Shoreline Birds at 400mm

This post is going to be mostly pictures and not as many words.

The Saturday after my defense (Feb 7th) I took a bike ride out to Shoreline and searched around for some birds to test my new Sigma 400mm f/5.6 APO Telemacro HSM on. I was not dissappointed and found a couple of snowy egrets, a great blue heron, geese, a hawk (not pictured since I only got it in flight at long distance), and a western grebe (I think).

As always, click on a picture to see it larger.

Most of these shots are from a snowy egret that was catching minnows or maybe crayfish in one of the drainage streams. At first I thought the bird was a bit nuts since it kept swishing its feet around and doing a little shuffling dance, then ducking its head into the water and coming up with a leaf.

Later on, I realized that the stream was full of little minnows this time of year and it was just disturbing the leaves at the bottom of the pool to stir up whatever it was eating.

A little further along I ran into a GBH. Sadly, I was a bit constrained on my angle and wasn't able to keep that leaf from behind his head (it was around the corner in the stream and I had to climb out on some sand-bags without startling it). Although, I have to admit I didn't see the leaf until I processed the image, but I don't think I would have been able to move enough to remove the leaf from the shot.

Later on, I ran across the grebe, diving in the bay. He (she?) would dive and disappear for a minute, then pop up in a new location. But he had those electric red eyes that look so cool!


The Sigma 400mm performed quite well. The weight honestly didn't bother me as much as I thought it would (in some spots I used a monopod, but most shots were hand-held). Likewise, since it was a sunny day, I didn't feel like I was banging against the limits of its light gathering ability, and most shots were at ISO 200 with a pretty high shutter speed (1/500s or shorter).

The thing that bugged me most, which is really more due to the camera, was the fact that most images were back focusing. In other words, I'd line up the center focus point on the eye of the bird, but the autofocus would focus slightly behind the bird, putting the bird's head a little out of focus. I've noticed this before on my 20D, but a 400mm lens at f/5.6 really highlights any focusing problems.

The typically thing to do for backfocusing is send the camera and lens in to the factory to be calibrating -- oftening costing $100 or more EACH. Yeah, that's not going to happen with my current photography budget. I honestly suspect my camera because I've detected the problem before. Overall, it is relatively minor (with only a slight bit of softness). As long as I'm aware of it, I can adjust the focus manually using the HSM.

Speaking of the HSM, it is really nice. With proper light, the lens focuses really fast. Definitely on par with my 70-200mm f/4's USM. I'm very glad I was able to get the HSM version and it makes clean-up of focusing problems very easy -- just focus, twitch the wheel a little forward, and shoot.

I do regret the Err 99 problem (forcing me to stay at f/5.6). The lens gives pretty sharp pictures wide open, but I know it'd sharpen up even more (and give me a larger depth of field) if I could stop it down to even f/6.3. Especially for closer subjects, that extra depth of field would be nice.

But, for $250, I'm pretty happy with the thing.

Flashing Hummingbirds

Friday night, as we ate dinner out on the back patio, the hummingbirds were still buzzing around the feeder above our heads. So, in typical Strobist "light-it-if-it-moves" fashion, I though, "I wonder if I can get some light on them with a flash?"

About half an hour later I had the shots on this page.

They aren't perfect. In particular, to keep the background (the sky) from ghosting horribly at the 1/250 sec sync speed I had to crank the flash up and close down the aperture (anywhere from f/8 to f/13). Even with that, there was still decent ghosting.

Also, the hummers were a bit wary of me and my equipment so I couldn't stand up and had to shoot up at them (with the flash in shallow camera right aiming up at them too).

After the first few sequences of shots the birds stayed away from me in general, possibly because every time they tried to eat there was a loud clicking noise and flashing lights!

Also, two of the male Anna's hummingbirds were having a little turf war and everytime one came near the feeder the other would start buzz-bombing runs at it.

I'd like to try it again, but I want to figure out a way to get a better (darker) background, a more pleasing angle, and a closer shot.

I also need to figure out why I had noticeable noise in the blue sky at ISO 100. Maybe the blue filters are more sensitive to noise? Something in the back of my memory tells me there's a connection between our lack of blue sensitivity and a camera's.

