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Author Topic: f/22 and diffraction  (Read 4571 times)

bholliman

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f/22 and diffraction
« on: March 11, 2013, 08:22:52 AM »
I'm not really sure which sub-forum this topic belongs in, so put it here.

I just finished reading Understanding Exposure by Bryan Peterson.  Excellent book, highly recommended!

Bryan recommends using f/22 or occasionally f/16 for landscape pictures that include foreground elements (should be most for good composition).

But, I've also read elsewhere that diffraction is a problem at apertures over f/11.  Thoughts?
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f/22 and diffraction
« on: March 11, 2013, 08:22:52 AM »

J.R.

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Re: f/22 and diffraction
« Reply #1 on: March 11, 2013, 09:53:16 AM »
Bryan wrote that book at a time when digital imaging was still in its nascent stages. Film SLRs were impacted by diffraction but it was not easy to spot the degradation in IQ because film ... was film. It was not possible to pixel peep the images the way you can do with your DSLR's images at 100%, 200% or 400%.
 
Though the theory says that over f/11 your images will be hit by diffraction in a DSLR, usually the difference will be negligible upto f/16.

BTW, diffraction impacts APS-C and FF sensors differently with APS-C's being less tolerant because of their higher MPs on smaller sensors.
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RLPhoto

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Re: f/22 and diffraction
« Reply #2 on: March 11, 2013, 10:37:08 AM »
Its surprising how much easier it is to make a lens sharper at wider apertures but very, very few lenses can be excellent at the diffraction limit.

It's a sacrifice of IQ to obtain greater DOF. A tilt-shift can cheat this for landscapes but a LF camera with bellows will always be the gold standard for deep DOF.

Dimson

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Re: f/22 and diffraction
« Reply #3 on: March 11, 2013, 10:40:47 AM »
most aps-c sensors are affected by diffraction from f/8
FF sensors are affected from f/11 and it gets critical after f/16

dont forget that when shooting digital you can always focus stack for DOF while staying in the sweet spot f range of your lens

i always go for the highest quality possible under the circumstances and never go beyond f/16

GMCPhotographics

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Re: f/22 and diffraction
« Reply #4 on: March 11, 2013, 10:51:19 AM »
most aps-c sensors are affected by diffraction from f/8
FF sensors are affected from f/11 and it gets critical after f/16

dont forget that when shooting digital you can always focus stack for DOF while staying in the sweet spot f range of your lens

i always go for the highest quality possible under the circumstances and never go beyond f/16

Sorry but no you can't focus stack a landscape without registration issues....most zoom lenses change their focal length when the focus ring changes. This is true of all the 70-200, 24-70, 16-35 lenses.

rs

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Re: f/22 and diffraction
« Reply #5 on: March 11, 2013, 11:25:06 AM »
It all depends on what you're shooting and what your personal preference is for that shot.

Most landscape shots won't have many things drastically out of focus at sensible apertures (unless something is very close in the foreground), so without a tilt shift you can argue in some cases it's worth sacrificing ultimate depth of field to avoid diffraction softness, although equally you could argue it the other way around.

However, with a much narrower depth of field such as macro, if the depth of field is too narrow, it'll be painfully obvious even in a thumbnail sized image. Stop that lens down loads, and it'll look much better overall to everyone except pixel peepers.

In summary, do what suits you. But if you want to be as close to perfection as is possible, start saving for a TS-E lens.
« Last Edit: March 11, 2013, 11:27:29 AM by rs »
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risc32

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Re: f/22 and diffraction
« Reply #6 on: March 11, 2013, 11:26:14 AM »
very timely. you should read what roger at lensrentals just recently wrote about diffraction.

http://www.lensrentals.com/blog/2013/03/overcoming-my-fentekaphobia

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Re: f/22 and diffraction
« Reply #6 on: March 11, 2013, 11:26:14 AM »

GMCPhotographics

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Re: f/22 and diffraction
« Reply #7 on: March 11, 2013, 11:52:13 AM »
It all depends on what you're shooting and what your personal preference is for that shot.

Most landscape shots won't have many things drastically out of focus at sensible apertures (unless something is very close in the foreground), so without a tilt shift you can argue in some cases it's worth sacrificing ultimate depth of field to avoid diffraction softness, although equally you could argue it the other way around.

