Hi everyone, i have 2 questions. first, i am creating a spinning GG adapter for my new hd camera i have coming in. i have a static, but that was jsut for my cheap sony 1ccd cam. anways. since it is a spinning adapter, how would grain size factor in. i am thinking in the range of 400-800 is fine for a spinner? i have a 1000 grit i used to make my static, but i dont like all that light loss. Which grain size most replicates the grain of a beattie intenscreen?
thanks

and, does anyone have a clear knowledge of how acutal 35mm cinema cameras use the viewfinder. How is the viewfinder able to show the image while exposing film at the same time. I was told there is a peice 45 degree angle glass placed in the light path, and that the image gets reflected onto that and into a cheap cmos camera to then be viewed. is this correct? thanks

For a spinning GG, keep with a low grit size. Try 200 - 600 range.

Thank you Wayne, would 200 be a pro for least light-loss. and, is there any loss in resolution by going to 200 grit. i have heard people say that there is a lower resolution, which makes sense for a static adapter, but if it is spinnign constantly, would that balance out the way the image is diffused onto the glass, thereby, your never getting the same diffusion every frame as you would in a static adapter. because if thats the case. 200 should be highly efficient for both resolution and lightloss. is this correct wayne? thanks in advance.

From my research and testing, the lower grit sizes give less light loss and crisper images, with much better contrast. 1000plus grit sizes are only usefull for static adapters, and i think reduce contrast of the image.

My personal preference is for dressing the spinning groundglass to a 5 micron aluminium oxide finish. I don't know how this corresponds to a grit grade as quoted above. I'm also using glass, not plastic.

My personal preference is for dressing the spinning groundglass to a 5 micron aluminium oxide finish. I don't know how this corresponds to a grit grade as quoted above. I'm also using glass, not plastic.

Bob,
I found this a while ago...
http://www.leco.com/customersupport/met-tips/met_tip15.pdf