How to see diffraction in photos

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cba_melbourne
cba_melbourne Veteran Member • Posts: 5,672
Re: How to see diffraction in photos
1

Pete Berry wrote:

cba_melbourne wrote:

BobT3218 wrote:

Out of curiosity. while on the subject of diffraction, would one of the optics gurus care to advise if theoretically, FL is a factor in diffraction?

Optically, diffraction only depends on the physical size of the aperture (not the f/number), the distance of the aperture to the focal plane, and the wavelength of light. Nothing else.

FL plays no role, because it is taken into consideration (or offset) by the way the f/number is defined. The f/number of a lens is the ratio of it's focal length to the diameter of the entrance pupil (for example f/8 means the FL is eight times the diameter).

It is often said that in m4/3, diffraction becomes notable higher than f8, but FL is never mentioned. I'd like to know because I regularly use FLs from 12mm to 600mm.

The effects of diffraction very much depend on sensor pixel size (and on the presence or not of an anti aliasing filter in the sensor stack). The smaller the pixel size, the sooner (at a smaller F/number) will diffraction begin to limit the image resolution. In m43 with our current 20MP sensors, that threshold is now somewhere between f/5.6 and f/8. With 16MP sensors is was more like f/8, and with future higher resolution sensors it may well shift towards f/5.6.

Back in the film days, the onset of diffraction depended on film grain size. And film grain size depended on ISO sensitivity, because the higher the film sensitivity, the bigger its grain was. So swapping from an ISO100 to an ISO1000 film, was very much like if today we swapped to a much larger pixel size (lower resolution) sensor.

An optically perfect lens of any FL or aperture will halve it's resolution with every two stops increase in F-number, which halves the physical aperture diameter - and decreases light transmission by a factor of (1/2 squared) = 1/4th.

But our imperfect lenses fall more slowly in resolution stopping down, but much the same in light transmission.

An optically perfect lens is said to be "diffraction limited". Meaning the lens is so good, it's performance is only limited by diffraction.

Diffraction-limited lenses are lenses with aberrations corrected to the point that residual wavefront errors are substantially less than one-quarter the wavelength of the energy being acted upon.

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cba_melbourne
cba_melbourne Veteran Member • Posts: 5,672
Re: How to see diffraction in photos
2

knickerhawk wrote:

cba_melbourne wrote:

BobT3218 wrote:

Out of curiosity. while on the subject of diffraction, would one of the optics gurus care to advise if theoretically, FL is a factor in diffraction?

Optically, diffraction only depends on the physical size of the aperture (not the f/number), the distance of the aperture to the focal plane, and the wavelength of light. Nothing else.

FL plays no role, because it is taken into consideration (or offset) by the way the f/number is defined. The f/number of a lens is the ratio of it's focal length to the diameter of the entrance pupil (for example f/8 means the FL is eight times the diameter).

It is often said that in m4/3, diffraction becomes notable higher than f8, but FL is never mentioned. I'd like to know because I regularly use FLs from 12mm to 600mm.

The effects of diffraction very much depend on sensor pixel size (and on the presence or not of an anti aliasing filter in the sensor stack). The smaller the pixel size, the sooner (at a smaller F/number) will diffraction begin to limit the image resolution.

Not true. Diffraction is just one form of lens blur and as such it is not dependent on pixel size.

Diffraction does not depend on sensor pixel size.

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

Another way to explain is this. As long as the airy disc is smaller than the sensor pixel, the lens outresolves the sensor. Only when the airy disc (due to diffraction) becomes larger than the pixel size, can we begin to notice a loss of sharpness.

https://www.edmundoptics.com.au/knowledge-center/application-notes/imaging/limitations-on-resolution-and-contrast-the-airy-disk/

Moreover, decreasing pixel size generally increases overall system resolution (which is what I assume you mean by referring to "image resolution"), and that's regardless of the lens blur being presented to the system sensor. My assertion is backed up by hard data at DXOMark. Check the sharpness profile charts in DXOMark for cameras with different pixel size and see for yourself that peak resolution for a given lens is virtually always achieved at the same f-stop regardless of pixel size and assuming same sensor size and AA filter status. For instance, compare the sharpness profiles for the Nikon D700 and D800 or for the Olympus EPL1 and EM1ii.

