Diffraction and the 4/3 sensor

[Tom Caldwell]

I must admit that I have never needed to shoot f32 "in anger". Maybe it would come in handy in an extreme. However f64? I have never seen a lens capable of f64 - i suppose that one or more of these beasts might exist.

Not sure what aperture a pinhole camera actually is but maybe this was what was behind the f64 "joke" aspect of their association name?

In a scenario where fast lenses are expensive and beautiful the "ugly" end is rare enough as well.

The pinhole is f/120 or higher, usually around f/160. Below 120, the contrast and sharpness drop drasticly.

I heard (one reason) that they use f/64 because 'ordinary' photographers can't get any image from that f/stop at all. To think of the ISO 100 is very high by that time ..

I must re-read the story about the f64 association. It is a while since I read it and I suspect that there is a bit of truth in all our assertions.

After reading through this including the manifesto of Group f64 I am not much the wiser for any deep meaning beyond what we all know - that f64 technically should give the sharpest image with greatest depth of field.

https://en.m.wikipedia.org/wiki/Group_f/64

This is a well written article but not quite what I remember from reading elsewhere.

The diagonal of 8x10 format is 12.8 in = 325mm. The diagonal of mFT is 21.6mm. Thus, the equivalence ratio between 8x10 and mFT is 325 / 21.64 = 15x so f/64 on 8x10 is equivalent to f/(64/15) = f/4.3 on mFT.

In short, if f/64 on 8x10 is good enough for Ansel Adams and the other members of Group f.64, then f/4 should be good enough for people shooting mFT who are looking to do the same type of photography. ;-)

I will have to remember that when I come across an f64 lens

Right at the moment an adapted lens capable of f32 is far too slow for internal available light even with IBIS assistance. Suggest: "Use tripod outdoors".

 

[Triplet Perar]

My question is the obvious: why do manufacturers of lenses for the 4/3 sensor bother to make lenses that have smaller apertures than f8 if diffraction is such a serious issue?

When fine graphite pencil was invented, art world did not banish charcoal stick from use.

Diffraction is not an issue in photography. It may be an issue in forensic use of photography, but most importantly, photography is an art.

In art, what is important is the unique character of the subjective message, and if diffraction is good to deliver it, or a smoky mirror, or out of focus image, or grainy image, it all can be used.

In science, though, there is only one certain way of delivering a precise objective message, and for those types of use, anything can be an issue.

 

[knickerhawk]

give the sharpest image with greatest depth of field.

https://en.m.wikipedia.org/wiki/Group_f/64

This is a well written article but not quite what I remember from reading elsewhere.

The diagonal of 8x10 format is 12.8 in = 325mm. The diagonal of mFT is 21.6mm. Thus, the equivalence ratio between 8x10 and mFT is 325 / 21.64 = 15x so f/64 on 8x10 is equivalent to f/(64/15) = f/4.3 on mFT.

In short, if f/64 on 8x10 is good enough for Ansel Adams and the other members of Group f.64, then f/4 should be good enough for people shooting mFT who are looking to do the same type of photography. ;-)

The other viewpoint.

While we, the mFT shooter, are happily firing the shutter at 1/2000s, and f/4 on the ISO 200 sensor, our f/64 grandpa was praying that his 1 second (or more) exposure with the ISO 25 film would have no blurring from vibration at all

Or in the case of Weston and his famous nautilus shot, the exposure (at f/64 and approx. ISO 16) was over four hours. Vibrations from his kids playing or possibly from truck traffic outside the house ruined multiple attempts at the shot. By the way, he apparently didn't understand the effect of diffraction until he complained to Adams in a letter about his troubles getting sharp images with a favorite lens beyond f/64.

Another viewpoint. The f/64 (aka equivalent f/4 on mFT or f/8 on FF) is the minimum for the whole-frame sharp image (of the landscape) at that time.

The general photographers at that time could go max at f/32, or lower; thus the partial sharp image.

..

..

..

..

..

Are you saying you're the great photographer?

Stop boasting. Proof yourself with the f/64 images.

Right, grandpa?

--
Flashes of my Memory.

