks of adapting FD lenses to EOS/EF cameras.

Sadly, when the lens arrived, it had some fungus on the main mirror, but it wasn't enough to return it and I don't think it is a major detriment to image quality. I did ask the buyer for a $15 refund, so my ultimate price for the lens was $77. Since then, I've shot a decent amount with the lens (maybe 700 shots over 10 hours) and I'm ready to give my review. And, in true backwards fashion, I'll start with the...


Conclusion:

Let me make my advice real simple for you if you are considering the Sigma 600mm for a digital camera (I don't have any experience with it on a film camera, so you're on your own there):

• The Sigma 600mm f/8 does have substantially better image quality than an up -sampled Canon 70-200mm f/4. That's a huge weight off of me, because I was very concerned about what this review said.
• The lens has high build quality but it is still a mirror lens and has plenty of limitations.
• It is VERY hard to get decent pictures out of the lens since it has narrow depth of field, is very sensitive to camera shake (even on a tripod since it has an equivalent focal length of 1000mm), and is relatively slow (f/8). Expect to do a lot of shooting at ISO 400+ and toss a lot of soft images.
  
• If you are strapped for cash but need the reach and you can get a Sigma 600mm for $150 or less (in a mount that fits your camera or can be adapted to your camera), do it. You won't be sorry.
  
• Don't pay more than $200 for one in any mount. Most of the EOS mounts, because of rarity, go for upwards of $250. I don't think it is worth it, because used 400mm refractive lens are available for $300+ without most of the limitations of mirror lenses.

Here's a widget that shows the 600mm Sigma lenses available on eBay right now:





The Minolta version is probably the cheapest and most popular version available (and there are Minolta to EOS converters available). The Canon FD mounts are pretty cheap too. Not all the lenses are black either -- I've seen auctions for at least one white one and one greenish/gray one. There may be different versions of the lens out there, but as far as I know, they are all optically identical and good quality.

Okay, now that I've given you the dessert first, how about dinner...


Physical Characteristics:

The lens itself is built like a tank: metal, well-toleranced, and heavy. Not solid cat heavy or refractive 500mm f/4 heavy, but still pretty heavy. I guess the weight needs to be put into perspective: it is heavy compared to my Tamron 17-50mm, but still under two pounds, and nowhere near the weight of a quality refractive 600mm lens.


The only functional part of the lens (since it lacks both autofocus and aperture control) is the focus wheel, which turns a total of a little over 180 degrees with nice action (smooth and well-damped). The damping has a strange response in the middle of the range (almost like air gets trapped or something) but the effect is only noticeable when you move the focus quickly. I never notice this when I'm actually using the lens. Also, the end of the lens does rotate with the focus wheel, but a front polarizer is pretty unrealistic with this lens anyway!

The Sigma 600mm reflex does include a built-in tripod mount which I really haven't had much use for. Since the front of the lens is so light, the tripod mount isn't that much of an improvement over just mounting the camera on the tripod. In my case, my tripod doesn't mount well at all to the lens mount (it rotates too easy; an issue with my tripod, not the lens mount). If you have a smaller camera like a Digital Rebel, you might prefer the tripod-mount. It allows 90 degree rotation to portrait mode.

The lens does include a filter holder and my package included a case and five 22.5mm filters of various shades. The filters are pretty useless if you are shooting on digital and I'm not sure if a polarizer would even work in the back position. On mine, I actually removed all the filters, including the clear/UV filter. Why put more optical elements in the light path if you don't need them?

My version of the lens has an old FD mount (breech-lock). It mounts securely and has zero interface with the camera since it lacks a diaphragm. Mounted on the camera, it is pretty solid although you can twist it slightly due to the FD-EOS converter. It doesn't cause problems in normal use though, except...

After taking it out a number of times, I started to notice excessive sloppiness when I rotated the lens, to the point where it had a loose feeling even when I was doing fine focus. At first, I thought it was the mount loosening up, but then I realized that the back of the lens (held on by three tiny screws, in the shadows of the image above but easy to see below) was actually loosening up. So, I took it to work where I had some jeweler's screwdrivers and went ahead and took the back off to see what it looks like (and to check for a huge mold infestation). This is what I saw:

I think this is the back of the mirror, but I didn't go any further with disassembly because that seal (which was already pulling out slightly) didn't look like it'd go back in easy. So, I put it back together, screwed the screws back in tightly, and everything works fine now.