However, with a much narrower depth of field such as macro, if the depth of field is too narrow, it'll be painfully obvious even in a thumbnail sized image. Stop that lens down loads, and it'll look much better overall to everyone except pixel peepers.

In summary, do what suits you. But if you want to be as close to perfection as is possible, start saving for a TS-E lens.

There are a few problems with TS-E lenses, mostly related to them being quite a faf in the field. Complex movements need to be mastered and they really are quite hard to master at first and are very hard to set up in changing light. There's filter issues with the wider TS-e lenses, which can be remedied but only add to the complexity of use. The new Photodios filters come to mind...I have a set. There's also the fact that these are primes and loose versatility to any zoom. It's quite likely that a photographer can't get the desired angle of view with just one TS-e lens. Then the photographer needs to lug about all four TS-e lenses for every eventuallity. They are heavy for what they do and four of them is a lot more heavy than a bag of f2.8 zooms....in my opinion, TS-E lenses are not practical for general landscape work and certainly not practical for low light landscape work. Sure they might be good for mid day work - architectural stuff, but for windy sunsets on the coast....er....no. I'd choose diffraction over a TS-e headache any day.
Don't get me wrong, I really like my TS-e lenses in the right contex. But for many applications, a zoom is a better choice.

KyleSTL

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Re: f/22 and diffraction
« Reply #8 on: March 11, 2013, 11:58:18 AM »
very timely. you should read what roger at lensrentals just recently wrote about diffraction.

http://www.lensrentals.com/blog/2013/03/overcoming-my-fentekaphobia
+1

I stand by the mentality that a higher MP camera at small apertures will always resolve as good or better than a low MP camera at the same aperture.  A higher MP camera will never perform worse at any given aperture, it can only perform better.  TS (used correctly) will almost always result in better sharpness for a given DOF, but all things being equal, one should not rule out certain apertures simply because pixel density is getting higher.  When deep DOF is needed, that is what must be done, even if the pixel-level sharpness is down slightly.
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yellowkamper

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Re: f/22 and diffraction
« Reply #9 on: March 11, 2013, 01:28:07 PM »
So much for todays digital cameras, I did a lot of church interiors with a Bronica and regularly used f32
and made 20x16 prints no fall off with film

risc32

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Re: f/22 and diffraction
« Reply #10 on: March 11, 2013, 01:51:26 PM »
i don't see how a pano would help in gaining depth of field. you could shoot at varying focus distances and combine later, but that looks like a huge pain. but maybe not with todays software, i don't know, never tried it.

 sure you could shoot at f32 with a MF camera. i guess you were using MF, when i think of bronica i think of mf. 645, but MF none the less. I'd have to check but i'm willing to bet that you will have much more DOF with either an APC or "FF" digital sensor even opened up much more than you would have gotten with that MF rig. f32 on MF doesn't = f32 on "ff" digital. a guess, more like digital f8.

ChilledXpress

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Re: f/22 and diffraction
« Reply #11 on: March 11, 2013, 01:55:50 PM »
Dunno, when I shoot F22's I haven't noticed much diffraction ;)


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serendipidy

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Re: f/22 and diffraction
« Reply #12 on: March 11, 2013, 02:04:25 PM »
Dunno, when I shoot F22's I haven't noticed much diffraction ;)


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Re: f/22 and diffraction
« Reply #12 on: March 11, 2013, 02:04:25 PM »

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Re: f/22 and diffraction
« Reply #13 on: March 11, 2013, 02:55:57 PM »
There are some actual examples at Photozone.  Most lenses are find at f/16, the resolution is highest at F/5.6 but drops 21% in the center by f/16.  It would drop a little more at F/22.
 
This is a 17mm TS-E on a 5D MK II
 
 

comsense

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Re: f/22 and diffraction
« Reply #14 on: March 11, 2013, 03:46:29 PM »
There are some actual examples at Photozone.  Most lenses are find at f/16, the resolution is highest at F/5.6 but drops 21% in the center by f/16.  It would drop a little more at F/22.
 
This is a 17mm TS-E on a 5D MK II
 
 

I think the more relevant question to ask from these MTF charts is whether it still has an acceptable levels of sharpness at f/16 or f/22. %ages matter less in 'bigger picture' even after assuming linear correlation between variables and final pictures....

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Re: f/22 and diffraction
« Reply #14 on: March 11, 2013, 03:46:29 PM »