 

[agott123]

Typically, diffraction will be the least problematic of the bunch, but, sometimes, it will be the most problematic (e.g. tripod macro photography of static scenes).

Hi Joseph

Could you please elaborate as to why with macro shots diffraction works differently ?

(I did my own test back then with the macro 50mm F2 lens, and saw the effect of diffraction on close up shots)

The reason "macro works differently" is because it is common to try to get as much DOF as possible which involves stopping down well into diffraction limited territory if one doesn't want to use multiple exposures with focus stacking.

Thx

Glad to be of help! By the way, someone in this thread or the other thread on diffraction posted some excellent macro photos at f/22 (f/45 FF equivalent). Of course, they'd have been more detailed had multiple exposures at, say, f/5.6, had been taken and focus stacked, but the photos, as they were, still retained excellent detail and would easily be "good enough" for many, if not most.

Personally, I would avoid F22

I did in the past (4/3) shoot some dental images at F22, but it had a lot to do with the flash I used back then.

For "Critters", up to F14 is fine for me, I´ve seen "Macromeds" uses F16 sometimes and his images are great.

Remember it´s not only about the subject being in focus, but also the background being defocused enough.

Yesterday @F10 (Exif intact)



Alex







First, a real macro lens is far better than



--
Couldn't help but make me feel ashamed to live in a land
Where justice is a game. From Bob Dylan's 'Hurricane'

 

[gardenersassistant]

Typically, diffraction will be the least problematic of the bunch, but, sometimes, it will be the most problematic (e.g. tripod macro photography of static scenes).

Hi Joseph

Could you please elaborate as to why with macro shots diffraction works differently ?

(I did my own test back then with the macro 50mm F2 lens, and saw the effect of diffraction on close up shots)

The reason "macro works differently" is because it is common to try to get as much DOF as possible which involves stopping down well into diffraction limited territory if one doesn't want to use multiple exposures with focus stacking.

Thx

Glad to be of help! By the way, someone in this thread or the other thread on diffraction posted some excellent macro photos at f/22 (f/45 FF equivalent). Of course, they'd have been more detailed had multiple exposures at, say, f/5.6, had been taken and focus stacked, but the photos, as they were, still retained excellent detail and would easily be "good enough" for many, if not most.

Personally, I would avoid F22

I did in the past (4/3) shoot some dental images at F22, but it had a lot to do with the flash I used back then.

For "Critters", up to F14 is fine for me, I´ve seen "Macromeds" uses F16 sometimes and his images are great.

It's worth bearing in mind that for those f/22 images the effective aperture was f/22 (because I was using close-up lenses). For a macro lens at 1:2 a nominal aperture of f/14 is an effective aperture of around f/21 and from there on to 1:1 the effective aperture is as small as and then progressively smaller than the effective f/22 used for the posted images.

Similarly for Mark's (Macromeds') images, which at 1:2 with nominal f/16 are around effective f/24 and at 1:1 with nominal f/16 are around effective f/32. Note also that Mark used close-up lenses for many years and used f/11 on an FZ50, which has a 1/1.8" sensor, for which f/11 is equivalent to around f/26 on micro four thirds.

Remember it´s not only about the subject being in focus, but also the background being defocused enough.

Yesterday @F10 (Exif intact)



Alex

First, a real macro lens is far better than

Intriguing ....

--
Couldn't help but make me feel ashamed to live in a land
Where justice is a game. From Bob Dylan's 'Hurricane'

--
Nick
http://www.flickr.com/photos/gardenersassistant/collections/
GardenersAssistant Photography Videos - https://www.youtube.com/channel/UCmBgEwRDfiQMYTPORSzDxvw
https://www.talkphotography.co.uk/t...-dslr-primes-a-journey-of-exploration.531050/

 

[Great Bustard]

I must admit that I have never needed to shoot f32 "in anger". Maybe it would come in handy in an extreme. However f64? I have never seen a lens capable of f64 - i suppose that one or more of these beasts might exist.

Not sure what aperture a pinhole camera actually is but maybe this was what was behind the f64 "joke" aspect of their association name?

In a scenario where fast lenses are expensive and beautiful the "ugly" end is rare enough as well.

