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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 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.

Direct lens comparison is occasionally of benefit for other reasons. 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 (or vice-versa). More people than ever are shooting lenses across brands using adapters, and they’re curious about pure lens performance, too.

Optical bench comparisons are useful for those considering third-party lenses, too. People sometimes read a review of a third-party lens shot on Camera A and then are surprised it behaves differently on Camera B.

The 35mm f/1.4 prime lenses in Canon and Nikon mount make a good optical bench comparison. Canon and Nikon each have their own 35mm f/1.4, but photographers using either brand have several other excellent options including the Zeiss 35mm f/1.4, the Sigma 35mm f/1.4 Art, and the Samyang 35mm f/1.4 (AKA Rokinon and Bower).

Today’s Contestants

We tested 7 copies each of the Canon 35mm f/1.4 L, Nikon 35mm f/1.4 G, Zeiss 35mm f/1.4, Sigma 35mm f/1.4 Art, and Rokinon 35mm f1.4 lenses on our Trioptics Imagemaster optical bench. All copies had been through our routine optical and Imatest screening and passed with flying colors.

From multiple past tests in our Imatest lab, we expected the Sigma 35mm f/1.4 would have the highest resolution, with the Zeiss and Canon versions just a little behind. We weren’t quite as sure what to expect from the Nikon and Rokinon 35mm lenses, although we expected them to also be quite good.

MTF Charts

It’s easy to look at Imatest or DxO numbers and say, “A has an MTF50 of 875 and B is 820, so A is better.” MTF charts give you a lot more information. That generally makes the summary a little more complex, which some people hate. But it also makes the summary a lot more useful.

If you don’t speak MTF, don’t worry. It’s not hard. Higher on the vertical axis is better. Dotted and solid lines of the same color close together are better (far apart is astigmatism). The horizontal axis goes from the center of the lens at “0″ to the edge of the lens at “20″. Lower lp/mm have association with strong contrast, while higher lp/mm are associated with ability to resolve fine detail.

 

Legend for all the MTF graphs

 

 

In general, the MTF graphs of the lenses on the optical bench agree with what we already assumed, although the differences are perhaps a bit greater than our standard MTF50 results suggested. The Sigma 35mm f/1.4 is clearly the sharpest lens of this group. Look carefully at the 20 lp/mm graph (red lines), for example. The Sigma stays above MTF 0.7 all the way to 12mm from the center of the image. The Canon and Zeiss lenses are competitive, although not quite as good away from the center. The Nikon and Rokinon lenses never get to 0.7 MTF on their 20 lp/mm graph, even in the very center.

While the Sigma does better than the Zeiss 35mm f/1.4 at higher frequencies (20-50 lp/mm) the differences between them aren’t massive. If you asked the inevitable ‘could you tell the difference in a picture’ question, I’d answer ‘sometimes’. It would depend what you shot and how carefully you compared them.

The Canon 35mm f/1.4, despite being an older design, hangs pretty well with the Zeiss and Sigma. You can see there are differences, but certainly in the center 1/2 of the lens the differences aren’t huge. The Nikon and the Rokinon just aren’t quite as good as the other lenses, although they are still good lenses. (As we do some more prime tests, you’ll get to see some bad lenses where the differences are much more dramatic than these.)

If you go to DxOmark or another site that lets you compare the Canon 35mm f/1.4 to the Nikon 35mm f/1.4 G you may find the Nikon rated slightly higher (depending upon which cameras were used for the test). That’s because the higher resolution camera gives the lens-camera combination a much higher rating.

You can also compare the Rokinon or Zeiss lenses on different camera bodies. Although the lenses are identical, again the camera-sensor combination will give a higher resolution value to the lens shot on the higher resolution camera. (As an aside, we tested both Nikon and Canon mounts for the Zeiss and Rokinon lenses in this test. They were identical on the optical bench, as they should be.)

