Monday, March 16, 2009

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.

Friday, March 13, 2009

Anatomy of a Photo: Haptic Device

I have a spare half-hour to post so I'll go ahead and get this up, finally. The images have been ready for quite a while, but I just haven't pulled the trigger on writing the text up.

Of course, it has been a long time since I wrote an Anatomy of a Photo post. Sadly, I have no set-up shots, didn't make a note of settings, and took the shots a month ago. I'll do my best though!

* * * * *

Word has gotten out around the lab that I dabble in photography, so a number of guys have asked me to take shots of various robots and robot related apparatuses. So far, I've done at least four different shoots, not including my own robot. I have to admit, I enjoy product/technical photography -- it is fun to have a subject that doesn't wiggle, complain, need breaks, and looks cool!

While I don't consider myself a professional product photographer, I feel like I am doing a pretty good job on these shots. In fact, one of my dissertation readers commented: "Your object photos are amazing - did you hire a photographer?" Too bad it is so hard to make money in product photography in this economy!

Anyway, in this case, a guy from the lab asked if I could shoot his haptic device. I liked the way the shoot turned out (the image at the top was used in one of his presentations) so I asked him if he minded if I posted about it here. He didn't, so here we go...

* * * * *

The primary goal was to get some shots that he could use for papers and presentations, highlight the use of his haptic device, and get a few detail shots. Actually, he didn't tell me those needs outright, but whenever I do research/product shots, I always try to get a cool 'overall' view, a cool 'in use' view, and then 'detail' views based on specific contributions.

In particular, I always ask: "What is the most novel thing about this robot?" In this case, his cable transmission was notable, so I made sure to get a shot of it. Actually, the transmission shot was my favorite of the shoot -- see it at the end of this post. And, as always, click to see any of the photos larger.

* * * * *

The shoot itself occurred in a nearby conference room and was rather painless. The conference room has large brown tables that tend to look nice with a black background, so I set the robot on a table and set up some lights. Before engaging flash though, I shot a few with available light (window) for safety. Overall, I found the available light shots unremarkable so I didn't post any here.

At the start, I was undecided if I wanted a light or dark background. Often, in research papers or on the web, a white or gray background flows better (and doesn't kill printer ink). So I shot the device on a large piece of white seamless to start, as above.

The only lighting in this case is a Sunpak 383 into an umbrella at camera left. I had a large piece of foam core as fill on the other side, if I remember correctly.

After shooting a few frames and chimping, I decided the white background was not letting the device 'pop' like it should. I usually don't like white with silvery products because there is not a lot of separation between the silver and the white. So I removed the seamless and shot on the bare table:

While I liked this a little better in terms of contrast, the edges of the motors were getting lost in the background. So I decided to use a hard light from behind the object to highlight edges (again, this is the cross-lighting trick I always tend to go back to). That necessitated a swap from the umbrella to a large white wall at camera right (moving the table to get the right angle). I also added an SB-20 in deep camera left, slightly below the level of the table, to get a backlight without too much specular on the table.

Overall, I like this shot a lot better. Note how the back light evens out the table and provides a nice outline on the edges of the motors. The table itself was brought up quite a bit by the change in lighting. In particular, the key is now farther away but much larger, resulting in less drop-off.

Once I got the shot locked in, I took a series of shots in this position, moving the robot to get the specular highlights where I wanted them. In these cases, I don't mind if small portions blow out, but I want to avoid a large area (like a pulley face) completely blowing out. I also brought in a hand model when it was too hard for me to hold the device and shoot at the right angle. I could have used a tripod, but it is always easier with an extra hand! The end result was the image that opened the post.

* * * * *

One thing I've been trying to work on lately is more variation in my shots, especially for product-style photography like this. I'll do a full shoot, then realize during processing that almost all of my shots are from the same point of view. Only after the fact will I think of other unique angles or lighting setups.

So after I got a number of safe (but quality) shots, I started to experiment a little bit. The first change was to rotate the device the opposite way, using the same setup:

With the pulleys facing the key light I also took the opportunity to get some detail shots, like the shot below:

I should also mention, in terms of detail shots, you can often get away with some aggressive cropping of overall shots for web display or within a paper or thesis. It is still nice to break out the macro lens to do a few on purpose in high-res, but if you forget, you can often derive them from your main shots.

I tried a few other views and angles, but the shot above really is my favorite from the whole shoot. No specific reason, I just like the close, technical feel of it. Overall I felt the haptic device was very photogenic, primarily because the red base really provides some pop against a dark background. A little bit of color can go a long way, even for a research paper!

Sunday, March 8, 2009


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!).