At least I got a Microstock shot out of it! (the second one from the top)

The Duck Pond

Obviously, I'm still around.

Today is a bit of a blog-dump of some pics from a trip to the Palo Alto duck pond. Nothing amazing, but if you are interested in bird photography, the duck pond is a great place to practice!





In other news, I'm considering a bit of microstock.

More to come on that.

Less Words, More Pictures

A few more shots from Shoreline last week:

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).

Anna's Hummingbird: What a Difference a Turn Makes!

This is an Anna's Hummingbird (WhatBird page, Wikipedia page):


This is the same bird a few moments later when it turns toward me:


Pretty big change, huh?

I took the shots an hour or two before sunset with my Sigma 600mm f/8. I'm not wild about the shots (mainly because of the distracting background which was way too light) but the reach of the Sigma really helps get shots that I couldn't before. Interestingly enough, both shots are at the same exposure -- the bird's coat really reflects light drastically differently based on the angle. Click to see the images larger.

Random trivia: an Anna's Hummingbird's heart beats at 21 times a second!


As a bonus, here's another decent shot I got out back of a Savannah Sparrow (I believe). Click to see it larger!

Sigma 600mm f/8 Pre-Review

I have a ton of tests, images, and documentation I want to do for the Sigma review, but I wanted to get some early information posted about the Sigma 600mm f/8 mirror lens I won on eBay with an EOS/FD mount adapter because the full review will take me a while.

As usual, all photos in this post can be clicked to see them larger.

First, the obligatory moon picture, shown at the top of the post. The Sigma 600mm with the 20D crop factor produces a 35mm equivalent of approximately 960mm. In reality, it is probably a bit longer than that (maybe 1100mm?) because the adapter works as a small teleconverter. The result is a full frame image shown below -- approximately 20x magnification and the diameter of the moon is half of the vertical frame dimension.

To put it in layman's terms, the thing feels like a friggin' telescope. Any minor hand shake is magnified in a big way, and getting solid shots requires a super-fast shutter speed (1/1000s or faster) or a quality tripod. For this setup, my cheap tripod doesn't cut it very well.

On the flip side, the lens itself handles like a dream. The focus wheel is wonderfully damped and it feels very solid in my hands. Nothing about the lens is cheap, from the rear-filter holder to the barrel markings to the machined metal hood.

Sadly, on my initial inspection I found some small blotches of mold/fungus on the main mirror. I'll talk more about that in another post with some images of it. To be honest, I'm not planning on returning the lens but I may ask for a partial refund. I don't think the damage hurts image quality noticeably but it will definitely hurt resale value of the lens if/when I decide to get rid of it.

Quality-wise, the images are so-so. The raw, 100% crop from above (with exposure compensation as needed) is below. Pretty soft by my standards, but still substantially better than upsizing an image from the Canon 70-200mm F/4 USM.

The moon pictures were taken the first night after the adapter arrived (Saturday night). Today I wanted to get some pictures outside, but as luck would have it, it was one of the rare overcast California days. On an overcast day, you absolutely need a tripod with this lens. My only subjects were some ravens (I believe) but I was able to get a few good images of them. Both these images are essentially uncropped.


Pretty good for shooting to my roof from about 15 yards away. Again, the Sigma 600mm has some extreme reach. Also, note the donut-shaped bokeh in the background of the second image which is a hallmark of all catadioptric lenses. In this case, I actually don't mind it at all.

For the images above I tried removing the glass from the FD to EOS converter and it seemed to help the quality some (not as much as I hoped though). Surprisingly, the lens focuses far enough past infinity that the unglassed converter almost gives me infinity focus. An unedited 100% crop is below.

I will say, even though the 100% sharpness isn't great, I love the quality at 50%; the lens has very few aberrations and the softness is relatively easy to address in post-processing as long as you aren't printing a poster. Ultimately, I think getting a clean shot without vibration will outweigh the image limitations of the lens. Considering I got a passable 600mm lens for about $100, I'm pretty happy. Once I've had some more time with the lens in sunny conditions, I'll be able to say more.