Let me point out one other thing I think you’ll find interesting. Notice, especially in the Canon MTF graph, how it ‘dips’ in the area from 10 to 16mm off axis, and then sharpens again in the corners? To a slightly lesser extent the other lenses do something similar (in the Zeiss lens it becomes an area of increased astigmatism). You want to know why that happens, don’t you? OK, I’ll show you why.

Field Curvature

We also ran field curvature tests on all the lenses. If you haven’t seen these graphs before, they’re a bit different than the MTF curves. (You can read more about them here.) Most people think of field curvature in kind of general terms, but tend to forget that the tangential and sagittal fields can have very different curvature and that the curves can be complex or simple. A perfectly flat field is actually rather rare.

There wasn’t a lot of shocking information in the field curvatures. The Canon has a complex ‘moustache’ sagittal curve. If you notice, the area of the moustache is the same area where the MTF curve ‘dips’. Since MTF of the entire lens is measured at best center-point focus, the field (or plane of focus, if you’d rather) curvature makes the MTF numbers dip in this region.

I know some of you are immediately going to say that the MTF is higher if we focused on that point, instead of using the center point. That is correct; when we recheck focusing specifically on that area the MTF numbers are higher. In practice, though, you’d have to have a ‘moustache’ shape subject of interest, though, to get it all in best focus at the same time. On the other hand, if you were using the camera’s AF point at that location, your image would look better in that area than the MTF curve suggests it would (at the expense of making the center of the image out-of-focus).

The Rokinon lens, while it has a lower MTF than most of the other lenses, has a very flat field. The Zeiss field is fairly flat, too, except on the very edges. The Sigma has a very flat sagittal field, while the tangential field curves at the edges of the image. The Nikon is fairly flat until the edges, but there the sagittal and tangential fields curve in opposite directions.

Why does this matter? If I were shooting a flat architectural feature I might find the flatter field lenses to be superior to the others, even though their MTF is not quite as good. If I had an area of interest out in the outer 1/3 of my image, and another in the center (a row people for a group portrait, for example), it’s going to be difficult to get both in focus with the Canon. See, this Geeky stuff does have some practical uses.

Oh, I also know 614 people are going to mention that you can just stop down the aperture and overcome that field curvature. Before you write that snarky note, are you absolutely certain that stopping down doesn’t change the field curvature? What if stopping down accentuates that moustache distortion? Are you sure that doesn’t happen? That sounds like the subject of some future blog posts, doesn’t it? So all 614 of you, hold that snarky comment. You might be glad you did.

Corner-to-Corner Variance

One nice thing that the optical bench does is give us very precise measurements at each of the 4 rotations that we measure for each copy of the lens. By comparing the 4 different measurements taken on each copy, we can get a very accurate measurement of the difference between the sharpest and softest side or corner.

Testing each copy at 4 rotation angles gives us an excellent way to tell how even each side and corner is.

 

For each lens, we calculate the difference between its highest and lowest MTF at each position — basically a very accurate way of determining how different the worst corner is from the best corner. We then average this difference for all of the copies of each lens tested. (Every lens, when measured to this degree of accuracy, is slightly different in the worst and best corners, although you’d have trouble telling it on a photograph.)

Before I show them to you, raise your right hand, look into the monitor and repeat after me: “I do solemnly swear not to make the stupid mistake of assuming the following information applies to lenses other than the 35mm f/1.4 lenses being discussed. I especially swear not to make a statement that one brand is better than another based on this one lens’ data, because I realize that Roger has already tested a lot of other prime lenses that he hasn’t written up yet.”

The following graphs should be simple to follow. The horizontal axis is change in MTF, so if you see a point on the variance graph that has a value of 0.1, that means the MTF at that position varies by 0.1 on the average copy of that lens. The MTF reading we show in the graphs above is for the average of all 4 rotations positions. So if the MTF graph says the MTF at that position is 0.7, and the variance is 0.05, then a single copy of the lens would have an MTF of 0.75 at it’s best corner, and 0.65 at it’s worst corner (or side, or whatever position it is).

