For those of you who haven't read our 'Just the Lenses' posts before, these take advantage of our Trioptics Imagemaster optical bench to compare lenses from different camera mounts with no camera involved. Why is that different? Because all other forms of testing (DxO, Imatest, or even photography) tests the camera-lens combination. Sensor architecture, micro lenses, in-camera image processing and other things affect those results. A third-party lens on a Canon 5DIII will have different results than the same lens on a Nikon D800 for example.
Our Trioptics Imagemaster MTF Station
Since we're into optics, we like testing just the lenses themselves, eliminating all of those other variables.
The 200mm focal length is one that people use frequently, whether for action photography, long portraiture, or as a short telephoto lens. There are a lot of different ways to get there, too. Most people use a 70-200 zoom lens. A few use a 200mm prime. And if you shoot Canon or Nikon, at least, there are both name brand and third-party options to consider at that focal length. So testing all of the lenses that can shoot at f/2.8 and 200mm for those mounts seemed like a fun idea.
Meet the Contestants
We stock a lot of lenses that can shoot at 200mm and f/2.8 aperture for Canon and Nikon mount cameras:
We tested each of these lenses at f/2.8, 200mm at infinity focus distance (another advantage of the MTF bench is that it tests at infinity, not at 20 feet or so). For each lens we tested 5 copies, and each copy was tested in 4 quadrants. The MTF results were averaged (we ended up with 20 readings for each lens). All lenses were checked for proper centering on OLAF, our 5-micron pinhole collimator prior to being tested.
Checking lens centering on OLAF. Optical adjustment mallet shown on right.
So What Did It Show?
Let's start with the best of the best, the MTF curves of the 200mm f/2.0 lenses tested at f/2.8.
These are both awesomely superb lenses and looking for differences between them is really just hair splitting. The Canon has a bit better resolution in the center, especially at higher frequencies. The Nikon has less astigmatism off axis. Because of the astigmatism difference the Canon has better sagittal resolution in the corners, the Nikon better tangential resolution. But both are just awesomely good.
Next, we'll go to the best of the rest, the 70-200 f/2.8 IS II and 70-200 f/2.8 VR II at 200mm and f/2.8.
Notice I'm not exactly letting the suspense build up here, am I?
Again, the minor differences are just hair splitting. The Nikon has a tiny bit better high frequency resolution in the center, the Canon is just a tiny bit better in the edges and corners. Not that you could tell any of this in a photograph, the differences are really small. These are widely considered two of the best zoom lenses made and the MTF graphs back that impression up.
Speaking of the best zooms ever made, let's flip the graphs around and (assuming you were going to shoot them at f/2.8) look at how well the MTF curves of the zooms compare with the equally legendary f/2.0 primes. Although let me be clear, there's a lot more to the differences in the prime and zoom lenses than just MTF.
Well, my comments are just stating the obvious. There's a reason people wax poetic about their 200mm f/2.0 lenses. They are spectacular. But the zooms are damn good.
Here's an example of how good, we'll compare the Canon 70-200 f/28 IS II with what was once one of my favorite lenses, the Canon 200mm f/2.8 prime. The MTF graphs will show you why it isn't my favorite anymore; the newer zoom designs are just better than this older prime lens. It's still a good lens, but clearly not as good as the Canon zoom. (Although it may still be a better value, you can get the f/2.8 prime pretty cheap. Not to mention that it's very small and stealthy for a 200mm lens.)
A similar comparison is the Canon IS II with the much less expensive, and still very good Canon 70-200 f/2.8 NON IS lens.
Scroll up and down and you can understand why I liked the 200mm f/2.8 rather than the non IS zoom back when the Non IS zoom was state-of-the-art. But neither can compete with the IS II zoom from a resolution standpoint.
OK, So What About Those Third-Party Zooms?
Glad you asked. Let's compare the Sigma 70-200 f/2.8 OS to the Tamron 70-200 f/2.8 VC first.
