A7R6 and diffraction
p.2 #1A7R6 and diffraction
aCuria wrote:
I'd argue that for the vast majority of images, DOF is more important than sharpness - not many images will be ruined by an overall decrease in sharpness but the same cannot be said for insufficient DOF, particularly when the details of both near and far subjects are equally important to the artistic intent.In the context of OP's landscape shooting I am not sure I agree. I think "the vast majority" of landscapes do not suffer from a lack of DOF even if you shoot at bright apertures like f/1.4.
For example, this one is shot at f/1.4 because it was handheld. I probably should have lowered the shutter too but this was just a test shot to see what the compression was going to look like before I put the subject into the frame.
https://live.staticflickr.com/65535/53949870014_8ec0c0c541_b.jpg7IV06347 by acurian, on Flickr
I would try to maximize the dynamic range for a landscape. If the shot has to be handheld, then using f/1.4 to achieve base ISO is an acceptable compromise.
If there is a tripod then I would try to do exposure stacking. There is no need to do focus stacking when the landscape subject is beyond the hyperfocal distance.I argued adequate DOF is more important than sharpness in the majority of landscapes. That's a bit different than saying a majority of landscapes suffer from lack of DOF.Sure, and I agree that sufficient DOF is more important than maximizing sharpness if those two things are actually in conflict.
However for a landscape DOF is very plentiful regardless of what aperture you set, so talking about DOF at all is not very meaningful
DOF is only plentiful if you make an argument that landscapes are done with wide lenses and not long lenses.
EBH
snapsy wrote
aCuria wrote
snapsy wrote
Putting aside the sensor-specific technical cutoff point between DOF/diffraction, I'd say the decision is scene and/or artistic-intent dependent. For some scenes, it's more important to maximize DOF, for others sharpness is more important. When both are important then focus stacking.I'd argue that for the vast majority of images, DOF is more important than sharpness - not many images will be ruined by an overall decrease in sharpness but the same cannot be said for insufficient DOF, particularly when the details of both near and far subjects are equally important to the artistic intent.
For example, this one is shot at f/1.4 because it was handheld. I probably should have lowered the shutter too but this was just a test shot to see what the compression was going to look like before I put the subject into the frame.
https://live.staticflickr.com/65535/53949870014_8ec0c0c541_b.jpg7IV06347 by acurian, on Flickr
I would try to maximize the dynamic range for a landscape. If the shot has to be handheld, then using f/1.4 to achieve base ISO is an acceptable compromise.
If there is a tripod then I would try to do exposure stacking. There is no need to do focus stacking when the landscape subject is beyond the hyperfocal distance.
However for a landscape DOF is very plentiful regardless of what aperture you set, so talking about DOF at all is not very meaningful
DOF is only plentiful if you make an argument that landscapes are done with wide lenses and not long lenses.
EBH
Aug 19, 2026 at 07:39 AM
p.2 #2A7R6 and diffraction
aCuria wrote:
The Nyquist theorem (or Nyquist-Shannon sampling theorem) states that to accurately record or digitize a continuous analog signal without losing information, you must sample it at a rate greater than twice the highest frequency component present in that signal.
This means we want the Airy disk to cover at least 2 pixels on the sensor. If you use 1.5 you are losing information.
Uhm, that way you do loose information. You generally loose information as your airy disk gets bigger and also if you sample with less pixels. So your requirement of using no more than two pixels per airy disk is the wrong way around if you do not want to loose information. Meanwhile it is a valid approach to reduce Moire.
If the lens is not perfect you can think of this as the airy disc being larger than the calculated value.
Approximately if the lens is soft. CA means that the airy discs for different colors do not coincide. Coma means that they are not round.
The Nyquist theorem (or Nyquist-Shannon sampling theorem) states that to accurately record or digitize a continuous analog signal without losing information, you must sample it at a rate greater than twice the highest frequency component present in that signal.
This means we want the Airy disk to cover at least 2 pixels on the sensor. If you use 1.5 you are losing information.
Uhm, that way you do loose information. You generally loose information as your airy disk gets bigger and also if you sample with less pixels. So your requirement of using no more than two pixels per airy disk is the wrong way around if you do not want to loose information. Meanwhile it is a valid approach to reduce Moire.
If the lens is not perfect you can think of this as the airy disc being larger than the calculated value.
Approximately if the lens is soft. CA means that the airy discs for different colors do not coincide. Coma means that they are not round.
Aug 19, 2026 at 09:05 AM
p.2 #3A7R6 and diffraction
EB-1 wrote:
I most always use focus stacking now, usually at f/8. My landscape lenses are typically between 50-500mm, mostly 100-400 range. About 8-12 images are often adequate for stacking prior to stitching. I'd probably focus bracket the a7RVI at f/6.3 or similar for the single frame/composition if necessary. I have not tested how well the increment of one covers depth however.