So, to summarize, the Sigma 600mm is a really well-built lens. Solid, everything is metal (even the lens hood!) and there's no slop in it at all.


Performance:

The next question, and probably the top question for most people who find this page, is how does the lens perform?

To test performance, I was originally going to go outside and post a target across my yard to get shots and compare them to the Canon 70-200mm F/4 USM. But then it rained. And rained, and rained... So, instead, I just taped a target (something out of a catalog my wife had; as luck would have it I yanked out the religion page) to a cupboard door in my kitchen and set up the tripod on the far side of the living room. Total distance is about 25 feet or so.

To guarantee only a test of optimal lens sharpness, I used a flash to illuminate the target from below, and put the 20D on a tripod with mirror lockup and the self-timer enabled. For each equipment combination I took the best results (focus, etc) of multiple images to really look at optimal performance. All shots were at 1/250s (sync speed), f/8, ISO 100, converted straight from RAW with no levels or sharpening. All Sigma shots used the FD/EOS converter but the optical element is the extra variable (did I include it or not).

The three full frame setups are (click to see them larger, but not the 100% crop):

Full frame Canon 70-200mm f/4 USM (CANON)

Full frame Sigma 600mm f/8, no corrective lens (SIGMA_A)

Full frame Sigma 600mm f/8, corrective lens (SIGMA_B)

As you can see, the Sigma, as expected, has a much smaller field of view. Both versions of the Sigma are darker than the Canon, which may be a result of the FD/EOS converter. And the corrective lens has a smaller field of view and darker image than with the corrective lens removed. I didn't measure the drop in light intensity scientifically but it is probably 1/3-1/2 stop without the corrective lens and maybe a full stop with the corrective lens. Also note the difference in contrast between the Sigma and the Canon, although contrast can be easily fixed in post (with the corresponding increase in image noise).

I did measure the distance between two features, in pixels, on all the images and compute an effective focal length. Assuming the Canon is truly 200mm at full zoom:

• Canon: 200mm (320mm effective on 1.6x crop sensor)
• Sigma w/o corrective optics: 665mm (1064mm effective)
• Sigma with corrective optics: 785mm (1256mm effective)

These rough calculations mean the Sigma is easily over 1000mm effective focal length on a crop body like the 20D. That's intense magnification! It does result in some difficulties when using the camera, which I'll get to in the handling portion of the review.

The Sigma also has a slight vignette to it, even on a small sensor camera like the 20D. I expect the vignette would be much worse on a full frame camera or film, but it isn't objectionable at all for my purposes (I sort of like it, actually). It'd be easy to remove if you wanted to. For example, in the helicopter image below, the blue intensity at the corner is about 85% of the blue intensity in the center.


Next, the real meat: at a 100% crop, how does the Sigma compare to the Canon? Below is a 100% crop from the Canon and the Sigma without the corrective lens:

100% crops: Canon on the left, SIGMA_A on right

The Canon clearly has better contrast and sharpness but the Sigma can resolve finer detail. How about up-sampling the Canon to directly compare at the same resolution?

Left: Upsampled Canon, Right: SIGMA_A 100%

Again, better contrast in the Canon, but the Sigma can clearly make out a lot better detail. Instead of just a rough idea of the words, you can actually read them and make out the edges of the letters. The tiny text at the bottom is a small blob on the Canon but readable on the Sigma.

Overall, I'd say the Sigma's sharpness is probably similar to a decent 400mm refractive lens like the Sigma 400mm f/5.6. Definitely, the Sigma isn't nearly as sharp as the Canon, but the 300+% increase in focal length (and 900+% increase in effective pixels) makes up for the lack of sharpness. The Sigma 600mm f/8 can get shots that you can't get with the Canon 70-200mm F/4. It'd be interesting to try the Canon with a teleconverter, and if I get one, I'll update this comparison.

The final question is whether the optical element in the FD/EOS converter hurts image quality as I hypothesized earlier. The addition of the optical element turns the converter from an effective extension tube to an effective teleconverter (with the accompanying increase in focal length and decrease in aperture). To test, I upsampled the sample without the optical element and compared it to the 100% crop with the optical element:

Left: SIGMA_A upsampled, Right: SIGMA_B 100% crop

Aside from the decrease in brightness, if you look closely you can see the optical element does hurt image quality slightly (the edges of the letters aren't quite as sharp). While the decrease in sharpness is minor, I recommend using the lens without the optical element whenever possible.

