Ignore this.

the distance from the end of the c-mount to the focal point of the ground glass is about 1 1/2"this is were you would start your first retaing ring . If you wanted you could use glass etching on a blank 50mm glass in fifteen minutes you would have a focusing ground glass
assemble the lens c-mout and tubes . just keep adjusting the thread with your fingernail untill it,s in focus . blow out the lens with compressed air and insert ground glass not touching the surface . blow dust out and place plcx on top thread down ring with fingernail . I bought the compressed air after I trapped dust in between. both the glass and the lens came dust free this was my error in assembling . the cool thing if you get the groundglass sealed with the plcx dust free It will stay that way. the tube and retaing rings solve the focusing and the dust problem of the
filter ring version


link to glass etching http://www.misterart.com/store/view/...rmour-Etch.htm

Cool. I think I can figure this thing out now. The etched glass is a great idea. I'll post some shots when I get mine up and running, probably in a couple of weeks as I'm out of town at the moment.

Fox

Richard -- what size step-down/up rings do I need on the tube end? 52mm or 55mm? And the tube to still lens goes up to 58mm, correct? Thanks.

Jason

the thorlabs tube is 52mm thread

Good thing I asked. I haven't been able for find a 72 to 52 step-down. I'll have use a 72 to 58, then 58 to 52 if I can't. Probably not an issue though.

Do you think it is possible that this could be used with a microcrystalline screen? Obviously, it would be hard to make your microcrystalline screen round...but say if you made a square screen...is their some sort of round holder that you could put it on/in?

I made a few attempts at a microcrystline wax diffuser with a 50mm glass blank. It is not good enough yet .
and if you did the plcx has to fit directly on the wax diffuser
somehow

I found a52 to 77 this company seems to have a wide range of adapters I did a search under the term lens adapter

http://www.adorama.com/FLU5277.html?...TER&item_no=25

I need a t 72 to 52. I can find 52 to 72, but not the other. Weird. Someone must make one somewhere.

I found a great site for step rings.

this should fit just about every camera.

great prices too


http://www.2filter.com/prices/products/rings.html

Nope, no go on that site, either. Thanks for looking. I just don't think that size adapter is made. Is there any real issue in using two step rings?

Jason I've never seen a 72 to 52 anywhere. It's always been done with a 72 to 58 to 52. I don't know why, but the step ring guys just overlooked that one entirely. Probably never entered their heads that someone with a 72mm front would to put something smaller on it. What are you putting this on? A DVX? A Canon?

Joshua, it's going on a DVX. I figured the double step rings wouldn't be a problem, it'd just be nice to a) have one less part and b) save 10 bucks.

Fox

Another question: what size step ring do I need to go from the tube to the c-mount adapter? I can find the adapter's diameter anywhere. Thanks.

Jason