Going beyond 90mm for Macrophotography

[george013]

It's "Airy" not "airy". At 555nm, it's 0.02438mm, not 0.0213mm.

Since the shot was mostly of a gray-scale subject, what lambda did you use in your calculation? (beware of the trap).

I claim that the image of a gray (neutral colored) point source would be a blur spot, not an Airy disk, i.e. many disks between, say, 450 and 650nm, overlaid.

Since you think it's important to write with a capital, you may contact cambridgeincolour.com. There it's written as airy.

The figures I used are from this forum also. https://www.cambridgeincolour.com/tu...hotography.htm. Since f18 is not mentioned I used the nearestby, f16. The pixelsize of a D300 is 0.0055mm.

Is it so difficult to understand the essence of a post? Or is it not willing.

George

I see you edited your post and added next

It matters little to Stagecoach, I suspect, because he is certainly not shooting at infinite focus, eh?

You really don't understand what I'm saying.
George

[george013]

John,

I didn't see that the first serie was taken with f5.6.
But if you compare them, I say that the f5.6 is much sharper.
George

[ajohnw]

Same telephoto setting but with the lower power Raynox clip on close up lens. F22 plus what ever the size of the close up lens removes.



Crop



I think this will be with me when ever I have the camera. It's so quick to fit.

John
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[ajohnw]

John,

I didn't see that the first serie was taken with f5.6.
But if you compare them, I say that the f5.6 is much sharper.
George

I would say that the difference if any is very marginal and down to the lighting change more than anything else.
And then there are the others taken with the Raynox.

John
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[george013]

I would say that the difference if any is very marginal and down to the lighting change more than anything else.
And then there are the others taken with the Raynox.

John
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I put them together. The first one, f5.6, is much better at the focuspoint.

George

[ajohnw]

Since you think it's important to write with a capital, you may contact cambridgeincolour.com. There it's written as airy.

The figures I used are from this forum also. https://www.cambridgeincolour.com/tu...hotography.htm. Since f18 is not mentioned I used the nearestby, f16. The pixelsize of a D300 is 0.0055mm.

Is it so difficult to understand the essence of a post? Or is it not willing.

George

I see you edited your post and added next

You really don't understand what I'm saying.
George

Seriously George there is all sorts of things about relating to diffraction and photography but in essence it is not that simple. I've posted this before. Might help. Here the optical path difference is changed by defocus - helps keep the mush round. In practice a lens might be at a very slight angle, or one side may be out of square with another or the spacing might be some tiny fraction of a mm out etc etc but the effect is the same. The net effect is that diffraction limited optics are more possible at smaller sizes as often they can be simpler. Errors stack up. The graph is normalised to zero is 2NA/wavelength so applies to any lens at any F number.



The vertical axis is contrast in against contrast out.

John
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[xpatUSA]

Since you think it's important to write with a capital, you may contact cambridgeincolour.com. There it's written as airy.

Clearly you think it is unimportant, george. Most people like to get it right. If cic chooses to be slightly less than professional in a particular tutorial, that is their privilege. Where I live, there's a old adage: "sayin' it don't make it so".

The figures I used are from this forum also. https://www.cambridgeincolour.com/tu...hotography.htm. Since f18 is not mentioned I used the nearestby, f16.

What a surprise. Effectively, you told us the wrong Airy disk size for f/18, but didn't mention the above. Feel free to continue writing f/18 incorrectly, BTW.

The pixelsize of a D300 is 0.0055mm.

The pixel size of a sensor bears no relationship to an Airy disk. Feel free to continue writing the pixel size in mm. Also feel free not to mention "pixel pitch" which is more meaningful when discussing Airy disks and such.

Is it so difficult to understand the essence of a post?

I will refrain from commenting on the understandability or otherwise of your posts.

Or is it not willing?

There is really no need for that comment, george - it implies that I am being deliberately obtuse.

I see you edited your post

You're going to like this, george. The first time I edited my post, I took out a sentence that said that you got the Airy disk size wrong. I should have left it in

As to the other edit, since I apparently did not understand, please explain to Stagecoach why he should be interested in infinite focus and the effects thereof, when shooting macro.

