Rethinking 4/3 Depth Of Field

Started Apr 11, 2013 | Discussions thread
Great Bustard Forum Pro • Posts: 41,999
Re: Lovely pix and excellent presentation of your argument

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

My definition of "not very good" is something like "significantly worse than peak performance".

Hmm.  My definition of "not very good" would be more like "doesn't deliver desired results".

I am not sure the two definitions are very different.

I'm thinking they're rather different, actually.  For example, consider two lenses:  a 50 / 1.4 and a 50 / 2.8.  Both lenses peak at f/4 and have the same resolution stop-for-stop, but the 50 / 1.4 is significantly softer wide open than the 50 / 2.8.  It seems to me that your definition of of "not very good" would make the 50 / 2.8 a superior lens to the 50 / 1.4, whereas I would consider the 50 / 1.4 the superior lens, since it could do everything the 50 / 2.8 could do, and more.

I think you "derailed" a bit here Joe. What we were talking about was not my definition of "not very good" but my definition of "not very good wide open". While the 50/2.8 would be better than the 50/1.4 wide open although not necessarily a better lens for the reason you point out, that's slightly beside the point here. So let's backtrack.

Hen3ry said that you needed expensive lenses for that razor-thin DoF with FF. You objected that there were quite a few fast primes for FF that aren't particularly expensive. And I objected that many of those were'nt very good wide open whereas most of those available for MFT are. So we're talking about differences between fast primes, not fast versus slower primes.

Have a look at these

versus these

That said, as your images convincingly demonstrate, it is certainly possible to take excellent pictures with the not so expensive Canon lenses you exemplify, at least under certain conditions. One reason why I have become more picky when it comes to wide-open performance is that with MFT, the likelihood that I would want to shoot wide open is, for obvious reasons, significantly greater than it was when I shot FF (film).

What I'm saying, for example, that simply because 50mm f/1.4 on FF isn't as sharp as 25mm f/1.4 on mFT, it's no hit on FF, since 50mm f/1.4 on FF is equivalent to 25mm f/0.7 on mFT.  Now, if 25mm f/1.4 on mFT were sharper than 50mm f/2.8 on FF, absolutely, I'd agree with you.

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