A77 vs A900 at 400 focal lengths (the "BIF case")

Started Oct 29, 2011 | Discussions thread
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Nordstjernen Veteran Member • Posts: 6,876
A77 vs A900 at 400 focal lengths (the "BIF case")

How should photographs from the A77 and A900 be compared? Using focal lengths so that the field of view is equal, or use the same focal length? Or compare pixel by pixel?

For most of my photography, field of view is the key. I am looking at a scene and then decide what I want to include in the frame. Next I find a position for the camera. Then I pick a focal length to frame the scene.

Then I am doing some birds in flight shooting too. For this I use my Sony 70-400 mm G lens, mostly at the long end, no matter if I use a full frame camera (A900) or an aps-c camera. For this kind of photography pixel density is more important than sensor size, since the subject will just fill a certain area, no matter how large the sensor is. Higher pixel density means more detail. This is what I name "the BIF case", and what this test is about.

The lens, Sony G 100-400 mm f:4-5.6 zoom lens, was zoomed to the long end for both the A77 and the A900. The lens was supported by two heavy tripods, and a cable release was used for the cameras. Exposure 1/30 sec at f:8. ISO was set to 200 and white balance to Daylight. Lightroom was used to open the RAW files. The gear was put outdoor some time before my test to eliminate focus shift caused by differences in temperature.

My conclusions after evaluating the results on my computer screen and prints:

  • When scaled down to A900 size, the results are equal

  • When scaled up to A77 size, the A77 files show more detail

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