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Will you still get lens diffraction past f8 even if you are on DX mode?

gqtuazon

FPO, US
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gqtuazon Registered since 18th Nov 2009
Mon 23-Jul-12 04:32 PM

Although I have not tried it yet, I was wondering if it is safe to get the optimal sharpness pass f8 if you are on DX or even 1.2x mode.

Will I still see lens diffraction in either DX or 1.2 crop mode? I'm not technically savvy when it comes to this. Thanks.


Regards,

Glenn

blw

Richmond, US
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#1. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 0

blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004
Mon 23-Jul-12 02:55 PM

Both of those are simple cropping - just like doing the crop in Photoshop. They don't affect the content of what does get captured. You wouldn't expect a physical crop of a paper print to change the sharpness of the remaining part of the print, right?

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JonK

New York, US
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#2. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 0

JonK Moderator Awarded for his high level skills and in-depth knowledge in various areas, such as Wildlife, Landscape and Stage Photography Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 03rd Jul 2004
Mon 23-Jul-12 10:40 PM

Don't be too hung up on never pasting the optimal sharpness minimum aperture (be that f/8 or whatever). Optimal sharpness may not always the means to the end for a given image. The tradeoff, as you have suggested, involves compromising sharpness due to diffraction in return for additional depth of field. For some images, the DOF may be more important.

Jon Kandel
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blw

Richmond, US
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#3. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 2

blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004
Mon 23-Jul-12 11:40 PM

And that would be particularly true in macro work.

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Brian... a bicoastal Nikonian and Team Member

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gqtuazon

FPO, US
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#4. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 3

gqtuazon Registered since 18th Nov 2009
Tue 24-Jul-12 02:56 AM

Jon / Brian - thanks for your replies. I appreciate it.


Regards,

Glenn

elec164

US
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#5. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 1

elec164 Silver Member Nikonian since 15th Jan 2009
Tue 24-Jul-12 12:19 PM | edited Tue 24-Jul-12 12:21 PM by elec164

>Both of those are simple cropping
>They don't affect the content of what does get
>captured.

In essence they are just simple crops, but doing so can impact what is captured and what one perceives as relative sharpness.

Diffraction is a property of a waveform as it encounters a barrier. As such the phenomenon is format size independent. It is, as DOF is, dependent upon the amount of enlargement and viewing distance.

You will often read that for an FX sensor diffraction occurs at about f/22 and for DX sensors it occurs at about f/16. But it’s not so much the format size that matters, but the amount of enlargement to achieve a specific sized print. And I believe the standard for the f/22 and f/16 is an 8x10 print viewed at about 18 inches. To achieve an 8x 10 the FX capture needs about an 8x enlargement and the DX needs about 13x. The size of the diffraction airy disk will vary depending upon the source quoted. For example Bob Atkins quotes that at f/22 the size is about 29.5 microns and for f/16 it’s about 21.5 microns. With the FX 8x enlargement the f/22 airy disk is about 236 microns and at 13x enlargement f/16 airy disk is about 279 microns. So as you can see they are about the same size perception wise and about the same size as the tolerable CoC for DOF or about .25mm. So now if you crop the FX capture to the DX FOV (or shoot in DX crop mode) you would then need a 13x enlargement to achieve the 8x10. At f/22 and a 13x enlargement the airy disk becomes about 385 microns or .38mm. At that point the detail will begin to be perceived as soft, and to maintain the same level of perceived sharpness you would need to shoot at a wider aperture.

Having said all that, I agree with the others in that often too much emphasis is placed upon effects of diffraction. Yeah it’s real, but often (such as in macro work) the gain in DOF often will offset the small loss of detail due to diffraction. And by using deconvolution the softness can be mitigated, granted you cannot recover the lost fine detail.

Well that’s my present understanding at the moment, unless I’m miss understanding or missing something.

Pete

Pete

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MotoMannequin

Livermore, CA, US
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#6. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 2

MotoMannequin Awarded for his extraordinary skills in landscape and wildlife photography Registered since 11th Jan 2006
Tue 24-Jul-12 04:11 PM

>Don't be too hung up on never pasting the optimal sharpness
>minimum aperture (be that f/8 or whatever). Optimal sharpness
>may not always the means to the end for a given image. The
>tradeoff, as you have suggested, involves compromising
>sharpness due to diffraction in return for additional depth of
>field. For some images, the DOF may be more important.

