How much does diffraction affect image quality?

[996GT2]

I shoot gigapans of my campus for a school organization, so the shots are taken with a 80-400mm VR telephoto lens. However, some of the shots must be done in manual focus to prevent the camera's AF from mistakenly choosing the wrong AF point. When I gigapans in MF mode, I just set the lens to its hyperfocal distance, which sometimes requires that I use f/16 or even smaller apertures.

So my question is, how much is image quality (resolution) degraded by using f/16 or f/22 versus f/8 or f/11? How about f/32 vs. f/22?

 

[PurdueRy]

I shoot gigapans of my campus for a school organization, so the shots are taken with a 80-400mm VR telephoto lens. However, some of the shots must be done in manual focus to prevent the camera's AF from mistakenly choosing the wrong AF point. When I gigapans in MF mode, I just set the lens to its hyperfocal distance, which sometimes requires that I use f/16 or even smaller apertures.

So my question is, how much is image quality (resolution) degraded by using f/16 or f/22 versus f/8 or f/11? How about f/32 vs. f/22?

Part of it depends on the lens itself. However, I've shot at F22 and the images are fine IMO. Yes they are a bit softer than they would normally be, but when viewed at normal distances/sizes I am not bothered by this.

Look here to see the resolution effects of diffraction:

http://www.photozone.de/

 

[Dark Penguin]

I'm not sure I would worry about it for a gigapan image.

I don't know how to quantify it other than to suggest what PurdueRy suggested. Resolution is impacted so run some tests to see if it matters to you.

 

[Cattykit]

What's your camera?
When it comes to Differaction, you camera matters quite a lot.

 

[PurdueRy]

What's your camera?
When it comes to Differaction, you camera matters quite a lot.

Actually not really true. Yes, different sensors have certain "diffraction limits". However, this is due to having higher resolution to resolve the detail in order to see the effects of diffraction. A 6MP sensor will show less detail than a 12MP sensor at the same F-stop (ex. F22).

It's similar to how sensors with higher pixel density have "more" chromatic aberration. They really don't have more...it's just their sensors resolve more detail resulting in the aberration being multiple pixels wide instead of just 1. However, when viewed at the same size, the width of the aberration is exactly the same.

So, just because a person has a camera with a higher pixel density does not mean they should limit themselves to a lower F-stop to stay under the "diffraction limit". If they want to take advantage of all the resolution possible...then yes they should. However, the image won't come out any worse than a lower density sensor.

 

[soydios]

Simple: try for yourself. I see no difference in sharpness between f/11 and f/16 because diffraction becomes an issue starting at f/16. f/22 and beyond is off-limits for me except if I have no other choice. But again, take some test pictures. You have a DSLR, so the only cost is your time.

 

[996GT2]

What's your camera?
When it comes to Differaction, you camera matters quite a lot.

Nikon D300 (12MP)

 

[PurdueRy]

Nikon D300 (12MP)

Like I said, the only way this affects diffraction is when diffraction becomes visible due to higher resolutions showing the effects earlier as they can resolve that level of detail. If you want to maximize the detail from your D300 you'll have to stay under the "diffraction limit" which is around F10-F11.

Now a higher resolution camera with a lower diffraction limit will not be any worse at F11 than the D300 is. It's just the higher resolution results in a drop from the ideal resolution sooner.

Same for a lower resolution camera. A 6MP camera will not look better at F11 than the D300 because its diffraction limit is higher. It just can't resolve the detail necessary to see the diffraction effect.

 

[Cattykit]

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm