Ground Glass Material Idea...

Andrew Brinkhaus

Andrew Brinkhaus

Veteran
I was tinkering around earlier, trying to find another way to find a material besides glass for the GG. I came upon a yogurt lid laying in my garage, and the material seemed perfect. The downside, its a soft plastic, resulting in it being flimsy. The good, is that the plastic is already frosted and seems to be just the right opacity. Also, it can be cut to the perfect size and obtained for under $1, or free. What are your thoughts on this? Is it feasible?
 
My guess is that it will probably work about as well as the plastic CDs
I can't imagine it will work any better than GG, and chances are it will be less effective.
 
My guess is (and this is just a guess) that it might be too thin (causing ghosting).
You mentioned that it's pretty flimsy. Also, I'd be suprised if it's level of diffusion happened to be exactly what you needed (odds just seem against that). The thing with GG is that you can mold it to the level of grit/diffusion that you are happy with. Also I would guess that GG is a better transmitter of light than plastic (just a guess there).

Lastly, who knows what sort of 'grain' is in that plastic that will be picked up by the CCD.
GG is made to be used in optics, this plastic was made to carry yogurt so I can't imagine that the purity of the material is all that important to the manufacturer.

But, great ideas come from many unexpected places. If you already have a home made adapter it should take much to do a quick test and see how it fares.
You might surprised.


Keep in mind, I have no idea what this stuff looks/feels like.
I'm going off your quick description...so it's just an initial reaction.
Obviously there is no way to give you a solid answer without seeing and testing the material.
 
I work at a scenic shop, so I have accesss to alot of stuff you all probably don't, but I found that a 1/4 or 3/8 inch piece of plexiglass works wonders. just cut out a piece with a hole saw, then hit it with the orbital sander - its quick (about 10min including prep, but I have a drill press) and its cheap (well for me, I use falloff, but I'm sure you could find a piece at homedepot etc, its sturdy, and its not getto rigged (a pringles can? really?)
-Brandon
 
Luis Caffesse said:
My guess is (and this is just a guess) that it might be too thin (causing ghosting).
Click to expand...

I'd think just the opposite. Depending on what you mean by "ghosting". To me, that means a doubled image, which would be caused by a too thick material, the image showing up on both surfaces.
 
Try and stay away from plastic if you can. Plastic leads to colour abberation. I have been at this for about 1 year (and other for about 4-5 years). It sucks yes, but if you want the best looking footage, you have to use better materials. CD are still the cheapest and easiest way of doing it, but you won't get P+S, Micro35 or Guerilla35 quality from it. Glass is the way to go IMHO.
 
GenJerDan said:
I'd think just the opposite. Depending on what you mean by "ghosting". To me, that means a doubled image, which would be caused by a too thick material, the image showing up on both surfaces.
Click to expand...
I suppose you're right, though I would add that it's not only an issue of thickness, but not enough diffusion (too transparent). My confusion came in thinking that if it's too thin it would be too transparent, allowing you to see the image on the opposite surface.
 
DavidD said:
Try and stay away from plastic if you can. Plastic leads to colour abberation. Glass is the way to go IMHO.
Click to expand...
Ordinary plastic, yes. By all means, but there are TONS of high quality "plastic" lenses in each 5M digital camera produced. Optical quality plastic, multi coated can be very helpful. Best glass filters are super multicoated and thin to further minimize ghosting. (Check your image in an ordinary mirror vs. a surface mirror.) (my 2c)
All SLR cameras (film or digital) have a focusing screen. They're made of acrylic:
http://www.intenscreen.com/technical_intenscreen.htm
All medium and large format (Bronica, Rolleiflex, etc) used to have a glass "ground glass".
See the difference plastic can do and also the ANSWER to "how do I get rid of vigneting" here:
http://www.intenscreen.com/pdf/How_Does_It_Work.pdf
How come MPIC does not "loose any light"?:
http://www.intenscreen.com/pdf/Article.pdf
In use for almost a year; (scroll down the page)
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7560882214
What IS value? What gives value? Is “the best” the same for all, or is it "the best I can afford"?
Best things in life are free. True or false?
 
lol, me too...
better yet let's call it: the philosophy of making the best GG (subject to defining what IS "the best")
lol
 
Dan,

Lemme get this right..

You suggest using something such as the Beattie Intenscreen as a focus screen for an adapter? And that they only reason you should use a "ground glass" is when you jump up to a medium format?

I am just asking for clarification.
 
DJ,
I don't have and I would not use a Thor lab tube for this application. The pipe is too thick (heavy) metal. No need for that (imo). Just mount it with scotch tape on a filter till you figure the tube. I can't see the pic of Rolyn. I know of them but I can't see the pic of the Fresnel (I doubt it the Fresnel is fine enough), even so, the mate side is the "other side" of the problem. If it does not move, you’ll see the grains. If you were to try and use micro wax (for matte side) and the Rolyn Fresnel on the other side, you will have to "glue" them together somehow to get light transmitted from one side to the other without light loss, reflections and/or diffusion and you will end up with a less than perfect-home-made-Beattie (that might still need a shake)
If you were to micro wax the other side of Fresnel, I don't know how you would do that, due to the process itself. my 2c.
 
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