What the 35 / 2 IS has done for me, and, more specifically, Canon.

Started Nov 6, 2012 | Discussions thread
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bobn2 Forum Pro • Posts: 48,872
Re: Not that big of a difference, however.

Great Bustard wrote:

ultimoamore wrote:

Great Bustard wrote:

Pultzar wrote:

Not to mention that 35mm 1.4 isn't 100% efficient anyway (they boost the signal digitally)

Yes, due to inefficient microlenses, f/1.4 does not put a stop more light into the photosensitive area of the pixel as f/2. For the 5D2, it looks like a 0.1 stop loss of light at f/2 vs a 0.4 stop loss of light at f/1.4, thus f/1.4 gives a 2/3 stop advantage over f/2 rather than a full one stop advantage.

How it works out with the 5D3, with its new microlens design, however, would be interesting to see. I imagine that it's not that much different.

Does this "loss of light" applies to DOF too? That is: is 1.4 "really" 1 stop less DOF than 2.0, or for the same effect it's not that much? I'm confused by this " inefficient microlenses" thing...

You know, I'm not entirely clear on that point, but Bob has said that it necessarily applies to DOF as well. However, given that f/1.4 is effectively 2/3 of a stop faster than f/2 as opposed to a full stop faster than f/2 on a 5D2, I imagine that 1/3 stop difference, both in terms of DOF and noise, would be rather hard to see.

The effect is caused by the microlens 'seeing' a reduced portion of the exit pupil, reducing the effective angle of the ray cone. Since the DOF depends on the angle of that ray cone, it increases DOF also.

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