In m43 with our current 20MP sensors, that threshold is now somewhere between f/5.6 and f/8. With 16MP sensors is was more like f/8, and with future higher resolution sensors it may well shift towards f/5.6.

Sorry, this simply isn't the case. Peak center sharpness for the best mFT lenses is somewhere between f/2.8 and f3.5. For the crappier zoom lenses, it's pretty much always at the lowest available f-number since most of those are f/4 or f/5.6. Again, this has not changed from the 12mp to the16mp and 20mp cameras in the DXOMark tests.

Back in the film days, the onset of diffraction depended on film grain size. And film grain size depended on ISO sensitivity, because the higher the film sensitivity, the bigger its grain was. So swapping from an ISO100 to an ISO1000 film, was very much like if today we swapped to a much larger pixel size (lower resolution) sensor.

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finnan haddie
finnan haddie Regular Member • Posts: 464
Re: How to see diffraction in photos

cba_melbourne wrote:

...

Diffraction does not depend on sensor pixel size.

True, that's for sure.

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

On a 20 MPix MFT sensor that would mean around f/2.8.

Another way to explain is this. As long as the airy disc is smaller than the sensor pixel, the lens outresolves the sensor. Only when the airy disc (due to diffraction) becomes larger than the pixel size, can we begin to notice a loss of sharpness.

Not true. In particular with non-circular apertures you'll notice the effects of diffraction way earlier, e.g. sunstars.

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alcelc
alcelc Forum Pro • Posts: 18,652
Diffraction is real

but it could be different on regular shooting vs close up shooting. Not a learnt person on this but in reality it is happening.

Using the idle time during the high of Covid I carried out a home testing on diffraction of my various M43 lenses and was reported as below:

https://www.dpreview.com/forums/post/63900203

The above test were based on the sharpness/resolution of focusing at infinity. Generally f/8 could be the limit of my lenses before entering the diffraction zone.

Later on, had been inspired by discussion on close up shooting, I carried out another testing as below:

https://www.dpreview.com/forums/post/65137203

I found that on close up shooting could be the DoF had out benefit the diffraction such that made f/11 be the sharpness and should have pushed the diffraction limit to f/22...

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Albert
** Please forgive my typo error.
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cba_melbourne
cba_melbourne Veteran Member • Posts: 5,672
Re: How to see diffraction in photos
1

finnan haddie wrote:

cba_melbourne wrote:

...

Diffraction does not depend on sensor pixel size.

True, that's for sure.

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

On a 20 MPix MFT sensor that would mean around f/2.8.

Interesting, is that with the Bayer mask, or without as in a black and white sensor?

Another way to explain is this. As long as the airy disc is smaller than the sensor pixel, the lens outresolves the sensor. Only when the airy disc (due to diffraction) becomes larger than the pixel size, can we begin to notice a loss of sharpness.

Not true. In particular with non-circular apertures you'll notice the effects of diffraction way earlier, e.g. sunstars.

Most modern lenses do have near circular apertures. But yes, some older repro lenses had indeed square shaped apertures. Beneficial for sharper edges when reproducing texts, or to create half-tone films (before the invention of contact screens in printing).

For $50 you can buy a used Schneider Componar enlarger lens with square aperture. It produces not round, but square bokeh, and 4-ray sunstars:

Or what about the 1964 Ricoh Rikenon lens with triangular aperture? Enjoy the video:

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finnan haddie
finnan haddie Regular Member • Posts: 464
Re: How to see diffraction in photos

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

...

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

On a 20 MPix MFT sensor that would mean around f/2.8.

Interesting, is that with the Bayer mask, or without as in a black and white sensor?

For both types of sensors. A Bayer mask just adds funny false colors at the edges.

Another way to explain is this. As long as the airy disc is smaller than the sensor pixel, the lens outresolves the sensor. Only when the airy disc (due to diffraction) becomes larger than the pixel size, can we begin to notice a loss of sharpness.

Not true. In particular with non-circular apertures you'll notice the effects of diffraction way earlier, e.g. sunstars.