This supports what many of you already know; these are both pretty good lenses. Of the two, the Sigma is a bit better tested on the optical bench. This may not agree with what you've heard, but remember this is a pure test of the optics of the lenses. How well the lens autofocuses, the effects of the camera's micro lenses and image processing, and some other factors are also going to influence performance quite a bit. Think of the optical test as 'how good the lens could possibly be', but realize a host of real-world factors are going to also influence 'how good the lens was on this shot'.
Just for comparison sake, let's look at how the Sigma fares against some of the other lenses we've looked at. (Sure, you can scroll back and forth, but this should make things easier.) First we'll compare the Sigma with the Canon 70-200 f/2.8 IS II; and the Canon is so close to the Nikon 70-200 f/2.8 VR II that you can pretty much extrapolate.
OK, the Sigma isn't quite as good, but it's still really good and a whole lot cheaper. Maybe a better comparison is to the Canon 70-200 f/2.8 NON IS.
I think those two graphs sum it up nicely. The third party lenses aren't as good as the newest Nikon and Canon zooms, but they probably are a bit better than the older models.
A Bit of Overview
A lot of people use their 70-200mm lenses largely at 200mm, so resolution at that focal length is a big factor. But there's a lot more to choosing the proper lens for the task than resolution at 200mm, of course. In reality things like fast and accurate autofocus, especially for sports shooters, is probably more important than absolute resolution.
The cost of 200mm lenses varies greatly and is certainly a big factor when people decide which lens they want. The Canon and Nikon 200mm f/2.0 lenses are nearly $6,000, while their image stabilized 70-200mm f/2.8 zooms are over $2,000. The Canon 70-200 f/2.8 NON IS is about $1,500, as is the Tamron zoom. The Sigma 70-200 is about $1,200 and the Canon L prime is the bargain of the bunch at about $800.
If one just considers price and resolution then the third party lenses, which are also image stabilized, certainly offer some advantages over the Canon NON IS lens. The Sigma price is more attractive than the Tamron and the Sigma arguably is a sharper lens in the lab. (Again, I emphasize that rapid and accurate autofocus may be more important than absolute resolution at 200mm.)
My opinion, though, is that the extra cost involved in getting the brand-name zoom lens in this category is probably worth it if you can possibly manage it. The Canon and Nikon f2.8 stabilized zooms are amazing optics. The f/2.0 primes, while wonderful lenses and even better optically than the zooms, are priced like the specialty items they are. The third-party lenses and Canon Non IS are cheaper, and probably good enough for many uses. But don't kid yourself; they aren't as good.
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Sometimes I put up posts basically because I find myself answering the same email over-and-over. One of the emails I get a lot is: "I want the best copy of the xxxx zoom lens."
People get irritated because my response is usually something like this: Which focal length do you want the best copy at? The long end, short end, or in the middle? By best copy do you want the highest center MTF, the best corners and edges, or is the middle of the image the most important to you? Or do you want the one with the flattest field? And again, at which focal length do you want whatever is the most important thing to you to be the best at?
Generally, people miss my sarcasm and just respond that they want the best overall lens. I could probably satisfy that request for a prime lens (it would be splitting hair, but it could be done). But there's no way to do it with a zoom; there are just too many variables, and the variables interrelate and counteract each other in complex ways.
So today I thought I'd just put up some pictures and demonstrate how one single variable, field tilt, changes on a given lens at different zoom distances. We chose Canon 70-200 f/2.8 IS II lenses because they are excellent. So you fanboys that want to take this out of context and say Canon 70-200 f/2.8 IS II lenses have tilt variation, trust me, it's less than the zoom you are a fan off. Every zoom lens made is like this.
Field Curvature Examples
All of these lenses had been tested just prior to running these field curvatures both with test-chart photographs and on our MTF optical bench. All of them were optically at least average, if not slightly better than average by my standards, which are quite a bit higher than what the factory standards are (we reject about 5% of lenses that factory service tells us are fine).