The other major conclusion is that the Sigma 600mm f/8 Mirror lens has a substantial advantage over an upsampled 200mm, but probably no advantage (and many disadvantages) compared to the 400mm f/5.6 lenses. So, again, if you can't afford a 400mm+ lens and you can get the Sigma for cheap (<$150) it is worth it. But, I've got to warn you now, the combination of the monster focal length and the catadioptric construction makes the lens really, really hard to use effectively.


To Be Continued...

This post has taken forever to write, and it will take a little longer to be finished. I'm going to split the handling of the lens (along with lots of sample shots) into a separate post to keep this from getting too long. Hopefully I'll get it up in the next day or two!

Lenses on eBay: Two Negative Experiences

Sorry for the long delay in posts. Life has gotten really busy in both of my jobs, so post frequency will likely decrease during the rest of February. The Sigma 600mm review is ready to be written, I just need to find the time to do it.

In my post A Guide to Buying Lenses on eBay, I mentioned that I'd had a few problems buying lenses. Oddly enough, out of the six lenses I've purchased, it has only been the last two Canon FD lenses that I've had trouble with: a Sigma 600mm f/8 Mirror and a Canon 100mm f/4 Macro.

Sigma 600mm f/8 Reflex

As I mentioned earlier, this was an impulse buy that I didn't fully research before bidding. More specifically, I didn't directly ask the seller if the glass was clear. I knew that the seller was inexperienced and would have normally asked, but I had decided not to buy it and only changed my mind less than a minute before the auction ended since the price was so cheap. FYI, I got the lens for $78 + $14 S/H, a very good price for the FD-mount version.

But, not asking the fungus question ended up coming back and biting me in the... derrière.

95% of the time, lenses on eBay are fungus free even if they don't specifically mention it in the listing. In this case though, the lens really was in great condition, except the main mirror had some spots of fungus on it. The outside of the lens is pretty much mint, which is probably why the seller didn't notice the fungus on the inside (I assume).

Here's a (soft) overview image to give you an idea of scale. The fungus/mold dots are on the upper part of the mirror (which is reflecting the blue sky in the middle of the image. There's two spots on the very edge and one lighter spot farther into the mirror between the other two.

Here's a detail image with better focus. Again, there's a nasty one on the left (almost looks like it ate through the mirror) a light one in the center and another light one on the right edge.

When I tilted the lens in the sunlight, I got a real idea of the damage. The dark spot on the left fans out quite a bit, the center one is larger than it seemed, and the one on the right is much larger than it initially appeared (note that a lot of it is obscured by the shadow edge). Note how the fungus spreads on the mirror (or any lens) outside of what you can see. From what I've heard, often fungus often etches the mirror permanently.
BTW, I know the lens looks super dirty, but in reality it is very clean. This angle (with the sun beating on it) really shows EVERYTHING. Also, the best way to avoid fungus is to store the lens as dry as possible (like adding a desiccant to your camera bag). The best way to remove it is... well, I'm still working on that.

So, after I realized the fungus problem, I was a little torn. On one hand, the seller stated the lens condition was 'mint' and fungus is obviously not a mint situation. I was also willing to keep the lens; the fungus shouldn't substantially damage image quality. And, in my mind, the seller obviously didn't know the fungus was there. I did withhold posting positive feedback because I knew that was my only leverage in this situation.

So, after some debate, I decided to ask for a partial refund. I actually felt quite bad doing it since it seemed a bit like feedback blackmail, but the lens condition is obviously not mint. FYI, if I'd actually asked if the glass was clear and the seller told me it was (like usual) then I would have very forcefully asked for a large percentage rebated.

In this case, I sent the seller an e-mail directly to her account:

Hi xxxx,

I received the lens last week and it is in great shape as you said, except... It has a small amount of fungus/mold on the main mirror. I've attached images to show you what I mean -- in 6569 you can see the three-four spots of mold, and in 6573 you can see the spread of the mold across the mirror for the spots.

I honestly think you didn't know about the fungus (which usually grows if there is moisture in/on the lens and it is stored for a long time). But you did list the lens as MINT in the listing and I definitely would not have spent so much if I had known about the fungus. Fungus is hard to get rid of, often permanently damages the lens, and significantly lowers the resale value. In this situation, I doubt it impacts the image quality much, but I'm going to have to take some steps to kill it and clean it up.

