I don't own a normal lens for my old Sony A900—I used to use it as a portrait camera with an 85mm. Recently I had the idea that a new lens might breathe new life into the old beast. And I had never tried the Sigma 35mm ƒ/1.4 Art that's been getting so much positive attention since it came out in 2012. So I thought I'd put the two together and see what happened.
At the same time, I wanted to try the Nikon D750 and the new Tamron SP35mm image-stabilized lens.
The lightbulb lit up, and I decided to ask LensRentals for two identical Sigma Arts—one for the Sony and one for the Nikon. (Shown above, on the cameras.) That way, not only could I see how the Sigma did when paired with the Sony, but I could see for myself how the Sony's aging sensor stacked up against a newer sensor with the same pixel count in the Nikon (both are 24-MP full-frame DSLRs). I also reasoned that it's the kind of "test" (I call them trials or tryouts—I don't work hard enough for them to be called tests) that isn't often done on the Internet. Most Internet reviews are of equipment when it's new. So if read a review of the A900 from 2008 and a review of the D750 from this year, both will talk about the sensors and the image quality in terms of the standards that prevailed when the reviews were written. It's difficult to get a clear picture of how older things stack up against newer ones.
The weather hasn't been good until today (I'm going to get out to shoot very soon) but here's a rainy-day trial intended to stress exposure range a.k.a. dynamic range. Shot at ISO 800 with both cameras.
The Sony needed quite a bit of noise reduction (NR), here applied to make the large file look good. But I was surprised at how pretty the result was.
The Nikon needed less noise reduction in the shadows and retained slightly better detail around the light; it was also noticeably easier to work with and had more flexibility in responding to the controls in ACR. I'd call this a win for the newer sensor. But not overwhelmingly; the Nikon doesn't kill the Sony as I expected it might.
Here's another attempt to find an extreme of highlights and shadows despite the overcast weather—a darkened interior with a window. At ISO 3200, I let the Nikon pick the exposure and manually set the Sony to match—ƒ/5.6 at 1/10 sec. Out of the camera the scene looked like this:
Then for each picture I HDR'd to the max: –100 highlights, +100 shadows in ACR.
To my surprise, the Sony result wasn't half bad. Detail out the window was very good in particular, although that could be due to the vagaries of exposure, which is never exactly identical whether at the mechanical or the electronic level.
The Nikon did better in the shadows, although I feel the Sony result is more true to the "feel" of the real situation as I experienced it, for what little that's worth. (That kind of judgement is called a "perceptual" appraisal. Once you determined that's what you wanted, you could probably match with the Nikon.) It looks to me like the Nikon just exposed a little more for whatever reason. The Sony might also be biased toward greater highlight detail, something I've long suspected just from using it (and probably the reason I liked it).
But then here's a pretty clear difference:
(You'll be seeing it at 100% after you click on it.) That's a detail of the noise from the Nikon file, captured as a screenshot from ACR. You can see "grain," but bear in mind this is ISO 3200 boosted +100 in the shadows, with no added noise reduction (NR). You could clean and sharpen this up a lot further.
This is the same thing from the Sony file. And bear in mind that Sony's engineers baked some NR even into the RAW files (we can turn to Imaging-Resource again for a good discussion of sensor NR—although I sure wish they'd date their articles).
This probably makes you remember how obsessed everyone was with shadow noise during the middle years of the decade of the 2000s, and why. The Nikon example makes you realize why it's no longer such an issue.
Result of this trial: the Sony did better than I thought it would, but the Nikon's sensor is clearly better. As I recall, I used to limit the A900 to ISO 1600 in real shooting.
But now here's a different situation, one where the old Sony actually came out on top:
Here's the shot. I was wandering around with both cameras focusing back and forth from near to far objects to get a handle on focusing speed for the kinds of things I shoot. (Verdict on that: the Nikon's faster but it's mainly noticeable when the lens has a longer way to rack. The A900 is Alydar, always second but running a good race. I was never bothered by the Sony's focusing speed.)
Here's the detail from the Nikon test shot. You'll notice that I managed to handhold 1/10th of a second with the unstabilized Nikon in the window shot above, but here, at 1/25th of a second, I've gotten just a slight amount of camera shake. (This is a degree of camera-movement degradation most shooters would have been unaware of in the film years, by the way, before we could easily examine detail at such high magnifications.)
Look at the same detail from the Sony:
(Again, if you click on these you'll see them at 100%.) Much sharper. Note the bluish blotching in the black block letters, though.
I added a little speed for the Nikon shot so I could more easily hand-hold it—1/25th vs. 1/10th. There's certainly the possibility that I merely happened to hold the camera more steady for the Sony shot; in the window shot above, I handheld the Nikon at 1/10th and I don't see any motion blur. But given that the Sony shot here is at 1/10th and I can't handhold 1/10th as a rule, I'm going to credit the Sony's IBIS for the sharper result here. That has not been demonstrated by this single test, but that's my story and I'm stickin' to it.
One for the old guy.
Tentative conclusion for now
It appears from my few comparisons (these and several more) that the Sony sensor in the D750, with Nikon's processor and implementations, is superior to the then-groundbreaking Sony 24-MP sensor from 2008, mainly in the area of shadow noise and high ISOs—and it appears to have more in reserve for manipulation in post. But just as nine-year-old Lulu-dog occasionally gets to the ball first by being clever, despite two-year-old Butters' youthful strength, speed, and agility, the Sony still has a trick or two up its sleeve. The A900 is still in the game. (Lulu has a ton of heart too. She's always game.) So far, the Sony is losing but putting up a decently impressive fight.
I should add the possibly apocryphal admonition of the old Leica lens designer: "all tests are just shortcuts. The way to really get to know a camera is to use it for a year."
I got outside today and shot a bunch of stuff with one camera after the other. If there's anything to talk about from those comparisons I'll get to it this week. I have another reader portfolio review tomorrow (Monday), which I'm looking forward to.
(Thanks to Ctein)
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Featured Comments from:
Ulf Aagerup: "It’s great to see a sober comparison of cameras from different generations. The idea that photos from old digital cameras is comparable to those from new ones is interesting, and in line with my experience. I have the EOS 5D and the 5D Mark III. I prefer the look of the original’s files. I also prefer the look of the Fuji X100 compared to that of the later versions, and the X-Pro 1 files compared to the latest Fuji Xs. I don’t know why this is the case. If it were not for the newer cameras’ superior handling, I would be happy with my old cameras."
Mike replies: There was something sweet-spotty about that original 5D. I know what you mean about the files—they looked great, and no one could ever quite figure out why. Black-and-white conversions, too. A landmark camera for Canon, in several ways.