a900 compared to Hasselblad MFDB system

Started Oct 23, 2008 | Discussions thread
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Douglas Boyd
Douglas Boyd Contributing Member • Posts: 587
a900 compared to Hasselblad MFDB system

To a900 fans,

Recent reviews of the a900 have compared it to the current crop of low-resolution DSLR cameras and the only available comparable DSLR, Canon 1DsIII. However, I have not seen a comparison to high-resolution Medium Format Digital Back (MFDB) systems. So today when my a900 arrived by UPS I decided to do an initial comparison to my Hasselblad H1 with Phase One P30 back. I had bought ther a900 as a back-up camera, and also a supplemental camera to exploit all the advantages of DSLR over MFDB (faster, higher ISO, wider range of lenses, more portable, etc.). Since the P30 has 30 megapixels (in 4:3 format), and the a900 has 24.6 megapixels (in 3:2 format), it would seem that the two systems might be fairly close in resolution.

The next photo shows my setup, in the late afternoon at Lake Jacueline in Las Vegas. On the left is the slightly tilted H1 with its standard 80mm f2.8 lens. On the right is the a900 fitted with a Minolta 24-105mm f3.5-4.5 AF lens recently received from eBay. Although this is not a prime lens, it said to be sharp up to 70mm. I did not have time to test this lens or adjust microfocus, but I assumed focus would be okay near infinity and at f8 and higher.
http://picasaweb.google.com/DouglasPBoyd/A900VsH1P30#5260166107020427586

I decided to test at ISO100 and ISO800 since this is the range of the Hasselblad system. The next picture compares the two cameras full-frame with 8-10% magnification. I set the a900 zoom to 60mm to approximate the field of view of the H1 system at 80mm. The Hasselblad is on the left, a900 on the right. All photos were converted from Raw using ACR4.6 and the same default settings. Noise reduction was turned off.
http://picasaweb.google.com/DouglasPBoyd/A900VsH1P30#5260166094272182018

Notice that the two cameras metered differently by 1/2 stop which seemed insignificant. In the next picture which is a 100% crop comparison, you can see the details of the exposure information. Note I did not use mirror lock up, although it is available on both cameras.
http://picasaweb.google.com/DouglasPBoyd/A900VsH1P30#5260166084550839010

Note the H1 image is far sharper than the a900 as can be easily seen in the pin stripe on the boat. I wonder if this could be a problem with the less than Pro caliber lens used on the a900? Or could it be due in part to an anti-aliasing filter on the a900?

The next picture compares the ISO800 results at 100% magnification. Here the a900 appears to have a slight edge in resolution.
http://picasaweb.google.com/DouglasPBoyd/A900VsH1P30#5260166099715353650

The conclusion seems to be that the a900 does not yet compete with MFDB, even an older model as I used, at this stage. Now I guess I will need to get a better lens for the alpha and test again. But in any case, it seems that DSLR is not yet competitive with MFDB in resolution, but closing the gap rapidly.

By the way, I love the a900. It is quick and light-weight. The controls are intuitive and far easier to use (and therefore not screw-up) then the Hasselblad, and my Nikon systems. The resolution is impressive, but not yet there.

Let me know if I should test something else, as I still have this setup ready to go on my deck. I do have the Minolta "Beercan" 70-200mm f4 lens, and could try this for comparison. Also if anyone is interested, I also posted the full-resolution 8-bit jpegs in the same directory on Picasso as the above images. There you can see the camera data in the header.

==Doug

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