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Old February 8th, 2006, 02:06 PM   #1
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Bonding PCX to diffusion sheet

I have a sheet of high transmisson diffusion film, with BOTH sides diffused. it's about as thick as a transparency sheet.

If I used Cyanoacrylate spray (what super glue is made of) on the flat side of a PCX, then laid the diffusion film on that, would it cancel out one of the diffused sides.?

It's my understanding that the flat side of PCX (Plano Convex Lense) should face the GG, and it should be as close as possible to GG, hence just gluing it straight on to pcx?

Like: Nikon Lens > GG Film glued to PCX > Achromat > Camera.

Would I need expensive optical glue instead, or will this not work at all because the GG is TOO close?

I probably won't figure out much without experimenting, just don't want to screw up a $34 lense if I can help it.
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Old February 8th, 2006, 02:26 PM   #2
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Hiya,
I dont think personally that the PCX touching the GG is the best setup. I think there is always a certain distance depending on the PCX lens used that will minimise barrell distortion.

Please see my (old) thread here:

http://www.dvinfo.net/conf/showthread.php?t=50884
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Old February 8th, 2006, 02:43 PM   #3
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Usually projection screens on SLR cameras have the PCX right on top of the GG screen. And they have no visible barrel distortion. But I don't know if the lens is really a PCX or an aspheric.

Then again from my experiments, separating the lens has given me a better illumination across the screen.

Solomon, the way the glue interacts with the screen material will depend on what glue it is and what the screen is made of. Cyanoacrylate tends to dry whiteish if exposed to humidity (which is what actually makes it bond).

You don't need to glue it. Just attach it.

What material are you using as diffusing screen?

PS. I am currently experimenting with adding a coating to one side of the diffusion materials I have and the results are really promising. The lightloss is reduced even more (if you can believe that) and the sharpness is increased.
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Old February 8th, 2006, 03:15 PM   #4
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Wow, quick replies. thanks.

How about glueing it to a larger diameter PCX with a slightly longer flocal length? the sweet spot (24mmx36mm??) shouldn't have to much barrel distortion then, no?

Quyen uses a 100mm FL rectangular PCX.

I could try experimenting by glueing the film to glass blanks and test different glues, cyanoacrylate, uv optical bonding glue, etc....


the reason I want to GLUE it instead of just have it up against PCX is because BOTH SIDES of film are diffused. if some kind of optical glue bonded the diffused material with the flat side of the PCX, I thought it might cancel out the secondary diffusion.
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Old February 8th, 2006, 03:18 PM   #5
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Diffusion film is "GE Advanced Materials" LEXAN® ILLUMINEX™ diffuser.

GRADE: XL4251
GAUGE: .005
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Old February 8th, 2006, 03:48 PM   #6
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Quote:
Originally Posted by Solomon Chase
I thought it might cancel out the secondary diffusion.
Oh and it will. I have tried it but not with glue but other compostions that have a similar refraction index to that of glass. It definitely makes the screen much more transmissive.

BTW, have your checked your screen for rotationally invariant diffusion? You don't want to get ugly bokeh. (just use a laser pointer and make sure the diffusion looks circular)
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Old February 8th, 2006, 04:12 PM   #7
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Quote:
Originally Posted by Alain Bellon
Oh and it will. I have tried it but not with glue but other compostions that have a similar refraction index to that of glass. It definitely makes the screen much more transmissive.

BTW, have your checked your screen for rotationally invariant diffusion? You don't want to get ugly bokeh. (just use a laser pointer and make sure the diffusion looks circular)
Yeah, diffusion is invariant and evenly circular.

Just tested with cyanoacrylate gel on a UV glass circle looked awesome before it dried, much more transmitance and sharper image. after a while it got cloudy though.

If I had optical glue, I'm sure it'd be awesome. anyone know where to get some for cheap?
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Old February 8th, 2006, 04:43 PM   #8
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Quote:
Originally Posted by Solomon Chase
...much more transmitance and sharper image. after a while it got cloudy though.
Yep, those are the results I am getting.

I do not know a source of cheap optical glue. But... ;) you may want to try some of those lens repair kits, or some similar acrylic based enamel (clear nail polish, liquid glass car protection, etc).
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Old February 8th, 2006, 05:55 PM   #9
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Quote:
Originally Posted by Alain Bellon
Yep, those are the results I am getting.

I do not know a source of cheap optical glue. But... ;) you may want to try some of those lens repair kits, or some similar acrylic based enamel (clear nail polish, liquid glass car protection, etc).
Good ideas...
I already went ahead and just ordered some 'Norland NOA 76 UV Adhesive" for bonding glass to plastic. $12 shipped.
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Old February 9th, 2006, 10:56 AM   #10
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Solomon, let us know how it all turns out.

Hopefully the diffusion on one side will be enough.

Is this to be a static adapter or a moving one?
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Old February 9th, 2006, 11:41 AM   #11
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I hope its static, hate the thought of that lens moving about ;)
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