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03-21-2016, 02:31 PM   #1
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OXO in my bokeh decagon

Here attached is a photograph, we could say it is an out of focus macro shot.

It was made with an enlarger lens Industar 100-U on bellows. The thing that bothers me is not that this ugly OXO in my bokeh decagon exists but the question why is it there and what causes it. I did not use filters.

Any thoughts?

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03-21-2016, 02:40 PM   #2
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The shape of the bokeh is usually determined by the shape of the aperture. So it depends - did you step down the lens? If so, try shooting wide open. Since it is an enlarger lens, it might not have an aperture mechanism and I wonder whether it could be the shape of the bellows. That would be my first guess...
03-21-2016, 02:48 PM   #3
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QuoteOriginally posted by antipattern Quote
The shape of the bokeh is usually determined by the shape of the aperture. So it depends - did you step down the lens? If so, try shooting wide open. Since it is an enlarger lens, it might not have an aperture mechanism and I wonder whether it could be the shape of the bellows. That would be my first guess...
The shape itself does not bother me, it is decagonal from wide open to completely closed. What bothers me is the origin of the lines that criss cross it OXO style. They are there from f/4 (wide open) to f/22 (closed). The lens does have an aperture mechanism, and a very fancy one if I may add (picture attached).
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03-21-2016, 03:39 PM   #4
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OXO I'm assuming is another name for "Tic Tac Toe" from the pattern.

Is the image resized? The dodecagon looks stretched out.

I could be talking completely out of my ... yeah... but the lines look like they may be reflections from the aperture blades. Looking at your photo of the lens interior, at least one blade seems to have lines on it.

03-21-2016, 03:45 PM   #5
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Curious. I've never seen aperture blades like that. My gut instinct, however, says the lines in the flare bubble are the
result of fine cleaning scratches on the lens, perhaps. As I understand it, the image inside the flare bubble is a reflection
off one of the lens surfaces. I suppose it could even be a reflection of those aperture blade grooves. Someone who
understands the optics better than I do needs to chime in.
03-21-2016, 04:14 PM - 1 Like   #6
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QuoteOriginally posted by narual Quote
OXO I'm assuming is another name for "Tic Tac Toe" from the pattern.

Is the image resized? The dodecagon looks stretched out.

I could be talking completely out of my ... yeah... but the lines look like they may be reflections from the aperture blades. Looking at your photo of the lens interior, at least one blade seems to have lines on it.
Exactly, "Tic Tac Toe" or "Criss-Cross" or "Noughts and Crosses". OXO is the first graphical interface computer game from 1952. In Serbia we call this game "iks-oks".

No resize, decagon is stretched because it appeared at the edge of the frame, otherwise would be closer to perfect.

Even wide open, OXO is still there, that is why I would exclude the aperture blades reflection.

QuoteOriginally posted by tvdtvdtvd Quote
Curious. I've never seen aperture blades like that. My gut instinct, however, says the lines in the flare bubble are the
result of fine cleaning scratches on the lens, perhaps. As I understand it, the image inside the flare bubble is a reflection
off one of the lens surfaces.
I thought the same thing the first time I saw it. In fact, it is just ten aperture blades, each cut at a right angle to form a decagonal aperture. For the scratches, I've excluded that as well, the glass seems mint, even dust is absent. That is why I think, due to the pattern of the thingy, that it might be a reflection of the camera innards.
03-21-2016, 04:24 PM   #7
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I'm wondering if the lines in the bokeh balls are reflections from the machining lines in those aperture blades??
03-21-2016, 04:27 PM   #8
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QuoteOriginally posted by BigMackCam Quote
I'm wondering if the lines in the bokeh balls are reflections from the machining lines in those aperture blades??
I've excluded that because the lines stay even when I am shooting wide open and the aperture blades are not visible.