In the meanwhile, let me give you a little teaser about posts I'm planning for the next few weeks:

• Full Sigma 600mm F/8 review with comparisons to Canon 70-200mm F/4 USM.
• Full FD/EOS converter review and discussion (I'm pretty happy with the $35 model I bought).
• A brief guide to buying used lenses on eBay.
• A guide to dealing with fungus on a lens.
• A brief teleconverter guide.
  
• A Canon FD 100mm F/4 Macro review (yeah, just bought one today!).
  

Inexpensive Super Telephotos

Unidentified backyard bird
Canon 70-200mm f/4 USM

You may think that "Inexpensive Super Telephoto" is an oxymoron. And you'd be right, at least if you want good images from it.

If you are seriously interested in birds or sports where you can't get close to the action, you'll need a super telephoto with focal length 400mm or longer. And suddenly, while you have tons of choices at shorter focal lengths, the choices out there get very few and, for the most part, very expensive.

I've already talked about mirror lenses, and my Sigma 600mm F/8 is on its way to me as I write this. I've also ordered the FD-to-EOS converter, so hopefully I'll get some sample images up by the weekend. Hopefully...

This time around, I want to discuss some of my research into inexpensive refractive lenses which give good quality results (i.e. not a $150 70-300mm Phoenix/Tamron/Sigma/generic lens). Granted, those entry level zooms have their place, but the main trade off of the cheap lenses is the long end, so if you are interested in shooting sports or birds outdoors, they aren't going to cut it. My Tamron 70-300mm f/4-5.6, while pretty short at the wide end, got unbearably soft above 200mm. In fact, I'd be better off upsampling from a quality 200mm than using the 300mm range of the Tamron (see full review). While newer or more expensive zooms (especially the Canon 70-300mm f/4-5.6 IS USM, $550 at Amazon) are improved in this range, the long end is usually where performance begins to decay, especially wide open.

Besides, if you need 300mm (which really is a 480mm equivalent for APS sensor dSLRs) you can always use a high quality 200mm zoom, like the Canon 70-200mm f/4L USM (review, $550 at Amazon). For the record, if you want to shoot anything indoors at 300+mm, good luck, you're going to have to just suck it up and spend on fast, heavy glass.


An Example...

Why is it really necessary to go beyond 200mm anyway? Well, let me illustrate with an example from birding.

I shot a sequence of images of the bird in the composite that began this post. It was shot on a Canon 20D with Canon 70-200mm f/4L USM @ 200mm, approx 1/2000sec, ISO 200. I'll explain the boxes and notations in a second.

Pretty decent shot, I didn't nail the focus but was pretty close, as you can see from the 100% crop below (click it to see it at full size, FYI).

The nice thing about the 70-200 L-glass is it really comes close to the theoretical limit of the sensor, especially if you convert from RAW like I did. Every pixel counts. The image could be posted with some minor processing at web-resolution and I'll be proud of it. But beyond web resolution (approx 75 dpi) it falls short, especially if you have have to use an ISO greater than 200 (some of the images were shot with ISO 400 and the noise was distracting and hard to remove). And a smaller bird, like a hummingbird, is very difficult to get (trust me, I've tried).

So, what will longer focal lengths give us? Refer back to the original image and note the green (400mm) and red (600mm) boxes. These are the areas that would be covered by the respective lenses. Crops of those areas, for examples, are below (not full-res though):


Essentially, if I crop from a 200mm, 8 megapixel shot to get the same magnification as a 400mm lens I'm only getting a 2 megapixel image. 2 megpix images are ok for printing as long as they are perfect technically (no problems with blurring, focus, etc). If I crop to a 600mm equivalent, I'm left with less than a megapixel (think cellphone camera). Obviously, if you care about using your images for anything but the web, either now or in the future, 200mm isn't going to cut it for taking pictures of birds smaller than chickens.

The other advantage of longer glass, which you'll know about if you've ever tried to take pictures of birds, is you can use a much longer working distance to get the same shot of a bird.


Let's Talk About Glass...

