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. Sony A700 APS-C
The Sony A700 uses the same 12.3MP sensor featured in the Nikon D300, but it was not as well received as the D300 when it was introduced. The main complaint was the poor quality of Sony's built-in JPEG processing and the fact that noise reduction (NR) could not be turned off in RAW mode. Sony has addressed the early criticisms with several firmware upgrades that have finally culminated in firmware Version 4 which was released at the same time as the A900. With firmware v4 the Sony JPEG processing is finally competitive with other top cameras, noise algorithms are more competitive, and you can finally adjust or turn off NR in both RAW and JPEG modes. Many consider output of the Sony A700 with v4 firmware finally to be competitive with the well-regarded Nikon D300.
Since high ISO noise is now much better controlled in JPEG mode on the v4 A700, it should be interesting to compare noise over the range of ISO adjustments to the Sony A900 full-frame. Even though the A700 is an APS-C size sensor, resolution at 12.3MP is about the same as the Nikon D700 and the Canon 5D. The actual view of a 150x250 pixel crop will be about the same as the Nikon D700 or Canon 5D.
Once again, we compare the Sony A700 to both same pixel size crops, and 0.5x crops that 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 which 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 12.3MP camera.
| ISO Comparison - Sony A900 vs. Sony A700 vs. Sony A900 0.5x | |||
| ISO | Sony A900 | Sony A700 | 0.5x Sony A900 |
| 100 |  |
 |
|
| 200 |  |
 |
|
| 400 |  |
 |
|
| 800 |  |
 |
|
| 1600 |  |
 |
|
| 3200 |  |
 |
|
| 6400 |  |
 |
|
Click on any of the above image crops for the full image. Note: Full size images are between 6.6MB and 11.4MB! |
|||
The resolution of the A900 sensor is astounding, but there is no escaping that it is also an inherently noisy sensor at high ISO. This is especially evident in comparing the A900 noise tests to the 12.3MP APS-C sensor used in the year old A700. This is the same sensor used in the Nikon D300 (and the new Nikon D90), and our A700 test shots were with a camera using the latest v4 firmware.
If we pixel peep the ISO 1600 output of the A900 is about as noisy as the ISO 6400 output of the A700, which came as quite a surprise. Since sensor density is a bit lower on the 24.6MP A900 than the 12.3 MP A700 this was not expected. If the comparison is made to 0.5x A900 crops the noise advantage for the A700 is still more than a stop. The only conclusion is that the A900 sensor is inherently noisier than the latest refinements of the A700, or that Sony can lower noise in the A900 further with firmware/software updates. It is also interesting that the Sony A900 tungsten color balance is much warmer than the tungsten balance of the A700.
Please do not misunderstand these conclusions in looking at pixel-level crops from JPEG test images. There could be other variables at play. However, Sony has trumpeted the v4 firmware for the A700 as incorporating all they learned in developing the A900. That leads to the assumption that processing should be very similar between these two Sony cameras. Provided that is the case the A900 sensor is noisier at high ISO values than the A700 sensor by at least one stop once the resolution differences are accounted for and two stops in pixel peeping.
If you look closely at the A900 images, there is also no escaping the incredible detail captured with the 24.6 MP sensor. Even with increased noise at higher ISO the captured detail is stunning.
Facebook
Twitter
RSS
45 Comments
View All Comments
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.