Simulating Sony a7II camera motion blur

I few days ago, I posted the results of simulating camera motion blur in a Sony alpha 7R (a7R), showing how the modulation transfer function, as measured by MTF50, varied with camera motion blur measured in pixels, and also showing simulated photographs with their motion distances and MTF50 values, so that you could see what the various MTF50 values translated to in terms of subjective impression of images.

Today, I’m doing something similar for the Sony alpha 7 Mark II (a7II). It’s turned out to be a little tricky because of the way that the a7II anisotropic antialiasing (AA) filter works. If you take a picture of a test chart like the ISO 12233 one, you’ll notice that the a7II doesn’t suffer any loss in resolution in the vertical direction (horizontal lines) due to the AA filter, but there’s a small amount of loss horizontally (vertical lines).

I added some features to the model so that I could emulate the behavior of the a7II’s AA filter. Here’s what Imatest‘s SFR function looks like for a conventional 4-way phase-shift AA filter and a horizontal edge with the 6um pixel pitch of the a7II and a simulated Zeiss Otus 55/1.4 set to f/5.6:

imatestboth

And here’s what it looks like with a vertical 2-way phase-shift AA filter:

imatestVAA

 

Almost identical, because the filter runs almost perpendicular to the slanted edge.

But things change if we simulate a horizontal 2-way phase-shift AA filter:

imatestHAA

Now the lens is resolving so much detail that there is significant aliasing. Not the overshoot. This is not due to deconvolution filtering, since I’m not using any. It is strictly a property of the Matlab implementation of the gradient-corrected linear interpolation demosaicing algorithm that I’m using.

I set up a run of the simulator with various amounts of motion blur, modeled as linear, constant speed movement of the image across the sensor at a forty-five degree angle.  By the way, these things take a long time to run:

a7IIAAtiming

Here are the MTF50 numbers in cycles/picture height for a horizontal edge with displacements from 0 to 8 pixels at a 45 degree angle:

a7iiNtfstatsYou can see that with a vertical AA filter (AAV), the results are essentially the same as with no AA filter. With a horizontal AA filter (AAH), the MTF50 is reduced considerably. That’s the price you pay for reduces aliasing.

Here are the 1:1 crops from the photographic scene enlarged 300%:

No motion blur -- MYF50V = 1356, MTF50H = 004

No motion blur — MYF50V = 1356, MTF50H = 004

1 pixel motion blur -- MTF50V = 1287, MTF50H = 963

1 pixel motion blur — MTF50V = 1287, MTF50H = 963

It’s really hard to see the effects of one pixel of camera motion blur in the a7II.

1.4 pixels motion blur -- MTF50V = 1225, MTF50H = 934

1.4 pixels motion blur — MTF50V = 1225, MTF50H = 934

2 pixels motion blur -- MTF50V = 1120, MTF50H = 884

2 pixels motion blur — MTF50V = 1120, MTF50H = 884

2.9 pixel motion blur -- MTF50V = 963, MTF50H = 795

2.8 pixel motion blur — MTF50V = 963, MTF50H = 795

4 pixel motion blur -- MTF50V = 769, MTF50H = 873

4 pixel motion blur — MTF50V = 769, MTF50H = 873

motion blur = 5.6 pixels == MTF50V = 572, MTF50H = 531

motion blur = 5.6 pixels — MTF50V = 572, MTF50H = 531

8 pixel motion blur -- MTF 50V = 416, MTF50H = 397

8 pixel motion blur — MTF 50V = 416, MTF50H = 397

If you compare these images to the a7R motion blur images, remember that the pixels is the a7II  are 6 um apart, while the pixels in the a7R are 4.88 um apart. Therefor, one pixel blur represents more camera motion in the a7II case than for the a7R.

 

The visibility of a7R shutter shock

Ever since the Sony alpha 7R (let’s call it the a7R) came out in late 2013, a furor has raged about its shutter shock, or, more precisely, on whether it had any. One group of people — and that includes moi — were analyzing its effects and developing ways to ameliorate it. Another group vehemently defended the position that a7R shutter shock was as real as the Easter Bunny, and posted lots of sharp-looking pictures made with the camera.

The battle continues, albeit at reduced intensity. I expect it will pick up again when and if a new version of the camera is introduced with electronic first curtain shutter (EFCS). Lots of people will trade up. Then there will be lots of the old cameras on eBay, and lots of posts on dpr asking whether the old camera is a good deal, and what about that shutter shock?