So, when I began, I took a survey of what refractive lenses are out there in the sub-$1000 range (for new lenses, I relaxed that a bit). You can get some pretty good quality for the price, but you mostly give up your maximum aperture, typically settling for f/5.6. Obviously, I don't own any of these lenses, so my brief comments are gleaned from looking at a ton of reviews online. Since I shoot Canon, this survey is Canon-centric, specifically EOS, although the third party lenses fit a lot of cameras (and are often cheaper than the Canon mounts). Also, I quote Amazon's price for the new lens for comparison, but look around before you make any big purchase. Finally, the LP[X/Y.Y] is the Lensplay rating, click the link to see the page.

Let's start with the fixed focal length primes:

• Canon 400mm f/5.6L USM ($1,080 at Amazon) LP[9/9.4] Top notch lens, expensive, but popular with bird photographers. This is the lens I'd get if I had the cash. None of these lenses have been listed on eBay in the last month -- that's the sign of a good lens. (Luminous-Landscape review comparing it to Canon 100-400mm F/4.5-5.6L)
  

Yeah, that's it. Nobody makes long primes anymore that aren't really fast (and expensive) because the general consumer would rather have a zoom. Which kinds of screws us, the cheap but knowledgeable photographer who'd rather have the better quality of a prime at a cheaper price.

Well, how about the zooms:

• Canon 100-400mm f/4.5-5.6L IS USM ($1,300 from Amazon) LP[8/9.0] Highly respected, includes optical image stabilization, highest price tag of any lenses on this list. I put it on here mostly for completeness. At the long end, wide open, sharpness isn't perfect (according to the Luminous-Landscape review). The Nikon equivalent is the 80-400mm.
  
• Sigma 50-500mm f/4-6.3 EX DG HSM ($920 at Amazon) LP[6/9.0] a.k.a. 'Bigma' since it is a 4 lb (2 kg) monster. The only known lens with a 10x zoom range and a 500mm long end. Well regarded, especially by birders. Includes HSM (like Canon's USM) but has a larger price tag than most of the other zooms.
  
• Sigma 80-400mm f/4.5-5.6 EX OS APO ($1,000 at Amazon) LP[7/8.5] Sigma's direct competitor to the Canon 100-400mm IS, since OS is Sigma's optical stabilization designation. Generally well-reviewed, but whether it is better than the Canon 100-400mm is up for debate (probably not).
  
• Sigma 135-400mm f/4.5-5.6 EX DG APO Aspherical ($525 at Amazon) LP[6/7.7] This seems to be the budget super-zoom in the Sigma line, but I'd generally avoid it in favor of the 170-500mm below. Even thought it is cheaper than most lenses, the 400mm end is supposed to be quite soft.
  
• Sigma 170-500mm f/5-6.3 DG RF APO Aspherical ($710 on Amazon) LP[6/7.7] This lens was actually news to me when I wrote up this post, but Amazon reviews seem to be quite positive (click link above). Photographyreview thread with sample pics and photographyreview lens page. Both those links talk about softness wide open and difficulty with autofocus with the f/6.3 aperture. Generally reviews are pretty mixed with a slant towards positive.
  
• Tamron SP Autofocus 200-500mm f/5-6.3 Di LD IF ($830 on Amazon) LP[7/8.4] The reviews I've been reading say this lens is good, but it is soft on the wide end after 400mm. Bob Atkins has an excellent review with lots of images at photo.net.
  
• Tokina AF 80-400mm f/4.5-5.6 AT-X Pro D ($650 at Amazon) LP[5/6] (may be old version?) Mixed reviews at photographyreview.com, but again, that may be an older version. General consensus is that it is a bit soft on the long end.
  

