What on Earth is going on here?......

[250swb]

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Ah, I can see the problem now, it's the spots! Given some are in focus and some not I wonder if it's pollen on the sensor?

[ianman]

39 minutes ago, pop said:

I don't think so.

I'm not sure what you mean. Like I wrote that is almost exactly as I saw them on my sensor. Others looked different. There were worm shapes, cross shapes, "H" shapes, etc. It must start at one spot and progress from there. Worms and other shapes didn't suddenly form spontaneously.

Edited September 18, 2021 by ianman

[pippy]

Thanks to all for your further thoughts. Taking them in some sort of order;

Yes; interference patterns or Newton's Rings. I did think about that but would have expected the spots to have been brighter in that scenario. Still my #1 'most likely'.

Yes Ian; I've checked all images both earlier and later. Nothing. As mentioned earlier - and I really cannot stress this point enough - these spots seen here can only be seen in the flared areas in this one image; nowhere else. During the snapping session I shot around 100 frames on two bodies mostly with the same lens and mostly at f1.5 (there's another of a spider spinning a web shot at f1.5 on the M Monochrom posted yesterday in the Looking Through Older Glass thread) without any issues in any other frame.

Files were shot as DNG (no chioce with the M-D Typ-262) and processed-out with no post-prod as TIFFs it showed them exactly as they are shown here.

Not corrosion marks, M9Reno, as I'm all too familiar with them having two 1st Gen. sensors fail. Also as the snap was taken at f1.5 this wouldn't fit either. Nothing on any subsequent frame.

Not pollen on the sensor. I checked the camera after noticing the things and absolutely nothing.

OK, I think I'll just let it lie. I'll try to excite a similar reaction when I next have the opportunity but, for now, I'd take the interference / Newton's Rings idea as having the most backing.

If I DO manage to recreate the reaction then I promise I'll spare you all the grief!

Thanks again!

Philip.

[frame-it]

1 hour ago, pippy said:

Sorry if I wasn't very clear in my earlier posts. I fully understand why there is flare.

Here are two magnified crops from within the flare wings - one from each area. I'm interested in knowing what has caused the concentric rings. These rings can only be seen in the area of the flare wings in this image and in no other image whatsoever;

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Thanks in advance again.

Philip.

 its dust on  the lens.

https://photographylife.com/the-effect-of-dust-on-lens-bokeh

 

[pippy]

39 minutes ago, frame-it said:

 its dust on  the lens...

Thanks for the suggestion, Frame-it, and although it could be I don't think it is. At any rate it isn't quite the same as it is in the linked image.

The issue isn't manifest in any bokeh-balls - as it is in the image in the link - only in the flared areas and the lens was cleaned, front and back, immediately before I started shooting with it on the M-D. I had a filter on when it was being used on the Monochrom less than a minute earlier and, by force of habit, always clean my lenses when filters are removed. The filter is also cleaned front and back before it gets returned to the lens - whose front element is also cleaned once again before the filter goes back on. It really is a very clean lens; you'll just have to trust me on that point.

Also I've checked all other frames shot at around the same time with similar backlight highlights bokeh-balls - but no flare - such as the Spider-Spinning image mentioned earlier and, as I've said, absolutely nothing.

There is clearly something going on here but only in the areas with flare. I will have to try to replicate the scenario; probably in the studio as things can be better controlled.

The funny thing is I don't even think the image is any good in the first place and would be unlikely to have ever looked at it again were it not for the rings!

Philip.

Edited September 18, 2021 by pippy

[ianman]

1 hour ago, pippy said:

The funny thing is I don't even think the image is any good in the first place and would be unlikely to have ever looked at it again were it not for the rings!

Well I didn't want to say anything...

You didn't happen to clean your lens & filters with compressed air I suppose?

[pippy]

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Yes; I know! I'm still at the 'playing around' stage with the Summarit wide-open just for the fun of seeing how it draws. It frequently has the power to surprise...