I'm with Jon on this. When people talk about diffraction robbing sharpness, they are talking about sharpness at the actual plane of focus. For a shot with large DOF, like a landscape, there may be a very small percentage of the photo's content at exactly that distance. So, as you stop down, the content at the plane of focus might begin to soften, but you'll also be including more content within your DOF, which makes the image seem sharper.

It's also a worthwhile exercise to do some test shooting at full-stop increments through the range of your lens. The stated diffraction limits (f/8 on D800) are really a mathematical calculation, and it's worthwhile to see how this really translates to image quality. I haven't done this yet with my D800, but testing previous cameras I've found that 1 stop smaller than the theoretical limit can be used without hesitation. 2 stops is usable with some visible softening. It really isn't until you get to 3 stops smaller that things fall apart to the point where you'd consider some alternative (like focus stacking).

Larry - a Bay Area Nikonian
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JonK

New York, US
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#7. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 6

JonK Moderator Awarded for his high level skills and in-depth knowledge in various areas, such as Wildlife, Landscape and Stage Photography Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 03rd Jul 2004
Tue 24-Jul-12 04:42 PM

Another factor is your intent. If you are downsizing the image to "reasonable" size, don't forget that the downsized D800 file gains sharpness and reduces noise. So again the "boundary" f stop moves maybe another stop. So now the theoretical f/8 is realistically more like f/16.

And when I shoot something worth printing really large (if ever), I'll shoot it at f/16, f/11, f/8. and f/5.6 and in post make the comparison of sharpness versus depth of field.

Jon Kandel
A New York City Nikonian and Team Member
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Bluefin

Danville, US
432 posts

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#8. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 5

Bluefin Registered since 14th Nov 2006
Tue 24-Jul-12 07:25 PM

Pete, your answer really confuses me.

As stated elsewhere, diffraction is at the focal plane. Output of the file does not alter diffraction, it merely alters the impact of diffraction to the viewer.

In addition, I believe f stop values are not universal as to their diffraction producing properties. Correct me if I'm wrong , but the lens construction and design has everything to do with diffraction at the focal plane. I wouldn't expect a 50mm f2 to have the same amount of diffraction as a 50mm f1.2 at f8 or f11.

Do I have this wrong?

Mark Sloane
Danville, CA

briantilley

Paignton, UK
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#9. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 8

briantilley Gold Member Deep knowledge of bodies and lens; high level photography skills Donor Ribbon awarded for his support to the Fundraising Campaign 2014 Nikonian since 26th Jan 2003
Tue 24-Jul-12 07:36 PM

>As stated elsewhere, diffraction is at the focal plane.
>Output of the file does not alter diffraction, it merely
>alters the impact of diffraction to the viewer.

At the risk of mis-interpreting another's post, I think that's what Pete meant.

>In addition, I believe f stop values are not universal as to
>their diffraction producing properties. Correct me if I'm
>wrong , but the lens construction and design has everything to
>do with diffraction at the focal plane. I wouldn't expect a
>50mm f2 to have the same amount of diffraction as a 50mm f1.2
>at f8 or f11.

If I understand it correctly (and that may well not be the case!), diffraction is dependent on the physical size of the diaphragm opening. Thus, a 50mm f/2 lens at f/8 should have the same diffraction characteristics as a 50mm f/1.2 (or a 50mm f/3.5) lens at the same aperture. I think there may be subtle differences due to variations in the shape of the diaphragm blades, if one lens has a more perfectly circular opening than the other, but the maximum available aperture on each lens should not be a factor.

Brian
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MotoMannequin

Livermore, CA, US
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#10. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 9

MotoMannequin Awarded for his extraordinary skills in landscape and wildlife photography Registered since 11th Jan 2006
Tue 24-Jul-12 08:50 PM

>If I understand it correctly (and that may well not be the
>case!), diffraction is dependent on the physical size of the
>diaphragm opening.

This makes sense to me, given my understanding that diffraction occurs as light bends around the edge of the diaphragm, and the smaller the opening, the greater percentage of light passing through is diffracted.

However, while this certainly implies that a 50mm f/1.4 lens and a 50mm f/2.8 lens both have the same (or at least very similar) diffraction characteristics at f/8 (in both cases having an entrance pupil of 50mm/8 or 6.25mm) does this not also indicate that a 200mm lens will have less diffraction at f/8 (with a 200mm/8 = 25mm entrance pupil) than a 50mm lens at f/8?

This would contradict the commonly repeated wisdom that states diffraction limits in the same terms as we state aperture, as a ratio of focal length.