I suspect that Dan shoots subjects more like me, in UT/AZ/NM/CO and places like that normally on a tripod. MS mode at ISO 100 looks great with the DGO. It certainly has more DR than the 5DsR, which was mostly...Show more →
For my landscape photography, that’s exactly right.
(I usually don’t use the tripod for bird photography and I essentially never use it for street/travel, and for those types I don’t shy away from higher ISOs when needed.)
- - -
Another reply to the same EB-1 post was…
aCuria wrote:
What do you think about pixel shift? I was thinking it might be more valuable than focus stacking for landscape photography, while focus stacking seems more useful for macro photography.
Its a pity the A9iii doesn't have pixel shift
Generally, I don’t think pixel shift has a whole lot of value with high resolution full frame cameras. There is obviously the potential plus of wildly higher pixel resolution (and some other stuff), but these high res cameras already have enough resolution to make very good, very large prints without introducing some of the issues that pixel shift can create. (Note: some of those can also be issues with focus bracketing, especially subject motion.)
I think that pixel shift may have more potential value for those using much lower pixel resolution cameras who occasionally want to get much higher pixel resolution. (Your A9 example makes sense.)
- - -
Jack Flesher wrote:
If we have to sample at 2x, doesn’t that imply the airy disc needs to be the inverse, or 0.5 pixel instead of 2?
We’re getting very deep into a thick growth of very tine weeds here, but I think that technically you are right. (Unless the goal is to most accurately record the blur?)
Larger blur will affect the degree of (never perfect) accuracy of what is recorded at a larger number of pixels.
Having said that, I urge people to maybe take a step back from the theory and take a look at actual photographs using these various combinations of apertures and photo site densities… and note that what things actually look like as finished products is the ultimate benchmark.
- - -
Or as woofwoof70 wrote:
I'm always a little surprised when people dive deeply into diffraction and discs but if someone is committed to doing this there's the theory and there's taking pictures and looking at the effects. With digital on screen viewing is cheap (but do we really need to look at pictures at 100% on screen?) but prints maybe not so much so.
I do on occasions stop down past f8 to f11 and even beyond and find that the main hit for me is reduced contrast and there's always the sliders if they can help with that. My own opinion is that if...Show more →
Amen.
- - -
Someone blustered: …hand wringing always seems to come from those that would prefer to think about taking about photos than actually going and doing it.
It turns out that “ think about taking about photos” and “ actually going and doing it” are not unrelated practices in photography.
Edited on Aug 19, 2026 at 09:37 AM · View previous versions
I most always use focus stacking now, usually at f/8. My landscape lenses are typically between 50-500mm, mostly 100-400 range. About 8-12 images are often adequate for stacking prior to stitching. I'd probably focus bracket the a7RVI at f/6.3 or similar for the single frame/composition if necessary. I have not tested how well the increment of one covers depth however.
I suspect that Dan shoots subjects more like me, in UT/AZ/NM/CO and places like that normally on a tripod. MS mode at ISO 100 looks great with the DGO. It certainly has more DR than the 5DsR, which was mostly...Show more →
For my landscape photography, that’s exactly right.
(I usually don’t use the tripod for bird photography and I essentially never use it for street/travel, and for those types I don’t shy away from higher ISOs when needed.)
- - -
Another reply to the same EB-1 post was…
aCuria wrote:
What do you think about pixel shift? I was thinking it might be more valuable than focus stacking for landscape photography, while focus stacking seems more useful for macro photography.
Its a pity the A9iii doesn't have pixel shift
Generally, I don’t think pixel shift has a whole lot of value with high resolution full frame cameras. There is obviously the potential plus of wildly higher pixel resolution (and some other stuff), but these high res cameras already have enough resolution to make very good, very large prints without introducing some of the issues that pixel shift can create. (Note: some of those can also be issues with focus bracketing, especially subject motion.)
I think that pixel shift may have more potential value for those using much lower pixel resolution cameras who occasionally want to get much higher pixel resolution. (Your A9 example makes sense.)
- - -
Jack Flesher wrote:
If we have to sample at 2x, doesn’t that imply the airy disc needs to be the inverse, or 0.5 pixel instead of 2?
We’re getting very deep into a thick growth of very tine weeds here, but I think that technically you are right. (Unless the goal is to most accurately record the blur?)
Larger blur will affect the degree of (never perfect) accuracy of what is recorded at a larger number of pixels.
Having said that, I urge people to maybe take a step back from the theory and take a look at actual photographs using these various combinations of apertures and photo site densities… and note that what things actually look like as finished products is the ultimate benchmark.
