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 Sony still has a long way to go.

Leica f/8

Leica f/8

Sony f/8

Sony f/8

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.

Heavy and light tripods with Sony a7R, a7II

For the past few days, I’ve been doing tests of image sharpness with the Sony 70-200 f/4 OSS FE lens mounted on a Sony a7R and a a7II camera. I’ve been using a really sturdy tripod — the RRS TVC-43 — and head — the Arca Swiss C1 Cube — for the testing when I’ve not been handholding.

I wondered what would happen if I used a much lighter weight tripod and head. I dug up a Gitzo 6X carbon fiber travel tripod with a light RRS ball head. Here are the two tripods next to one another:

tripods

You can see that the legs of the travel tripod get pretty skinny towards the floor. You can also see that I extended the column nearly all the way. Yeah, I know that’s not a good idea, but I wanted to create a pretty flexible camera mounting device. You’ll note that the RRS monster tripod doesn’t even have a center column; RRS probably figures that, if you want a tripod this big, you’re not going to want to take any chances with a center column detracting from the stiffness that you paid all that money for.

I used my usual protocol:

  • RRS L-plate on camera base. This is not the usual way to mount the 70-200, which has its own collar mount, but it produces less image-blur from shutter shock with the a8R than the conventional mounting method using the collar, so I used it for both cameras.
  • Landscape orientation.
  • Lens zoomed to 200mm.
  • No filter.
  • The lighting: a single Fotodiox LED-200WA-56 daylight balanced variable-output flood.
  • ISO set to 1000, f-stop set to f/8.
  • Focusing using single shot autofocus. The focus point is a Siemens star on the target.
  • Drive set to single
  • EFCS on, in the case of the a7II
  • Manual exposure mode.
  • Self-timer set to 2 seconds
  • OSS set to off. On the a7II, this turns off IBIS.
  • Lamp to full, shutter to 1/1000 second, make 16 exposures with new focusing for each, turn the light down a stop, turn the shutter speed down a stop, make 16 exposures… until you get to 1/60 of a second.
  • OSS to on. On the a7II, this turns on IBIS.
  • Repeat exposure sequence.
  • Develop in Lightroom 5.7.1 with standard settings.
  • Crop, export as TIFFs, analyze for horizontal edge MTF50 in Imatest.
  • Export the results to Excel, crunch the stats, and graph.

Here’s what happens with the a7R on the heavy tripod:

a7Rheavytripod

The bold lines are the average (aka mean, aka mu) values. The lighter lines are the average value plus and minus the standard deviations (aka sigma). If the statistics are Gaussian, about two thirds of the expected results will lie between the two pair of lighter lines. Orange is OSS on, and blue is OSS off.

And here are the results on the light one:

a7Rlighttripod

You can see that the camera’s vibration affects the lighter tripod much more than the heavier one. Now let’s zoom in a bit:

Heavy tripod:a7RheavytripodcloseLight tripod:

a7Rlighttripodclose

You can see that leaving the OSS on on the heavy tripod doesn’t make much difference, but it produces materially worse results with the light tripod than leaving it off.

Here’s what the a7II — with EFCS on — looks like on the heavy tripod:

a7iiheavytripod

On the light tripod:

a7iilighttripod

The light tripod is a little worse with OSS on at moderate shutter speeds, but the difference is not dramatic at all. At 1/60, OSS on is actually a tad better.

Our test situation was a bit special. It was indoors. There was no wind. The footing was vinyl tile over concrete. Therefore, almost all the camera motion can be expected to be the result of the camera’s internal motions. Under those circumstances, a camera with large and violent internal motions like the a7R needs a much heavier tripod than one with not much internal motions that affect the exposure, like an a7II with EFCS enabled.

I probably could have guessed that, couldn’t I? Still, it’s nice to have it quantified.

 

 

 

a7R and a7II camera motion blur compared

Two days ago, I posted data for the Sony a7R and a7II paired with the Sony 70-200mm f/4 OSS FE lens. I did tests on a tripod and handheld, and with and without image stabilization. Slicing and dicing the data another way, we can see when the a7R shutter shock degrades sharpness to a7II levels, if MTF50 is your sharpness metric.

First, let’s look with both cameras on the heavy tripod, and no stabilization.

a7ra7ii

The bold lines are the average (aka mean, aka mu) values. The lighter lines are the average value plus and minus the standard deviations (aka sigma). If the statistics are Gaussian, about two thirds of the expected results will lie between the two pair of lighter lines.

The a7R starts out better at high shutter speeds, but as the shutter speed drops, so does sharpness. By 1/60 second exposure, the a7R is actually worse than the lower-resolution a7II. The a7II does not have nearly as much shutter-induced blur since it has electronic first-curtain shutter (EFCS), which I invoked for these tests.

Handheld, with stabilization off:

a7Ra7iihh

Thanks to the a7R’s shutter shock, the a7II is actually sharper at all the shutter speeds save 1/60.

Turning OSS on:

a7Ra7iihhOSS

Now you’re better off with the a7II, except at 1/1000 second, where it’s tied, and 1/500 where it’s close. The parasitic interaction of the a7R shutter shock and the OSS means that you shouldn’t use OSS on the a7R except at the shutter speeds where you really don’t need it.

Using a zoom — and using it at the most unfavorable part of its range to boot — creates a situation where the extra resolution of the a7R can’t give it the advantage that it would have at high shutter speeds with a sharper lens.

Sony 70-200 f/4 OSS lens on Sony a7II

In the previous post, I reported on the performance of the Sony 70-200mm f/4 OSS FE lens on the a7R camera, with and without OSS turned on. In this post, I’d like to present similar results for the same lens on the a7II, with and without in-body image stabilization (IBIS), and with electronic first-curtain shutter (EFCS).

