Diffraction

As a rule I never drop below f18 on the 5D, Diffraction does occure around f18 but it is minimal. On the 350D I never went below f16, this was a good compromise for DOF, sharpness and slow waterfall exposures. On 350D the difference between f16 and f22 was noticable on details.

I've got a book of wildlife photos and one of the photographers uses f45 with a telephoto Nikon lens and film camera. I don't understand why though.

maybe a typo. That has got to be one slow bit of wildlife, Macro?
Maybe lichen growing

curiousgeorge wrote in post #2229397
I've got a book of wildlife photos and one of the photographers uses f45 with a telephoto Nikon lens and film camera. I don't understand why though.

Probably a Nikon F4S as the camera and a typo. It would have be some slow moving wildlife at f/45

Bluedog_XT wrote in post #2228919
I've kinda found as a rule of thumb to not let diffraction hold you back from using smaller apertures on the APS-C sensor. I've got several excellent f/22 photos taken while slowing down water flow for motion blur. Kinda hard not to use f/22 in that situation.

An alternative would have been to use the ND filter in your signature to increase the exposure time instead of stopping down.

can someone post a pic and point out some signs of diffraction.

Maybe this will help.
http://www.cambridgein​colour.com …ffraction-photography.htm

malla1962 wrote in post #2229929
Maybe this will help.
http://www.cambridgein​colour.com …ffraction-photography.htm

yea I read that, which is why I had my questions, but I am looking for an everyday picture that might show diffraction.

Rant:

Diffraction is but one of many things that affect sharpness, and it is the least among them. Others, in approximate order of significance to our daily practice, include:

- Depth of field (increased by smaller apertures, decreased by wider apertures)
- Camera shake (improved with faster shutter speeds, requiring wider apertures)
- Subject movement (improved with faster shutter speeds, requiring wider apertures)
- Focus accuracy (minimized by greater depth of field, which is increased by smaller apertures)
- Lens faults (improved by smaller apertures)

All of these are bigger issues than diffraction.

Diffraction is not a problem that just turns on at a certain aperture. It's an unavoidable effect of having a lens diaphragm. It smoothly increases as the percentage of the light affected by bending around the diaphragm opening increases. There is no one point where it becomes a problem big enough to overcome other influences.

In fact, I will happily live with visible diffraction if it means I can get enough depth of field to provide the needed apparent focus. And often the small aperture will cause much greater problems than diffraction as a result of too slow a shutter speed. The proper aperture will be selected to balance those competing objectives, and diffraction won't even be a consideration.

So, choose the shutter speed you need to control camera and subject movement. Choose the aperture you need to provide the needed depth of field. If that leads you to an aperture at f/16 or smaller, and if you can achieve your objectives by opening up to, say, f/8 or f/11, then and only then worry about diffraction.

One example I can think of is on a copy stand. I used f/22 for a series of copy photos because my lights were too bright. The result was visible diffraction in a situation where resolution was important. I didn't need that aperture for any other reason than I was too lazy to hang more diffusers over the lights, and so I had to do it over again. But if I need f/22 to provide enough depth of field when photographing a landscape, then the diffraction that results is gonna do a lot less damage than the lack of depth of field. And if I need f/1.8 to provide the blurry background I want for a portrait, it won't matter than I'm also minimizing the effects of diffraction.

Knowing a lot about diffraction without knowing those other things won't help us much. Thus, forget getting a rule of thumb concerning diffraction. Use the aperture that balances all your other objectives, because they are more important.

Okay, my rant is over, and I'm sorry for the tone of it. I feel much better now.

Rick "afraid this will offend the OP but needing to be clear" Denney

jedwards wrote in post #2229495
Probably a Nikon F4S as the camera and a typo. It would have be some slow moving wildlife at f/45

No typo!

Sorry, it wasn't a Nikon. Fujinon 180mm lens, 1 second at f45.

It's a beautiful shot of a moose in Alaska, and no signs of diffraction.

Obvisously he specifically wanted such a small aperture, as the 1 second exposure is not ideal for wildlife.

Maybe diffraction is not such an issue with film.

curiousgeorge wrote in post #2231326
No typo!

Sorry, it wasn't a Nikon. Fujinon 180mm lens, 1 second at f45.

It's a beautiful shot of a moose in Alaska, and no signs of diffraction.

Obvisously he specifically wanted such a small aperture, as the 1 second exposure is not ideal for wildlife.

Maybe diffraction is not such an issue with film.

Diffraction is not media related. That's a lens designed for LF and as such f/45 is no problem for diffraction on large formats (4x5" etc).

rdenney wrote in post #2230642
Rant:

Diffraction is but one of many things that affect sharpness, and it is the least among them. Others, in approximate order of significance to our daily practice, include:

- Depth of field (increased by smaller apertures, decreased by wider apertures)
- Camera shake (improved with faster shutter speeds, requiring wider apertures)
- Subject movement (improved with faster shutter speeds, requiring wider apertures)
- Focus accuracy (minimized by greater depth of field, which is increased by smaller apertures)
- Lens faults (improved by smaller apertures)

All of these are bigger issues than diffraction.

Diffraction is not a problem that just turns on at a certain aperture. It's an unavoidable effect of having a lens diaphragm. It smoothly increases as the percentage of the light affected by bending around the diaphragm opening increases. There is no one point where it becomes a problem big enough to overcome other influences.

In fact, I will happily live with visible diffraction if it means I can get enough depth of field to provide the needed apparent focus. And often the small aperture will cause much greater problems than diffraction as a result of too slow a shutter speed. The proper aperture will be selected to balance those competing objectives, and diffraction won't even be a consideration.

So, choose the shutter speed you need to control camera and subject movement. Choose the aperture you need to provide the needed depth of field. If that leads you to an aperture at f/16 or smaller, and if you can achieve your objectives by opening up to, say, f/8 or f/11, then and only then worry about diffraction.

One example I can think of is on a copy stand. I used f/22 for a series of copy photos because my lights were too bright. The result was visible diffraction in a situation where resolution was important. I didn't need that aperture for any other reason than I was too lazy to hang more diffusers over the lights, and so I had to do it over again. But if I need f/22 to provide enough depth of field when photographing a landscape, then the diffraction that results is gonna do a lot less damage than the lack of depth of field. And if I need f/1.8 to provide the blurry background I want for a portrait, it won't matter than I'm also minimizing the effects of diffraction.

Knowing a lot about diffraction without knowing those other things won't help us much. Thus, forget getting a rule of thumb concerning diffraction. Use the aperture that balances all your other objectives, because they are more important.

Okay, my rant is over, and I'm sorry for the tone of it. I feel much better now.

Rick "afraid this will offend the OP but needing to be clear" Denney

Good post, Rick.

For the sole purpose of testing the visibility of diffraction on 100% crops (and nothing else), I did some comparison testing with my 5D and 30D. The conclusion - diffraction becomes visible on the 30D at around f/14 or so, while it becomes similarly visible on the 5D at around f/22 or so.

Depends a great deal on subject matter, of course. And it's a gradually-increasing effect (as Rick points out) that will have to be weighed against other effects that can take away from an image. Also, final print size will dictate whether the effects are visible or not.

I compared at 100% crop on the computer screen, using a tripod, mirror lockup, and about 1000 watts of light so that I could keep the ISO relatively low (200, I believe) and eliminate camera shake as a factor. That's a great setup for inspecting diffraction alone, but it's not generally a realistic setup for most shooting. I don't expect that what I saw at f/14 on my 30D would be noticeable on most prints, nor would what I witnessed on my 5D at f/22.