- - -
Or as woofwoof70 wrote:
I'm always a little surprised when people dive deeply into diffraction and discs but if someone is committed to doing this there's the theory and there's taking pictures and looking at the effects. With digital on screen viewing is cheap (but do we really need to look at pictures at 100% on screen?) but prints maybe not so much so.
I do on occasions stop down past f8 to f11 and even beyond and find that the main hit for me is reduced contrast and there's always the sliders if they can help with that. My own opinion is that if...Show more →
Amen.
- - -
Someone blustered: …hand wringing always seems to come from those that would prefer to think about taking about photos than actually going and doing it.
It turns out that “ think about taking about photos” and “ actually going and doing it” are not unrelated practices in photography.
Edited on Aug 19, 2026 at 09:37 AM · View previous versions
Aug 19, 2026 at 09:09 AM
p.2 #4A7R6 and diffraction
A simple equation to calculate an f-number that maximizes depth of field while keeping diffraction negligible.
a7r6 pixel size = 3.6 microns
2.5 * 3.6 (pixel size in microns) * .75 = best f-number = 6.75
Lumariver Depth of Field Calculator Manual
a7r6 pixel size = 3.6 microns
2.5 * 3.6 (pixel size in microns) * .75 = best f-number = 6.75
Lumariver Depth of Field Calculator Manual
Aug 19, 2026 at 09:20 AM
p.2 #5A7R6 and diffraction
newhaven wrote:
A simple equation to calculate an f-number that maximizes depth of field while keeping diffraction negligible.
a7r6 pixel size = 3.6 microns
2.5 * 3.6 (pixel size in microns) * .75 = best f-number = 6.75
Lumariver Depth of Field Calculator Manual
Okay, so f7.1 is it. That actually aligns pretty well with what I am seeing with my best lenses; f5.6 is about as sharp as it gets, and by f8 I am seeing visible micro detail degradation at 100% view. Granted that it’s tiny and probably irrelevant to most of my images, but nonetheless visible. I can probably accept f9 some of the time but f11 is definitely into iffy territory except when I want sun stars with my extreme wide angle lenses.
A simple equation to calculate an f-number that maximizes depth of field while keeping diffraction negligible.
a7r6 pixel size = 3.6 microns
2.5 * 3.6 (pixel size in microns) * .75 = best f-number = 6.75
Lumariver Depth of Field Calculator Manual
Okay, so f7.1 is it. That actually aligns pretty well with what I am seeing with my best lenses; f5.6 is about as sharp as it gets, and by f8 I am seeing visible micro detail degradation at 100% view. Granted that it’s tiny and probably irrelevant to most of my images, but nonetheless visible. I can probably accept f9 some of the time but f11 is definitely into iffy territory except when I want sun stars with my extreme wide angle lenses.
Aug 19, 2026 at 09:38 AM
p.2 #6A7R6 and diffraction
2.5 is somewhat arbitrary as there is no consensus. After all we are talking about acceptable sharpness.
Aug 19, 2026 at 09:53 AM
p.2 #7A7R6 and diffraction
I'm trying to learn more about the technical side of discussions like this as a relatively new photographer. Can someone explain what an airy disk is, or point me to an article they found particularly good at describing it? Yes I could google it, but part of the enjoyment of this site is direct interaction with some of the more knowledgable people here.
Much appreciated.
Much appreciated.
Aug 19, 2026 at 09:53 AM
p.2 #8A7R6 and diffraction
You could start here.
https://www.cambridgeincolour.com/tutorials/diffraction-photography.htm
https://www.cambridgeincolour.com/tutorials/diffraction-photography.htm
Aug 19, 2026 at 09:59 AM
p.2 #10A7R6 and diffraction
Keep in mind that while you might be able to calculate (or not?) the "best" sharpness of a lens with a particular sensor, there are multiple apertures that will still produce "excellent" sharpness. Yes, "excellent" is a fuzzier concept than "best" (or so we hope), but excellent really matters more.
- - -
Tarekith wrote:
I'm trying to learn more about the technical side of discussions like this as a relatively new photographer. Can someone explain what an airy disk is, or point me to an article they found particularly good at describing it? Yes I could google it, but part of the enjoyment of this site is direct interaction with some of the more knowledgable people here.
Much appreciated.
It is interesting and useful to understand the concept, though do be careful about going down the technical rabbit hole that sometimes is alluring but maybe less relevant to real photography than it might seem. This is a special list for "new photographers." :-)
- - -
Tarekith wrote:
I'm trying to learn more about the technical side of discussions like this as a relatively new photographer. Can someone explain what an airy disk is, or point me to an article they found particularly good at describing it? Yes I could google it, but part of the enjoyment of this site is direct interaction with some of the more knowledgable people here.