Every single copy of every lens we’ve ever tested has a best and worst corner (or side, or whatever). None have ever been absolutely equal. They are just equal enough that you don’t notice it in a photograph.  But lenses with lower variance (remember, the variance is the average variance of many copies) tend to have more similar corners while lenses with high variance have more differences.

A quick glance at the charts shows you the Canon and Nikon 35mm f/1.4 lenses have less variance than the others do. I know some of you are just dying to say that’s because your favorite manufacturer has better quality control. Trust me on this, as I write up more of these prime lens results you’ll see that generalization isn’t accurate. When we do other focal length prime comparisons you’ll see the ‘low variance’ supplier changes depending on which lens we’re considering.

Some of you are screaming that there’s something wrong with the Zeiss results because you absolutely know that Zeiss lenses have the best quality control. (They probably do, actually, but there’s more going on here than just QC.) The Sigma and Rokinon have a bit more variance, probably enough that on the average copy you could detect one slightly softer corner if you did some pixel-peeping tests.

Remember that optical designs that give very high resolution sometimes require tighter tolerances. In some cases, a design with slightly lower resolution has wider tolerances. Put another way, a 0.01 degree tilt in a given element may have a much larger effect in the highest resolution lens and a smaller effect in a lower resolution lens.

Remember also that the amount of optical adjustability built into a lens differs. Some lenses have 6 different elements than can be adjusted to fine-tune copy-to-copy variance. Others have none; what you get is what you get. That can be a two-edged sword, of course. Having too many optical adjustments may make things so complex that it’s hard to get them all done just right.

Until I publish some more of these prime results to give you enough comparisons to draw your own conclusions, let me say all 5 of these lenses are pretty reasonable. The Canon and Nikon 35mm f/1.4 lenses are two of the lowest variance prime lenses we’ve tested (we’ve done about 30 so far). The Sigma and Zeiss 35mm f/1.4 are about average, while the Rokinon is slightly worse than average.

Summary

The optical bench results for the Sigma 35mm f/1.4 lens show that it does has the best MTF, as most testing suggests. All of these lenses are quite good, however, and the Canon and Zeiss lenses aren’t far behind the Sigma.

The field curvature may be a bit surprising to many of you, and may actually be of more practical value than the MTF results. We’ll be discussing the field curvature of these lenses a bit more in the next post.

The variation between best and worst areas on each lens is amazingly good for the Canon and Nikon lenses. The Sigma and Rokinon 35mm f/1.4s have a bit more variation, enough so that on most copies, if you really, really tested carefully, you could probably detect one corner a bit softer than the other.  I doubt you’d see it in a photograph for the ‘average’ lens, but since the variance is higher, there’s probably a higher chance of getting a copy with a corner soft enough to notice in photographs.

Over all, though, all five of these lenses are very good from an MTF standpoint. Some are better than others, obviously, but price range, bokeh, and a number of other factors will make a bigger difference than the MTF for a lot of photographers.

 

Roger Cicala and Aaron Closz

Lensrentals.com

September, 2014

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.

I chose these specific lenses because I get asked every so often whether a 24-70 f/2.8 lenses at 70mm is sharper than the 70-200 f/2.8 lenses at 70mm. This again is a bit of a moot point, since there’s actually a focal length difference (the 24-70s are about 67mm when the lens says 70, while the 70-200 lenses are closer to 73mm).

But hey, I usually find the opportunity to do a meaningless test hard to resist.

Today’s Contestants

We tested 7 copies each of the Canon 24-70 f/2.8 Mk II, Canon 70-200 f/2.8 IS II, Nikon 24-70 f/2.8G AF-S, and Nikon 70-200 f/2.8G AF-S VR II lenses on our Trioptics Imagemaster optical bench. All copies had been through our routine optical and Imatest screening and passed with flying colors. These are all pretty modern designs (the Nikon 24-70 is the oldest, released in 2007) and I don’t think we’ll be seeing a replacement for any of them any time soon. All were tested at their 70mm settings according to the zoom ring, at f/2.8, and at infinity focus setting. (The actual focal lengths were about 67mm for both the 24-70 lenses, 73mm for both of the 70-200 lenses.)

