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Does diffraction affect your image sharpness at a practical level?

Has anyone ever printed something and run down the street (naked) yelling "Damed diffraction is killing my prints!"

Are there any notorious lens/camera combinations to avoid?

Is it bad to shoot landscapes at f29 (as I commonly do). Would it bite me in the a$$ when(or IF) I try to print them large?

I would be keen to hear your thoughts...

usually diffraction happens when you shoot at high f stop
but it's negligable i think dust bunnies would show up more and cause more of an issue than diffracxtion at f29
shooting at f8 is enough
depending on the distance of foreground and background elements and where you focus

surenj wrote:Does diffraction affect your image sharpness at a practical level?

Has anyone ever printed something and run down the street (naked) yelling "Damed diffraction is killing my prints!"

Are there any notorious lens/camera combinations to avoid?

Is it bad to shoot landscapes at f29 (as I commonly do). Would it bite me in the a$$ when(or IF) I try to print them large?

I would be keen to hear your thoughts...

yes it does and yes it will. the bigger you print the more it effects the image. diffraction is not really determind so much by lens/ camera...its more factor of light physics. the more you squeeze light thru a tiny hole, the more light diffraction occurs. there is an excllent article about it here.

http://www.cambridgeincolour.com/tutori ... graphy.htm

and here...

http://www.luminous-landscape.com/tutor ... tion.shtml

I have to admit that I know it has to be there but I seldom notice it with my longer exposure stuff....

Very true about dust bunnies though!

Suren,

trying to achieve better depth of field by closing down will not get you there as you can read in the links that Rooz points you to. As well, have a read on hyperfocal distance. See:
http://www.dofmaster.com/

That should help in you not having to go to such small apertures.

Another reason that I suspect you want to use small apertures is to slow down your shutter speed. For that, the good old ND filter will be very useful, alternatively if possible, a different time of day

Focus stacking can also work in increasing your depth of field but that may not be always possible when there is movement in the scene you want to shoot.
cheers,

André

5 or 10 years ago I was obsessed by MTF charts for lenses and as such almost never stopped down below f8, being predominantly a lansdcaper this wasnt ideal but i was blinded by the science and forgot the art. front to back sharpness just isnt the same at f16 or f22 as it is with f8. My images may have been slightly sharper but the lack of DOF probably had a greater detrimental effect. Now I just shoot what i think is needed or if going for the close foreground to infinity type shots stich a pano together and shoot it at f8.

To give you an idea of the effect of diffraction in terms of objective resolution check out this for example- there is about a fair amount of loss in resolution when stopped down- and bear in mind this is a Macro lens where the design will be to limit diffraction as DOF is very shallow at close focus so other lenses will probably be worse.

Centre MTF for the new 100mm L macro.
f2.8 3391
f5.6 3511
f8 3349
F11 3092


I used to use large format cameras and stopping down to f64 was sometimes the only way to get enough depth of field!!
Robert

f22 2478

Thanks Wendell and Cameron. I was a little worried that I am not really noticing any obvious difference. In saying that, I can see the sharpness difference on my camera LCD when shooting at f32! I don't have a problem with dust bunnies...

Thanks Chris and Andre for those links. I have procrastinated about the hyperfocal enough. I think I need to figure it out and use it when required.

Yes, I need to have slow shutter.
About the ND filter; I guess I am looking for a thin rimmed one that can go on my 10mm lens which may enable me to use one graduated filter with the cokin P wideangle holder. I am finding that the reverse grad is quite nice for seascapes.
Otherwise I will have to upgrade to the larger Cokin Xpro (or Lee) sizes which come at a major premium...

surenj wrote:About the ND filter; I guess I am looking for a thin rimmed one that can go on my 10mm lens which may enable me to use one graduated filter with the cokin P wideangle holder. I am finding that the reverse grad is quite nice for seascapes.
Otherwise I will have to upgrade to the larger Cokin Xpro (or Lee) sizes which come at a major premium...