I'd still like the lens, but I'd like to ask you for a partial refund based on the condition of the lens, maybe $15. Are you willing to do this?

Thank you for your time. I apologize to hassle you with this and I firmly believe you had no knowledge of the damage.

-Sean

PS If you have other lenses from your Dad's collection I recommend checking them for fungus too. Often, growth can be avoided by putting a silica gel in with the equipment to absorb moisture and changing it every once in a while.

I got no response, but a few days later, I got a message asking for feedback which indicated she hadn't received the e-mail above (SPAM filter). So I resent it through eBay and she immediately wrote me back:

$15 is VERY reasonable. I appreciate you getting back with me, as I had NO IDEA of the mold issue. It was stored in a very dry, dark place, but I can't speak for how it was stored prior to me inheriting it from my father. He's always so good about those things. Anyway, thanks for getting with me to work things out! Just send me an invoice for the $15.00 and I will be more than happy to pay it right away! Thanks again!

So, after that, everything went smoothly. Ultimately, I paid $92-15 = $77, including shipping, for a slightly fungus-damaged lens. I'm quite happy with the way things turned out (maybe I should have asked for a larger refund?) and I gave her positive feedback. My plan with the fungus is to keep an eye on it and if it gets any worse, I'll open the lens and figure out how to clean it. At this point though, it isn't worth the risk of damage to clean it. I did irradiate it in the sun for a few hours so hopefully that will stop the growth.


Canon 100mm f/4 Macro

The other eBay problem I've had is with a Canon 100mm f/4 Macro (FD-mount) I purchased Jan 20th for $50 + $15 S/H (a really good price).

The problem is, it hasn't arrived yet. Here's the tracking info on the lens:

Label/Receipt Number: 0479 7634 5650 3603 3692 Detailed Results:

• Acceptance (APC), January 22, 2008, 1:06 pm, MONTROSE, CO 81401
• Undeliverable as Addressed, January 25, 2008, 4:15 am, MOUNTAIN VIEW, CA 94043
• Processed, January 29, 2008, 10:05 pm, DENVER, CO 80217
• Processed, February 08, 2008, 5:03 am, SAN FRANCISCO, CA 94188
• Processed, February 11, 2008, 6:57 pm, DENVER, CO 80266

Yeah, seriously. So it got here, had a bad address on it or something, went back to Colorado. Sat around somewhere for almost two weeks, went back to SF, then went back to Colorado. What the hell is going on?

The seller told me he'd send it out as soon as it got returned to him. But it has yet to arrive back after three weeks. I have to assume the seller screwed something up when he sent it out (he said a bunch of other items he mailed had similar problems) but I have to place some blame on the USPS too. I'd call them to track it down, but the seller is the only one that can do that. The seller did offer me a refund, but at this point, I'm fine waiting for the lens since I got a really good deal on it.

That is, assuming the lens doesn't get stuck in CO for another couple of weeks.

Update 2/19: The Canon 100mm f/4 finally arrived (I had gotten notice on Friday that the seller had received it from the USPS and sent it out again). I expect the problem was the seller put my house number as 722 instead of 772 (which is surprising, since he included a shipping list with the correct address, and you'd think he'd correct the address after the first delivery problem). I'm lucky it found my house the second time around. The condition is pretty rough, but for the price, it seems good. I'll clean it up and post a review in the next few weeks once I've spent some time with it.

Attaching Canon FD Lenses to an EOS/EF Body

How to make sense of Canon FL/FD/FDn/EF mounts:

If you are the type of person that looks for deals on camera equipment (like me) you may have considered attaching old manual lenses to your modern dSLR. If you shoot Nikon, you are in good shape, since the basic F-mount is still compatible with autofocus cameras almost 50 years later (almost -- I'm not going to get into that here; do some reading before you attempt to mount an old lens on a new body because some aren't compatible without modifications). Similarly, the Pentax K mount, has maintained the same basic lens mount through the years.

Not so with Canon.

When Canon introduced the EOS system in 1987, it scrapped the previous FD mount (which was also backwards compatible with the FL mount ['64-'71]) and began again with a completely new EF mount, which includes gold plated contacts for electronic autofocus. The FD mount and EF mount are completely incompatible, but by doing so, Canon was able to streamline the EF mount and avoid a lot of difficulties keeping compatibility.