Here’s the protocol:

  • RRS L-plate on camera base. This is not the usual way to mount the 70-200, which has its own collar mount, but it’s the way I mounted the a7R, and I didn’t want to make a change.
  • RRS TVC-34 heavy-duty carbon fiber tripod.
  • Arca-Swiss C1 Cube head.
  • Landscape orientation.
  • Lens zoomed to 200mm.
  • No filter.
  • The lighting: a single Fotodiox LED-200WA-56 daylight balanced variable-output flood.
  • ISO set to 1000, f-stop set to f/8.
  • Focusing using single shot autofocus. The focus point is a Siemens star on the target.
  • Drive set to single
  • EFCS on
  • Manual exposure mode.
  • Self-timer set to 2 seconds
  • OSS set to off. On the a7II, this turns off IBIS.
  • Lamp to full, shutter to 1/1000 second, make 16 exposures with new focusing for each, turn the light down a stop, turn the shutter speed down a stop, make 16 exposures… until you get to 1/60 of a second.
  • OSS to on. On the a7II, this turns on IBIS.
  • Repeat exposure sequence.
  • Develop in Lightroom 5.7.1 with standard settings.
  • Crop, export as TIFFs, analyze for horizontal edge MTF50 in Imatest.
  • Export the results to Excel, crunch the stats, and graph.

70-200a7iiOSS

The bold lines are the average (aka mean, aka mu) values. The lighter lines are the average value plus and minus the standard deviations (aka sigma). If the statistics are Gaussian, about two thirds of the expected results will lie between the two pair of lighter lines. Orange is OSS on, and blue is OSS off.

Even more so than the a7R, if you’ve got a good solid tripod, you don’t absolutely have to heed Sony’s warning to turn off OSS when you mount the camera on a support.

Now let’s do the whole thing again hand held:

70-200a7iiOSSHH1p1

Whoa! Something terrible is going on at 1/500 second (0.002 second). I checked the firmware level on the camera. 1.10. I upgraded to 1.20 and re-ran the test:

70-200a7iiOSSHH1p2

That makes more sense. The combination of OSS and IBIS (Sony says with an OSS lens mounted to the a7II, the camera will use the OSS for pitch and yaw, and use IBIS for roll, up/down and right/left) helps a tiny bit with the spread but not the mean at 1/1000, helps a bit with the mean at 1/500, helps some with both at 1/250 and 1/125, and really makes a big difference at 1/60.

Note the absolute value differences in the MTF50 scores on the two runs with OSS off. That proves that 16 exposures is not enough to give good solid MTF50 numbers for handheld exposures.

If you’re going to mix OSS and IBIS, update your firmware, folks. I know that Sony doesn’t make it easy, but it does make a difference, at least with the a7II and the 70-200 f/4 lens.

Sony 70-200 f/4 OSS lens on Sony a7R

Rishi Sanyal, one of the reviewers on DPR, mentioned that he was seeing parasitic interaction of Sony a7R shutter shock and optically-stabilized (OSS, in Sony-speak) lenses that meant that users were often better off leaving OSS turned off.

I thought I’d do some testing. I mounted a Sony 70-200mm f/4 OSS FE lens on an a7R, and put the combination through the following protocol:

  • RRS L-plate on camera base. This is not the usual way to mount the 70-200, which has its own collar mount, but has proven to be more resistant to shutter shock than using the collar mount.
  • RRS TVC-34 heavy-duty carbon fiber tripod.
  • Arca-Swiss C1 Cube head.
  • Landscape orientation.
  • Lens zoomed to 200mm
  • No filter.
  • The lighting: a single Fotodiox LED-200WA-56 daylight balanced variable-output flood.
  • ISO set to 1000, f-stop set to f/8.
  • Focusing using single shot autofocus. The focus point is a Siemens star on the target.
  • Drive set to single
  • Manual exposure mode.
  • Self-timer set to 2 seconds
  • OSS set to off
  • Lamp to full, shutter to 1/1000 second, make 16 exposures with new focusing for each, turn the light down a stop, turn the shutter speed down a stop, make 16 exposures… until you get to 1/60 of a second.
  • OSS to on.
  • Repeat exposure sequence.
  • Develop in Lightroom 5.7.1 with standard settings.
  • Crop, export as TIFFs, analyze for horizontal edge MTF50 in Imatest.
  • Export the results to Excel, crunch the stats, and graph.

70-200tripod OSS

Well, OK. Even though Sony says not to use OSS on a tripod, if the tripod is heavy like the RRS TVC-34, it doesn’t make much difference until you get to 1/60 second. Some would argue that it doesn’t make much difference even then.

Now for the interesting part. Let’s do the whole thing over with the camera handheld using the Pete Sousa grip: left palm under base, left fingers bracing the underside of the front part of the lens, elbows against chest. I use my left eye, which gets the camera a little closer to my body.

 

70-200a7ROSS

The bold lines are the average (aka mean, aka mu) values. The lighter lines are the average value plus and minus the standard deviations (aka sigma). If the statistics are Gaussian, about two thirds of the expected results will lie between the two pair of lighter lines. Orange is OSS on, and blue is OSS off.

At 1/1000 second (0.001 second) OSS is helping quite a bit, mostly be reducing the probability of blurring frames. At 1/500, it is helping a tad less. But at 1/250 and 1/60, the average with OSS on is the same as with if off, and at 1/125, it’s actually, on average, worse to have OSS on! Rishi was right. I should point of the OSS reduces the statistical spread in all cases, though.

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

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