The pinhole is f/120 or higher, usually around f/160. Below 120, the contrast and sharpness drop drasticly.

I heard (one reason) that they use f/64 because 'ordinary' photographers can't get any image from that f/stop at all. To think of the ISO 100 is very high by that time ..

I must re-read the story about the f64 association. It is a while since I read it and I suspect that there is a bit of truth in all our assertions.

After reading through this including the manifesto of Group f64 I am not much the wiser for any deep meaning beyond what we all know - that f64 technically should give the sharpest image with greatest depth of field.

https://en.m.wikipedia.org/wiki/Group_f/64

This is a well written article but not quite what I remember from reading elsewhere.

The diagonal of 8x10 format is 12.8 in = 325mm. The diagonal of mFT is 21.6mm. Thus, the equivalence ratio between 8x10 and mFT is 325 / 21.64 = 15x so f/64 on 8x10 is equivalent to f/(64/15) = f/4.3 on mFT.

In short, if f/64 on 8x10 is good enough for Ansel Adams and the other members of Group f.64, then f/4 should be good enough for people shooting mFT who are looking to do the same type of photography. ;-)

I will have to remember that when I come across an f64 lens

If mounted on an mFT body, then there is no Equivalence involved. That is, f/64 = f/64 when used on the same format, regardless of the format the lens was designed to cover.

Right at the moment an adapted lens capable of f32 is far too slow for internal available light even with IBIS assistance. Suggest: "Use tripod outdoors".

Typically, if you need DOFs so great that you'd be using f/32 or smaller on mFT, I'd highly recommend focus stacking unless, of course, resolution isn't that particularly important.

 

[Great Bustard]

My question is the obvious: why do manufacturers of lenses for the 4/3 sensor bother to make lenses that have smaller apertures than f8 if diffraction is such a serious issue?

When fine graphite pencil was invented, art world did not banish charcoal stick from use.

Diffraction is not an issue in photography. It may be an issue in forensic use of photography, but most importantly, photography is an art.

In art, what is important is the unique character of the subjective message, and if diffraction is good to deliver it, or a smoky mirror, or out of focus image, or grainy image, it all can be used.

In science, though, there is only one certain way of delivering a precise objective message, and for those types of use, anything can be an issue.

...but inasmuch as resolution matters in a photo, diffraction also matters. So, if you are making the case that resolution is not always important to the "success" of a photo, absolutely. But one can make the same argument for any other element of IQ, such as noise, DR, bokeh, flare, distortion, etc., etc., etc. -- there is always at least one form of photography where one or more elements of IQ play little to no role in the "success" of the photo.

Of course, there is the "good enough" requirement. That is, while these technical elements may play a role in the "success" of a photo, there is a point beyond which any additional improvements fail to add to the "success". So, for example, if you are getting "enough" resolution at f/22, then, so long as the associated motion blur and/or noise that may well accompany such a narrow aperture does not adversely affect the "success" of the photo, then, by all means, shoot f/22 without any concerns!

 

[bobn2]

My question is the obvious: why do manufacturers of lenses for the 4/3 sensor bother to make lenses that have smaller apertures than f8 if diffraction is such a serious issue?

When fine graphite pencil was invented, art world did not banish charcoal stick from use.

Diffraction is not an issue in photography. It may be an issue in forensic use of photography, but most importantly, photography is an art.

In art, what is important is the unique character of the subjective message, and if diffraction is good to deliver it, or a smoky mirror, or out of focus image, or grainy image, it all can be used.

In science, though, there is only one certain way of delivering a precise objective message, and for those types of use, anything can be an issue.

...but inasmuch as resolution matters in a photo, diffraction also matters.

I'm always surprised when people who wax lyrical about the sharpness of lenses seem not to worry about diffraction.

 

[Great Bustard]

My question is the obvious: why do manufacturers of lenses for the 4/3 sensor bother to make lenses that have smaller apertures than f8 if diffraction is such a serious issue?

When fine graphite pencil was invented, art world did not banish charcoal stick from use.

Diffraction is not an issue in photography. It may be an issue in forensic use of photography, but most importantly, photography is an art.

