Cracking Open the 7D II

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OK, I have to admit I really like the 7D Mark II. I didn't want to because it wasn't what I wanted. I wanted to see the new Canon chip foundry that would be cranking out high-resolution sensors. But despite wanting to hate the 22-megapixel APS-C camera, after a fairly short exposure to the autofocus system, I have to admit I like it. There's just something about getting every shot in focus every time that's appealing to me.

However, when I read that Canon claimed the 7D II has "4 times better weather sealing than the original 7D" I went mildly nuts. Most of you know I hate marketing drivel. HATE IT. Most of you know I'm generally not impressed with weather sealing claims. Unless something has changed in the last 30 seconds, weather sealing still means, "the warranty doesn't cover water damage."

So when I read the claim "4 times more weather sealing" my inner cynic just thought 4 times zero equals zero. But I wanted to be fair so I decided I'd open up the 7D II before I wrote a scathing article about making ridiculous weather sealing claims. Which results in me once again writing an article where I have to admit my assumptions were wrong less correct than I would have liked. (Sorry, I forgot for a moment this was the internet where no one ever says "I was wrong.")


The 7D and 7D Mk II looking awfully similar in front view.


For those who want to take my word for it and skip on to some other blog, the Canon 7D Mk II may be the best weather-sealed camera I've run across. It's excellent. For those who would rather see for themselves, gory camera dissection pictures follow!!

I'll add, because someone always wants to comment about the poor quality of my dissection photos, that you're welcome to try shooting with one hand while taking two cameras apart with the other hand under 4 tungsten hot-lights, making sure you have the camera back together by the end of your lunch break. We don't do high-quality product photos back in the repair department. But better this way than if we let the product photo people try to take the cameras apart.

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About That 25-300mm f/2.8 You Wanted

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I get an email or text about once a month asking me if I think Canon, Nikon, or some other photo manufacturer will ever make something like a 24-300mm f/2.8 zoom lens. I'm usually gentle with those people, because I realize that a lot of people truly believe that if they want something badly enough, someone could make it for them. Occasionally, someone exhibits the Dunning-Kruger Effect and tells me that they know it's a plot on the part of the manufacturers to make us buy multiple lenses instead of just one that could do everything.

I had another one of those emails a few days ago, so I thought it might be interesting to show everyone what a 25-300mm f/2.8 would (approximately) look like. We don't actually have a photo lens of that specification, but our video friends do: The Fujinon 25-300mm T3.5. (For those who don't know, f is a calculated value, T is actual light transmission. Most f/2.8 lenses are T3.5 to T3.8.)

The Fujinon is a PL mount lens, so I'm afraid you won't be able to adapt it to your 5DIII or D810. If you really want to, though, you could buy a PL modified Canon 7D camera and use this as your walk-around lens.

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Quick Zeiss 85mm Otus MTF Charts

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Well, we finally got a few copies of Zeiss' newest Big Ass Lens, the 85mm f/1.4 Otus in Friday afternoon. I didn't have time to do a whole lot with them other than take a few shots, and run them through the optical bench for MTF testing, so this will be a short post. (Assuming I get a little more time with them Monday before they ship out, I'll add field curvature graphs as an addendum to this post.)

The summary is short and sweet: the Otus is every bit as good as it's supposed to be, and the best 85mm f/1.4 lens we've tested. At $4,600 and 2.5 pounds of manual focus lens, we sort of expected it to be the best 85mm f/1.4 we'd ever tested. But still, life does like to chew up some tasty expectations and leave a pile of disappointment in the front yard sometimes. So it was nice to see the Otus 85 was as good as advertised.


MTF curves for 5 copies of the Zeiss 85mm Otus compared to the standard ZE 85mm f/1.4


I put the original ZE 85mm f/1.4 MTF charts up for comparison, since it's a nice middle-of-the-road 85mm f/1.4. You can make some more comparisons from our last article on 85mm lenses in general. And yes, I'm looking forward to seeing how the Sigma 85mm f/1.4 Art stacks up against the new Otus.

The quick summary is this is an amazing performance. Notice that the Otus at 50 line pairs / mm (orange lines) is about as good as the original ZE 85 is at 30 line pairs / mm. That really is amazing. But the performance difference is there at every frequency and at every spot across the lens field. If you want the sharpest 85mm money can buy, well, you have to buy the most expensive 85mm money can pay for.

We also checked variance on these copies. Again, I'll use the ZE version for comparison since it's a lens with very good variance numbers. As one would expect for this price, the Otus is even better than the ZE 85mm, meaning the difference between best and worst corner on the average Otus 85mm is quite small -- too small to detect in a photograph or even with some pixel-peeping.

I'd love to have some profound conclusion here. But like the 55mm Otus, what we expected is exactly what we got: a very expensive, very large lens that is the best lens available optically in this focal length.

Addenedum: Field Curvature

The Otus field curvatures are really remarkable, both tangential and sagittal are nearly perfectly flat. Below are the field curvature graphs wide-open at 30 line pairs / mm. The flattest we've seen so far on any lens.

Roger Cicala


October, 2014

Introducing LensRentals Keeper

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Saying goodbye can be the hardest part of any rental. With our new Keeper program, you can try it, then buy it!