MTF Charts

One thing about looking at MTF charts that people either lover or hate is that it gives a lot more data than just Imatest resolution numbers. It’s so easy to look at Imatest numbers and say, “A is 875 and B is 820, so A is better.” MTF charts give you a lot more information. That generally makes the summary a little more complex, which some people hate. But it also makes the summary a lot more useful.

If you don’t speak MTF, don’t worry. It’s not hard. Higher on the vertical axis is better. Dotted and solid lines of the same color close together are better (far apart is astigmatism). The horizontal axis goes from the center of the lens at “0″ to the edge of the lens at “20″.

Legend for all the MTF graphs

 

Painting with a broad brush, the MTF graphs show that one thing that most people assumed is accurate. At 70mm, the Nikon 24-70 f/2.8 G isn’t quite as good as the other three lenses. The Nikon 24-70 is a good lens, but the other 3 are absolutely awesome lenses.

The MTF charts showed several things that I didn’t expect, though. First among those is that the Canon 70-200 f/2.8 IS II is actually a bit better at 70mm than the Canon 24-70 f/2.8 II. Imatest results on a large number of copies gave a slight edge to the 24-70.

There are a number of reasons for the difference. First, optical bench tests are done at infinity focusing distance, while the Imatest results were at about 15 feet. Second, Imatest shows only the MTF50 — a snapshot along the 0.5 line on the vertical axis of the MTF chart. Finally, Imatest results show a lot of averaging that the MTF graphs don’t do. I usually lump the readings for center, average of the entire lens, and average of the corners, for example. Additionally, Imatest doesn’t separate out astigmatism (the difference between sagittal and tangential lines). On the other hand, Imatest can look a bit further out into the corner than on the optical bench does.

Going into this test I expected the Nikon 70-200 f/2.8 VR II was as good in the center as the Canon lenses, which it is. I thought it would be a bit weaker off center, but it’s not that simple. If you look at just the sagittal numbers (solid lines) the Nikon has a steady fall-off, while the Canon gets softer, then sharper. So in the area from about halfway to 2/3 of the way to the edge of the image the Nikon is better, while the Canon gets better out on the edges. The Nikon also has less astigmatism.

Field Curvature

We also ran field curvature tests on all the lenses. If you haven’t seen these graphs before, they’re a bit different than the MTF curves. (You can read more about them here.) Most people think of field curvature in kind of general terms, but tend to forget that the tangential and sagittal fields can have very different curvature and that the curves can be complex or simple. A perfectly flat field is actually rather rare.

The field curvature graphs give us a lot of information about the lens that we can’t really get any other way. Basically these show what the area of sharpest focus across the lens looks like, assuming you had carefully focused on the center point.

Notice the Nikon 24-70 has some significant field curvature. It’s going to be very difficult to get the center and corners both in sharpest focus without stopping down quite a bit. The Canon 70-200 has a more complex ‘sombrero’ type sagittal curvature with a simpler tangential curvature. The Canon 24-70 Mk II and Nikon 70-200 VR II both have impressively flat fields of focus.

The sagittal field curvature on the Canon 70-200 f/2.8 IS II explains a bit about its MTF chart. If you look at the sagittal field curvature graph notice how the area of sharpest focus has curved away from the “0″ line between 10mm and 15mm from the center, then curves back so it’s in sharp focus again at 18mm. Now go back and look at the sagittal MTF curves for the lens and you get some idea as to why it gets softer, then sharper, then softer again.

You might have noticed a bit of tilt in a couple of the field curvature examples. These are minor and would be impossible to detect in optical testing. Just to reassure you, below are the tangential and sagittal graphs for a Nikon 24-70 f/2.8 that was tilted enough to be obvious in an image (it is not one included in the testing).