In art, what is important is the unique character of the subjective message, and if diffraction is good to deliver it, or a smoky mirror, or out of focus image, or grainy image, it all can be used.

In science, though, there is only one certain way of delivering a precise objective message, and for those types of use, anything can be an issue.

...but inasmuch as resolution matters in a photo, diffraction also matters.

I'm always surprised when people who wax lyrical about the sharpness of lenses seem not to worry about diffraction.

There is that, isn't there? ;-)

However, I was thinking about something -- mFT cameras don't have an AA filter (or they have a cancelled AA filter). So, wouldn't diffraction simply serve as an AA filter and make the mFT camera perform better than a camera that had an AA filter at narrow apertures, since that camera would be hit with a double-whammy?

 

[Tom Caldwell]

I must admit that I have never needed to shoot f32 "in anger". Maybe it would come in handy in an extreme. However f64? I have never seen a lens capable of f64 - i suppose that one or more of these beasts might exist.

Not sure what aperture a pinhole camera actually is but maybe this was what was behind the f64 "joke" aspect of their association name?

In a scenario where fast lenses are expensive and beautiful the "ugly" end is rare enough as well.

The pinhole is f/120 or higher, usually around f/160. Below 120, the contrast and sharpness drop drasticly.

I heard (one reason) that they use f/64 because 'ordinary' photographers can't get any image from that f/stop at all. To think of the ISO 100 is very high by that time ..

I must re-read the story about the f64 association. It is a while since I read it and I suspect that there is a bit of truth in all our assertions.

After reading through this including the manifesto of Group f64 I am not much the wiser for any deep meaning beyond what we all know - that f64 technically should give the sharpest image with greatest depth of field.

https://en.m.wikipedia.org/wiki/Group_f/64

This is a well written article but not quite what I remember from reading elsewhere.

The diagonal of 8x10 format is 12.8 in = 325mm. The diagonal of mFT is 21.6mm. Thus, the equivalence ratio between 8x10 and mFT is 325 / 21.64 = 15x so f/64 on 8x10 is equivalent to f/(64/15) = f/4.3 on mFT.

In short, if f/64 on 8x10 is good enough for Ansel Adams and the other members of Group f.64, then f/4 should be good enough for people shooting mFT who are looking to do the same type of photography. ;-)

I will have to remember that when I come across an f64 lens

If mounted on an mFT body, then there is no Equivalence involved. That is, f/64 = f/64 when used on the same format, regardless of the format the lens was designed to cover.

Right at the moment an adapted lens capable of f32 is far too slow for internal available light even with IBIS assistance. Suggest: "Use tripod outdoors".

Typically, if you need DOFs so great that you'd be using f/32 or smaller on mFT, I'd highly recommend focus stacking unless, of course, resolution isn't that particularly important.

I am far from expert, but I do have a lot of legacy lenses. From what I can see a smallest aperture of f16 is most common and a few lenses (mainly telephoto) might have f22 or f32.

But in any case I just use what I feel is necessary at the time and don't let "the issue" worry me.

The main object of my intitial post was to point out a possble contradiction - that if there was a serious problem with diffraction after about f8.0 then why do lens manufacturers make lenses that have smaller apertures.

I think that "why" has been satisfactorily explained in this thread by many wise heads.

Diffraction exists - it is a problem - but it is a relatively small problem where other necessities or benfits exist and, like many rules, it is safe enough to be broken with some impunity.

--
Tom Caldwell

 

[Great Bustard]

Right at the moment an adapted lens capable of f32 is far too slow for internal available light even with IBIS assistance. Suggest: "Use tripod outdoors".

Typically, if you need DOFs so great that you'd be using f/32 or smaller on mFT, I'd highly recommend focus stacking unless, of course, resolution isn't that particularly important.

I am far from expert, but I do have a lot of legacy lenses. From what I can see a smallest aperture of f16 is most common and a few lenses (mainly telephoto) might have f22 or f32.

And if mounted on an mFT body, they'll perform like any other mFT lens with the same focal length and relative aperture (at least with regards to things that pertain to focal length and aperture).

But in any case I just use what I feel is necessary at the time and don't let "the issue" worry me.

Sure.

The main object of my intitial post was to point out a possble contradiction - that if there was a serious problem with diffraction after about f8.0 then why do lens manufacturers make lenses that have smaller apertures.

Two things:

1. Better to have the choice than not, and
2. f/8 on one format doesn't have the same effect as f/8 on another format.

I think that "why" has been satisfactorily explained in this thread by many wise heads.

Diffraction exists - it is a problem - but it is a relatively small problem where other necessities or benfits exist and, like many rules, it is safe enough to be broken with some impunity.

The rules with regards to diffraction are simple:

1. Avoid using a more narrow aperture than is needed to get the desired DOF.
2. The more narrow aperture will result in greater motion blur or less light on the sensor which will result in a more noisy photo.
3. Once the aperture narrows beyond a certain point (which will depend on the lens and where in the frame you are looking), you will begin to lose resolution.
4. None of this is to say that the resulting motion blur, noise, or resolution loss will necessarily affect the "success" of the photo -- they are simply things to be aware of when choosing the relative aperture or when letting the camera choose for you.

Not all that controversial, I should think. ;-)

 

[bobn2]

My question is the obvious: why do manufacturers of lenses for the 4/3 sensor bother to make lenses that have smaller apertures than f8 if diffraction is such a serious issue?

When fine graphite pencil was invented, art world did not banish charcoal stick from use.

Diffraction is not an issue in photography. It may be an issue in forensic use of photography, but most importantly, photography is an art.

In art, what is important is the unique character of the subjective message, and if diffraction is good to deliver it, or a smoky mirror, or out of focus image, or grainy image, it all can be used.

In science, though, there is only one certain way of delivering a precise objective message, and for those types of use, anything can be an issue.

...but inasmuch as resolution matters in a photo, diffraction also matters.

I'm always surprised when people who wax lyrical about the sharpness of lenses seem not to worry about diffraction.

There is that, isn't there? ;-)

However, I was thinking about something -- mFT cameras don't have an AA filter (or they have a cancelled AA filter). So, wouldn't diffraction simply serve as an AA filter and make the mFT camera perform better than a camera that had an AA filter at narrow apertures, since that camera would be hit with a double-whammy?

Diffraction makes a nice AA filter, one part the drive to get pixels to diffraction limited scale. Part of the sharpness benefit of cancelling the AA filter is to do without that AA filter, and for many manufacturers, it's becoming a thing of the past. Nikon now only has them on its FF cameras 24MP and below, mFT hardly at all. You still do get the odd aliasing artifact, but it's not as bad as I feared. Pentax has its sensor wobbling programmable AA filter, which doubles up the IBIS to blur only when needed.

 

[Le Frog]

I have been using cameras for quite a long time but only in the last 10 years or so really seriously. But I still have a lot to learn - for me it is much of the attraction of photography itself. Such a basic subject: but a modern camera and lens, set it to "Auto" and with card and battery installed and some necessary but very basic initial housekeeping you are ready to go.

Switch it on and in a moment it is focused - then a click and you have an image. Depending upon some luck or unperceived innate skills of composition the image can be excellent.

And yet for those who want to understand there is much to learn. Enough for a headache or three.

In the case of diffraction I undertand the basics - that diffraction issues can reduce the quality of images taken with apertures smaller than f8.

My question is the obvious: why do manufacturers of lenses for the 4/3 sensor bother to make lenses that have smaller apertures than f8 if diffraction is such a serious issue?

I can only presume that this is because that even with the dreaded diffraction effects it is still often better to accept this as the lesser of evils when the smaller aperture contributes its own particular benefits. That is - the user chooses and diffraction is not always the end of all photography.

Or is it simply that diffraction is hideous and must be avoided at all costs but the lens manufacturers would be laughed out of the industry if they actually only made lenses that had minimum apertures of f8?

Personally I suggest that diffraction is just another of the number of variables that must be taken into account when composing a photograph and in the days of ever simpler photography even on auto perhaps the camera will choose to use an aperture less than f8 and we will still be very pleased by what can be done by a simple soft press and click and the camera will do the rest.