I just purchased a B+W ND10 from Mainline Photographics. It's well made as expected from B+W and has a low profile. A code of 2009 gave me 20% off as well since they have a Photokina promotion on at present. What size does your 10mm take? If it's 77m you're in luck and can try out my filter

stubbsy wrote:What size does your 10mm take? If it's 77m you're in luck and can try out my filter

Indeed it is! I will give you a holler at some stage...

Did you say it's 10 stops? That's quite a few stops but still would be nice to try out.[I should have tried with Andres filter!]
I only really need about 2-4 stops as I am hoping to use the graduated to knock the sky down anyway.

B+W also makes a 3 stop and a 6 stop ND which may suit your needs Suren

Robert, thanks for your advice. I guess what I really want to know is whether those MTF numbers actually translate into bad prints. For example, can you say, at 2478 that you can't print at 8X12 ?

Cameron, looked it up. They make all sorts. I might spring for one of those... Quite tempted by the Lightcraft vari ND 8-stopper though I don't know whether that can take an attachment in the front...

surenj wrote:

stubbsy wrote:What size does your 10mm take? If it's 77m you're in luck and can try out my filter

Indeed it is! I will give you a holler at some stage...

Did you say it's 10 stops?

Yep 10 stops - should make interesting effects even with more light present

surenj wrote:Robert, thanks for your advice. I guess what I really want to know is whether those MTF numbers actually translate into bad prints. For example, can you say, at 2478 that you can't print at 8X12 ?

cant print is a non issue surenj...its just that it wont be AS sharp as it could have been at its critical aperture. diffraction wont really pop up too much at that size though so its sweet. its beyond that size, (or a cropped image), that it starts to become notiecable. it also depends what the subject is...if it has fine detail then it will become more of an issue. try it for yourself.

thing is though, its all about compromises and priorities; if f22 is what you need to make the shot then thats what you have to use and diffraction be damned.

Most of the time I shoot macro diffraction is the lesser of two evils (diffraction vs depth of field). Sure, I will get less diffraction at f/8 or f/11 than at f/16 to f/32, but the lack of DOF is more noticeable at f/11 than the diffraction at f/32.

The ladybug I had printed up on canvas (greater than 60x100cm) was taken at f/32 and I still didn't have enough DOF for the far antenna to be sharp, but the areas that are sharp (e.g. the foot closest the camera) look very sharp (sharper than can be determined due to the "grain" of the canvas).

Thanks Andrew, That's quite reassuring.

Cambridge in color wrote:
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Are smaller pixels somehow worse? Not necessarily. Just because the diffraction limit has been reached with large pixels does not mean the final photo will be any worse than if there were instead smaller pixels and the limit was surpassed; both scenarios still have the same total resolution (although one will produce a larger file). Even though the resolution is the same, the camera with the smaller pixels will render the photo with fewer artifacts (such as color moiré and aliasing). Smaller pixels also provide the flexibility of having better resolution with larger apertures, in situations where the depth of field can be more shallow. When other factors such as noise and depth of field are considered, the answer as to which is better becomes more complicated.

Does this mean, that a camera with higher pixel density (7D) would have same diffractive properties as a camera with less pixel density (D700)

I think there are a few other factors in play when it comes to the loss in sharpness due to diffraction. The quality of the lens being used, the type of aperture blades in the lens, the focal length of the lens, the camera to subject distance and even the type of subject being photographed. It's normally most destructive in flat field macro photography (stamps, bank notes and other documents from a document copy stand), where the subject contains a lot of very fine detail. There will be a definite drop off in sharpness beyond F16 with most macro lenses. Luckily with this type of photography depth of field is not often required so that F8 or F11 will give much sharper results. Where DOF is critical then the choices are to accept this loss of sharpness or move the camera back a little (increases DOF) and enlarge or crop the image digitally, incurring a slight loss of quality. With cheaper or poor quality optics this is often a better technique.