Comparing FF vs. APS-C

[Jon Ruyle]

to compensate for the narrower apertures, I increased Speedlite power.

You mean you gave the 5DII more light? Or do you mean you let the meter decide?


To make a fair comparison, each camera should get the same amount of light. So the shutter speed should be the same in ambient light, or the speedlight should be set to some fixed *equal* output value rather than relying on the meter. The 5DII will probably require a higher ISO to expose reasonably.


I don't think you stacked things in favor of the 5DII by using different shutter speeds, but if you let the meter decide, you ultimately allowed the meter of each camera to decide how much light to give the sensor. This could lead to a largeish difference one way or the other (I have no idea which way the bias would be, though)


If you told the flash to give the 5DII more light to compensate for the smaller aperture, you stacked the test heavily in favor of the 5DII. (I don't think you did this, though, because the 5DII would appear brighter if you had... after all, you already mostly compensated for the narrower aperture with ISO)


Unless the DXO Mark guys screwed up, the 7D should come out ahead in this comparison. It has lower read noise and lower photon noise.

[HDNitehawk]

Unless the DXO Mark guys screwed up, the 7D should come out ahead in this comparison. It has lower read noise and lower photon noise.

Jon


I haven't looked at the DXO guys data. But just from using the cameras I have it is very evident to me that in equal situations the 7D has more noise than the 5D II. As well the 1D IV has less than the 7D. The 1D IV seems to be close to the 5D II in this respect, but I can sense a slight edge with the 5D but not enough to notice or matter.


It might be worth looking at how DXO did their comparison to see if it is legitimate.

[Jon Ruyle]

But just from using the cameras I have it is very evident to me that in equal situations the 7D has more noise than the 5D II.

By "equal situations", do you mean equal f-numbers, or equal in the sense John did his experiment (with the larger sensor stopped down)? At the same f-number, the larger sensor of course has a major advantage.

It might be worth looking at how DXO did their comparison to see if it is legitimate.

The DXO description of their tests looks good to me, but that does not mean they did not make mistakes.