...quote an earlier post, I think it might answer the question that I have highlighted in bold above (I have also highlighted portions of my reply in bold that are particularly relevant):

In terms of the optics, there are two primary sources of blur:

• Lens aberrations
• Diffraction

Both are always present. However, as you stop down, lens aberrations lessen and diffraction softening increases. The point at which diffraction softening overtakes lens aberrations is called the diffraction limited aperture.

The diffraction limited aperture will vary from lens to lens and depend where in the frame you are looking because lens aberrations vary from lens to lens and where in the frame you are looking. However, as a general rule, the diffraction limited aperture for the edges of a lens typically come about a stop after the diffraction limited aperture for the center of the lens because lens aberrations are greater at the edges.

As a general rule, mFT lenses will become diffraction limited in the center within a stop of f/4 and diffraction limited at the edges within a stop of f/5.6. This means that as you stop down further, you are losing resolution *for the portions of the photo within the DOF*.

However, as you stop down, the DOF deepens, so more of the frame typically comes into sharper focus, so even though diffraction is getting worse for the portions of the photo that were within the DOF at wider apertures, more of the photo comes within the DOF, making for a sharper photo overall.

On the other hand, stopping down results in either a longer exposure time, increasing the risk/severity of motion blur, or, for a given exposure time, results in less light on the sensor, and thus more noise.

So, in practice, we have the following to contend with as a result of aperture:

• DOF
• motion blur
• noise
• diffraction

Not to mention that it depends also on how sharp was the lens to begin with?

Typically, diffraction will be the least problematic of the bunch, but, sometimes, it will be the most problematic (e.g. tripod macro photography of static scenes).

Hope that helps!

Thank you for your clear explanations of how diffraction fits into the scheme of image quality. It seems that like all things technically photographic it is the combination of many factors and how they sit together that matters. Diffraction, it seems, cannot be isolated from all the other connected issues.

As I suspected the risk of diffraction can be compensated by other potential benefits of small apertures. Makes sense.

--
Tom Caldwell

 

[bobn2]

So, in practice, we have the following to contend with as a result of aperture:

• DOF
• motion blur
• noise
• diffraction

Not to mention that it depends also on how sharp was the lens to begin with?

That's one of the points about diffraction, it's a leveller. Once you're into diffraction limiting, it's diffraction that determines the sharpness, not the quality of the lens or the number of pixels.

 

[gardenersassistant]

So, in practice, we have the following to contend with as a result of aperture:

• DOF
• motion blur
• noise
• diffraction

Not to mention that it depends also on how sharp was the lens to begin with?

That's one of the points about diffraction, it's a leveller. Once you're into diffraction limiting, it's diffraction that determines the sharpness, not the quality of the lens or the number of pixels.

Quite so, to a large extent. It took me some time to convince myself about this but my choice of kit for single-shot small aperture working is now pretty much down to flexibility/usability. I've had an MPE-65 and I still have good 1:1 macro lenses for APS-C and MFT, but much of the time I use a 12 mpix tiny sensor bridge camera with close-up lenses.

I'm not convinced that it is a complete leveller though in terms of image quality. I haven't been able to disentangle the exact quality differences (I find it really difficult to get real world examples which are sufficiently - as in almost exactly - like for like to be sure, and post processing complicates the issue). But at equivalent apertures (f/45 FF equivalent) with close-up lenses on my (no AA filter) G80 and FZ330 bridge camera I have the impression that at least some of the G80 images have something about them that makes them more appealing to my eye. More perhaps to do with clarity and the rendition of colours and textures than with sharpness/detail. But my sample size is not yet large enough for me to be convinced that this is a systemic difference rather than happenstance.

On the other hand, the FZ330 is more flexible/usable in the range of scene widths from around 70mm to 14mm, which is where I mainly work. The G80 becomes relatively more usable as the scene width decreases, being much more usable once the scene width has dropped below 10mm or so.

 

[medon78]

...

In the case of diffraction I undertand the basics - that diffraction issues can reduce the quality of images taken with apertures smaller than f8.

My question is the obvious: why do manufacturers of lenses for the 4/3 sensor bother to make lenses that have smaller apertures than f8 if diffraction is such a serious issue?

...

It is not such a serious issue. With my lenses, I have to pixel-peep to see the diffraction effects creep in from around f/11 onward. Of course, it also depends on the actual focal length you are using.