03-21-2016, 04:42 PM   #9
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QuoteOriginally posted by Audi 5 cyl Quote
I've excluded that because the lines stay even when I am shooting wide open and the aperture blades are not visible.
Hmm. Interesting. Back to the drawing board....
03-21-2016, 05:00 PM   #10
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QuoteOriginally posted by BigMackCam Quote
Hmm. Interesting. Back to the drawing board....
For me it's back to bed

I will test the lens some more to see if there are any changes if it's rotated or similar. Hopefully tomorrow

The photograph here-under has been taken wide open. OXOs everywhere...
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03-21-2016, 05:22 PM   #11
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That is quite strange. The only time I've seen anything in my bokeh orbs is when there is dust on a rear element, so I guess it's possible there are cleaning or manufacturing marks on the rear element - but it seems too uniform to be cleaning marks. Fascinated to see what you find out...
03-21-2016, 09:22 PM   #12
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The only thing that I can think off is that lens has flat rear element and that those are sensor reflections. You might have a small light leak somewhere in your bellows that is causing those reflections and pattern in your pictures. The light leak will reflect from the lens rear element as well but will have sometimes strange pattern. Cover your bellows with something very dark and make sure that light does not go through and then we can eliminate that as well or find what causes this.
03-22-2016, 04:26 AM - 1 Like   #13
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When I hear "oxo" I think "ergonomic kitchen utensils"

Do you get this on non-macro, not using bellows, too? And stopped down a bit?
03-22-2016, 05:20 AM - 1 Like   #14
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No filter I assume?

Could it be a flaw in a lens element? This lengthy article has an example on page 32 of a circular pattern in the out of focus highlights that apparantly indicates how one of the aspherical elements was manufactured and is not perfectly smooth: Zeiss - Depth of Field and Bokeh. Obviously yours is something different, but it looks like tiny variations in an element's surface can have a noticeable impact in the highlights.

If it's something in/on the lens and you rotate the lens on the bellows in between shots, the lines should rotate as well. You could narrow down where it's coming from this way.
03-22-2016, 01:33 PM   #15
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QuoteOriginally posted by BigMackCam Quote
That is quite strange. The only time I've seen anything in my bokeh orbs is when there is dust on a rear element, so I guess it's possible there are cleaning or manufacturing marks on the rear element - but it seems too uniform to be cleaning marks. Fascinated to see what you find out...
Exactly, I could say the same. Sometimes I've seen it as a consequence of the coating damage as well, but generally, if not in the rear group, it's rarely visible.

QuoteOriginally posted by RAART Quote
The only thing that I can think off is that lens has flat rear element and that those are sensor reflections. You might have a small light leak somewhere in your bellows that is causing those reflections and pattern in your pictures. The light leak will reflect from the lens rear element as well but will have sometimes strange pattern. Cover your bellows with something very dark and make sure that light does not go through and then we can eliminate that as well or find what causes this.
Sensor reflection crossed my mind several times but all I could find on that topic presents itself as a centrally positioned blur rather than OXO pattern. Nevertheless, bellows checked, no leaks, tested with m42 and m39 extension rings, OXO still present.

QuoteOriginally posted by narual Quote
When I hear "oxo" I think "ergonomic kitchen utensils"

Do you get this on non-macro, not using bellows, too? And stopped down a bit?
EKU are coming to as all, sooner or later. Yep, it is there whatever I use, but a lot less visible in regular use.

QuoteOriginally posted by BrianR Quote
No filter I assume?

Could it be a flaw in a lens element? This lengthy article has an example on page 32 of a circular pattern in the out of focus highlights that apparantly indicates how one of the aspherical elements was manufactured and is not perfectly smooth: Zeiss - Depth of Field and Bokeh. Obviously yours is something different, but it looks like tiny variations in an element's surface can have a noticeable impact in the highlights.

If it's something in/on the lens and you rotate the lens on the bellows in between shots, the lines should rotate as well. You could narrow down where it's coming from this way.
No filter.

Thank you for sharing this article Brian, I do find it well put together in all its lengthy appearance. Rotation of the lens actually rotate my OXOs as well.

Therefore it must be in the lens. I've dismantled and cleaned the lenses and OXO is still there. There are no visible imperfections on the lens surfaces so I guess they are internal. Maybe the chef mixed the wrong ingredients while cooking my glass

Thank you all for your comments and ideas.
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