Much appreciated.
It is interesting and useful to understand the concept, though do be careful about going down the technical rabbit hole that sometimes is alluring but maybe less relevant to real photography than it might seem. This is a special list for "new photographers." :-)
Aug 19, 2026 at 10:44 AM
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p.2 #11A7R6 and diffraction
Well used to that kind of thing from the audio world (I'm an audio engineer and musician). People argue all the time about concepts and theory that don't make a lick of difference to writing good songs 
Aug 19, 2026 at 12:35 PM
p.2 #12A7R6 and diffraction
Tarekith wrote:
Well used to that kind of thing from the audio world (I'm an audio engineer and musician). People argue all the time about concepts and theory that don't make a lick of difference to writing good songs
Ah, yes. I have a sort of odd academic background — my speciality was what we used to call “electronic music” — synths and recording and all that, with a focus on composing. But my background is wider than that, and in my college teaching life my position also involved teaching classical stuff… and years ago I was a dare-carrying union musician who free-lanced.
Like you, no doubt, I’ve heard a lot of nonsense about music and audio. ;-)
I could tell stories, but I’ll keep it to one. At one point I was the stage manager for a professional symphony orchestra. I got to know the fellow who recorded the concerts and whose business was live recording of classical and jazz performances. At one point he related to me that he had been reading about an audiophile product that was, IIRC, called “Wonder Solder.” As he explained that one was supposed to achieve an “expanded sound stage” and other acoustic wonders by UNSOLDERING the components of expensive gear and resoldering them with Wonder Solder, he began to chuckle, then laugh out loud, and soon he was laughing so hard that he couldn’t control himself…
;-)
I don’t know where you are on your “new photographer” path, and you may well have already figured out what I’m about to write, but what the heck: Lots of times, for all kinds of reasons, new photographers focus a whole lot on the gear. Gear is important — you want to get stuff that meets your needs. But it is easy to get distracted by all of the people swearing up and down that you need Perfect Camera A or Astonishing Lens B and so on.
You really don’t. Decent gear, acquired slowly and used to gain more experience will make you a smarter shopper and better photographer in the long run.
And, most importantly, photography isn’t really about the gear — it is about learning to see and think visually. That’s the thing to focus on. :-)
Well used to that kind of thing from the audio world (I'm an audio engineer and musician). People argue all the time about concepts and theory that don't make a lick of difference to writing good songs
Ah, yes. I have a sort of odd academic background — my speciality was what we used to call “electronic music” — synths and recording and all that, with a focus on composing. But my background is wider than that, and in my college teaching life my position also involved teaching classical stuff… and years ago I was a dare-carrying union musician who free-lanced.
Like you, no doubt, I’ve heard a lot of nonsense about music and audio. ;-)
I could tell stories, but I’ll keep it to one. At one point I was the stage manager for a professional symphony orchestra. I got to know the fellow who recorded the concerts and whose business was live recording of classical and jazz performances. At one point he related to me that he had been reading about an audiophile product that was, IIRC, called “Wonder Solder.” As he explained that one was supposed to achieve an “expanded sound stage” and other acoustic wonders by UNSOLDERING the components of expensive gear and resoldering them with Wonder Solder, he began to chuckle, then laugh out loud, and soon he was laughing so hard that he couldn’t control himself…
;-)
I don’t know where you are on your “new photographer” path, and you may well have already figured out what I’m about to write, but what the heck: Lots of times, for all kinds of reasons, new photographers focus a whole lot on the gear. Gear is important — you want to get stuff that meets your needs. But it is easy to get distracted by all of the people swearing up and down that you need Perfect Camera A or Astonishing Lens B and so on.
You really don’t. Decent gear, acquired slowly and used to gain more experience will make you a smarter shopper and better photographer in the long run.
And, most importantly, photography isn’t really about the gear — it is about learning to see and think visually. That’s the thing to focus on. :-)
Aug 19, 2026 at 01:53 PM
p.2 #13A7R6 and diffraction
Daran wrote:
This means we want the Airy disk to cover at least 2 pixels on the sensor. If you use 1.5 you are losing information.Uhm, that way you do loose information. You generally loose information as your airy disk gets bigger and also if you sample with less pixels. So your requirement of using no more than two pixels per airy disk is the wrong way around if you do not want to loose information. Meanwhile it is a valid approach to reduce Moire.
Approximately if the lens is soft. CA means that the airy discs for different colors do not coincide. Coma means that they are not round.
I think you are right I made a mistake there.
We want to use a fast enough aperture such that the airy disk covers 2 or less pixels.