I have always maintained that the root of the disagreement was that many of the shutter-shocked images made with the a7R have only modest sharpness impairments, and that they are plenty sharp for their intended purpose, and, without a picture of the same subject with the same lens at the same time with no shutter shock (something impossible to set up until the D810 shipped), there was no way to tell how much, or even whether, the a7R image was degraded.

It occurs to me that, with the images from yesterday’s post, we now have a way to, through the magic of simulation, do that very comparison.

Consider these MTF50 curves for the a7R on a tripod with a Sony 70-200mm f/4 OSS FE lens, with OSS on and off:

a7Rheavytripod

We can see that shutter shock reduces the MTF50 from about 1600 cycles/picture height (cy/ph) to about 1200 cy/ph as the shutter speed changes from 1/1000 second to 1/60 second.

Let’s look at the 3x blowups from yesterday’s post that are closest to those MTF50s:

1 pixel blur -- MTF50 = 1516

1 pixel blur — MTF50 = 1516

2.8 pixels blur -- MTF = 1151

2.8 pixels blur — MTF = 1151

Yes, there’s some difference. No, it’s not striking. You’d have to look hard to see it in a print of this detailed image. You’d probably never see it in a print of a wildlife or sports subject.

Therefore, when people claim that the a7R has no shutter shock, they may be saying that it doesn’t affect their pictures in any way that they can see. And they could be right.

I believe that there is another group of people who are a7R shutter-shock deniers, who are affected by what I call the dancing bear view. Proverbially, if you see a dancing bear, you’re just blown away that a bear can dance, and you don’t ask how well it can dance. If you’ve never had a 36 MP camera before, you may be amazed at all those pixels, and not question whether they are perfectly sharp.

By the way, the MTF50 numbers in the graph and the ones in the simulated photographs weren’t measured in exactly the same way. It’s not an important point, but I mention it in the spirit of full disclose. I’ll have more on that nerdy little point in a future post.

Simulating motion blur: MTF50 and pictures

Yesterday, I reported on the results on simulations of a Zeiss Otus 55/1.4 at various f-stops, and showed how MTF-50 values translated into picture sharpness with simulated photographs.

Today I’ll do something similar, but varying motion blur instead of f-stop. I set up the sim with the pixel pitch set to 4.88 um (same as a7R or D800 or D810), and a simulated Zeiss Otus lens, at f/5.6. For the motion blur, I assumed constant rate with displacement 1, 1.4, 2, etc pixels at a 45 degree angle, and calculated MTF50 in cycles/picture height.

The MTF50 numbers:

displacement blur

 

Here’s what the full frame would look like:

_DSC1512

 

And here are the simulated 1:1 crops, blown up to 300%:

 

1 pixel blur -- MTF50 = 1516

1 pixel blur — MTF50 = 1516

1.4 pixels blur -- MTF50 = 1443

1.4 pixels blur — MTF50 = 1443

2 pixels blur -- MTF50 = 1331

2 pixels blur — MTF50 = 1331

2.8 pixels blur -- MTF = 1151

2.8 pixels blur — MTF = 1151

4 pixels blur -- MTF50 = 928

4 pixels blur — MTF50 = 928

8 pixels blur -- MTF50 = 506

5.6 pixels blur — MTF50 = 928

 

5.6 pixels blur == MTF50 = 928

8 pixels blur — MTF50 = 506

The real test of what sharpness is acceptable for printing is to make some test prints. Therefore, I encourage anyone who wants to know what 36MP prints with MTF50s between 1000 cycles/picture height or so and 1600 cycles/picture height or so download the files,  resize them — without resampling! — to your printer’s native driver resolution (360 ppi for Epsons, 300 ppi for Canons) and print them. Then look at them to find what is your own personal minimum acceptable sharpness. Note the f-stop. Now go to the table above and note the MTF50 associated with that f-stop. Congratulations! You’ve just found your minimum acceptable MTF50.

The files are available in two ways: a Photoshop layer stack, with the layers labeled appropriately:

And as zipped TIFFs:

Each download is a little over 70 MB.

What’s MTF50 = x look like: sim pix

Last week, I wrote this post on producing images that show visually the effect of image capture blur on Bayer-CFA cameras. I briefly discussed this simulation-based approach:

Start out with a slanted edge. Dial in some diffraction, some motion blur, some defocusing, take the captured image, run it through a slanted edge analyzer, and get the MTF50. The, leaving the simulator settings the same, run a natural world photograph through the simulator. Do that with various simulated camera blur, and we’ll get a series of images that people can look at, and we’ll know their MTF50.