Field curvature graphs for a decentered and tilted lens.

The Best Lens?

Life was nice and simple when we averaged some Imatest numbers and easily declared a lens ‘better’ or ‘sharper’ than another. We can still do that, of course. When there’s a big difference between lenses it’s just as apparent on the MTF bench as it was with Imatest. When we compare a couple of good lenses, though, the information is not so much ‘better and worse lens’, but rather  ’stronger and weaker points’ of each lens.

These lenses provide a good example. When I just provided MTF numbers, I found the Canon 24-70 f/2.8 a bit better than the Canon 70-200 f/2.8 IS II at 70mm. Very close, but a bit better. Comparing them here my original thought was things might be different at infinity focus compared to the closer focus used for Imatest. But the additional information we get with bench testing shows us more than just better or worse. The 70-200 is a bit sharper in the center while the 24-70 has a much flatter field.

If you look at the MTF chart there’s not much question the Canon 24-70 has a higher MTF than the Nikon 24-70 in most locations and at most frequencies. However, the Nikon has less astigmatism in the outer areas, and that may give it a ‘look’ that some prefer over the absolute resolution of the Canon.

Before doing this test, if you had asked me I would have told you I thought the Canon 70-200 was just a bit sharper than the Nikon. It might be, by just a tiny bit in the center. Away from center, though, the Nikon 70-200 is better at higher frequencies. The Nikon 70-200 also has less astigmatism in the outer edges and a flatter field than the Canon.

The field curvature in the edges of the 70-200 f/2.8 IS II at 70mm would make some people (including me) prefer the very flat field of the Canon 24-70 f/2.8 Mk II, at least at 70mm. It depends what you use the lens for. For portraiture or action sports, it would be completely meaningless but I do some architectural shooting at 70mm.

Saying one of these three lenses is clearly better than the other at 70mm is rather silly. They have some different characteristics; some slightly different strengths and weaknesses. The reality is if I shot Nikon and carried these two zooms, I’d use the 70-200 for work around 70mm. If I shot Canon and carried these two, I’d prefer the flat field of the 24-70 once in a while, need the IS of the 70-200 once in a while, but generally wouldn’t worry about changing lenses to get a 70mm shot.

Still, I find the comparisons interesting, even if not very useful, and we’ll be doing some more.  And who knows — someday when I’m shooting my interchangeable mount 50mpix SLR I might actually be making a decision as to whether I want the Zeiss, Canon, or Nikon lens for it in a given focal length.

Roger Cicala and Aaron Closz

Lensrentals.com

September 2014

 

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.

What These Graphs Are

The graphs are pretty simple: the machine finds the best focus point in the center of the lens (“0″ on the vertical axis). It then measures 20 other points from one side to the other of the field, finding the best focus and highest MTF at each point. The relative MTF is shown by color (white>red>orange>yellow, etc.). The focus position compared to best center focus is shown on the vertical axis. The horizontal axis shows position from the left side of an APS-C size sensor to the right.

These lenses were all tested at f/4 to level the playing field for the wider aperture lenses. But this means the field curvature wide open would probably be larger than what you see here. They were done at infinity focus, so the field curvature might be a bit different at shorter focal lengths.

One thing these graphs will show (that you probably don’t really want to know) is that a lot of lenses have a very slight bit of tilt to the field. These are all good copies, tested multiple times. The tilt that is noticeable on these graphs isn’t noticeable in real-world photography, at least not without a great degree of pixel peeping.

The other thing that you may not have thought of is that the sagittal and tangential fields often have different field curvature.

Does this have real-world implications? Yes. The lens with wicked field curvature may give amazingly sharp portraits, but not sharp landscapes or architectural shots, for example. I’m sure someone is going to ask something like, “Well, now many feet does a 100 micron focusing distance equal at infinity?” I don’t have the math to answer that question and don’t have time to go look it all up, but if one of you wants to we’d welcome your input.

