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Old December 28th, 2004, 03:49 PM   #1
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Best GG Diffuser?

Since I'm living in the UK, it's a bit harder to find the parts needed for the static adaptor, and while I've got the spacers and CU lenses ready, I still don't know what the best GG to use is. I tried scrubbing a UV lens (rookie mistake) and it looked rather awful, and I tried pitting a clear CD with a screwdriver end (the soft bit) and that turned out better, but still nowhere near good enough.

Since Knight Optical seems to be the best distrubuter here for this kind of thing, what type of GG would you reccomend using from them?
Quote:
http://www.knightoptical.co.uk/acatalog/Diffusers.html
They have regular ground glass, opals, plastics and anti-newtons (apparently), and I'm not sure what would give the best diffusion, and minimum grain. Any suggestions?
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Old December 28th, 2004, 07:44 PM   #2
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WAO5 ground glass or microcrystalline wax. Wax is better. I'm putting a tutorial up on microwax diffusers shortly -- should be up by the week's end.

- jim
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Old December 29th, 2004, 03:46 AM   #3
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That would be brilliant, I've heard of the wax ones being used alot. The only type of glass this company sell is LEGB, B270 or UV fused silica... out of those, which would be the best to use, do you think?
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Old December 29th, 2004, 08:29 AM   #4
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I'm not familiar with what you're mentioning. I'm fusing two UV filters together with a very thin layer of microcrystalline wax. You can get a low melting microwax from companies like Strahl and Pitch -- http://www.spwax.com/spparaff.htm

If you write them in a somewhat professional manner, explaining to them that you intend to experiment with their wax with the hopes of using it in a future product, they will likely send you a 1lb sample free of charge.

- jim
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Old December 29th, 2004, 03:48 PM   #5
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Yeah, you mentioned the WAO5 ground glass, but I was saying I couldn't see anything at Knight Opticals that resembled that type of GG... unfortunate that this place seems to be just about only GG distributer in the UK. I'm intrieged by the wax techinque, but must admit I hadn't considered it as a viable option before you mentioned it. Would using wax give a significant improve of diffion from glass? And are there any known internation microcrystalline distributors?
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Old December 29th, 2004, 04:15 PM   #6
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ground glass

after trying 5 different ground glass companies, this was by far the best. http://www.optosigma.com/miva/mercha...+%26+Apertures


the one I used was the 50mm 1500 grit
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Old December 29th, 2004, 04:24 PM   #7
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cheap ground glass

I found this company It has a super cheap ground glass $7
It is 500 grit .I have not tested this one yet . the thorlabs was $15 but so far opto sigma is the best . It is the most expensive though.http://www.catalognavigator.com/roly...ompanyid=64329
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Old December 30th, 2004, 09:17 AM   #8
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Thats for the links, the OptoSigma GGs look like they'd certainly give great diffusion - do you have any images taken with that glass, Richard?
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Old December 30th, 2004, 09:54 AM   #9
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The microwax glass diffusion is different, optically speaking, than that of the WAO5 glass. Diffusion on the ground glass is a series of pits and ridges across a surface, the pits catching the image. WAx, on the other hand, diffuses the light by bouncing it on (in?) pieces of crystal suspended in a clear medium. For this reason, it's more crisp where detail is concerned.

On the other hand, producing properly thin and error free wax glass is a bitch, as I'm finding out. On my fifth try today -- doing two at a time with the hopes that one will work out :(

- jim
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Old December 30th, 2004, 11:48 AM   #10
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From all my experimenting, microwax definately produces the best surface, in terms of grain (and brightness, if a thin enough layer is achieved). I will say that there is NO grain noticeable ( at least when used with an SD camera - I have no HD camera to test )

However, as Jim stated, it is really difficult to work with.

I find myself using larger sheets of glass and after the wax has cooled, pointing the camera at whatever part of the glass is bubble-free. LOL!
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Old December 30th, 2004, 11:49 AM   #11
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What kind of errors can one expect from using the wax? Would it give a rippled type image if incorrectly applied, and would flashed opal GGs give good diffusion in comparison?
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Old December 30th, 2004, 12:04 PM   #12
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Steve: My first attempts were with a layer of wax coating one side of a single piece of glass. You definately don't want to go this route. You can easily get ripples, the thing would be near impossible to keep clean, if it melts then that's that.

However, with wax sandwiched inbetween two pieces of glass (and then sealed after you get a good layer), you can clean it, don't have to worry about ripples, and if it ever melts, it won't really go anywhere (It would just be transparent until it cools.)
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Old December 30th, 2004, 12:13 PM   #13
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flashed opal would be interesting to try. It provides excellent diffusion but has very, very low transmittance so it's probably not a good idea for this sort of thing.

regarding using glass with wax adapters:

Since the glass is uncoated you are going to loose at least 15% of your light.
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Old December 30th, 2004, 12:22 PM   #14
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There is definately some noticeable light loss (I haven't calculated how many stops), but this is mainly due to the wax. I'm not sure how much light loss is caused by the glass alone.
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Old December 30th, 2004, 12:56 PM   #15
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The problem is I'm using a GS120 which has horrible low-light capabilities, or so it seems to me, I'm not entirely sure how it fares in compaired to other DV cams. This means that I'll need to use something that gives a very bright image, but I'm not sure how worse wax would be when compaired to other options such as regular ground UV filters. Thres also the silica-uv glasses, but again I'm not sure how bright an image I'd get in compaired to wax. On the other hand, if the wax gives a very sharp image and doesn't reguire high-level pitting like the GGs do, then I think it would be worth considering. Does wax give a drasticaly darker image than glass?
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