Most modern lenses do have near circular apertures. But yes, some older repro lenses had indeed square shaped apertures. Beneficial for sharper edges when reproducing texts, or to create half-tone films (before the invention of contact screens in printing).

For $50 you can buy a used Schneider Componar enlarger lens with square aperture. It produces not round, but square bokeh, and 4-ray sunstars:

Or what about the 1964 Ricoh Rikenon lens with triangular aperture? Enjoy the video:

Yup.

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cba_melbourne
cba_melbourne Veteran Member • Posts: 5,672
Re: How to see diffraction in photos
1

finnan haddie wrote:

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

...

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

On a 20 MPix MFT sensor that would mean around f/2.8.

Interesting, is that with the Bayer mask, or without as in a black and white sensor?

For both types of sensors. A Bayer mask just adds funny false colors at the edges.

No, it increases the effective pixel size. Two green, one blue and one red pixel are demosaiced, and result in a larger pixel size for the purpose of diffraction visibility in a picture.

It depends on the mask layout and the demosaicing algorithms used. But the diffraction-effective pixel size is definitely greater than one pixel, and smaller than four pixels. You are not far off assuming it is about 2.5 pixels.

Another way to explain is this. As long as the airy disc is smaller than the sensor pixel, the lens outresolves the sensor. Only when the airy disc (due to diffraction) becomes larger than the pixel size, can we begin to notice a loss of sharpness.

Not true. In particular with non-circular apertures you'll notice the effects of diffraction way earlier, e.g. sunstars.

Most modern lenses do have near circular apertures. But yes, some older repro lenses had indeed square shaped apertures. Beneficial for sharper edges when reproducing texts, or to create half-tone films (before the invention of contact screens in printing).

For $50 you can buy a used Schneider Componar enlarger lens with square aperture. It produces not round, but square bokeh, and 4-ray sunstars:

Or what about the 1964 Ricoh Rikenon lens with triangular aperture? Enjoy the video:

Yup.

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finnan haddie
finnan haddie Regular Member • Posts: 464
Re: How to see diffraction in photos

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

...

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

On a 20 MPix MFT sensor that would mean around f/2.8.

Interesting, is that with the Bayer mask, or without as in a black and white sensor?

For both types of sensors. A Bayer mask just adds funny false colors at the edges.

No, it increases the effective pixel size. Two green, one blue and one red pixel are demosaiced, and result in a larger pixel size for the purpose of diffraction visibility.

Diffraction doesn't care about Bayer masks, as you can easily see in RAW files. Also diffraction doesn't care if you develop your picture in black and white or color of choice.

Another way to explain is this. As long as the airy disc is smaller than the sensor pixel, the lens outresolves the sensor. Only when the airy disc (due to diffraction) becomes larger than the pixel size, can we begin to notice a loss of sharpness.

Not true. In particular with non-circular apertures you'll notice the effects of diffraction way earlier, e.g. sunstars.

Most modern lenses do have near circular apertures.

There are also still modern lenses, e.g. the Voigtländers with straight non-rounded aperture blades.

But yes, some older repro lenses had indeed square shaped apertures. Beneficial for sharper edges when reproducing texts, or to create half-tone films (before the invention of contact screens in printing).

For $50 you can buy a used Schneider Componar enlarger lens with square aperture. It produces not round, but square bokeh, and 4-ray sunstars:

Or what about the 1964 Ricoh Rikenon lens with triangular aperture? Enjoy the video:

Yup.

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cba_melbourne
cba_melbourne Veteran Member • Posts: 5,672
Re: How to see diffraction in photos

finnan haddie wrote:

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

...

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

On a 20 MPix MFT sensor that would mean around f/2.8.

Interesting, is that with the Bayer mask, or without as in a black and white sensor?

For both types of sensors. A Bayer mask just adds funny false colors at the edges.

No, it increases the effective pixel size. Two green, one blue and one red pixel are demosaiced, and result in a larger pixel size for the purpose of diffraction visibility.

Diffraction doesn't care about Bayer masks, as you can easily see in RAW files. Also diffraction doesn't care if you develop your picture in black and white or color of choice.