My 7.5mm Fisheye has a hole smaller than 0.7mm when at f/11, while my 75-300mm at the long end still would have an comfortable 27mm hole.

One thing I would consider though:

Many m43 lenses have a "modern" design which means: Quite evenly sharp across the frame, already wide open. The Sigma "Art" philosophy, so to say.

Therefore, stopping down cannot really improve the IQ any more and in best case does not detoriate IQ.

The only lenses I really want to stop down a little are my 25mm f/0.95 Speedmaster, my 14-140 at the long end, and my 75-300 at the long end. Everything else is perfectly fine wide open.

BR Medon

 

[bobn2]

So, in practice, we have the following to contend with as a result of aperture:

• DOF
• motion blur
• noise
• diffraction

Not to mention that it depends also on how sharp was the lens to begin with?

That's one of the points about diffraction, it's a leveller. Once you're into diffraction limiting, it's diffraction that determines the sharpness, not the quality of the lens or the number of pixels.

Quite so, to a large extent. It took me some time to convince myself about this but my choice of kit for single-shot small aperture working is now pretty much down to flexibility/usability. I've had an MPE-65 and I still have good 1:1 macro lenses for APS-C and MFT, but much of the time I use a 12 mpix tiny sensor bridge camera with close-up lenses.

I'm not convinced that it is a complete leveller though in terms of image quality. I haven't been able to disentangle the exact quality differences (I find it really difficult to get real world examples which are sufficiently - as in almost exactly - like for like to be sure, and post processing complicates the issue). But at equivalent apertures (f/45 FF equivalent) with close-up lenses on my (no AA filter) G80 and FZ330 bridge camera I have the impression that at least some of the G80 images have something about them that makes them more appealing to my eye. More perhaps to do with clarity and the rendition of colours and textures than with sharpness/detail. But my sample size is not yet large enough for me to be convinced that this is a systemic difference rather than happenstance.

On the other hand, the FZ330 is more flexible/usable in the range of scene widths from around 70mm to 14mm, which is where I mainly work. The G80 becomes relatively more usable as the scene width decreases, being much more usable once the scene width has dropped below 10mm or so.

I think this has to do with the lack of an AA filter, as discussed previously. The AA filter adds blur on top of diffraction. In many cases, diffraction is all the blur you need to stop aliasing.

 

[Guy Parsons]

It is not such a serious issue. With my lenses, I have to pixel-peep to see the diffraction effects creep in from around f/11 onward. Of course, it also depends on the actual focal length you are using.

My 7.5mm Fisheye has a hole smaller than 0.7mm when at f/11, while my 75-300mm at the long end still would have an comfortable 27mm hole.

One thing to consider is, why is f/11 always f/11?

Because at any focal length the sensor "sees" the same size hole no matter what the focal length.

One is a 0.7mm hole up close, the other is a 27mm hole much further away, so they look the same size "hole to let light in" as far as the sensor is concerned.

Regards.... Guy

 

[medon78]

...

One thing to consider is, why is f/11 always f/11?

...

One is a 0.7mm hole up close, the other is a 27mm hole much further away, so they look the same size "hole to let light in" as far as the sensor is concerned.

Regards.... Guy

Interesting idea... but I guess there might be another thing to consider:

The actual hole, which you can measure (e.g. 27mm), and the optically effective aperture. Not sure if it is always the same.







BR Medon

 

[Jon555]

It is not such a serious issue. With my lenses, I have to pixel-peep to see the diffraction effects creep in from around f/11 onward. Of course, it also depends on the actual focal length you are using.

My 7.5mm Fisheye has a hole smaller than 0.7mm when at f/11, while my 75-300mm at the long end still would have an comfortable 27mm hole.

One thing to consider is, why is f/11 always f/11?

Because at any focal length the sensor "sees" the same size hole no matter what the focal length.

One is a 0.7mm hole up close, the other is a 27mm hole much further away, so they look the same size "hole to let light in" as far as the sensor is concerned.

Regards.... Guy

I really like that way of putting it, plus not even talking about entrance pupils, I might borrow it sometime if you don't mind...