Also, the FD/FL mounts were breech lock, meaning you have to push the lens onto the camera then twist a ring to lock the lens on (which prevents the lens flange from wearing out the camera ring, changing the film distance and hurting image quality). The later FD mounts (called "new" FD, nFD, or FDn) were bayonet mounts like the EF series -- insert the lens into the mount and then twist the lens itself to attach. Realistically, bayonet mounts are just as good as breech-lock mounts and more convenient to use. See more here.

Canon made a TON of FD lens which have now been orphaned by the new EF mount. For us cheap photographers, this is both good news and bad news. The good news is that there are a lot of old lenses on the used market which can't be used on new cameras, meaning high quality glass for cheap. The bad news is that attaching the lenses to an EF mount is a real hassle which I'll get into in a bit.

First though, what lenses are out there? How about this awesome list of FD lenses by Denis Baron. It lists all the major FD lenses made by Canon and gives specifications. A great resource if you are looking for old lenses online or on eBay. Note that FDn lenses are listed as 'new' FD, of which most have the S.S.C. coating even though the designation was dropped; S.S.C. is a better coating than S.C. Also, Photography in Malaysia has a great FD lens archive with reviews and tons of images. Don't forget about third party manufacturers, especially Sigma, Vivitar, and Tamron, because many of them supplied a lot of FD lenses.

Also, I should note that the most popular FD mount camera by far was the Canon AE-1 (review). The AE-1 sold over 5 million units due to a strong advertising drive, like the commercial below...




The Challenges of Mounting FD on EF:

In 1987, when the EOS system was introduced, the Canon photography world was thrown into a temporary upheaval. The new mount, while it included autofocus and a number of other advancements, caused most photographers to have to decide whether to stay with FD lenses or move to the new system. Most amateurs stuck with the old system a while longer, while most professionals moved quickly since they had the money and could make the investment in a better autofocus system. The good news is Canon pushed hard to get photographers to make the switch, and the brand was strengthened because of it.

The new EOS system did catch on relatively quickly with amateurs too, in large part to the big push to sell the Rebel series. If you were born before 1985, you probably remember the commercials centered around Ain the 70s or 80s, you probably remember the commercials centered around Andre Agassi like this classic:



At the time, I didn't do anything with photography, but I definitely remember the commercials!

I alluded to the significant hassle of mounting an FD lens on an EF camera -- the primary reason is the new EOS mirror box is deeper than FD with a longer distance between the lens mount and the film plane. This made it impossible to insert any sort of adapter between the mount types and preserve the lens to film distance. The end result, if you want to use an FD lens on an EF body with an adapter ring, is you will lose infinity focus. Essentially, you are adding a small extension tube between the camera and the lens.

This isn't just a problem for FD lenses either. Photonotes has a page about adapting manual focus lenses to the EOS system which mentions other lenses and what is needed, plus many of the other little issues you'll encounter. Some lens types you can adapt, some you can't. Bob Atkins has a great page up outlining the flange to film distances and which may allow an adapter (without optics) to EOS. POTN also has a good thread discussing FD-EOS converters which outlines which lens mounts work and which don't. I've been focusing on FD lenses because there are so many out there and they seem to be inexpensive compared to many alternatives.


Solutions for FD-EOS Attachment:

Of course, Canon realized that this would be an issue, so they did supply two versions of FD-EOS adapters. The macro adapter was similar to many of the existing adapters on eBay like the Bower/Hartblei item I reviewed in my last post in that it was thin and had no optics. This page shows both the Canon macro converter and the Hartblei I reviewed. For macro purposes, losing infinity focus is not a big deal. There's a good thread on the Photo.net forums too about the different options with lots of pictures.

The non-macro adapter was only supplied to those professionals who had a supply of very expensive multiple wide telephotos so that they didn't need to immediately update their expensive lenses. It included a lot of glass, acted like a small teleconverter, and is very rare and expensive now (PIM review). In the past month, only one has shown up on eBay and it didn't sell for the asking price of $740. Needless to say, it isn't practical for a budget photographer like myself.

The good news is that the Hartblei and equivalent adapters are available on eBay for good prices and the quality is quite good as I reviewed. My recommendation is to get one with a removable optical element so you can improve image quality if you aren't concerned about infinity focus. It is also possible to make an adapter yourself, but I don't recommend it because if a homemade adapter breaks it will drop either your lens or your camera on the ground, which won't be desirable. The commercial adapters are cheap enough on eBay that you don't really have an excuse not to go with one of those.