If you say so...

but I disagree

Maybe this helps: https://www.scantips.com/lights/diffraction.html

What matters is, at which aperture can we start just barely noticing a loss of sharpness on a 20MP sensor camera, when comparing identical pictures taken at various apertures. And I like to claim, that with the 10% very best resolution lenses we have in m43, we just barely can see the diffraction effect taking off at f/5.6. For the remaining 90% of lenses, it is at f/8 or somewhere in between. But hey, your eyes may be better than mine

Another way to explain is this. As long as the airy disc is smaller than the sensor pixel, the lens outresolves the sensor. Only when the airy disc (due to diffraction) becomes larger than the pixel size, can we begin to notice a loss of sharpness.

Not true. In particular with non-circular apertures you'll notice the effects of diffraction way earlier, e.g. sunstars.

Most modern lenses do have near circular apertures.

There are also still modern lenses, e.g. the Voigtländers with straight non-rounded aperture blades.

Sure, but for the purposes of diffraction visibility on a normal picture (not a sunray picture, not a bokeh picture) they are still very much near circular apertures.

But yes, some older repro lenses had indeed square shaped apertures. Beneficial for sharper edges when reproducing texts, or to create half-tone films (before the invention of contact screens in printing).

For $50 you can buy a used Schneider Componar enlarger lens with square aperture. It produces not round, but square bokeh, and 4-ray sunstars:

Or what about the 1964 Ricoh Rikenon lens with triangular aperture? Enjoy the video:

Yup.

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JasonTheBirder
JasonTheBirder Senior Member • Posts: 3,886
Re: How to see diffraction in photos

It can be hard to tell definitively but a good sign that diffraction is around is a general softness, which is definitely present it the pixel level in your photos. Whether that's a serious problem for you depends on what you want, but to me it doesn't look like a big deal here. When you're cropping, it definitely is a big deal.

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finnan haddie
finnan haddie Regular Member • Posts: 464
Re: How to see diffraction in photos
1

cba_melbourne wrote:

...

What matters is, at which aperture can we start just barely noticing a loss of sharpness on a 20MP sensor camera, when comparing identical pictures taken at various apertures.

Sorry, that might matter for you. I'm not a pixel peeper, so I don't care.

What matters for me is the maximum sharpness of a lens, regardless of size and pixel count of any camera's sensor.

Diffraction is always there, even wide open. Yes, its effects are increasing when stopping a lens down. Nevertheless I do that when I want more DoF. I just know that around f/8 and beyond the sharpness of the lens becomes really irrelevant for me. Still I have no qualms stopping down when needed, even all the way down to f/32.

And I like to claim, that with the 10% very best resolution lenses we have in m43, we just barely can see the diffraction effect taking off at f/5.6. For the remaining 90% of lenses, it is at f/8 or somewhere in between. But hey, your eyes may be better than mine

LOL. I never bothered about that.

YMMV.

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thinkinginimages
thinkinginimages Senior Member • Posts: 2,028
Re: How to see diffraction in photos

Dann-Oh wrote:

Hello all,

I am wondering if you guys could help me understand what diffraction is and how to spot it in my photos?

I was trying out my new flash and I was trying to get a black background, so I stopped down to f16.

Diffraction would be a slight softness everywhere, almost like a very light diffusion. Usually I use a lens test target and photograph it. MFT cameras tend to correct lens flaws. Here's an excellent write-up about lens testing:

https://www.lensrentals.com/blog/2014/02/setting-up-an-optical-testing-station/

As for the black background and flash that's a different topic: fill flash. The gist is that you don't want the flash to be the primary light. You don't say what flash. Is it TTL? I would get the flash off the camera so you have more lighting control.

Great images!

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OP Dann-Oh Contributing Member • Posts: 856
Re: How to see diffraction in photos

River Photography wrote:

shutter speed controls background exposure when using flash, aperture and flash control subject exposure.

Rp

I understand that but its hard to increase a shutter speed beyond the flash sync speed, 1/250th. If I remember correctly I was starting to see "banding" in the images when I used 1/250th, see image below. This is what lead me to use 1/125th.

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OP Dann-Oh Contributing Member • Posts: 856
Re: How to see diffraction in photos

thinkinginimages wrote:

Dann-Oh wrote:

Hello all,

I am wondering if you guys could help me understand what diffraction is and how to spot it in my photos?

