I recently bought my first FF DSLR an Sony Alpha 900 with a Sony SAL 24-70/2.8 ZA lens. I had some doubts before buying and I want to share some initial experience.
To begin with the image quality is impressive. There has been a lot of discussion about the high ISO quality (or lack thereof) of the Alpha 900 images. High ISO shooting is not what I normally do, and I cannot compare to other DSLR's but I share the impression that the Alpha 900 is less than optimal for high ISO work. Regarding the 24-70/2.8 my personal impression is that it is much better at shooting real life pictures than test charts. My guess, based on testshots, may be that it has less than ideal flat field corner performance at close distances but I'm not in the lens testing business so I won't evolve in commenting that.
The real question for me was if I would see a benefit in sharpness from the Alpha 900 over the Alpha 700. I felt that the Alpha 700 was good enough for reasonably good A2 prints. So the two questions I had was how much better A2s I would get with the Alpha 900.
Three different comparisons were made. The first was based on downloaded images "Imaging Resource", for the Alpha 700 I only found JPEGs, but I found "raw" images for the Alpha 900. I made A2 prints from these. Initially I couldn't tell them apart, later I learned to see the difference and could tell them apart from 1 meter distance.
When I got the camera, but without the 24-70/2.8 lens I shot a comparison with my Alpha 700 with a similar result. First I had difficulty to tell my prints apart, after learning to see differences I could tell them apart with some reliability.
In the third comparison I photographed a large painting on display at a parking lot. It contains a lot of fine detail. First I was doing some pixel peeping. Both images were scaled to 70 cm width at 360 PPI that is 9920 pixel wide using bicubic softer. The images were compared in PS CS3 at actual pixels. The difference in the image quality was striking. http://www.pbase.com/ekr/image/107619976/original
(A900 to left and A700 to the right)
Now I cropped the image into half and printed on A4 which corresponds to A2 for the full image and printed from Lightroom 2.1 (because 2.2 doesn't work for me ) on my Epson SP 3800 at 2880 DPI. Settings in LR were Landscape Preset capture sharpening,
480 PPI output and medium sharpening for glossy.
The result was that I could not see any difference, period!
Both prints were scanned at 300 PPI and compared in Photoshop at actual pixels. Here I could see a significant difference.http://www.pbase.com/ekr/image/107823207/original
Yesterday I asked a couple of colleagues to check out my prints. Like me they could easily tell apart my first test but not the second one. On the second sample (based on the painting) my elder colleague who has much experience of professional printing, as he worked at one the best professional labs in Sweden, actually preferred the A700 print which according to him might give a sharper impression. He also pointed out that the A700 print had slightly higher contrast and was more bluish, a difference lost on me. My friend also explained that the higher contrast can make a print look sharper.
When we compared the scanned images on screen we all agreed that there was a significant difference.
The conclusion from this very limited testing my be that:
1) APS-C and 12.5 MPixel sensor with good technique can give nearly optimal A2 prints.
2) Technique and subject may play a significant role, some subjects may be more critical than others
3) There is no doubt that the images from FF and 24.5 MPixels contain more and better detail, the question is if it can bee seen in a print
4) FF and 24.5 MPixels allow for more cropping and larger prints
The difference between APS-C and FF was in this case less than what I would have expected. Possible explanations may be that the Alpha 700 may have a very weak AA (Anti Aliasing) filter. This may be indicated by the extremely high "extinction resolution" reported by "DPreview" for most Sony Alphas. Another explanation may simply be that Lightroom does a very good job on scaling and ouput sharpening.
Some high res sample pictures from the Alpha 900 are available here: http://www.pbase.com/ekr/a900_samples
Here are some: 24-70/2.8 ZA test pictureshttp://www.pbase.com/ekr/2470za_test1
And some Konica-Minolta 28-75/2.8 test:http://www.pbase.com/ekr/km_28_75_test
All samples are in full size JPEGS, to see full image click on "original" size button below the picture.
I hope that this info may be helpful for some people considering full frame in general or specially the Alpha 900.
You may also check this excellent article by David Kilpatrick: http://www.photoclubalpha.com/2008/10/16/d...d-an-alpha-900/