[Stagecoach]

I just wonder that the f-number is not mentioned as a varaible that also has influence on the photo quality.

George, in real world photography the significance of the f number used for taking that particular image is way down in the priority list of all the different variables that would affect the final image.

The last photo, of Stagecoach, is shot with a D300 and f18.
Given a subject on infinity, that would give a airy disk of 0.0213mm. But if you do macro at a magnification of 1, your working f-number will be f36, giving an airy disk of 0.0426mm. Twice as big as the CoC used here.

The image was taken with an effective aperture of f/18 for the 105mm lens as indicated in it's Exif.

[ajohnw]

I put them together. The first one, f5.6, is much better at the focuspoint.

George

I see lighting effects and more contrast in the 2nd one than the first plus some loss of contrast in some tiny places purely down to the lighting... However I respect the right for people to hold what ever opinion they like. I don't mean that in any sort of nasty way. Optics are one of my long term hobbies and I also take note of what I find happens in practice. With macro work I feel magnification levels tend to be more important in terms of revealing detail and to a large extent diffraction takes a step back and doesn't in many circumstance apply at all. I also own several pieces of kit which really are diffraction limited.

John
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[george013]

John,

I assume the 2 photo's are made under equal conditions. With only difference the f-number and the exposuretime.
I don't know that graph you are showing and for what condiotions it was made. To less explanation.
But you agree that the 5.6 photo is better?


Ted,

It's a long time ago I left the kindergarden. But as you still don't want to see the essence of my writing I will do only one effort more.

Out of my post

Given a subject on infinity, that would give a airy disk of 0.0213mm. But if you do macro at a magnification of 1, your working f-number will be f36, giving an airy disk of 0.0426mm. Twice as big as the CoC used here. https://www.cambridgeincolour.com/tut...hotography.htm

And your reaction

As to the other edit, since I apparently did not understand, please explain to Stagecoach why he should be interested in infinite focus and the effects thereof, when shooting macro.

George

[ajohnw]

John,

I assume the 2 photo's are made under equal conditions. With only difference the f-number and the exposuretime.
I don't know that graph you are showing and for what condiotions it was made. To less explanation.
But you agree that the 5.6 photo is better?

George

You might find a pdf copy of modern optical engineering by Smith on the web. A well regarded man. A simpler one by the same person is called practical optical layout.

The lighting in the 2 shots are entirely different which I did mention in the posts. Afraid not. I don't see any differences at all other than by mechanisms I have already mentioned. Plus DOF of course.

John
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[george013]

You might find a pdf copy of modern optical engineering by Smith on the web. A well regarded man. A simpler one by the same person is called practical optical layout.

The lighting in the 2 shots are entirely different which I did mention in the posts. Afraid not. I don't see any differences at all other than by mechanisms I have already mentioned. Plus DOF of course.

John
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I googled on Smith and had 1.490.000.000 hits. The first one sells sunglasses.
George

[James G]

I think the full reference for John's 'Smith on the web' is: -
Modern Optical Engineering: The Design of Optical Systems 2nd Editionn (Optical and Electro-Optical Engineering Series), by Warren J. Smith

[ajohnw]

I think the full reference for John's 'Smith on the web' is: -
Modern Optical Engineering: The Design of Optical Systems 2nd Editionn (Optical and Electro-Optical Engineering Series), by Warren J. Smith

The one I posted was from Modern Optical Engineering The Design of Optical Systems Warren J Smith 3rd Edition. There are probably newer versions now but they add little. In fact earlier versions may be better in some ways. Practical Optical System Layout is far more understandable for many though. Both are rather expensive new but can be relatively cheap in used book stores if out of print or newer editions. The design one is very much intended for people who are very interested in that. The layout one is more concerned with 1st order design and the use of lenses etc but does go into other aspect - in some ways hence the graph. The nice thing about Smith is that he seldom illustrates design processes where the numbers have been initially chosen to get the right results.