I went on to discuss ways to do similar captures with real, not simulated cameras. I’ve decided to pursue the simulator approach. It allows me to have identical scenes with different amounts and kinds of camera blur, and give me great freedom in the kinds of input images that I use.

However, there is a technical problem. Because of the way the simulator works, it needs an image of at least 8 times the linear resolution of the output image for accurate results at MTF50s of over 1000 cycles/picture height. That means that it’s not practical for me to simulate the entire capture of a full-frame camera, but only a crop from that capture. Even then, I need to go to extraordinary lengths to get sufficiently high resolution in my input images.

Let’s work through an example. I first computed MTF50 values for with pixel pitch set to 4.88 um (same as a7R or D800 or D810), and a simulated Zeiss Otus lens, at f/2.8 through f/16.

488umMTF50

I set up on this scene, shown captured by a 24mm lens (Leica 24mm f/3.4 Elmar-M ASPH, if you care) on a Sony a7II:

_DSC1512

Then I put a Leica 180mm f/3.4 Apo-Telyt on the camera, focused manually, set the aperture to f/8, and made a three-row series of exposures. I stitched them in AutoPano Giga, and got this 14825×8037 pixel result:

House180cr

 

Consider it a crop from the full frame first image represented by the 24mm picture.

Then I ran the 14825×8037 image through the camera simulator with pixel pitch set to 4.88 um (same as a7R or D800 or D810), and a simulated Zeiss Otus lens, at f/2.8 through f/16. I set the reduction factor to 8, so the resulting images were 1853×1005 pixels. Note that the ratio between the focal length I used for the pano is about eight times the 24mm lens I used for the overall FF shot; that’s the same as the reduction ratio.

I made some 1:1 crops from the images, and blew them up to 300% just like I do when I’m doing lens testing.

f/5.6

f/5.6 — MTF50 = 1589

f/11

f/11 — MTF50 = 1354

f/16

f/16 — MTF50 = 1093

I didn’t include the f/2.8, f/4, and f/8 images because they were so similar to the f/5.6 one.

The real test of what sharpness is acceptable for printing is to make some test prints. Therefore, I encourage anyone who wants to know what 36MP prints with MTF50s between 1000 cycles/picture height or so and 1600 cycles/picture height or so download the files,  resize them — without resampling! — to your printer’s native driver resolution (360 ppi for Epsons, 300 ppi for Canons) and print them. Then look at them to find what is your own personal minimum acceptable sharpness. Note the f-stop. Now go to the table above and note the MTF50 associated with that f-stop. Congratulations! You’ve just found your minimum acceptable MTF50.

The files are available in two ways: a Photoshop layer stack, with the layers labeled appropriately:

https://dl.dropboxusercontent.com/u/45825451/House180-a7Rstack.psd

And as zipped TIFFs:

https://dl.dropboxusercontent.com/u/45825451/House180-a7R.zip

Each download is a little over 60 MB.

After I get some feedback on this, I’ll start simulating motion blur.

Note that I’m using gradient-corrected linear interpolation, which is not the most sophisticated demosaicing algorithm in the world, and there are artifacts — mostly in the swing set — that are worst at the sharpest apertures, but are still visible at f/16.

Comments and questions are welcome.

2 180mm lenses on the Sony a7II

The title is a bit misleading. I’ve been asked to compare the Sony 70-200mm f/4 OGG FE lens to the Leica 180mm f/3.4 Apo-Telyt-R. For this test, I set the Sony lens to about 180mm. The camera was the Sony alpha 7 Mark II, hereafter called the a7II. It was tripod mounted with a RRS L-plate to an Arca Swiss D4 head, which was attached to a set of RRS TVC-43 legs. EFCS was on, IBIS was off. Selftimer set to 2 seconds. Manual focus at f/3.4 in the Leica’s case, and f/4 in the Sony’s. Developed in Lightroom 5.7.1 (where is Lr 6?) with default settings except a +0.12 EV exposure move in the Leica’s case, and switching to Daylight white balance because the camera chose different WB points for the two lenses.

The overall scene at f/4 through f/11:

Leica f/4

Leica f/4

Sony f/4

Sony f/4

About the same amount of falloff in both cases.

 

Leica f/5.6

Leica f/5.6

Sony f/5.6

Sony f/5.6

Maybe a bit more falloff  — look at the upper left corner — in the Leica’s case.