Some wide-angle M-mount lenses.

First we’ll show 4 wide-angle lenses. You may notice the Leica 18mm is very mildly tilted, although this is not something you’d notice in a photograph. The Voigtlander 21mm is a good example of a lens with quite different sagittal and tangential curvatures.

 

A few that are not quite that wide.

The Leica 28mm f/2.8 gives us a nice example, at least in the sagittal field, of a lens with double (sometimes called Sombrero) curvature.

 

And lastly some 35mm lenses

The Voigtlander 35mm f/1.4 (and remember, this is stopped down to f/4) shows some pretty wicked curvature. Because I know some Voigt fanboy is going to tell me his 35mm has no field curvature I’ll go ahead and tell you that I tested 5 copies and they were all identical. The double field curvature seems to be pretty much standard for these M-mount 35mm lenses.

 

I don’t have any dramatic conclusions to add, other than I think this is a very useful tool. We’ll be presenting field curvature graphs on all of our lens reports going forward. I’ll also apologize in advance to all of you who want to see the curvature of some specific lens or other. We have over 150 more lenses that need to be tested, minimum of 8 copies of each one, and the zooms at 3 different focal lengths minimum. I’m just not in a position to take requests right now. But we’ll be publishing more of them soon.

 

Roger Cicala and Aaron Closz

Lensrentals.com

August 2014

HandeVision IBELUX 40mm f/0.85

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Image credit Lensrentals.com

Preconceptions

I try to start these articles by putting my preconceptions out there first. Every reviewer or blogger has them, they affect our opinions, and you have a right to know them. So I’m writing this introduction the day before our first copies arrive.

The HandeVision IBELUX 40mm f/0.85 is designed by IB/E Optics GmbH in Germany and manufactured by Kipon (aka Shanghai Transvision Photographic Equipment Co. Ltd). IB/E has developed a number of lenses and adapters for the Cinema world and other optics, so I figured the design would be good; probably a telecentric lens with a built-in Speedbooster-type element or group. Kipon is known as a lens adapter company, although Shanghai Transvision has also manufactured and distributed video and photo accessories. They are rumored to manufacture lenses for other brand names, so they have some lens manufacturing experience.  But, I have to say, my expectations for build quality weren’t great. I expected a lot of variation between copies. I don’t know if I even had any expectations regarding image quality.

Okay, so much for what I expected. There are now five new copies sitting on my desk so let’s take a look. Continue reading

A Useful Metabones EF to Black Magic Pocket Camera Article

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Way back in the old days, before everything was plug and play, you could buy a computer and accessories from one manufacturer and be certain it would all work together. The cool kids, though, would mix-and-match different pieces and end up with a better system that could do more things than any one manufacturer’s system would, and for less money. They realized they might have to spend some time getting this to work with that, and once in a while things wouldn’t work at all. That’s the price you pay for being a cool kid and getting more for less money.

The people who had problems bought the same thing the cool kids did, but just got irritated when things didn’t all work together right out of the box. The cool kids laughed, felt even cooler, and made some money debugging the other kids’ systems for them.

We do the same thing today with cameras. It’s simple to use a rig, lenses, monitors, whatever of the same brand. It will probably cost a little more and you may have a few less capabilities, but it’s just about guaranteed everything will work fine with everything else. But if you want to save some money and expand your capabilities, you mix-and-match systems, often using an adapter or two.  The problems come when people don’t realize that not everything is going to play nice with everything else. The problem is compounded because the people who make the widgets just don’t have the capabilities of testing everything with everything else.

A few weeks ago Metabones sent me one of their new EF lens to Black Magic Pocket Camera Speedboosters to play with. I did the usual optical testing and let some of the video guys shoot with it, like all the other bloggers do. I planned on writing a piece saying how awesome the optics were (they are) and how many cool things it lets you do with a Pocket Camera (it does) like all the other bloggers do. But in our testing we found a few things that didn’t work well together, and it occurred to me that rather than adding yet another “The EF to Pocket Camera Speedbooster is Really Great” blog post, I could do something useful and actually list what it works well with and what it doesn’t.