I was trying out my new flash and I was trying to get a black background, so I stopped down to f16.

Diffraction would be a slight softness everywhere, almost like a very light diffusion. Usually I use a lens test target and photograph it. MFT cameras tend to correct lens flaws. Here's an excellent write-up about lens testing:

https://www.lensrentals.com/blog/2014/02/setting-up-an-optical-testing-station/

As for the black background and flash that's a different topic: fill flash. The gist is that you don't want the flash to be the primary light. You don't say what flash. Is it TTL? I would get the flash off the camera so you have more lighting control.

Great images!

good catch, I am using the Godox/Flashpoint MF12 macro flash kit. These photos were taken with the Godox version but I was able to get the Flashpoint version for $80 less so the Godox is being returned.

The flashes (2 of them) were set to the 3 and 9 o'clock positions and they were set to manual power (maybe 1/32 or 1/64).  I have no idea how ttl works so Ive stayed away from it.

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thinkinginimages
thinkinginimages Senior Member • Posts: 2,028
Re: How to see diffraction in photos

What camera and flash? Onboard flash or external? It's not hard to sort out I just need details. Daylight fill in flash is always a bit of alchemy, but there's a lot written on the techniques.

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finnan haddie
finnan haddie Regular Member • Posts: 464
Re: How to see diffraction in photos

Dann-Oh wrote:

...

The flashes (2 of them) were set to the 3 and 9 o'clock positions and they were set to manual power (maybe 1/32 or 1/64). I have no idea how ttl works so Ive stayed away from it.

Then again you might alternativly achieve the desired black background without having to stop down the lens that much, e.g. by using a ND filter for the lens, and setting the flashes to full power.

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Pete Berry Veteran Member • Posts: 4,303
Re: How to see diffraction in photos

cba_melbourne wrote:

Pete Berry wrote:

cba_melbourne wrote:

BobT3218 wrote:

Out of curiosity. while on the subject of diffraction, would one of the optics gurus care to advise if theoretically, FL is a factor in diffraction?

Optically, diffraction only depends on the physical size of the aperture (not the f/number), the distance of the aperture to the focal plane, and the wavelength of light. Nothing else.

FL plays no role, because it is taken into consideration (or offset) by the way the f/number is defined. The f/number of a lens is the ratio of it's focal length to the diameter of the entrance pupil (for example f/8 means the FL is eight times the diameter).

It is often said that in m4/3, diffraction becomes notable higher than f8, but FL is never mentioned. I'd like to know because I regularly use FLs from 12mm to 600mm.

The effects of diffraction very much depend on sensor pixel size (and on the presence or not of an anti aliasing filter in the sensor stack). The smaller the pixel size, the sooner (at a smaller F/number) will diffraction begin to limit the image resolution. In m43 with our current 20MP sensors, that threshold is now somewhere between f/5.6 and f/8. With 16MP sensors is was more like f/8, and with future higher resolution sensors it may well shift towards f/5.6.

Back in the film days, the onset of diffraction depended on film grain size. And film grain size depended on ISO sensitivity, because the higher the film sensitivity, the bigger its grain was. So swapping from an ISO100 to an ISO1000 film, was very much like if today we swapped to a much larger pixel size (lower resolution) sensor.

An optically perfect lens of any FL or aperture will halve it's resolution with every two stops increase in F-number, which halves the physical aperture diameter - and decreases light transmission by a factor of (1/2 squared) = 1/4th.

But our imperfect lenses fall more slowly in resolution stopping down, but much the same in light transmission.

An optically perfect lens is said to be "diffraction limited". Meaning the lens is so good, it's performance is only limited by diffraction.

Diffraction-limited lenses are lenses with aberrations corrected to the point that residual wavefront errors are substantially less than one-quarter the wavelength of the energy being acted upon.

Yes. My Intes-Micro 1500mm f/10 Mak-Cass scope came with certification of 1/6th wavefront error over a 1 deg. field, and a Strehl ratio of 94%, which in my understanding is the percentage of light falling on the central image spot "Airy disk" from a star point source, vs. the light in its diffraction rings.

