Hi,
I got my Sony Alpha 900 in december 2008, and I was surprised at that time how well my pictures from the 12 MP Alpha 700 in APS-C held up to the full frame Sony Alpha 900. At least in one of the early test shots I could no observe any difference between the 12 MP Alpha 700 and the 24 Alpha 900. The difference in file quality was impressive, but in A2 size prints, the difference was nil. I tested that shot on quite a few observers.
Since that time I have repeated that kind of test many times. Essentially I found that 12 MP are adequate for A2 size prints, with 24 MP offering a small advantage
if the stars are in proper alignment. For instance at one time it was windy and dark. On the Alpha 900 I didn't want to use high ISO, but with the Alpha 55 (16 MP APS-C) I could risk a bit higher ISO, I also had live view so I could have pin point focus, so I could use a larger aperture, and because of the crop factor I could use my 24-70/2.8 instead of the 70-300/4.5-5.6.G.
In the final evaluation the A2 print from the Alpha 900 was a bit sharper when viewed obscenely close, but the Alpha 55 picture had a better DoF and was sharper overall because of the larger aperture and the shorter exposure time.
Now that I have the P45+ I found a similar experience. The images from the Alpha 99 are good enough and although the files from the P45+ are better most of the advantage is lost in print.
Now, what we see in print is depending on eyesight. I have 20/20 vision with corrective glasses, and it is my understanding that you have 20/14. I am near sighted so I can focus quite close without glasses, and I still don't see differences in A2 prints, but I can clearly observe differences with a loupe. What I would see with younger or better eyes, I cannot tell.
In general, I try to verify my findings with friends and colleagues but they tend to be of similar age than me.
Getting back to the lenses, I have a few of them.
What I use mostly is the 24-70/2.8. It is weak in the corners at 24 mm, but I seldom have an issue with that. At the long end it seems to loose a lot of sharpness of axis, but is still mostly OK. I have also a Sigma 12-24/4.5-5.6 (I think), a Samyang 14/2.8 which happens be one of the sharpest lenses I own, but with an awful distortion. The Minolta 20/2.8 is sort of acceptable, but I feel it needs to be stopped down to f/11 for good corners. It is a bit better in the corners than the 24-70/2.8 but I may feel the 24-70/2.8 may be more "snappy".
I also have a 28-70/2.8 Minolta (made by Tamron). Little doubt it outperforms the 24-70/2.8 "Zeiss" in the corners at large apertures. For some reasons I use the Zeiss. The SSM and the "Zeiss" label may be part of that. I don't know…
When I got my Alpha 77, I found that neither of my zooms, the 80-200/2.8 or the 70-300/4.5-5.6G were good enough, so I bought the 70-400/4-5.6G. In initial tests it performed similar to my 400/4.5 APO. I was quite happy with that lens as I could handle weight limits when flying.
With the Hasselblad 555 I have now I have 5 lenses:
- Sonnar 180/4 CFi, excellent across the field. Only issue is a lot of longitudinal chromatic aberration (LoCA)
- Macro Planar 120/4 CFi, main problem is field curvature needs to be stopped down to f/11 - f/16 at infinity. A bit low contrast? *)
- Planar 80/2.8CFE, very good at center but dismal in the corners, at least what I see now.
- Distagon 50/4 FLE, a bit soft, possibly
- Distagon 40/2.8 FLE, I don't know, sometimes very sharp sometimes not. I guess field curvature is part of the explanation.
I'm mostly shooting with those lenses and not doing that much testing.
My findings agree decently well with published MTF data from Zeiss and Hasselblad. I guess that it was one of the reasons Hasselblad chose to design their own lenses for the H-series.
It seems that Zeiss made a couple of new lenses for the Hasselblad, including the Distagon 40/4
IF which is dramatically improved over the older designs. I am interested in that lens. Another interesting lens is the 100/3.5 which is extremely well corrected. The 100/3.5 is an older lens.
Best regards
Erik
*) I have switched quite a few of my lenses. First I had a Sonnar 150/4 CB but later I found that I preferred the CF designs. So I upgraded my 150/4 CB to 150/4 CF. Later I felt that I used the 120/4 a lot, and found that the 150/4 was a bit to close so I replaced it with an 180/4CFi. I have a very helpful dealer ;-) The aperture in my 120/4 had issues, so I replaced it with the 120/4 CFi, which according to Zeiss (but not their MTF data) is much better. If it is better I still need to find out.
If I may come back to your article and questions.
As I said: I have been printed in A2 size from the Sony A900 for the past 3 or 4 years. The results are generally very good. Therefore your article does not come as a surprise.
From the photographs you have posted, you seem to be mainly interested in landscape photography. With landscape photography and your A99, the only defect anyone is likely to notice on A2 prints would be lens defects, because 35mm wide-angle lenses are rarely perfect. If you limit yourself to the following wide-angle lenses, you will have excellent A2 prints:
-the Sony Minolta 20mm at f/8, if you correct lateral chromatic aberration
-the Sony Zeiss 24mm from f/4 onwards.
-your Sony Zeiss 24-70mm between 35mm and 50mm at f/8.
Under these conditions, your A99 will give A2 prints which will be as good as anything from a MF camera.
The difference with a MF camera will only show:
-on landscape if you print larger than A2 and look at the prints from the same distance
-on portraits or generally tridimensional subjects with limited depth of field, because the bokeh is different. On this subject I should add that classic Minolta lenses and some lenses like the Sony Zeiss 24mm already have very good bokeh, so that the difference may not be dramatic.