No; not compressed air. Microfibre cloth. A clean one! I have different cloths; some for bodies and others for lenses.

I'm almost ridiculously fastidious about keeping my kit clean and in good nick; so much so that when I traded-in my M9-P Ivor at Red Dot had to double-check the actuation-count because although it looked nearly-new it had amassed some 77k clicks.

Philip.

[adan]

The saturn rings (thanks for the blow-ups) look very much like Airy disks. Which are caused by diffraction.

I think these are very, very small dust specks (nearing the scale of a wavelength of light - 400-700 nanometers) inside the lens. Far too small to be visible by simply eyeballing the lens with anything less than a powerful microscope.

https://en.wikipedia.org/wiki/Airy_disk

https://en.wikipedia.org/wiki/Diffraction#Patterns

A key point here is that while diffraction is normally depicted as light passing through a narrow slit or pinhole (or multiples thereof, when studying interference patterns), light can also diffract around the edges of a solid object. It is the edges that bend/diffract light, not the "hole" per se.

https://fphoto.photoshelter.com/image/I0000W.razIRRjaI

https://fphoto.photoshelter.com/image/I0000kalfCBx2_vU

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-27-7-9372&id=407479

https://en.wikipedia.org/wiki/Arago_spot

I would even speculate that 1) the dust is on the surfaces closest to the aperture (thus are being "imaged" in the same way that a 5-blade aperture produces 5-sided "bokeh balls" (Hassy Super-Wide background crop))...

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...2) that the effect is enhanced by the narrow reddish or bluish spectrums available at that point, caused by the color flare, and closer to a single-wavelength laser color...

.....and 3) stand out due to the textureless, low-contrast background (veling flare plus extremely-blurred background). I suspect if the background was sharply-focused grass or other natural texture, the "saturn rings" would be virtually unnoticable.

Edited September 18, 2021 by adan

[pippy]

1 hour ago, adan said:

The saturn rings (thanks for the blow-ups) look very much like Airy disks. Which are caused by diffraction. I think these are very, very small dust specks (nearing the scale of a wavelength of light - 400-700 nanometers) inside the lens. Far too small to be visible by simply eyeballing the lens with anything less than a powerful microscope...

I would even speculate that 1) the dust is on the surfaces closest to the aperture......

...2) that the effect is enhanced by the narrow reddish or bluish spectrums available at that point, caused by the color flare, and closer to a single-wavelength laser color...

.....and 3) stand out due to the textureless, low-contrast background (veling flare plus extremely-blurred background). I suspect if the background was sharply-focused grass or other natural texture, the "saturn rings" would be virtually unnoticable.

Hi, Andy, and I thank you very much for your quite clearly well-reasoned and well-researched response. Having only just now managed to digest the Airy Disc idea I certainly think that you are very much on the right track as much of what is written in the link makes perfect sense in regard to the image. I will go through the rest of the links when my brain has fully recovered from trying to follow the maths...

There are a couple of points which I would like to have been able to discuss - as not everything fits - but more fits than doesn't. The point raised in your first speculation would also help to explain why the rings are apparent even although the snap was taken at f1.5 where, that being the case, minor dust specks on either fron or rear elements would have been entirely inconsequential to the captured image.

I'll conclude this post (dinner's being put on the table as I type!) by posting one final (I hope!) slightly enhanced snap. The image is split 'virtually' at the half-way (reddish) area from left to right which are, in turn, 'flared area' and 'non-flared area'. I'd still like to know - all the above info taken into consideration - why the Airy Discs are only visible in the left-hand-side flared area as there is really no great chasm of a difference in either contrast nor colour-pallete in the two halves;

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But thanks to yourself and all others here for helping me out in this post!

Philip.

Edited September 18, 2021 by pippy

[adan]

Some ideas:

1) simply because the dust is more centralized in the lens and image - as is the flare. It may have collected centrally in the "bowls" of the convex glass before/behind the aperture, if the lens was stored face-up or face-down over its 60-70 years of existence. (sorry for the low res image from the Leica Forum Wiki!)

