DXOMARK.com, did you notice

Started 11 months ago | Discussions thread
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Re: DXO scores are like MTF charts
In reply to Anders W, 11 months ago

Anders W wrote:

Ulric wrote:

Anders W wrote:

I see no principal reason why a 150 mm lens with an MFT image circle could not behave as a 300 mm lens with an FF image circle (at the same f-stop). What would that be?

If the comparison is performed at the same f-number across formats, the behaviour will not be the same for any non-flat scene.

I know. I just mentioned the comparison for which I'd expect pretty much the same design challenges and therefore pretty much the same performance (at any given level of ambition and until we enter serious diffraction territory for either format).

If, instead, we compare at equivalent f-stops, I'd expect FF to be ahead by an amount varying with the point at which we compare as follows: virtually nil at f/8 (MFT) versus f/16 (FF), barely noticeable at f/4 versus f/8, noticeable but not very significant at f/2 versus f/4, and pretty dramatic at f/1 versus f/2.

If the shutter speed and ambient light are also kept the same, interaction with the sensor performance should have an impact on the results. But I haven't been paying enough attention to the DxO lens tests to know if they do that or not.

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