Diffraction Limit

Started Aug 28, 2013 | Discussions thread
Great Bustard Forum Pro • Posts: 41,787
Re: Yep.

Dr_Jon wrote:

Not arguing because you agree - indeed, the tone of my voice didn't get conveyed well there!

Them's fightin' words, Mister!  Draw! 

The rest of this should all be vocalised in a laid-back and light conversational tone...

I'd disagree with the smaller format always being better.

"Almost always better for the same DOF and shutter speed" -- very important qualifications for my statement.

It's usually lighter, which is good, but I still see noise and/or noise reductions artifacts at base ISO on the GH3 which are simply not there on the Canon FF. Not that I can't get great shots with the GH3...

The advantages of the larger sensor system come from the use of more shallow DOFs and/or longer shutter speeds for a given DOF at base ISO.

As to diffraction, in the real World I find having a mental view of apertures not to go below without careful consideration to be a useful concept in m43 (but less so in FF due to the wider range of apertures available, well unless m43 users are shooting bokehramas, but after trying it I find that really needs FF). You could see it as a limit of some sort...

Myself, it's incredibly rare for me not to be able to get the DOF I wanted for a scene by f/8 on FF (F/4 on mFT), so it's a non-issue for me.  But, there are those who can never seem to get enough DOF, so it is an issue for them.

BTW I suspect you'll have significant difficulty spotting diffraction blur in anything FF at f2.8 or less for real-World photographs. It's a scientific point, but not really important to people taking photographs, IMHO.

Keeping in mind, of course, that diffraction is merely one of many sources of blur, and the effect of f/2.8 differs in proportion to the size of the sensor.

Finally I personally really think when people (generally, not meaning you in particular, I just have a bugbear here, so thought I'd say where I'm coming from) are talking about sharpness and blur using a CoC (or whatever) that assumes a certain size print viewed at a certain distance by someone with a certain standard of eyesight they shouldn't generalise, as, for example, someone who has done a big crop to zoom will see something different.

Well, the CoC used for online DOF calculators typically presumes viewing an 8x10 inch photo from 10 inches (or is it 12 inches?) away with 20-20 vision.

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