Leica f/8

Leica f/8

Sony f/8

Sony f/8

Pretty similar. The Sony’s a tad evener in illumination.

Leica f/11

Leica f/11

Sony f/11

Sony f/11

Too close to call.

Now the center crops, blown up 3:1:

Leica f/4

Leica f/4

Sony f/4

Sony f/4

The Leica’s a little bit crisper, not there’s not much difference.

Leica f/5.6

Leica f/5.6

Sony f/5.6

Sony f/5.6

A tie.

Leica f/8

Leica f/8

Sony f/8

Sony f/8

Also a tie.

Leica f/11

Leica f/11

Sony f/11

Sony f/11

Are you bored? Hang in there.

The upper right corner:

 

Leica f/4

Leica f/4

Sony f/4

Sony f/4

Not even close. The Sony is a zoom lens, remember.

Leica f/5.6

Leica f/5.6

Sony f/5.6

Sony f/5.6

The  Leica is a bit crisper. The Sony still has a long way to go.

Leica f/8

Leica f/8

Sony f/8

Sony f/8

This is the Leica’s sharpest f-stop overall. The Sony is not there yet.

Leica f/11

Leica f/11

Sony f/11

Sony f/11

The Leica has started to soften due to diffraction. On the Sony, it’s not sharp enough for diffraction to be an issue.

The only things that were unexpected for me in this test were that the Sony was as sharp as it is in the center, and that even stopping down to f/11 doesn’t crisp up the corner.

Remember that the Leica is a tough lens to compete with.

What’s MTF50 = x look like?

When I did the analyses of images produced with the Sony a7R and a7II and the Sony 70-200mm f/4 OSS FE lens with mountings of varying stability, I used MTF50 as a metric for sharpness, and presented the results as graphs with that metric as the vertical axis. Over on the DPR E-Mount forum, my results were attacked by some who said that they didn’t want to see graphs, just pictures.

I answered as follows:

First off, in the case of camera vibration and its effect on image sharpness, the statistics are what’s important. Sure, I could take a single shot at each SteadyShot setting and shutter speed and post those shots, but it wouldn’t mean much. Just because of the luck of the draw, we might get a sharp shot from a series that’s mostly blurry, or a blurry shot from a series that’s mostly sharp. Then you’d get the wrong idea about which setup was better than which.

Second, once I’ve stepped up to making enough exposures to get reasonably accurate statistics — and I would like to do even more than the 16 per data point that I now do — we’re talking a lot of exposures. Each graph that I post is the result of analyzing 320 exposures. You don’t really want to look at all 320, do you?

But the requests (and I’m characterizing them politely) got me thinking. I’ve been working with slanted edge targets and MTF analyses for more than a year. I’ve got a reasonable feel for what, say, 1800 cycles/picture height (cy/ph) means in terms of sharpness (really crisp), and what 400 cy/ph means (pretty mushy). But most people don’t. So, when I present curves like the following:

a7Rlighttripod

People can tell that higher up on the page is sharper, and sharper is better, but they don’t have a feel for how to interpret how sharp any point of the curve is. They need a Rosetta Stone to translate between various MTF50 values and images that they can look at and judge sharpness for themselves.

I started thinking about how to provide that bridge between the two worlds.

My first thought, and what I still think is the high road, is to do it all in my camera simulator. Start out with a slanted edge. Dial in some diffraction, some motion blur, some defocusing, take the captured image, run it through a slanted edge analyzer, and get the MTF50. The, leaving the simulator settings the same, run a natural world photograph through the simulator. Do that with various simulated camera blur, and we’ll get a series of images that people can look at, and we’ll know their MTF50. There’s one little technical problem: the natural world images with have photon noise (that’s why I’ve been using Bruce Lindbloom’s ray traced desk so much). To a first approximation, I can deal with this by turning off the photon noise in the simulator.

There’s another, more practical problem with this approach. Many, if not most, of the people whom I’d be trying to reach have an distrust/aversion/antipathy to math and science, and would have a hard time understanding what the simulator is doing, and a harder time believing that there wasn’t some nefarious activity going on.

So, I set the simulator approach aside, although I may pick it up again at some point in the future.

My next thought was to take a slanted edge target, plunk it down in the middle of a natural scene, photograph the whole thing with various shutter speeds, mounting arrangements, defocusing, etc, measure the MTF50 of all the shots, and publish blowups of various parts of the natural scene together with the MTF50 number for that shot. Easy, peasy, right?

The more I thought about it the less easy it seemed.