The first lens I'll show you was the weakest of the 12 we tested (although I'll mention again, it was still an "average" copy). It looked fine on all of our usual optical tests, but on the optical bench the MTF chart had some detectible astigmatism at 200mm. The field curvatures at 70mm, 120mm, and 200mm zoom lengths show why. There's a bit of field tilt at the wider focal lengths (about normal for most zooms) but at 200mm the tilt becomes more dramatic and the tangential field is much more tilted than the sagittal field.
About a year ago, Andrew from SLR Magic came and spent a couple of days in our lab, testing some of the SLR Magic lenses and getting input on improving the optical adjustments on their lenses. At the time Andrew made it clear their company wanted to up their quality and compete with the better lenses on the market. He contacted me a couple of weeks ago to let me know he was sending a copy of their new 50mm APO T2.1 Cine lens for optical bench testing.
During our conversation it became very obvious that Andrew was very comfortable this new lens was going to test very well. You know me, there's nothing I like better than using our optical testing equipment to crush the comfort right out of a manufacturer, so I was pretty eager to take a look at this lens.
While this isn't a review, I will say the SLR Magic lens was mechanically well made with smooth, steady resistance focusing and aperture rings and had a nice compact size. As an apochromatic lens, one of its major advantages is that longitudinal chromatic aberrations are neutralized, so out-of-focus highlights in both the foreground and background remain color-neutral. But this lens is also designed to be high resolution, capable of shooting excellent 6K images, so some MTF testing seemed in order.
Optical Bench Results
We will compare the SLR Magic 50mm T2.1 with a couple of similar lenses: the Zeiss 50mm T2.1 and the Leica 50mm f/2 APO Summicron-M. While I don't know what the final pricing on the SLR Magic 50mm will be, I assume it be similar to the Zeiss CP.2 (about $4,000) and certainly less than the Leica (over $8,000). Let me note that we tested a single copy of the lens, so I can't make any comments on sample variation.
As you can see in the MTF comparison below, the SLR Magic lens definitely is holding its own with the Zeiss 50mm. In the center of the image they are nearly identical at lower frequencies, while the SLR Magic lens is actually a bit better at higher frequencies. The Zeiss holds it's higher frequencies a bit better in the middle 1/3 of the image. The SLR Magic is superior in the absolute edges. (Remember, the 20mm distance from center we show would be at the very edge of 35mm full-frame edge image. If you are shooting a smaller sensor the outer areas of these MTF charts don't matter to you.)
The 50mm Leica Summicron-M f/2.0 is arguably the best 50mm lens we've tested, particularly at higher frequencies. When we compared the SLR Magic to the Leica, the results shocked me a little - not that the Leica was better, but that the SLR Magic lens was actually fairly close to it, except at the higher 40- and 50- line pair/mm frequencies. That's an outstanding performance.
As long as we had it on the machine, we did field curvature maps of the SLR Magic 50mm, too. They were very nice, with tangential and sagittal fields very similar, as you would expect from the MTF curves. The field curvature demonstrates that this lens is designed to give a nice flat field from edge-to-edge with just a tiny bit of 'mustache' curvature. This particular copy had just a very slight amount of tilt in the field (0.01 degree), which is excellent -- we don't think anyone could notice less than 1 degree in an image.
A Bit of Summary
This is not a lens review but since we are able to do these tests and most reviewers can't I thought them worth putting up. When we met with SLR Magic way back our primary input was on methods to minimize copy-to-copy variation. Testing one copy doesn't give us any insight into the progress they've made there (although I completely agree with the steps they've taken and am optimistic). However, the perfectly flat field with no tilt in this sample gives some evidence that things are looking good. With many lenses almost every single copy has some tilt.
Until final pricing is established there's no way for me to say if this lens is a bargain or not. But assuming the price is reasonable, it certainly provides excellent image quality from an MTF standpoint. Some early reviews indicate the goals of the APO lens in removing color aberrations have also been met. It looks to me like SLR Magic has upped their game quite significantly here.
