Our 12-35mm preview updated with samples

Started May 21, 2012 | Discussions thread
Anders W
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Re: False!
In reply to Steen Bay, May 21, 2012

Steen Bay wrote:

Anders W wrote:

Comparisons of apertures across always formats tend to lead to the same needless misunderstandings.

As some of you try to say, f/2.8 is always f/2.8 from an exposure point of view.

And as some of you try to say, f/2.8 on MFT is not the same as f/2.8 on some other format from a DoF or light accumulation point of view. From those two points of view, a 12-35/2.8 on MFT is equivalent to a 24-70/5.6 on FF.

So you are both right.

I might add that the reason why light accumulation is important is its impact on image noise. A 24-70/2.8 used wide open on FF will accumulate four times more light than a 12-35/2.8 used wide open on MFT. Consequently, the FF image will show less noise given equivalent sensor technology.

Yes, in terms of exposure f/2.8 is f/2.8, and also in terms of lens design (it's just as difficult to make a good f/2.8 mFT lens as it is to make a good f/2.8 FF lens), but in terms of noise, DoF and diffraction f/2.8 on mFT is equivalent to f/5.6 on FF.

Yes you are basically right about the lens design issue too, although I have seen some suggestions that a smaller sensor might have certain advantages compared to a larger one here. But certainly not two stops worth of advantage.

Does that make a f/2.8 mFT lens 'slower' than a f/2.8 lens on FF? Well, that's probably open for discussion, but I'd prefer to say that f/2.8 lenses are equally 'fast' on all formats

So do I, although it is of course worth keeping the equivalence stuff (what is comparable in terms of DoF and light accumulation) when comparing across formats.

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