Is your camera diffraction limited? If so, why?

[DPNow]

Here is a summary or excerpt from an article that has just been published on DPNow:

If you have noticed that when using a very small lens aperture you get disappointing sharpness in your photos, this article explains why. By learning a simple fact about one characteristic of your camera you can avoid accidentally losing sharpness in your photos. It's all down to light diffraction. But don't let that put you off; the article is designed to be simple and easy to follow.

Click here to read the whole article...

[Ian]

Re: Is your camera diffraction limited? If so, why?

The sample images shot at the smaller apertures are scarily bad compared with the wider apertures!

Ian

[Patrick]

Re: Is your camera diffraction limited? If so, why?

The sample images shot at the smaller apertures are scarily bad compared with the wider apertures!

Ian

Interesting exercise, can we know the lens used for the sample pictures. The problem I imagine will vary from maker to maker depending on the design, but will be there at one level or another with all lenses whoever makes them.

Patrick

[Ian]

Re: Is your camera diffraction limited? If so, why?

Interesting exercise, can we know the lens used for the sample pictures. The problem I imagine will vary from maker to maker depending on the design, but will be there at one level or another with all lenses whoever makes them.

Patrick

The diffraction effect is not directly linked to lens quality or design. It's basically down to physics. Like depth of field, it's down to the laws of optics, not the design of the lens.

The lens and camera used is mentioned in the article: a 35-100 f/2.0 Olympus Zuiko Digital (Olympus' equivalent of Canon's top of the range 'L' series) and an Olympus E-3 DSLR.

Ian

[Bob Ross]

Re: Is your camera diffraction limited? If so, why?

Hi Ian,
That certainly a sharp lens....I have been resisting......
One additional dimension to a discussion of diffraction is the dimension of the viewed picture. The smaller the print, the less you will notice softness and the farther into the diffraction zone you can go ..... of course, the same holds true for camera shake blur....
An example for the magnification factor: my FX500 has a 1/2.33" sensor and at the tele end, max aperture of f/5.9. Wide open diffraction will start showing in prints bigger than 5" X 6.6". People were calling the lens soft at the tele end. but they were looking at 100% and that would be a huge print.... well at least a bit bigger than 5" X 6.6....
The trick, I suppose is to just make a few prints and see for your self where your rig limits out.
Bob

[Ian]

Re: Is your camera diffraction limited? If so, why?

Hi Ian,
That certainly a sharp lens....I have been resisting......
One additional dimension to a discussion of diffraction is the dimension of the viewed picture. The smaller the print, the less you will notice softness and the farther into the diffraction zone you can go ..... of course, the same holds true for camera shake blur....
An example for the magnification factor: my FX500 has a 1/2.33" sensor and at the tele end, max aperture of f/5.9. Wide open diffraction will start showing in prints bigger than 5" X 6.6". People were calling the lens soft at the tele end. but they were looking at 100% and that would be a huge print.... well at least a bit bigger than 5" X 6.6....
The trick, I suppose is to just make a few prints and see for your self where your rig limits out.
Bob

Hi Bob, you make a very good point. And I think an article about the resolution limits for viewing under different outputs (screen, print) is something that is tempting me

Ian

[leinorackham]

Re: Is your camera diffraction limited? If so, why?

Thank-you. I have learnt something today. A question - why would camera makers then make their lens apertures capable of going much smaller than the defraction limit?

Ah, have just re-read the article. Macro. Forget I asked.

[Bob Ross]

Re: Is your camera diffraction limited? If so, why?

Hi Bob, you make a very good point. And I think an article about the resolution limits for viewing under different outputs (screen, print) is something that is tempting me

Ian

Hi Ian,
That would be a good topic, kind of a "where the rubber meets the road" for digital output. Yesterday I ran across an interesting thread on the Pro Talk forum on dpr, where they were talking about viewing distance and got into all the myths and what they were actually doing with customers. The link is http://forums.dpreview.com/forums/re...ssage=37549132
An interesting sidebar to an article on that topic would be "where is digital electronic display tech going?" and, of course, how will that alter our visual environment.
Bob

[Ian]

Re: Is your camera diffraction limited? If so, why?

Hi Ian,
That would be a good topic, kind of a "where the rubber meets the road" for digital output. Yesterday I ran across an interesting thread on the Pro Talk forum on dpr, where they were talking about viewing distance and got into all the myths and what they were actually doing with customers. The link is http://forums.dpreview.com/forums/re...ssage=37549132
An interesting sidebar to an article on that topic would be "where is digital electronic display tech going?" and, of course, how will that alter our visual environment.
Bob

Some interesting ideas, Bob - as usual

Ian

[chicagonature]

Re: Is your camera diffraction limited? If so, why?

Hi Ian,

Great website! I just signed up.

The Technical Guide to the Nikon D800/D800E was just published and I believe it is saying that the D800E (the one with effectively no anti-aliasing filter) is more Diffraction Limited. Here's the quote, "The D800E offers better resolution at apertures where diffraction is not an issue. The effects of aperture may therefore be more noticeable than with the D800, and care may be required to avoid loss of defi nition due to diffraction." Does this makes sense from a physics point of view. Plus, it uses the word "may," which throws me off a bit.