Edited on Aug 19, 2026 at 10:15 PM · View previous versions
aCuria wrote
The Nyquist theorem (or Nyquist-Shannon sampling theorem) states that to accurately record or digitize a continuous analog signal without losing information, you must sample it at a rate greater than twice the highest frequency component present in that signal.This means we want the Airy disk to cover at least 2 pixels on the sensor. If you use 1.5 you are losing information.
Earlier quote
If the lens is not perfect you can think of this as the airy disc being larger than the calculated value.I think you are right I made a mistake there.
We want to use a fast enough aperture such that the airy disk covers 2 or less pixels.
Edited on Aug 19, 2026 at 10:15 PM · View previous versions
Aug 19, 2026 at 09:44 PM
p.2 #14A7R6 and diffraction
Jack Flesher wrote:
My question is what is the optimal aperture for DoF vs diffraction on the A7R6?
My empirical testing suggests that f8 is about the pinnacle of the two curves intersecting for a typical landscape shot. Beyond that, diffraction seems to start negating the DoF gains. This is viewing at 100%. Things improve viewing at print size, possibly allowing f9 for a large print. I can actually see some loss when viewing at 100% going from f5.6 to f8, minimal but visible in central frame detail. I noted similar behavior with my GFX100 and its best lenses.
If I calculate DoF...Show more →
Airy disk diameter on a perfect lens is 2.44 * λ * N
where λ is the light frequency (400nm = blue, 550 = green, 700 = red)
and N is the f-stop.
A7RVI pixel size is 36mm / 9984 = 0.0036mm = 3605.769230769231nm
To maximize dof, we want the airy disk diameter to be similar to the size of 2 pixels. so we solve for
Red:
3605.77nm * 2 = 2.44 * 700 * N
N = f/4.22
Green:
3605.77nm * 2 = 2.44 * 550 * N
N = f/5.37
Blue:
3605.77nm * 2 = 2.44 * 400 * N
N = f/7.39
Note that 2.44 * λ * N is the airy disk diameter for a perfect lens. If the lens is not perfect then you can stop down more than the computed f-stops before running into diffraction.
Based on this (lenses in real-life are not perfect) I would try to shoot faster than f/4.5 when possible.
My question is what is the optimal aperture for DoF vs diffraction on the A7R6?
My empirical testing suggests that f8 is about the pinnacle of the two curves intersecting for a typical landscape shot. Beyond that, diffraction seems to start negating the DoF gains. This is viewing at 100%. Things improve viewing at print size, possibly allowing f9 for a large print. I can actually see some loss when viewing at 100% going from f5.6 to f8, minimal but visible in central frame detail. I noted similar behavior with my GFX100 and its best lenses.
If I calculate DoF...Show more →
Airy disk diameter on a perfect lens is 2.44 * λ * N
where λ is the light frequency (400nm = blue, 550 = green, 700 = red)
and N is the f-stop.
A7RVI pixel size is 36mm / 9984 = 0.0036mm = 3605.769230769231nm
To maximize dof, we want the airy disk diameter to be similar to the size of 2 pixels. so we solve for
Red:
3605.77nm * 2 = 2.44 * 700 * N
N = f/4.22
Green:
3605.77nm * 2 = 2.44 * 550 * N
N = f/5.37
Blue:
3605.77nm * 2 = 2.44 * 400 * N
N = f/7.39
Note that 2.44 * λ * N is the airy disk diameter for a perfect lens. If the lens is not perfect then you can stop down more than the computed f-stops before running into diffraction.
Based on this (lenses in real-life are not perfect) I would try to shoot faster than f/4.5 when possible.
Aug 19, 2026 at 10:02 PM
p.2 #15A7R6 and diffraction
snapsy wrote:
I'd argue that for the vast majority of images, DOF is more important than sharpness - not many images will be ruined by an overall decrease in sharpness but the same cannot be said for insufficient DOF, particularly when the details of both near and far subjects are equally important to the artistic intent.In the context of OP's landscape shooting I am not sure I agree. I think "the vast majority" of landscapes do not suffer from a lack of DOF even if you shoot at bright apertures like f/1.4.
For example, this one is shot at f/1.4 because it was handheld. I probably should have lowered the shutter too but this was just a test shot to see what the compression was going to look like before I put the subject into the frame.
https://live.staticflickr.com/65535/53949870014_8ec0c0c541_b.jpg7IV06347 by acurian, on Flickr
I would try to maximize the dynamic range for a landscape. If the shot has to be handheld, then using f/1.4 to achieve base ISO is an acceptable compromise.