The new Canon 11-24mm f/4 is their widest ever beast of a zoom. Roger has tested it and said it's as sharp as we had hoped, but I wanted to know how it looked in a real world comparison with the other beautifully bulbous ultra wide, the Nikon 14-24mm f/2.8.
Canon 11-24mm on a 5DmkIII & Nikon 14-24mm on a D750
I'll be honest. I'm pretty excited about the Canon 11-24mm f/4 L lens. I love shooting ultra-wide and the chance to shoot this wide with a rectilinear lens on a full-frame camera has me pretty excited. But I'm also very aware of how near-impossibly difficult designing a lens this wide would be, so my expectations were tempered a bit. There's a reason I'll often stitch together a couple of 24mm shots for a landscape rather than take one 16mm shot. Okay, there are several reasons, but image quality is high among them.
So I couldn't wait to get the new lens on the optical bench to see if it was even close to acceptable at the wide end. But there is a bit of a problem there. We've never had the opportunity to test anything at 11mm focal length before. So what do we compare it to? I decided we'd compare the 11-24 to itself. We'd get an idea of how well it did at the long end compared to other 24mm options, and then compare those results to the wide end. The wide end can't possibly be as good as the long end, of course, but we can see how close it is.
This is not a detailed lens review, of course, just a nice quick assessment of resolution with the new lens.
This Sucker is Heavy, BTW
Looking at a comparison of the wide f/4 zooms most of us are familiar with, the new Canon 11-24mm is a little shorter and wider than the Canon and Nikon 16-35 f/4 lenses.
Left to right: Nikon 16-35 f/4, Canon 11-24 f/4, Canon 16-35 f/4 Roger Cicala, Lensrentals.com, 2015
The new Canon lens actually most resembles the Nikon 14-24 f/2.8 lens, not just in size and shape but also in the very protruding front element.
Nikon 14-24 f/2.8 (left) and Canon 11-24 f/4. Roger Cicala, Lensrentals.com, 2015
What the pictures don't show is the weight. The new Canon weighs in at 2.6 pounds, which is twice the weight of the 16-35 f/4 IS lens, and half a pound heavier than the Nikon 14-24 f/2.8.
Our Just the Lenses posts are optical tests where we compare various lenses on the optical bench. Unlike DxO or Imatest test results, no cameras are involved, eliminating one of the major variables. It's particularly useful when we're looking at third-party lenses that can be used on various cameras. It's hard to extrapolate the results of a test made using a third-party lens on a Canon 5D Mk III when you are trying to determine how it might compare to one shot on a Nikon D800, for example. Testing on the optical bench gives a direct comparison between lenses without any other variables.
You know Aaron and I love doing teardowns of almost anything. The two types we look forward to most, though, are Sony cameras and Canon lenses, because those tend to be on the cutting edge of engineering elegance. For a couple of weeks now, we've been wanting to sink our screwdrivers into the new Canon 100-400 IS Mk II lens, and yesterday we finally got a few free hours to do it.
For those two or three of you who don't like a little lens strip-tease I'll give you the quick summary: the build quality on this thing is amazing. I usually laugh when people describe a lens as "built like a tank" because what I know is the lens they are describing has a thick, heavy outer metal shell filled with tiny delicate pieces that break and wear out with great frequency. But this lens is built like a tank inside and out. Continue reading →
When I posted our Imatest results from the single copy of the Nikon 300 f/4E PF ED VR that we had received, I pointed out that the copy was slightly decentered and therefore the results were questionable. We got a second copy of the lens in today, and this one was perfectly centered.
I had planned on waiting until we had a half-dozen samples tested before writing anything else, but apparently I stirred up such a hornet's nest with the first results that I thought I'd go ahead and post the results of this well-centered copy. Especially since it looks like it will be several weeks before we actually have six copies in stock to run a series.
My guess when testing the previous copy was that a well-centered copy might or might not be better at peak resolution, and probably would be better in the corners. Turns out, for those who want the short version, my guess was pretty much correct. Continue reading →
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