Larry - a Bay Area Nikonian
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Bluefin

Danville, US
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#11. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 9

Bluefin Registered since 14th Nov 2006
Tue 24-Jul-12 08:55 PM

Brian and Pete,

This quote is from Luminous landscape:

"At larger apertures this diffracted light is only a small percentage of the total amount of light hitting the sensor or film, but as the aperture is stopped down the amount of diffracted light becomes a larger percentage of the total amount of light being recorded.

This is why it's important to test each lens in your arsenal for the point at which they are visibly affected by diffraction."

I agree that the diaphragm blades induce diffraction however, logic would dictate that the quality and physical characteristics of the each piece of glass and the complex design of the multiple optics within the lens would impact the light before it hits the diaphragm and how that light is recorded at the focal plane once the light leaves the diaphragm. Therefore, each lens will have a different reaction to f11.

The problem is, I am only using logic and have no science to back me up. And even if I did have the data, I probably wouldn't be able to understand it so I will ultimately defer to your experience.

Mark Sloane
Danville, CA

David D Busch

US
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#12. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 0

David D Busch Silver Member Nikonian since 07th Nov 2011
Tue 24-Jul-12 09:57 PM

>Although I have not tried it yet, I was wondering if it is
>safe to get the optimal sharpness pass f8 if you are on DX or
>even 1.2x mode.
>
>Will I still see lens diffraction in either DX or 1.2 crop
>mode? I'm not technically savvy when it comes to this.
>Thanks.

People tend to worry about diffraction more than they need to. A stock D800 will exhibit some diffraction effects at all f/stops, but it doesn't become bothersome until you go past f/8. The D800E doesn't seem to produce diffraction until f/8, but does exhibit it at smaller f/stops. How you happen to crop the sensor image doesn't make a difference.

Above f/8, diffraction becomes a depth-of-field/sharpness trade-off. You decide which is more important to you, and select an f/stop accordingly. I routinely use the D800 at f/22 for close-up product photography because it works for me. I don't use f/32 as much as I did when I was shooting this stuff with a D3x, but that's just my preference.

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jhearl

Milford, VA, US
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#13. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 0

jhearl Registered since 16th Apr 2007
Wed 25-Jul-12 11:01 AM

Nearly the first thing I did when I got my D800E was test my most-used lens, the Tamron 180 macro, to see where diffraction set in. After reading all the stories about not being able to shoot beyond f8, I was surprised to see that to my eye, at 100%, I could not see a difference in fine detail between f11 and f16 and, in fact, both looked a tiny bit better than f8. There was a clear degradation at f22, however. So for me, at least, I have no problems shooting at f16 with that lens. I would use f22 if necessary but avoid it if I can. F32 is bad enough that I would likely avoid it completely. The lens is also soft at f4 and f5.6, but again, I'll use those f-stops if I need to for a specific look.

Cheers -
John

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RWCooper

Winnipeg, CA
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#14. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 0

RWCooper Silver Member Nikonian since 04th Jul 2004
Wed 25-Jul-12 09:18 PM

I've been doing macro work at f/11 and even f/16 with my D800 and have been satisfied with the results. I don't stop down unless I feel that I need to, but if I need to I'm not afraid I'll have a useless image.

Enjoy!

Randy

Wingman

Kimberley, CA
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#15. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 14

Wingman Silver Member Awarded for sharing his excellent work and continued contribution to the forums, most notably at the Aviation forum. Donor Ribbon awarded for his generous support to the Fundraising Campaign 2014 Nikonian since 02nd Dec 2002
Wed 25-Jul-12 11:58 PM

I got curious about this whole diffraction issue after recent discussions, and dug into some old magazine articles that I've saved over the years. An old Pop Photo article that I found said very clearly that the "diffraction limit" is very different for wide angles than with longer lenses -- that a 24mm might show similar diffraction effects at F5.6 as a 300mm at F16 (I don't have the article in front of me so I don't know the exact figures used). The article even had a table of the theoretical ideal apertures for a range of focal lengths. It very clearly said, backed up by mathematics, that diffraction sets in at a much larger aperture for wides than for longer lenses.

Neal Nurmi

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Clint S

Chula Vista, US
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#16. "RE: Will you still get lens diffraction past f8 even if you are on DX mode?" | In response to Reply # 0

Clint S Silver Member Nikonian since 02nd Jan 2011
Thu 26-Jul-12 01:13 AM | edited Thu 26-Jul-12 01:16 AM by Clint S

Diffraction is a little overrated but when shooting for details can become very important. If detail is of a concern, one should test their own equipment.

As a demonstartion of diffraction vs DoF here is an example of a photo taken at an extreme f/40 with a 70-180mm Nikkor lens.

Click on image to view larger version

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