If there is a tripod then I would try to do exposure stacking. There is no need to do focus stacking when the landscape subject is beyond the hyperfocal distance.I argued adequate DOF is more important than sharpness in the majority of landscapes. That's a bit different than saying a majority of landscapes suffer from lack of DOF.Sure, and I agree that sufficient DOF is more important than maximizing sharpness if those two things are actually in conflict.
However for a landscape DOF is very plentiful regardless of what aperture you set, so talking about DOF at all is not very meaningfulIf that's the case then I guess Jack can close this thread 
No, the thread is about sharpness maximization, stopping down some reduces aberrations and increases sharpness. Jack is asking exactly how much to stop down, its a reasonable question.
aCuria wrote
snapsy wrote
aCuria wrote
snapsy wrote
Putting aside the sensor-specific technical cutoff point between DOF/diffraction, I'd say the decision is scene and/or artistic-intent dependent. For some scenes, it's more important to maximize DOF, for others sharpness is more important. When both are important then focus stacking.I'd argue that for the vast majority of images, DOF is more important than sharpness - not many images will be ruined by an overall decrease in sharpness but the same cannot be said for insufficient DOF, particularly when the details of both near and far subjects are equally important to the artistic intent.
For example, this one is shot at f/1.4 because it was handheld. I probably should have lowered the shutter too but this was just a test shot to see what the compression was going to look like before I put the subject into the frame.
https://live.staticflickr.com/65535/53949870014_8ec0c0c541_b.jpg7IV06347 by acurian, on Flickr
I would try to maximize the dynamic range for a landscape. If the shot has to be handheld, then using f/1.4 to achieve base ISO is an acceptable compromise.
If there is a tripod then I would try to do exposure stacking. There is no need to do focus stacking when the landscape subject is beyond the hyperfocal distance.
However for a landscape DOF is very plentiful regardless of what aperture you set, so talking about DOF at all is not very meaningful
No, the thread is about sharpness maximization, stopping down some reduces aberrations and increases sharpness. Jack is asking exactly how much to stop down, its a reasonable question.
Aug 19, 2026 at 10:09 PM
p.2 #16A7R6 and diffraction
Tarekith wrote:
I'm trying to learn more about the technical side of discussions like this as a relatively new photographer. Can someone explain what an airy disk is
At a high level, when light from a point source passes through a lens, diffraction prevents the lens from focusing the light to an infinitesimally small point. Instead, the light forms a small diffraction pattern, whose central bright region is known as the Airy disk.
I'm trying to learn more about the technical side of discussions like this as a relatively new photographer. Can someone explain what an airy disk is
At a high level, when light from a point source passes through a lens, diffraction prevents the lens from focusing the light to an infinitesimally small point. Instead, the light forms a small diffraction pattern, whose central bright region is known as the Airy disk.
Aug 19, 2026 at 10:11 PM
p.2 #17A7R6 and diffraction
aCuria wrote:
I'd argue that for the vast majority of images, DOF is more important than sharpness - not many images will be ruined by an overall decrease in sharpness but the same cannot be said for insufficient DOF, particularly when the details of both near and far subjects are equally important to the artistic intent.In the context of OP's landscape shooting I am not sure I agree. I think "the vast majority" of landscapes do not suffer from a lack of DOF even if you shoot at bright apertures like f/1.4.
For example, this one is shot at f/1.4 because it was handheld. I probably should have lowered the shutter too but this was just a test shot to see what the compression was going to look like before I put the subject into the frame.
https://live.staticflickr.com/65535/53949870014_8ec0c0c541_b.jpg7IV06347 by acurian, on Flickr
I would try to maximize the dynamic range for a landscape. If the shot has to be handheld, then using f/1.4 to achieve base ISO is an acceptable compromise.
If there is a tripod then I would try to do exposure stacking. There is no need to do focus stacking when the landscape subject is beyond the hyperfocal distance.I argued adequate DOF is more important than sharpness in the majority of landscapes. That's a bit different than saying a majority of landscapes suffer from lack of DOF.Sure, and I agree that sufficient DOF is more important than maximizing sharpness if those two things are actually in conflict.
However for a landscape DOF is very plentiful regardless of what aperture you set, so talking about DOF at all is not very meaningfulIf that's the case then I guess Jack can close this thread No, the thread is about sharpness maximization, stopping down some reduces aberrations and increases sharpness. Jack is asking exactly how much to stop down, its a reasonable question.
Jack's first sentence in his OP:
"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"
snapsy wrote
aCuria wrote
snapsy wrote
aCuria wrote
snapsy wrote
Putting aside the sensor-specific technical cutoff point between DOF/diffraction, I'd say the decision is scene and/or artistic-intent dependent. For some scenes, it's more important to maximize DOF, for others sharpness is more important. When both are important then focus stacking.I'd argue that for the vast majority of images, DOF is more important than sharpness - not many images will be ruined by an overall decrease in sharpness but the same cannot be said for insufficient DOF, particularly when the details of both near and far subjects are equally important to the artistic intent.