I've set up a search widget below which should show some the current auctions for the EF to FD adapters.

Review: Bower EOS/FD Converter

After my impulse buy of a Sigma 600mm in a Canon FD mount, I had to scramble to get an EOS/EF-FD adapter that would let me put it on my Canon 20D. eBay has a number of adapters to choose from, but I went with a Bower/Hartblei adapter from HartbleiOptic. The same product is sold by a number of sellers online. The seller seems to have a strong Russian/Ukrainian connection (both the e-mail address and the fact another seller was using identical listings (based out of New York with Kiev in the name)). That made me a little nervous (not the Russian thing, the identical listing thing) but their service was great, shipping fast, and I have no complaints. I highly recommend HartbleiOptic as a seller, (edit: HartbleiOptic is no longer an eBay seller (suspicious!) but the Bower converters are still available). An eBay search is below:




Total cost (including shipping) was $36, which was the lowest I could find for the given adapter. From the pictures, there were a number of eBay suppliers with the same item. It was very important to me to get an adapter with a removeable correction lens so that I could improve image quality at the expense of infinity focus. To help you identify the adapter, I included the box in the image below; note the adapter is marked Hartblei and the box is marked Bower. Bower is a well-known low-end Japanese manufacturer of photographic lens accessories. Hartblei is a German company (I think) specializing in medium format tilt-shift lenses and accessories.
For the record, the adapter comes with NO DOCUMENTATION, so I had to figure out everything through trial and error.


Physical Characteristics:

The adapter came inside the box wrapped in plastic with the correction lens installed. The box also includes two caps (the EOS cap is nice, the FD cap is little more than a rubber sheath and quite cheap). I was very surprised at the quality of the machining -- everything seems high precision which is a surprise this day in age. Also, the whole adapter is covered with matte black paint (powder coating?) which seems pretty durable. The lens is obviously coated, although I can't imagine it is the best quality lens given the price.

The adapter itself seems extremely sturdy and is entirely made out of metal. Placing it between the camera and lens I noticed no flex or give at all, with the exception of the outer aperture control ring. The outer ring seemed to flex a little when I squeezed it hard at one point, but didn't get damaged. As long as you aren't super hard on it, I can imagine this item will last a long time. The aperture ring has a nice click to it too.


Operation:

Obviously, the goal of this adapter is to attach on one end to an FD breech lock mount lens and the other end to an EOS camera body with an EF mount (FYI, EOS is the camera system; EF is the mount). In the next post I'll cover why you might want to do this; in this post I'll focus on the review of the converter.

When attached between my Sigma 600mm f/8 Mirror and my 20D, the converter worked admirably -- no slop and very sturdy. As it should be. It doesn't really have many moving parts because it doesn't really need them.
The main moving part is the aperture ring, which, as far as I can tell, is used to manually trigger the aperture lever and switch between the lens's stopped down setting and the fully-open setting. This could be very useful for acquiring focus wide-open, then stopping down at the last minute to shoot. Whether it will be convenient to use remains to be seen, since I am unable to test it (the Sigma 600mm has a fixed aperture). I'm also not wild about the screw being silver (since the screw will be on the lens side there may be internal reflections), but it should be an easy thing to pick up a black screw at a hardware store and replace it. The screw and the ring (marked Lock/Open) are easily seen in the image above.

The other moving part of the adapter is the internal lens element, which unscrews for removal as shown below. Again, since I didn't have instructions, I had to figure this out on my own. Be careful as you remove the lens, because you could slice your fingers on the threads (it is a bit tight from the factory). There are some indentations which may be used to loosen it with a screwdriver, but I don't recommend it because you could scratch the matte finish. Rubber gloves might help protect your fingers and maintain your grip.

Once removed, the adapter acts like a small extension tube, increasing magnification (and bring the focusing distance closer so you can't focus the lens at infinity). Since I don't need infinity focus (for most purposes I've got other, better lenses for that) I'll probably keep it out most of the time. And, as extension tubes go, it should work great, since it has an internal wall to block some of the light.

I'll talk more about performance in the Sigma 600mm review, including a comparison between using the adapter with the lens and without it. I'm very curious how much the lens reduces resolution of images. My hypothesis is that it is significant, but I'd love to be surprised.


Conclusion:

If you decide/need to use older FD lenses, I think this converter is an excellent deal. It has great workmanship, can be used both with or without the correction lens, and has everything I could ask for. I highly recommend it!