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05-27-2010, 11:21 AM   #16
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this makes me wonder about my 135mm F2.8 Rikenon, and whether it is correctable, although I am sure it is sensor reflection in my case because it is not visible on th eviewfinder, you should have been able to see this when viewing.

05-27-2010, 03:19 PM   #17
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It is visible in the viewfinder, but it doesn't look nearly as bad as in the actual photos. So maybe you should try a bit of sock in your Rikenon. (Of course, it might be the whole inside (and not just the final tube), I can't imagine it would be worth the effort then, 135mm f/2.8 lenses aren't exacly the most exclusive.)
05-27-2010, 06:07 PM   #18
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QuoteOriginally posted by drougge Quote
It is visible in the viewfinder, but it doesn't look nearly as bad as in the actual photos. So maybe you should try a bit of sock in your Rikenon.
I think I'll pass, i can;t see the problem in the viewfinder and it is worse than yours
QuoteQuote:
(Of course, it might be the whole inside (and not just the final tube), I can't imagine it would be worth the effort then, 135mm f/2.8 lenses aren't exacly the most exclusive.)
how true
05-27-2010, 08:59 PM   #19
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QuoteOriginally posted by drougge Quote
Today I tried putting some cloth (a piece of sock) in the adapter, and the improvement is considerable. I'll have to get something better of course, but there's definitely hope. Same 120mm at f/8 as in the first post but now with sock attached, and an image of the sock in the adapter, to show how completely professional it looks while still working acceptably. (The sock isn't even black, but dark blue.)
You could glue some velvet or add some sticky black flock tape rather than paint, just need to make sure you vacuum well to make sure no dust enters the camera.

Velvet Flock Sticky Back Craft Paper

Cheers,

05-27-2010, 10:32 PM   #20
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Shooting with scopes I use a lot of adapters so I know the problem.

I use an old German opticians trick.

Get some black letterpress ink. This stuff if very thick and tacky. Mix into it some baking powder until you have a paste.
The powder gives it a fine rough dull texture.

Get a bit on the tip of your finger and just lightly tap tap tap on the surface you want to cover. The tapping raises random micro ridges in the tacky paste and further dulls out the final coating.

I've even gone so far as to bring some of my long extension tubes into the local tech school and have them cut fine threads into the inside diameter of the tube and then apply the above coatings.

I can think of nothing that is so flat and dull and black. You will be amazed at what this coating will do for your contrast. Most consumer lens tubes are not coated as well for reflections.
05-29-2010, 07:53 AM   #21
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That puts a whole new meaning on "put a sock in it".
05-29-2010, 06:34 PM   #22
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I would certainly consider sending a note to the adapter's manufacturer indicating that their design is deficient for the function that the item was intended to perform. They certainly could not have tested the design much, other than mechanical form and fit.

Excellent suggestions!!
05-29-2010, 07:14 PM   #23
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QuoteOriginally posted by interested_observer Quote
I would certainly consider sending a note to the adapter's manufacturer indicating that their design is deficient for the function that the item was intended to perform. They certainly could not have tested the design much, other than mechanical form and fit.

Excellent suggestions!!
I made significant improvements in the contrast on my Nikon LS-8000 film scanner by treating the reflective surfaces in optical path, you would think that they would have known.

06-01-2010, 10:19 AM   #24
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experiments

I tried a couple of experiments with my rikenon 135F2.8 which had demonstrated terrible glare / reflections off the sensor.

After rethinking the issue found by the OP, I tried 2 things, first, I inserted a 27 mm skylight filter in the rear of the lens, which seemed to have little or no effect.

Second, I looked carefully at the rear of the lens and found the ring that holds the rear element/group in place was shinny, not flat. Painting this quickly with some black acrylic craft paint (all that I had at the time) it almost completely resolved the problem. Further inspection showed I had not covered the entiure surface, so I am now doing a neater second coating.

While the lens only cost $30, and I have replaced it (due to this problem) with a tele lentar 135 F2.8 preset with 15 blade aperture, and an SMC tak 135 F3.5(found at such a bargain I couldn't pass on it) it still bothered me that I had spent $30 for a lens I could not use. It appears now I can

It makes me think that the issue with reflection off the sensor is more about the lens parts than the coating.
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