The size of the central star spot defines the scope's resolution limit: the larger the aperture, the smaller it's central spot - in my case, 13.8 microns giving a resolution of 0.8 arc-sec. to just separate two point sources edge-to-edge.

OP Dann-Oh Contributing Member • Posts: 856
Re: How to see diffraction in photos

finnan haddie wrote:

Dann-Oh wrote:

...

The flashes (2 of them) were set to the 3 and 9 o'clock positions and they were set to manual power (maybe 1/32 or 1/64). I have no idea how ttl works so Ive stayed away from it.

Then again you might alternativly achieve the desired black background without having to stop down the lens that much, e.g. by using a ND filter for the lens, and setting the flashes to full power.

Unfortunately, the flash kit Im using (Flashpoint MF12) is a filter thread mounted kit.   Im not too sure how I could use a ND filter on the MF12.  Im sure there is a YouTube video out there showing it.

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OP Dann-Oh Contributing Member • Posts: 856
Re: How to see diffraction in photos

thinkinginimages wrote:

What camera and flash? Onboard flash or external? It's not hard to sort out I just need details. Daylight fill in flash is always a bit of alchemy, but there's a lot written on the techniques.

I'm using the EM1-3 with the 60mm and 30mm  macros, the flash kit is the Flashpoint MF12 (its a filter ring mounted kit). The MF12 has 2 flash heads, but you can up to a total of 6 flash heads.

Link to Flashpoint MF12

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I take photos, not particularly good photos, mostly abstract photos. Yeah abstract is what I would call them, you might call them blurry.

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knickerhawk Veteran Member • Posts: 7,555
Re: How to see diffraction in photos

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

finnan haddie wrote:

cba_melbourne wrote:

...

But the effects of diffraction only become apparent in our picture, when the size of the airy disc exceeds the pixel size of our sensor. And that happens the sooner, the smaller the pixel size is.

On a 20 MPix MFT sensor that would mean around f/2.8.

Interesting, is that with the Bayer mask, or without as in a black and white sensor?

For both types of sensors. A Bayer mask just adds funny false colors at the edges.

No, it increases the effective pixel size. Two green, one blue and one red pixel are demosaiced, and result in a larger pixel size for the purpose of diffraction visibility.

Diffraction doesn't care about Bayer masks, as you can easily see in RAW files. Also diffraction doesn't care if you develop your picture in black and white or color of choice.

If you say so...

but I disagree

Maybe this helps: https://www.scantips.com/lights/diffraction.html

Not really. It's a rambling discussion primarily about the tradeoffs between diffraction and DOF and barely touches on the critical factor here - the tradeoff between optical aberrations and diffraction (and the role that pixel size plays).

What matters is, at which aperture can we start just barely noticing a loss of sharpness on a 20MP sensor camera, when comparing identical pictures taken at various apertures.

And I like to claim, that with the 10% very best resolution lenses we have in m43, we just barely can see the diffraction effect taking off at f/5.6. For the remaining 90% of lenses, it is at f/8 or somewhere in between. But hey, your eyes may be better than mine

Now you're singing a very different tune from when you wrote:

The effects of diffraction very much depend on sensor pixel size (and on the presence or not of an anti aliasing filter in the sensor stack). The smaller the pixel size, the sooner (at a smaller F/number) will diffraction begin to limit the image resolution.

I don't believe anybody in this sub-discussion has disputed that lens quality plays a major role with regard to which f-stop we begin to "see the diffraction effect taking off." Of course lens quality is critical to when diffraction becomes the primary source of blur! The dispute is about whether the visibility of the "diffraction effect taking off" varies because of pixel size, not because of lens quality.

Your original assertion was that there has been (must be!) a shift in the f-stop at which "the diffraction effect [visibly and measurably] takes off" because there's been a progressive decrease in pixel pitch in mFT cameras over the years. Rather than celebrating the increased sensor resolution this implies and therefore overall system resolution, you're fretting about Airy Disk limits.  Well, to date, I've seen no evidence that supports your bolded claim above in the real world of photography, and I provided counter-evidence as well (DXOMark sharpness profiles for virtually all lenses that have been tested on cameras with differing pixel pitches) that you chose to ignore.

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