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 vs. Nikon D700
Before we begin our noise comparisons we asked the question, "How do you actually compare a 12MP full-frame sensor to a 24.6MP full-frame sensor?" This question is important since the same image shot with the A900 from the same position with the same lens will contain twice as many pixels in a given picture area than an image shot with a 12MP sensor. This was a moot point when image resolution went from 8 to 10MP or 10 to 12MP, but the Sony sensor is double the resolution of competing full-frame cameras and the question becomes more important.
Any who have printed large images from a digital file will immediately understand our question. It is very clear that a larger noisy image when printed smaller often looks like it has very low noise. This is why we often say noise would be good enough for small prints but not for big enlargements. The noise becomes more apparent as the image size is increased.
Our tests didn't land on either side of this issue. Instead the decision was made to provide both same pixel size crops and 0.5x crops; the latter represent the same area of the image as the 12mp cameras 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 12MP camera. That is the reason for the two crops for the Sony A900. The regular view is a pixel-level 150x250 crop, while the 0.5x is a double the pixels crop adjusted for the same image area as the 12MP crop. We will leave it to you to decide which is the more relevant of the two crops for the A900.
| ISO Comparison - Sony A900 vs. Nikon D700 vs. Sony A900 0.5x | |||
| ISO | Sony A900 | Nikon D700 | 0.5x Sony A900 |
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| 25600 |  |
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Click on any of the above image crops for the full image. Note: Full size images are between 3.2MB and 10.4MB! |
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The Nikon D700, which was introduced just a couple of months ago, uses the same full frame sensor used by Nikon in the $5000 D3. The incredibly wide ISO sensitivity range to an expanded 25600 is also maintained, but the price has been reduced to just below $3000. The Nikon D700 also features one of the fastest burst rates in the full-frame class at 5 FPS, and that can be extended to 8 FPS with the battery grip powered by the Nikon Pro battery or six AA cells.
Looking at the 0.5x samples for the A900 it is hard to escape the fact that looking at noise alone the Nikon D700 is about two stops better than the A900 in high ISO performance. The D700 ISO 6400 output is very similar in noise to the A900 at ISO 1600. Similarly, the A900 ISO 3200 and 6400 compare to the D700 ISO 12800 and 25600. Noise is only part of the A900 story, however. If you look closely at the amount of detail in the A900 crops and pixel peep the full images, you will see the A900 captures more detail than the D700 - even at high ISOs when noise begins to intrude in the A900 images.
The high ISO performance of the Nikon D700/D3 sensor, as everyone already knows, is without equal. That should not come as a surprise since the pixel density of the Sony A900 is double the Nikon D700. On the other hand, nothing currently on the market really comes close to the resolution and detail captured by the A900 sensor. Those who thought 24.6MP would make little difference are just wrong, as the increase in captured detail is very clear.
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CEO Ballmer - Monday, October 27, 2008 - link
These things are very nice, but the ZuneCam will prove they are waaaaay over-priced!http://fakesteveballmer.blogspot.com">http://fakesteveballmer.blogspot.com
strikeback03 - Monday, October 27, 2008 - link
I'm guessing default settings in JPEG. Which is a valid baseline, but given different manufacturers different philosophies on JPEG processing, makes commenting on apparent sharpness of the image somewhat difficult. Also, was any form of dynamic range expansion turned on? I'm surprised at how much color noise is already appearing in the A900 shots at ISO 400, wonder if it is a result of boosting some shadows?As you guys are buying your test bodies, I can understand not having a 1DIII, but making statements such as "At Lower ISOs, 100-400, nothing on the market comes close to the Sony." seems a bit odd without at least trying it against a body with 86% of the pixel count. And obviously if those in the market have the means to get a medium-format back and associated gear, you are far beyond the capabilities of the A900.
Wesley Fink - Monday, October 27, 2008 - link
Yes, default settings were used in all parameters, including dynamic range expansion. We tried to be careful to say compared to others in its class, which is obviously full-frame 35mm-size sensors. We have not compared any of the full-frame cameras to medium forma or anything like the new Leica medium format that uses the Kodak sensor, nor do we plan to.As for comparisons to the 1Ds Mark III, the comments were based on conversations we had with Pros who have shot both the Sony A900 and the Canon 1Ds III. We also looked at images shared with us by a couple of them. We would be more comfortable with our own hands-on with the $8000 1Ds III but that will be a moot point once we have the 5D Mark II. Canon claims the 5D II sensor, with the same resolution, is superior to the 1Ds III so we will soon get our first hand look.
melgross - Monday, October 27, 2008 - link
Some odd conclusions both here and DPR.One thing that stands out here though, is the strange notion that with all the noise, the higher resolution is of any use.
I don't know of anyone who wouldn't control noise with noise reduction once it reaches the levels of the a900 at ISO 800. Even 400 isn't great, just ok.
Once that is done, the higher resolution will be no better than anywhere else. The more noise, the more noise reduction, the less detail.
It would have been more interesting if noise reduction was applied to see the effects of bringing it in line with the other cameras. Where would the detail have gone?
In addition, if noise is so high at higher ISO's, as it is, making smaller prints so as to not see it, would also mean making smaller prints than would allow you to see the higher resolution as well. No gain, no pain.
I also find it interesting that field reports about this camera from both DPR and the Luminous Landscape have agreed that real-world pictures show less detail that the Canon 1Ds mkIII. The high detail is smeared because of the non removable noise reduction done before the A/D converter (as opposed to the noise reduction that can be turned off after the A/D converter.
The subject used for the comparisons is also pretty bad. I'm sure something more suitable that that could be found.
JarredWalton - Monday, October 27, 2008 - link
I shoot plenty of objects at ISO 100-400, sometimes using a tripod. In such cases, the differences between 12MP and 26MP will definitely be apparent. That said, I don't do print work and will just end up cropping and resizing down to a manageable resolution. Still, for details of a motherboard as an example, that increased resolution could be very handy.As for the subject matter of the ISO comparisons, I'm of the opinion that as long as it's static (i.e. the same in each review) it serves its purpose. We've all seen the various chart photographs (which are widely available elsewhere), but I suppose Wes can reproduce those if necessary. I just don't see how it makes much of a difference one way or the other; the sample images at the end do a good job of showing other possibilities with the camera, and personally I think some of the images look very nice indeed. Just stay away from ISO 800 or higher if possible.
strikeback03 - Monday, October 27, 2008 - link
My complaint with the ISO image subject is a lack of anything to help differentiate between good NR software and a low-noise sensor. With a test image composed almost entirely of smooth single-color areas, good NR software could make those pretty smooth while maintaining the borders between colors. A subject with more detail makes it harder to just blur noise away without seeing the results in detail captured.haplo602 - Monday, October 27, 2008 - link
and on a color checker chart you can evaluate sensor performance in high ISO for colo/saturation drifts ... this cannot be seen on the current simple 3 color test target ...LTG - Monday, October 27, 2008 - link
This review kept reminding me of the DPReview.com review of the same camera.It's definitely different works, but the emphasized points are very similar like choosing to commend sony for lack of gadgetry.
I guess that fine we all build thoughts from some starting point - but I'll eat my left shoe if the author didn't read the dpreview article before writing this.
yyrkoon - Monday, October 27, 2008 - link
You know, you could have just as easily not left a comment at all.No one really cares what your thoughts are on web plagiarism . . .
Wesley Fink - Monday, October 27, 2008 - link
Plese read my Sony A900 Preview where I praise the same points long before dpreview published their review of the Sony A900. We all read other reviews but I have no problem reaching my own conclusions.