For example, this one is shot at f/1.4 because it was handheld. I probably should have lowered the shutter too but this was just a test shot to see what the compression was going to look like before I put the subject into the frame.
https://live.staticflickr.com/65535/53949870014_8ec0c0c541_b.jpg7IV06347 by acurian, on Flickr
I would try to maximize the dynamic range for a landscape. If the shot has to be handheld, then using f/1.4 to achieve base ISO is an acceptable compromise.
If there is a tripod then I would try to do exposure stacking. There is no need to do focus stacking when the landscape subject is beyond the hyperfocal distance.
However for a landscape DOF is very plentiful regardless of what aperture you set, so talking about DOF at all is not very meaningful
Jack's first sentence in his OP:
"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"
Aug 20, 2026 at 01:30 AM
p.2 #18A7R6 and diffraction
aCuria wrote:
No, the thread is about sharpness maximization, stopping down some reduces aberrations and increases sharpness. Jack is asking exactly how much to stop down, its a reasonable question.
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snapsy wrote:
Jack's first sentence in his OP:
"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"
You guys are both right. My question was perhaps poorly worded, or not adequately worded. I am interested in finding the optimal balance point; where the negative effects of diffraction from stopping down begin to negate the resulting DoF resolution gains made from that same stopping down.
I’m hearing from some it’s image dependent, apparently going by their gut instinct depending on the image. Others tend to limit their maximum aperture and more carefully set focus point for the image at hand so most of the important details are captured within the DoF of their accepted minimum aperture. Others focus stack.
My brain says there should be a calculable “ideal” point where the diffraction curves resolution falling with increased aperture intersects the DoF’s rising resolution gains with increased aperture curve.
No, the thread is about sharpness maximization, stopping down some reduces aberrations and increases sharpness. Jack is asking exactly how much to stop down, its a reasonable question.
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snapsy wrote:
Jack's first sentence in his OP:
"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"
You guys are both right. My question was perhaps poorly worded, or not adequately worded. I am interested in finding the optimal balance point; where the negative effects of diffraction from stopping down begin to negate the resulting DoF resolution gains made from that same stopping down.
I’m hearing from some it’s image dependent, apparently going by their gut instinct depending on the image. Others tend to limit their maximum aperture and more carefully set focus point for the image at hand so most of the important details are captured within the DoF of their accepted minimum aperture. Others focus stack.
My brain says there should be a calculable “ideal” point where the diffraction curves resolution falling with increased aperture intersects the DoF’s rising resolution gains with increased aperture curve.
Aug 20, 2026 at 07:38 AM
p.2 #19A7R6 and diffraction
Jack Flesher wrote:
---------------------------------------------
"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"You guys are both right. My question was perhaps poorly worded, or not adequately worded. I am interested in finding the optimal balance point; where the negative effects of diffraction from stopping down begin to negate the resulting DoF resolution gains made from that same stopping down.
I’m hearing from some it’s image dependent, apparently going by their gut instinct depending on the image. Others tend to limit their maximum aperture and more carefully set focus point for the image at hand so most of the important details are captured within the DoF of their accepted minimum aperture. Others...Show more →
Jack, I don’t think there is a single, unified answer to this, as in “f/11 is that aperture.”
If these is an “ideal point,” it is not going to be the same in every situation. And finding yourself a bit to one side or the other of that ideal isn’t going to make much of a difference.
It really is situational, with a range of factors playing into the decision. If you will print extremely large and. expect people to inspect at nose-length distances, that might pus you in the direction of focus bracketing. (Though if you look at highly regarded large prints of great work in galleries and at exhibitions you’ll almost always find that it isn’t as perfectly sharp as people imagine.) If you will reproduce at relatively smaller sizes and/or for less-close viewing (or for screens in general), you can worry a lot less about diffraction blur at the borderline apertures. If your subject really depends on super detail, you might be a bit more conservative about how small of an aperture you’ll use, but if that’s not the case in a particular shot you can use even smaller apertures and the photo will still work well.
I think that the answers come largely from experience making photographs and prints — something you have — and then applying that experience and your judgment situationally.
aCuria wrote
No, the thread is about sharpness maximization, stopping down some reduces aberrations and increases sharpness. Jack is asking exactly how much to stop down, its a reasonable question.snapsy wrote
Jack's first sentence in his OP:"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"
I’m hearing from some it’s image dependent, apparently going by their gut instinct depending on the image. Others tend to limit their maximum aperture and more carefully set focus point for the image at hand so most of the important details are captured within the DoF of their accepted minimum aperture. Others...Show more →
Jack, I don’t think there is a single, unified answer to this, as in “f/11 is that aperture.”