If I were to go to all this trouble, I’d want things in the image with high spatial frequencies, or else the difference between say, an MTF50 of 1600 cy/ph and one of 1200 cy/ph wouldn’t be noticeable.

I’d want natural objects that were flat enough to be in critical focus with lens openings wide enough to provide high on-sensor MTF, and that I could get close to the plane of the slanted edge chart. I’m starting to envy Lloyd Chambers his apparently permanent doll scene. I know that my wife would tolerate my setting something like that up for a day at most. I’ll get back to this.

The characteristics of anti-aliasing (AA) filter effects, diffraction, mis-focusing, and camera motion all are subtly different, even at the same MTF50. If would be nice to be able to change one with changing the others.

If I’m going to make exposures at varying shutter speeds, because of the point above, it would be nice to do that without changing f-stop, since that will change lens characteristics. Several alternatives come to mind. One is changing the illumination level. That requires an indoor scene, and my variable-power LED source gets pretty dim if it’s expected to light a large area. I can use strobe illumination and get plenty of light, but can’t test camera motion effects that way. Another is using a variable neutral density (ND) filter in front of the lens. That costs more than a stop of light (in theory – in reality, closer to two stops), even when the ND filter is set to minimum attenuation. Another is just letting the lighting level drop, and pushing in post, or compensating with the in-camera ISO control. In both cases the noise level will rise as the light hitting the sensor goes down. Using fixed ND filters is just too error-prone; I know I’d knock the camera out of position changing them.

Getting enough light is a problem. If I want the fastest shutter speed to be 1/1000, and I do the exposures outside, and want to shoot at f/8, that means ISO 250. Throw a variable ND filter on there, and we’re up to close to 1000. Slanted edge software is really good at averaging out noise. Humans aren’t. Maybe I can get the target and the real-world objects into close enough to the same plane and use f/5.6 and ISO 500. Going to f/4 and ISO 250 just seems like pushing it too far.

Returning to the subject matter for the scene. I’m thinking that a piece of cloth with a fine weave (or at least one that is on the order of the pixel pitch when projected onto the sensor) would be good. Lloyd Chambers has those dolls with fine hair and eyelashes; maybe I could get a doll? Cereal and cracker boxes? Wine bottles? Feathers? Or just include a photograph in the scene?

Any and all comments and questions are appreciated.

Field curvature with the 24mm f/3.5 PC-E Nikkor

A reader suggested that the disappointing showing of the PC-E 24mm f/3.5 Nikkor D ED might have been caused by field curvature. In order to check that out, I made an aperture series focusing in the upper right corner.

The scene:

_8105395

The upper right corner, blown up 3:1:

f/4

f/4

f/5.6

f/5.6

f/8

f/8

f/11

f/11

Looks a lot better, doesn’t it?

Now let’s look at the center, where I didn’t focus:

f/4

f/4

f/5.6

f/5.6

f/8

f/8

f/11

f/11

Yep. That’s field curvature all right. The center is really fuzzy at f/4, and gets progressively better right through f/11, and it isn’t really crisp even there.

I checked to see if the shift adjustment center marker was off. It was fine. The tilt axis was set up as right/left, so, if the tilt was off, the upper left corner would suffer:

f/4

f/4

f/5.6

f/5.6

f/8

f/8

f/11

f/11

That’s not it. Field curvature it is.

By the way, Roger Cicala has written a nice article on field curvature. Here’s a key quote:

The takeaway message is that stopping down a lens doesn’t flatten the field. You have to stop down enough that the depth of field becomes greater than the curvature.

 

 

 

4 24mm lenses on the D810, part 3

This is a continuation of the lens test of the previous post. The lenses are:

  • Sigma 24mm f/1.4 DG Art
  • AF-S Nikkor 24mm f/1.4 G ED
  • AF-S Nikkor 24-70mm f/2.8 G ED
  • PC-E Nikkor 24mm f/3.5 D ED

Today we test all four lenses at f/8 and f/11.

In the center:

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

Yawn…

In the corner:

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

The Sigma wins. The Nikkor f/1.4 is next. The zoom is OK. The tilt/shift remains a huge disappointment.

At f/11:

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

Not much difference. A tad softer than at f/8, but not enough to keep f/11 from being useful.

In the corner:

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

The tilt/shift is starting to come around, but it’s not as good as either the Sigma or the Nikkor f/1.4. The Sigma’s the best. The Nikkor f/1.4 CA never did resolve. The zoom is once again, good for a zoom.