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Of Course We Took One Apart

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A Look Inside the Canon 16-35 f/4 IS

This is a Geek Article. Many of you don’t understand the term ‘Geek’ properly, so perhaps this will help. As the graph shows, if you aren’t both intelligent and obsessed with photo gear, you won’t enjoy this article. 

I’ve tried hard to find whom to credit for this, but haven’t been able to. If you know, please let me know so I can credit this brilliant work.

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Canon Wide-Angle Zoom Comparison

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Left to right: Canon 16-35 f/2.8 II, 16-35 f/4 IS, 17-40 f/4. Can you spot the one with the wrong hood? The intern obviously couldn’t. 

 

As is so often the case, I bit off more than I wanted to chew when I came back from vacation. The Canon 16-35mm f/4 IS lens had just been released, a few copies were in stock, and I thought I’d do a nice quick test. But one of the reasons I’d wanted an optical bench was because I don’t trust Imatest results with wide-angle lenses. At 16mm, even with the very largest test charts, we’re testing at about 4 feet shooting distance.

So I after I did our standard Imatest on the 16-35 f/4 IS, I wanted to repeat the results on our optical bench. Of course, I don’t have a big database of optical bench results to compare against like I do with Imatest. So I had to do optical bench tests on some other wide zooms for comparison purposes. Then I had to do some more comparison with other lenses to see if the variations we were seeing on the optical bench were simply a new, higher resolution testing method, or if they were telling me something about variation with wide-angle zoom lenses. (Both things were true.) Anyway, the testing I thought would take a week has taken three.

I realize some of you just want to see the usual Imatest results on a group of these lenses since that’s what you’re used to seeing. Others are also interested in the optical bench results showing how the lenses resolve at infinity, rather than just close up. And of course there are a few of you who want all the gory details of Geekiness that the optical bench reveals. So I’ll try to present this in three parts: the Imatest results first, the optical bench optical test results second, and the geeky stuff third. It’s a buffet; just grab what appeals to you.

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Save 15% This Summer

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Get 15% off this summer when you reserve your order a week in advance. Just place your order at least 7 days in advance of the arrival date and save!

Enter the code SUMMER15 during checkout and get 15% off on your order.

  • Order must be placed 7 days in advance
  • Eligible arrival dates: 7/28/14 – 8/29/14
  • May not be combined with other offers

A New Old Lens

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Like a lot of photo history buffs, I’ve been quite excited about Lomography’s new iteration of the Petzval lens in 85mm focal length. For those of you who don’t know about the Petzval lens, I wrote about it a few years ago. It really has a rather a fascinating story.

Since writing that article, I’ve been rather obsessed by this lens. I own several of them, made in the late 1800s, but I haven’t been able to adapt them to work on a modern camera. Now Lomography has reproduced the Petzval lens in a nice brass housing, for either Canon or Nikon mounts. Our first copies arrived yesterday and I grabbed them for a bit before they headed out the door.

The new Petzval is quite a handsome bit of kit.

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Sensor Stack Thickness Part III: The Summary

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Well, I have to admit this has been a fun series. I’ve learned a whole lot. That’s what makes this so fun — I get some results I don’t understand, get some help figuring out what is going on, and before I know it, I’ve learned something that explains other things I haven’t been able to understand.

In the second part of this series, we started a database of sensor stack thickness and exit pupil distances, hoping that it would help people decide which lenses would adapt best to which cameras. (And, of course, determine which lenses would not adapt well to which cameras.) A number of people have added information to the database since it was first posted — enough to make it pretty useful.

Since the database is now large enough to be useful, I thought it would be a good idea to make a summary of what we know about lenses and sensor stacks. The best thing about all this, for me at least, is that it lets us make some generalizations about which lenses would be expected to have problems on which cameras.

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