The first 35 Summicron-M v.4 I ever bought had quite a collection of naked-eye black particles in the center of the lens (in both dimensions). I suspect they were "scrapings" from whatever black coating is/was used on the aperture blades. I did get a nice price because of them back in 2001 - $650. And did not notice any particular effects from them - but again they were at least 1/30th of a mm in size (33.3 microns, rather than 700 nm or less), and I don't recall any pictures made with exactly that lighting and flare.

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2) It has something to do with the optics of the flare itself. For example, the flare has striations ////////////, especially visible in the blue part. What is causing that - but only in the flare? Is the flare light collimated in some way? Do the striations have to do with the simple - and possibly imperfect - coating used at the time, and the fact that the coating itself uses "destructive interference" to reduce reflections at glass/air surfaces?

I'm not saying the striations directly cause the disks - they aren't death-rays aimed at targets. Just that the glass and coatings obviously are doing several weird things to light, which may (repeat, may) have related causes.

But since correlation does not equal causation, we are rather at the point where we need more empirical evidence, not just theory, to dig into those questions.

 

[a.noctilux]

Philip,

To be investigated ...

Your saturn rings could be air bubbles in glasses 'focussed'.

Those air bubbles are in the glasses of lenses in my two Summarit 1.5.

You would be surprised as I'm, looking with a magnifier (x10 for negatives) 'inside' the glasses of your cleaned lens (so no dust on surfaces).

The 'air bubbles' I see in the thickness of the glass are randomly spaced.

Maybe this is one of the explanations.

 

[pippy]

1 hour ago, adan said:

Some ideas:

1) simply because the dust is more centralized in the lens and image - as is the flare. It may have collected centrally in the "bowls" of the convex glass before/behind the aperture...

2) It has something to do with the optics of the flare itself. For example, the flare has striations ////////////, especially visible in the blue part. What is causing that - but only in the flare? Is the flare light collimated in some way? Do the striations have to do with the simple - and possibly imperfect - coating used at the time, and the fact that the coating itself uses "destructive interference" to reduce reflections at glass/air surfaces?...

Thanks again, Andy, for putting in even more effort.

Right from the start it has seemed that it is the particular angle of incidence of the sun's rays on the front element of the lens which, in some way, lies at the heart of the matter. That appeared to be the most likely explanation as to why the disc marks were restricted only to those areas which were affected by flare. Back then, of course, I wasn't considering matters at such microscopic levels but, as we are now there, diffraction occurring where the wavelengths of light interact with - or are interfered by - microscopic dust particles? Affected by lens coatings which were, in all honesty, still at the experimental stage? Surely it is not a coincidence that the 'direction' of the striation marks you mention align with the sun's position in the sky relative to that of the lens? As you, yourself, said at the end of your post;

"But since correlation does not equal causation, we are rather at the point where we need more empirical evidence, not just theory, to dig into those questions."

Yup! Shame I don't know anyone with a Doctorate in "Theoretical and Applied Physics; Optics a Particular Speciality!" nor any other images which 'suffer' from the same phenomenon for the sake of comparison. Yet.

Next time I'll drag along the Summicron as well as the Summarit and do back-to-backs......

Thanks to all once more!

Philip.

Edited September 18, 2021 by pippy

[pippy]

38 minutes ago, a.noctilux said:

Philip...

Your saturn rings could be air bubbles in glasses 'focussed'.

Those air bubbles are in the glasses of lenses in my two Summarit 1.5.

You would be surprised as I'm, looking with a magnifier (x10 for negatives) 'inside' the glasses of your cleaned lens (so no dust on surfaces).

The 'air bubbles' I see in the thickness of the glass are randomly spaced.

Maybe this is one of the explanations.

Thanks for the idea, Arnaud! I'll have a really good look at the innards of the lens when I get a chance. Everything I've read about air bubbles in lenses has stated that they make no difference whatsoever to any lens' performance but I'm not ruling out many ideas at this time.

Philip.