Summary: The Sigma is quite a lens. The Nikkor 24mm f/1.4 has been dethroned. The 24-70 is pretty good at 24mm. The tilt/shift lens is a disappointment. [Turns out that the tilt/shift problems are due to field curvature.]

 

4 24mm lenses on the D810, part 2

This is a continuation of the lens test of the previous post. The lenses are:

  • Sigma 24mm f/1.4 DG Art
  • AF-S Nikkor 24mm f/1.4 G ED
  • AF-S Nikkor 24-70mm f/2.8 G ED
  • PC-E Nikkor 24mm f/3.5 D ED

Today we test all four lenses at f/4 and f/5.6.

The center, at f/4:

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

I’m amazed at how well the zoom does. The Nikkor f/1.4 is still suffering from some veiling.

In the corner:

 

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

The Sigma and the fast Nikkor are doing great, if you don’t count the CA that the Nikkor is afflicted with (and I don’t think you should weight it heavily; it’s easy to fix it in post). The zoom is OK for a zoom, but the worst performer in this portion of the test. The tilt/shift lens is a lot softer than I thought it would be, since it is not working near the limits of its image circle, as the other three lenses presumably are.

At f/5.6 in the center:

 

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

Not a lot of difference.

In the corner at f/5.6:

 

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

Nikkor zoom

Nikkor zoom

Nikkor tilt/shift

Nikkor tilt/shift

The Sigma looks great. There’s a bit of CA. The Nikkor 24mm f/1.4 is next. The zoom looks OK for a zoom. The 24mm f/3.5 continues to underwhelm. Anybody want to buy a tilt/shift lens?

4 24mm lenses on the D810, part 1

The new Sigma 24mm f/1.4 Art lens is getting a lot of good press these days, and I thought it might be instructive to do one of my informal tests that included it.

I rounded up the following 24mm lenses:

  • Sigma 24mm f/1.4 DG Art
  • AF-S Nikkor 24mm f/1.4 G ED
  • AF-S Nikkor 24-70mm f/2.8 G ED
  • PC-E Nikkor 24mm f/3.5 D ED

The camera was a Nikon D810, operated with EFCS on and a 3-second shutter delay programmed in, manually focused in the center. The raw files were developed in Lightroom 5.7.1 with default settings. The zoom was tested at 24mm only, and the PC-E Nikkor, a tilt/shift lens, was tested with the movements centered. Here’s the scene, with each lens wide open:

Sigma

Sigma

24mm Nikkor G

24mm Nikkor G

24-70 Nikkor

24-70 Nikkor

24mm tilt/shift Nikkor

24mm tilt/shift Nikkor

The edge falloff is the worst for the faster lenses, as you’d expect, and pretty much non-existent for the tilt/shift lens, also as you’d expect.

The center blown up 3:1, at f/1.4 for the two lenses that are that fast:

Sigma

Sigma

Nikkor f/1.4

Nikkor f/1.4

The Sigma is sharper, punchier, and doesn’t suffer from the veiling haze that the Nikkor has, which makes the center look like it is overexposed.

Upper right corner:

Sigma

Sigma

Nikkor 24mm f/1.4

Nikkor 24mm f/1.4

Not bad for f/1.4 with a lens this wide. It’s close for sharpness, but I’d give the nod to the Nikkor. The Nikkor has more chromatic aberration.

Stopping both lenses down to f/2:

 

Sigma

Sigma

Nikkor 24 f/1.4

Nikkor 24 f/1.4

The Sigma is sharper, has better contrast. It isn’t even close.

In the corner:

Sigma

Sigma

Nikkor 24mm f/1.4

Nikkor 24mm f/1.4

The Sigma is sharper and more contrasty than the Nikkor, and has less CA.

At f/2.8, we can include the Nikkor zoom:

 

Sigma

Sigma

Nikkor 24mm f/1.4

Nikkor 24mm f/1.4

Nikkor zoom

Nikkor zoom

The Sigma is the sharpest, followed by the Nikkor 24mm, with the zoom surprisingly close.

In the corner:

Sigma

Sigma

Nikkor 24mm f/1.4

Nikkor 24mm f/1.4

Nikkor zoom

Nikkor zoom

The Sigma and the Nikkor 24mm are very close for sharpness. The Nikkor zoom is very soft by comparison, but not bad for a zoom wide open. There is CA apparent in all three images, with the Sigma having the least,and the Nikkors about tied for second place.

Next up, all four lenses at f/4.

Photography meets digital computer technology. Photography wins — most of the time.

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