In terms of path difference there is plenty on the web Optical Path Difference / OPD. One free book on the internet archive that gives a simple over view of diffraction and OPD after a fashion plus alignment problems is How to Make a Telescope by Texereau (? spelling ) He was a practical optician - he made things.

John
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[xpatUSA]

Ted,

It's a long time ago I left the kindergarden.

OK

But as you still don't want to see the essence of my writing . .

You are still accusing of me of that? Lets get down to brass tacks, George. You make mistakes in your posts (as do we all) but when you are questioned, you get defensive, make accusations and, as often as not, you avoid any questions that might reveal a lack of knowledge.

. . . I will do only one effort more.

Out of my post:

"Given a subject on infinity, that would give a airy disk of 0.0213mm. But if you do macro at a magnification of 1, your working f-number will be f36, giving an airy disk of 0.0426mm. Twice as big as the CoC used here. https://www.cambridgeincolour.com/tut...hotography.htm "




And your reaction:

"As to the other edit, since I apparently did not understand, please explain to Stagecoach why he should be interested in infinite focus and the effects thereof, when shooting macro."

I admit to cropping that bit out. I shouldn't have done that.

However, your doubling of the Airy Disk size at 1:1 is only true for the thin-lens equations, not for modern macro lens or even my old Sigmas for that matter.

No need to respond. This is my last, too.

[george013]

However, your doubling of the Airy Disk size at 1:1 is only true for the thin-lens equations, not for modern macro lens or even my old Sigmas for that matter.

You still don't understand it.

George

[Stagecoach]

You still don't understand it.

George

I'm still totally confused as to where the f/36 comes into all of this but further when

Reading this thread and not being a macro-photographer, I wonder that the used f-numbers are not mentioned
On one hand a high f-number gives a deeper DOF, but on the other hand more negative influence due to diffraction. Especially when using macro.

when the 'challenge' or more correctly put, all these useful observances of different ways of achieving the 'Going Beyond' aspect of the thread with odd bits of gear to produce a real world image rather than a ruler was

a) Produce an image that shows the ball on the end of a ball point pen specifically to show the area at the interface of ball and pen. (the manufacturer needs this for his advertising blurb)

[george013]

I'm still totally confused as to where the f/36 comes into all of this but further when....

The calculator works with the f-number. The f-number is focal-distance/aperture-diameter. The airy-disk is calculated with the image-distance. With a magnification of 1, the image-distance is 2 times the focal-distance. So f18 becomes f36.

I still stand that the 5.6 photo of Jhon is sharper then the f16. Look at the roundings of the ball. The exposure is also the same f16 and 1.5 against f5.6 and 0.16. To me it's due to diffraction, but I don't want to say it's only to that.

I just wanted to say that in macro diffraction is more prominent.

George

[xpatUSA]

You still don't understand it.

If that's the best you can do, please do not keep responding to my posts, do you understand?

When I said "No need to respond", I meant it.

[ajohnw]

The calculator works with the f-number. The f-number is focal-distance/aperture-diameter. The airy-disk is calculated with the image-distance. With a magnification of 1, the image-distance is 2 times the focal-distance. So f18 becomes f36.

I still stand that the 5.6 photo of Jhon is sharper then the f16. Look at the roundings of the ball. The exposure is also the same f16 and 1.5 against f5.6 and 0.16. To me it's due to diffraction, but I don't want to say it's only to that.

I just wanted to say that in macro diffraction is more prominent.

George

Some of that relates to a simple single lens George not a compound system of lenses. One aspect of that is when ever the object is moved the image plane moves too and the image circle size will also change as well.. Does that happen on a camera lens? I some how suspect you are also relating magnification with light loss on a surface area basis and trying to pull that into diffraction effects. Light captured is purely a function of the "equivalent" area of the glass that is capturing the light. Magnification based light loss doesn't have any significant effect on diffraction otherwise microscope objectives would have a terrible time. On those F ratio still sets resolution but they have the advantage that they are designed for a very specific fixed object distance. Very high resolution ones need focusing to with 1/2 a micron.

It's pointless keeping this up. You need to spend some time studying this subject from some reliable source - not odd ball comments that you may have picked up on the web some where.

John
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