The reason I ask is because I have a D800E on pre-order (along with the 14-24mm lens) and I have an opportunity to switch to the D800 without losing my place in line. My application is this: Landscape photographs with the foreground subjects placed very close to the lens, requiring very small apertures. With my Pentax 645NII medium format film camera, I frequently shoot at f/32 with a 33mm lens (the same as using a 20mm lens at f/20 on 35mm full-frame camera).

So, I'm wondering if I should just switch over to the D800 even though pictures taken at f/8 or larger apertures will be a tad softer. What do you think?

Thanks!

[chicagonature]

Re: Is your camera diffraction limited? If so, why?

Regarding my comparison of Nikon D800 & D800E, shouldn't it be just the opposite that what Nikon is saying because the Nikon D800 is causing the Airy Disk to be larger through increased blurring by the anti-aliasing filter?

[Ian]

Re: Is your camera diffraction limited? If so, why?

Hi there chicagonature! I think you raise a very interesting point re the anti-aliasing filter and diffraction limits.

In the real world I do tend to see a start to diffraction softening at slightly larger (brighter) aperture than predicted by the calculations. So I have wondered if this is caused by the anti-aliasing filter. But the information you are querying suggests that without an AA filter diffraction comes on earlier.

I'm sure that once these cameras are widely tested we'll see which version, if at all, has a diffraction advantage.

There are examples of the same sensor having different AA filter strengths - like the Olympus E-5 (low AA) and the earlier E-30 (higher AA strength) - I could do a resolution test using the same lens on these and compare the results...

Ian

[chicagonature]

Re: Is your camera diffraction limited? If so, why?

Hi there chicagonature! I think you raise a very interesting point re the anti-aliasing filter and diffraction limits.

In the real world I do tend to see a start to diffraction softening at slightly larger (brighter) aperture than predicted by the calculations. So I have wondered if this is caused by the anti-aliasing filter. But the information you are querying suggests that without an AA filter diffraction comes on earlier.

I'm sure that once these cameras are widely tested we'll see which version, if at all, has a diffraction advantage.

There are examples of the same sensor having different AA filter strengths - like the Olympus E-5 (low AA) and the earlier E-30 (higher AA strength) - I could do a resolution test using the same lens on these and compare the results...

Ian

I can't imagine how MORE blur (from AA filter) would cause LESS blur in the image. But, I can't tell exactly what Nikon is saying because they aren't being definitive. So, any test you're willing to do makes me happy!

Here's another point, though. I'm coming from medium format film (645) shooting with a super-wide 33mm lens at f/32 using hyperfocal distance. And, after scanning, I get a yummy 70 to 100 Megapixel file. But, because I scan, I rarely pixel peep because the files are so large in the first place. With 12 megapixel files from my D300, in a couple of zoom clicks I'm already at 100%.

I tend to work some magic in Photoshop to make the (scanned) image as crisp as possible. I can make sharp 24x36" prints on my Epson 9800 quite easily and I've made them as large as 43x56" (360 dpi). It's important to note that I don't have anything else to compare the pictures to, like a side by side shots of a digital camera like there is on the Internet. So, here's what I'm wondering:

It just may be that I'm so used to viewing slightly soft, yet acceptably sharp, images from using Hyperfocal Distance for all these years that all the concerns about diffraction is a moot because, though, the 36MP Nikon D800/D800E may not give superior results if shot at f/20, it won't be any worse than what I'm getting now from film. And, if I'm having no complaints about the quality of my prints right now from scanned film, the prints from the Nikon D800/D800E won't be any worse. Does this seem reasonable?

By the way, don't the effects of diffraction decrease when you downsample the image? If so, this would give making smaller prints from a 70 to 100 megapixel file some advantage over a digital camera at 36MP.

Yet, it'd still be nice to see how an AA filter matters when it comes to diffraction.

[chicagonature]

Re: Is your camera diffraction limited? If so, why?

Sorry, this is dummy post because my newbie status, the website won't let me post a link until my 6th post. This is the 5th. Read next post

[chicagonature]

Re: Is your camera diffraction limited? If so, why?

Ian,

One more thought. According to a technical paper that I cannot include because (at this link http:\\www.northlight-images.co.uk/a...mits_long.html), digital is 3 to 5 times sharper than film for the given format. If so, then the D800/D800E will clearly be sharper. He also talks about how digital is very different from film in that digital sensors are far more diffraction limited than film and you can't be shooting at f/22 anymore without getting very soft images and losing a lot of information. So, I was wondering this:

What's the difference between softness caused by diffraction and softness caused by something being out of focus. So, if I would take a shot at f/20 on film, but now I shoot the same shot at f/10 on the digital camera, how will the image quality compare based on the standard that EVERYTHING SHOULD APPEAR ACCEPTABLY SHARP? In other words, what might the comparison show between film and digital? I mean, if it's correct that a digital image is MUCH sharper by its very nature, can we use a wider aperture with digital and still get something that looks as good as film?

Mike