Sony A900: A Closer Look at 24.6MP Resolution and Noise
by Wesley Fink on October 27, 2008 2:00 AM EST- Posted in
- Digital Camera
Sony A900 Full Frame vs. Canon 5D
The Canon 5D was the first "popular" priced full-frame DSLR introduced at the $3500 price for body only about three years ago. It is interesting that during the last couple of months Nikon and now Sony also offer $3000 or less full-frame cameras. The Canon 5D features a 12.8MP sensor, which is about half the resolution of the Sony A900 24.6MP sensor.
Again, the Canon 5D is compared to both same pixel size crops, and 0.5x crops which represent the same area of the image in each capture. The same pixel crops are 150x250 actual pixels captured from both images. The 0.5x crops are twice the number of pixels in a 212x353 capture that has been adjusted from the standard 350dpi to 248dpi so the crop you are viewing is approximately the same size as the crop from the 12.8MP camera.
| ISO Comparison - Sony A900 vs. Canon 5D vs. Sony A900 0.5x | |||
| ISO | Sony A900 | Canon 5D | 0.5x Sony A900 |
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| 200 |  |
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| 400 |  |
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| 800 |  |
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| 1600 |  |
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| 3200 |  |
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| 6400 |  |
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Click on any of the above image crops for the full image. Note: Full size images are between 4.1MB and 10.4MB! |
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It is very interesting that the Canon 5D internal processing is just as sharp at ISO 100-400 as the Sony A900. Beginning at ISO 800, however, you can clearly see that noise is being minimized by increasingly softening the image. By ISO 3200 the difference between noise-reduction approaches of the Sony and Canon are very obvious. The A900 output is sharper and much higher resolution. It also extends to ISO 6400 where the three year old Canon 5D stops at ISO 3200. However, in fairness the noise or grain on the A900 is so obtrusive at ISO 6400 that it hardly matters, except for small prints.
It should be clear by now that the A900 shows three distinct noise ranges in these tests. At ISO 100-400 nothing comes close to the combination of the incredible detail combined with low noise. ISO 800-1600 output is also excellent, though noise is certainly starting to impact the captured image. We would not hesitate to shoot anything up to ISO 1600. However, at ISO 3200 and 6400 noise has become a problem. Those settings are good for capturing something when you have no choice as the resolution detail is still pretty amazing, but noise is degrading the image to the point where images are only useful for smaller prints.
The announced (but not yet shipping) Canon 5D Mark II will be a very interesting camera to compare to the Sony A900 when it finally starts shipping in late November. A more detailed comparison of the Sony A900, Canon 5D Mark II, and Nikon D700/D3 is planned when the Canon full-frame update is available.
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kalow - Monday, November 17, 2008 - link
Hi Wesley,Can you confirm if your a700 has firmware 4? I looked into the exif and it says v03
Gantlett - Friday, October 31, 2008 - link
The photographed subjects in the photo reviews pose 0 challenge for my VGA camera, let alone a multi-megapixel multi-thousand $ professional DSLR.With all due respect, I think AnandTech.com should focus on computers and not photography (even if they really like digital photography...)
oldscotch - Wednesday, October 29, 2008 - link
Hi there, thanks for the update. Nice to see informed and unbiased evaluations of the s900.I just had a couple of questions about the test conditions, or maybe I missed them? Mostly, are these test results raw conversions? or are they jpegs out of the camera? Also curious what lenses were used for each camera.
I find the a900 vs. a700 test most interesting, I've been looking for a controlled comparison of the two at higher isos. The fact that the a700 actually takes cleaner shots at higher isos leaves me believing that the noise out of the a900 is largely due to its processing - meaning it can be improved upon (and there's definitely room for improvement, even with raw).
Do you know what might have caused the different colours on the a700 though?
Thanks again,
Wesley Fink - Wednesday, October 29, 2008 - link
All test shots used each manufacturer's prime 50mm f/1.4 lens (Canon, Nikon, Sony/Minolta). Test conditions are in the test introduction, but all shots at at f/4 with shutter speed varied as ISO changes. This provides a constant depth-of-field. The tripod location was the same in all shots and a shutter timer was used to minimize camera shake.As for the samples images on the last page we used the famous Minolta beer can (70-210mm f/4), a Sigma 105mm f/2.8 EX Macro, a Minolta/Sony 24-105mm f/3.5-4.5, and a 50mm f/1.4 for the various shots. You can determine the lens from this list by looking at the EXIF data in each full-sized image.
We used the Tungsten WB preset for the test shots on all tested cameras. It seems clear that the A900 and A700 have a different color temperature default for Tungsten. ALL shots used camera defaults and in-camera JPEG processing. RAW is very useful in many situations, but with a new camera like the A900 which RAW converter is the best choice for processing is very much a question mark. A couple of PROs we know who are shooting the A900 in their studio use Capture One RAW conversion software.
jamesbond007 - Wednesday, October 29, 2008 - link
As a semi-pro, I find Sony's images to be very soft. For a lens with an aperture capable of f/1.4, one would at least HOPE it would be sharp by f/4 or especially f/5.6. It is appropriate to offer a client a variety of images, including various crops. I would be ashamed if a $3,000 body and added glass could not deliver such capable images. Additionally, Sony's noise performance leaves much to be desired.Granted, while lighting is by far the most important element of photography, sharpness/AF accuracy is among my top priorities as well. Although I am sure no Unsharpen Mask or High-pass sharpening was applied to any of the sample images, Sony's still appear far softer than what I'm accustomed to.
Wesley Fink - Wednesday, October 29, 2008 - link
The results would also likely improve in sharpness if we had used the microadjust feature to tweak AF for each lens. I have seen results of the 70-210mm f/4 before and after microadjust and it certainly did improve performance, so that may also be the case with the f/1.4.We have been working with the A900 just over a week and tweaking the microadjust can be very time-consuming with lots of samples to carefully evaluate. Sony makes this even more difficult since there is no zoom or magnify feature in Intelligent preview. That feature alone would have made the micro-adjust faster.
jamesbond007 - Thursday, October 30, 2008 - link
Really, even at f/4? I've seen some slight variations with faster lenses (f/1.2-f/2.8) using the microadjustment tweaks inside the custom settings, but I really have my doubts at f/4 or even f/5.6 if a noticeable difference would be visible. Perhaps the lens you had was simply a lemon. :Pstrikeback03 - Thursday, October 30, 2008 - link
Remember, the full-frame sensor has a more shallow DOF at a given aperture value than APS-C, so if you are used to seeing shifts at f/2.8 on APS-C, that is ballpark what you can expect on FF at f/4. Check the DPreview images from the Sony and Canon 1DsIII, both sensors are high enough resolution to show parts of their test scene moving in and out of the plane of focus which all looked in focus in previous tests of lower-resolution sensors.forest23 - Friday, August 14, 2009 - link
Oh no , not someone else who believes that putting a lens ona half frame camera gives greater depth of field. But see Coxes Optics
1974 pages 68-97
Wesley Fink - Thursday, October 30, 2008 - link
The Minolta 50mm f/1.4 is the same lens used in noise tests of the Sony A700 and the past review of the Sony A200. We have 50mm f/1.4 lenses available for all tested brands except Olympus/Panasonic. Because of the 2X lens factor we use an Olympus 35mm Macro lens as the test lens for 4/3 cameras.