[beholder3]

Dark sky. Thunder. Rain. Haunted house full of insane people. Haunted by the scary, scary "diffraction" ghost.
They flee the place and then visit forums and tell everyone to fear the scary "diffraction limit". Their god / spaghetti monster / what have you has set a clear limit to how far man shall stop down their lenses at most.
If you are unworthy and only own a measly APSC sensor camera the law is to never - ever - go beyond F5.6. Only the bravest of the brave risking their peace of mind sometimes use F8. Otherwise the diffraction monster eats your pictures alive. They all end up inacceptably soft und unsharp.
That is what they all know.

---

Surprisingly the exact same poor people also tend to read "reviews" and "lens tests" of their prophets.
It is actually so surprising because it seems reading the resolution charts completely is forbidden in the asylum.

Secret knowledge is hidden there my friends. Look here (ssshhh!):

One of the most common cheap fast lenses:
Canon EF 50 mm f/1.4 USM review - Image resolution - LensTip.com
And one very new and much acclaimed fast lens:
Tamron SP 85 mm f/1.8 Di VC USD review - Image resolution - LensTip.com
Or the much liked Sigma 85mm:
Sigma 85 mm f/1.4 EX DG HSM review - Image resolution - LensTip.com

If you stop down the Canon lens right down to the end at F22 (!) the lens resolved quite better than if you did use it wide open (the key reason why you bough this type of lens).
Very much the same (a tiny bit less good at F16 than wide open, but not much to talk about) with the new Tamron and same with the Sigma.

So basically if you are able to withstand the demons of wide openness devouring your holy image resolution then you can easily stop down your lenses as far as you please and not have to worry about the concept of "diffraction" at all. F22 on APSC is (can be) absolutely acceptable. If it is not, shooting fast lenses open is not for you as well. You should stick to kit lenses then.

The fun bit here is that "diffraction" is a general physical phenomenon and it therefore works the same with all lenses everywhere. So if the minions of diffraction now find other lenses where stopping down does make the situation much worse than in the lenses mentioned above, it only proves that this all is mostly due to individual lens design and has much less to do with diffraction itself.

You can laugh at the inmates of diffraction asylum. But don't do it publicly or their sinister henchmen will come and get you in the deep of night.

[Giklab]

I'm not sure how many people you've planned to offend, but that was a strong effort.

[Scintilla]

F22 on APSC is (can be) absolutely acceptable. If it is not, shooting fast lenses open is not for you as well. You should stick to kit lenses then.

Ignoring the fact that fast lenses stopped down even one stop still tend to give you a lot of usable stops above and beyond the kit lenses.

I almost never shoot my 35mm f/1.4 any wider than f/2.0, but indoors, I'll gladly take even 2 stops advantage over any kit lens.

[stevebrot]

Huh?


Steve

(...not sure what fast lenses have to do with diffraction...or how lenstip.com ended up as an authority on anything...)

(...reminds of a line from the musical, "Angry Housewives", "...work with the medication..." )

[biz-engineer]

If you stop down the Canon lens right down to the end at F22 (!) the lens resolved quite better than if you did use it wide open (the key reason why you bough this type of lens).

You seem to have discovered something that other people did not figure out. Waow. If until now you had your brain fixed opening at f5.6, from now on-wards, feel free to fully open it up :-) or close it down to f22 if you wish, it won't diffract.

[Alex645]

At the risk of oversimplifying my response to the OP, according to every other site, source, experience, etc, diffraction occurs at smaller apertures like f/22, not large ones like f/2. Unless DxO Mark sites like dpreview and fstoppers got every lens test wrong, I believe the OP is confusing depth-of-field and/or resolution with diffraction.

The general trend in most lenses is that:
a) With a smaller aperture (high f/stop number) depth of field increases (more stuff in focus) on all lenses
b) With a smaller aperture diffraction increases
c) With a smaller aperture chromatic aberration increases
d) In terms of sharpness or resolution, this is usually an aperture in the middle of the range (f/4-f/8 on a prime; f/8-f/11 on a zoom).

[aleonx3]

huh? not sure if I understand what you are talking about... I shoot mostly wide-open (may be one or two stop down), or at the most f8.0 since that is the sweet spot for most lenses I own..

[bxf]

I think, but I'm certainly not sure, that the OP is saying that if you can tolerate the IQ wide open, then you should be able to accept the IQ at smaller apertures, even given the resulting diffraction effects.

[reeftool]

I just spent a 10 day vacation hiking in Nevada and in Death Valley just across the CA border and 90% of my shots are f11 - f16. My walk around lens of choice was my Sigma 17-70C and stopped down it is an excellent performer. My DA 15 also saw some love and I normally always shoot at f11 with this lens when doing landscape shots and it's pretty sharp across the frame. If there is a lack of sharpness stopped down with either of these lenses, it's because of my mistakes, not my gear.

[osv]

roger has tried to justify diffraction blur with rez testing: https://www.lensrentals.com/blog/2013/03/overcoming-my-fentekaphobia/

how well it works looks to be lens/camera dependent, with really sharp glass taking a much bigger beating in the center than on the sides(see the d3x/zeiss 50/1.4 test)... it doesn't work the same with all lenses.

[civiletti]

I think, but I'm certainly not sure, that the OP is saying that if you can tolerate the IQ wide open, then you should be able to accept the IQ at smaller apertures, even given the resulting diffraction effects.

Yes, I believe that is the point. To which I reply, that depends. Some worthwhile images do not depend on high resolution across the frame. Some do. Some images need great depth of field. Some need shallow depth of field. Most every photographic decision concerns balancing several factors. Sometimes I shoot a f5.6. Sometimes I do not.

[quh86]

nicely written, i had a few chuckles

i agree with what civiletti wrote

[Zygonyx]

+1

No real relation btw fast lenses and diffraction risk/occurence.

I only can confirm that diffraction is less - if ever - a concern or a problem with good lenses, stopped down beyond theoretical threshold (that depend not only of aperture or sensor format, but also on pixel pitch), that standard formula (incl. airy disk and so on) have theoretically established the risk.

[Rondec]

I think the OP's point, as bxf says, is merely that if you are OK shooting a 50mm f1.4 at f1.4 then you won't see any more softness when you stop it down to f22.

For the most part, I shoot between f2 and f8, depending on the lens. But if I need to go to f11 or f14, it certainly isn't the end of the world.

[pathdoc]

You do what the situation demands and worry about how it affects the shot afterwards. If stopping down all the way is required to get a shot in bright light, do it. If the spider needs f/32 to keep all the interesting bits in focus, do it. If the alternative is not taking the shot at all, just freakin' take the shot and quit griping about what your f/stop is.