Just rent an eligible item, and then we'll give you a starting purchase price based on the age of the copy we send you. We'll even give you a credit for a portion of the rental fees. Even better, you can handle the entire transaction with just a few clicks on our website (although we'd be more than happy to handle it over the phone if you are just dying to talk to one of our friendly customer service agents). Continue reading

Just the Lenses: Canon and Nikon Mount 85mm f/1.4 (and 1.2) Primes

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We'll continue our Just the Lenses posts with the 85mm wide-aperture prime lenses. We'll get through all of the wide aperture primes eventually, for those of you who like this series. If you haven't read the previous posts, then you might want to go back and skim the introduction of the previous one to see the reasons we're doing this.

Today's Contestants

We tested seven copies each of the Canon 85mm f/1.2 L Mk II, Nikon 85mm f/1.4 AF-S GZeiss 85mm f/1.4Sigma 85mm EX DG HSM f/1.4 lenses on our Trioptics Imagemaster optical bench. All copies had been through our routine optical and Imatest screening and passed with flying colors. Continue reading

Field Curvature and Stopping Down

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Ignorance more frequently begets confidence than does knowledge. Charles Darwin

What I know that I don't know doesn't cause me much trouble. I don't know the formulas for 7th order optical aberrations for example. I don't know enough math to calculate those formulas even if I did memorize them. But I've got shelves of books on optics and friends who know way more optical theory than I do. So if I need to find out something about 7th order aberrations (mercifully, to date that hasn't been necessary) I can go find out about them.

What I don't know that I don't know causes me all kinds of trouble. I had yet another learning experience last month relating to field curvature (more accurately, the plane of focus curvature). Like everyone else I knew that when I stopped the aperture down on a lens the image got sharper and the depth of field got larger. I knew that the center might sharpen up more than the corners, at least at first. But I assumed that if the corners were getting sharper, and the center was getting sharper, than everything in between was getting sharper, too. It turns out that isn't always the case.

I'd also never really thought about what happens to field curvature when you stop down.  If I thought about it at all, I probably assumed it would flatten out. Or maybe stay the same but the increasing depth of field would make it less noticeable. Turns out that isn't always the case either. So, because I made assumptions and didn't know what I didn't know, I wasted a lot of time. Weeks of time. Continue reading

The Itsy Bitsy Spider

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We spend a lot of time here at Lensrentals getting dust out of lenses. Dust doesn't affect an image, except in very rare circumstances, but people want their rental lenses to look nice and clean inside and out, and our inspectors check the inside of every lens with spotlights and send any dusty ones over to the repair department.

Yesterday one of the inspectors sent over a Canon 135mm f/2 L lens with a fairly unique note: "Contains a large dust chunk and the internal elements are scratched." Now, we see a lot of scratched elements, but that really is pretty limited to the front and rear ones. Scratching internal elements is, well, unusual. When we took a look inside the lens, though, we were pretty impressed. There was indeed a big chunk deep in the center of the lens, and what at first glance appeared to be multiple scratches on the internal elements. Continue reading

Just the Lenses: Canon and Nikon Mount 35mm f/1.4s

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As I discussed in the last post, it's impossible to accurately compare lenses from different mounts using any form of computerized target analysis testing (methods like DxO or Imatest). Target analysis tests an entire system (camera and lens). That's a very practical thing, of course, but it has some limitations.

Directly comparing the lenses on an optical bench without any camera involved is interesting for several reasons. The most important is that the optical bench gives some information about a lens that is difficult or impossible to get using Target Analysis methods.  Field curvature is a good example of information that is easy to get on an optical bench, but nearly impossible to obtain with Target Analysis. Plus, optical bench testing shows performance at infinity, rather than the closer focusing distances used for target analysis. Continue reading

Just The Lenses: Canon vs Nikon Zooms at 70mm

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It's impossible to accurately compare lenses from different mounts using any form of Computerized Target Analysis testing (methods like DxO or Imatest). Target analysis tests an entire system (camera and lens). People try to, of course, but it's not accurate since you always have the added variables of camera sensor, microlenses, in-camera image processing, etc. Some people try to use adapters to test different lenses on the same camera, but then you have added variables from the adapter and sometimes from sensor stack thickness.

In general, it doesn't really matter. If you shoot Nikon you aren't really interested in Canon lenses, and vice-versa. Still, directly comparing the lenses without any camera involved is interesting to some people, I think. Some people are thinking of changing brands - they know the other brand's camera has higher resolution, but aren't sure if the other brand's lenses are as good. More people than ever are shooting lenses across brands using adapters, and they're sometimes curious, too.

It is, of course, possible that nobody but me is interested in direct cross-brand lens comparisons. But since I am interested and since I have to test all of the lenses in our inventory anyway, I thought I'd show some of that data. If others find it interesting, too, I'll write up some more comparisons like this. Continue reading

Some M-Mount Field Curvatures

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I haven't posted very much lately. We've had some new equipment installed and we've been doing a LOT of testing as we develop our new database of lenses on the optical bench. As the database fills out I'll be posting more than ever, just because a lot of this stuff is just fun. Today's post is largely for fun, but will have some additional interest for those who shoot Leica or shoot M-mount lenses adapted to other cameras.

One thing that optical bench testing gives us that is hard to find elsewhere is a clear map of field curvature. We had a client interested in determining field curvatures for a several M-mount lenses and thought there would be a few among you who also wanted to see them. Continue reading