If these is an “ideal point,” it is not going to be the same in every situation. And finding yourself a bit to one side or the other of that ideal isn’t going to make much of a difference.
It really is situational, with a range of factors playing into the decision. If you will print extremely large and. expect people to inspect at nose-length distances, that might pus you in the direction of focus bracketing. (Though if you look at highly regarded large prints of great work in galleries and at exhibitions you’ll almost always find that it isn’t as perfectly sharp as people imagine.) If you will reproduce at relatively smaller sizes and/or for less-close viewing (or for screens in general), you can worry a lot less about diffraction blur at the borderline apertures. If your subject really depends on super detail, you might be a bit more conservative about how small of an aperture you’ll use, but if that’s not the case in a particular shot you can use even smaller apertures and the photo will still work well.
I think that the answers come largely from experience making photographs and prints — something you have — and then applying that experience and your judgment situationally.
Aug 20, 2026 at 08:03 AM
p.2 #20A7R6 and diffraction
gdanmitchell wrote:
---------------------------------------------
"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"You guys are both right. My question was perhaps poorly worded, or not adequately worded. I am interested in finding the optimal balance point; where the negative effects of diffraction from stopping down begin to negate the resulting DoF resolution gains made from that same stopping down.
I’m hearing from some it’s image dependent, apparently going by their gut instinct depending on the image. Others tend to limit their maximum aperture and more carefully set focus point for the image at hand so most of the important details are captured within the DoF of their accepted minimum aperture. Others focus stack.
My brain says there should be a calculable “ideal” point where the diffraction curves resolution falling with increased aperture intersects the DoF’s rising resolution gains with increased aperture curve.Jack, I don’t think there is a single, unified answer to this, as in “f/11 is that aperture.”
If these is an “ideal point,” it is not going to be the same in every situation. And finding yourself a bit to one side or the other of that ideal isn’t going to make much of a difference.
It really is situational, with a range of factors playing into the decision. If you will print extremely large and. expect people to inspect at nose-length distances, that might pus you in the direction of focus bracketing. (Though if you look at highly regarded large...Show more →
I hear you Dan, and I accept my above curve intersection thoughts coupled with a given lens’ optimal resolution aperture curve overlaying on that same graph, the situational image setup may allow for a broader or tighter aperture range inside the resulting trisectional overlap zone.
Regardless, the concerning point is I am seeing more detectable diffraction loss in my images than I’ve ever noticed previously. Whether that’s due to the camera sensor or better lenses —and given the somewhat insignificant changes post-processing sharpening adjustments make, it’s probably a combination of both— I’m noticing diffraction softening more and hence the deeper dive query.
Or perhaps good enough is, and I’m tilting at windmills…
Jack Flesher wrote
aCuria wrote
No, the thread is about sharpness maximization, stopping down some reduces aberrations and increases sharpness. Jack is asking exactly how much to stop down, its a reasonable question.snapsy wrote
Jack's first sentence in his OP:"My question is what is the optimal aperture for DoF vs diffraction on the A7R6?"
I’m hearing from some it’s image dependent, apparently going by their gut instinct depending on the image. Others tend to limit their maximum aperture and more carefully set focus point for the image at hand so most of the important details are captured within the DoF of their accepted minimum aperture. Others focus stack.
My brain says there should be a calculable “ideal” point where the diffraction curves resolution falling with increased aperture intersects the DoF’s rising resolution gains with increased aperture curve.
If these is an “ideal point,” it is not going to be the same in every situation. And finding yourself a bit to one side or the other of that ideal isn’t going to make much of a difference.
It really is situational, with a range of factors playing into the decision. If you will print extremely large and. expect people to inspect at nose-length distances, that might pus you in the direction of focus bracketing. (Though if you look at highly regarded large...Show more →
I hear you Dan, and I accept my above curve intersection thoughts coupled with a given lens’ optimal resolution aperture curve overlaying on that same graph, the situational image setup may allow for a broader or tighter aperture range inside the resulting trisectional overlap zone.
Regardless, the concerning point is I am seeing more detectable diffraction loss in my images than I’ve ever noticed previously. Whether that’s due to the camera sensor or better lenses —and given the somewhat insignificant changes post-processing sharpening adjustments make, it’s probably a combination of both— I’m noticing diffraction softening more and hence the deeper dive query.
Or perhaps good enough is, and I’m tilting at windmills…
Aug 20, 2026 at 08:18 AM