If you've already got a good quality lens in the <=200mm range and our looking for great quality at the long end, zooms generally aren't the way to go. Most, if not all, zooms give up sharpness at the long end which is usually your biggest concern if you are wanting to shoot birds. Yes, even the Canon 100-400mm. So don't expect perfect sharpness wide open at the long end. Another big factor is image stabilization. I've never used IS/OS so I can't testify if it is worth the increased premium it adds to the lens price. I expect it'd be very useful if you like to handhold your camera at the long end, so it might be something to keep in mind. Currently only the Canon 100-400 and Sigma 80-400 include it. Another thing to note is the sheer number of lenses in Sigma's range. I'm shocked they don't reduce the number of zooms by cutting one or two out (I expect they will soon). The 50-500mm is super heavy but great if you want a crazy long zoom. The image quality is supposed to be quite good and the price reflects that. My personal opinion would be either the Sigma 50-500mm, Sigma 170-500mm or Tamron 200-500mm if you are interested in birding. The extra length allows you to compensate for the decreased performance at the long end. Ultimately, I'm not planning on buying a new zoom, so I haven't done a detailed comparison of these three lenses. Expect to spend a decent chunk of change no matter what zoom you choose, and for the price, do whatever you can to try out the lenses before purchasing. Being the cheap guy I am, I think the used market has some better deals...

The Used Market

• Tamron AF 200-400mm f/5.6 LD IF LP[6/7.7] [eBay prices from $200 to $300] I had a real hard time finding reviews on this lens on the web. It has been replaced by the Tammy 200-500mm. I'd generally steer clear of this lens since reviews point to it being soft at 400mm wide open. The good news is there are plenty floating around on the used market for all camera mounts.
  
• Photo.net thread mentioning it is a bit soft on the long end and recommending the Sigma 400mm instead.
  
• Momentcorp.com review which actually includes example 100% crops. You can definitely see the softness on the long end, so if you are interested in bird or sports photography, the soft long end will probably bother you a lot.
  
• Tokina 400mm f/5.6 AT-X SD LP[not posted] [eBay prices from $200 to $300] This is an older lens, and seems to lack some of the special coatings/lens materials of the newer lenses, which causes more CA. I'd be happy to own it though. Update 12/31/08: An eBay seller reported that they do not suffer from the Error 99 problem. That one sold for $250 including shipping.
  
• Dyxum page w/ four review links
• Sigma 400mm f/5.6 APO HSM LP[7/8.3] [eBay prices from $350 to $500] This is my top choice for a used lens, if I had the money. All reviews are very positive and there are a decent number out on the used market. Update 1/2/09: Turns out there's four versions of this lens out there (details) -- non-APO (not recommended, maybe $150 used?), APO but non-HSM (smaller focus wheel, ~$200-$250 used), APO telemacro, but no HSM ($250-$300 used, monster focus wheel, filter size 72mm), and HSM (filter size 77mm). The HSM is the newest and the best, but the APO telemacro is pretty good too. All suffer from the Sigma Err99 problem on 10D?, 20D+, 5D+ Canon cameras though, so assume that you won't be able to use apertures other that wide open reliably unless the lens has been rechipped. FYI, Sigma no longer rechips these lenses.
  
• Dyxum page w/ three review links
• Photozone Review
• Nice review with some great bird pics.

For me, it ultimately comes down to choosing between the Sigma and Tokina because I'd prefer the increased sharpness of a prime. A direct comparison of the two can be found at this Dyxum page comparing the Sigma and Tokina 400mms. Even though the sample images seem to show the Tokina as a bit sharper, the author prefers the Sigma for real-life use. The Sigma definitely has more chromatic aberration than the Tokina.

Especially notable is the difference in price -- if you can get a Tokina 400mm for $200, that's a great deal and worth purchasing, even if it isn't quite as good as the Sigma. So, if you are patient, the best budget birding lens is probably the Tokina 400mm. Overall, you can cut the cost in half or less if you are willing to go with a used prime vs a new zoom.

Hopefully this compilation of cheap super telephoto options will be helpful to you. I know I'll be able to use it as a resource once I can finally scrape together enough cash for a good birding lens.

Oh, and my Sigma arrived yesterday, although I'm still waiting on the converter to mount it to my 20D. More details to come.


Random References:

• Sigmaphotography.org: Bird photography equipment Good overview of birding lens options.
• TeraPeak.com Great way to look up eBay prices for the last month to figure out what the going rate of lenses is.
  

Search on eBay:

For convenience, here's an eBay gadget listing the current sales of 400mm budget f/5.6 lenses. Always double-check the listing to make sure they aren't the FD versions (there's a bunch floating around). I was careful with the search terms, so there should be only a few good matches listed at any one time.