one more thing, i'm using a uv filter for the ground glass as many people have. so which direction should the frosted side be facing, towards the 35mm lens or the camera?

An idea occured to me recently:

Would it be possible to use some form of semi-rigid polyurethane as a GG? What sort of grain structure does this stuff have? As far as I am aware it's grainless.

CONDENSERS
 

Hey guys!

Ok, I've been working on my microcrystalline wax adapter and, although the hotspot isn't as bad as with a glass adapter, I still have vignetting so I want to get some condensers.

I've seen references to this before:
http://www.surplusshed.com/pages/item/l2119.html

Anyone using these? Can I get some user feedback?

Also, what about this one here:
http://www.surplusshed.com/pages/item/l3136.html

They're not expensive, so it's not like I'm taking a risk here, but I would still like to know what sort of quality they are.

Thanks!

Frank I think you would want the aspheric condenser rather than the rectangle. It may end up having some strange anamorphic type squeeze effects otherwise. I could be wrong though - someone please correct me if I am!

On an entirely separate note:

Since I seem to be great at coming up with bad ideas for diffuse surfaces to use in place of a ground glass I thought I may as well suggest one more option: Polyethylene film. This stuff is plastic so it's in all practicality grainless, it lets in approx 84% of colored light while blocking out UV! That could provide for an amazing alternative. I'm going to go buy some tomarrow and see if I can't throw something together. Will post results!

Aaron: Thanks for the quick reply! The plano convex lens looked to be curved on all sides, as opposed to just a cylindrical curve, but I may be wrong.

Mmm good point. If the lens is square you should be fine. I can't quite tell from the photo. That said I have this unexplicable feeling that a fully round lens would provide less distortion. Don't take that too seriously though. Just a feeling.

Hrm...you guys are probably right.

Well at those prices I can maybe get two of each type and experiment. :-)

Thanks for the feedback!

If you do let us know which works best.

You might also want to wait and hear others opinions. It might save you some money and frustration.

parts list
 

http://www.thorlabs.com/ProductDetai...roduct_ID=1481

two of thesehttp://www.thorlabs.com/ProductDetai...roduct_ID=1483

http://www.optosigma.com/miva/mercha...+%26+Apertures
you want the 50mm with 70 fl and the 50mm groundglass with 1500 grit
http://www.optosigma.com/miva/mercha...herical+Lenses
you will be able to mount the plcx directly on the ground glass
the threaded retaining rings will allow perfect focal length from the slr lens to the groundglass.

Rich you rock!! What type of camera do you have, and how do you end up mounting it?

Thanks

p.s. Maybe we could start a thread with just parts listed and where to get them? And focus discussion in this thread? It's so hard to wade through all these posts looking for something, and it keeps growing.

Good info, thanks. But how does the lens mount fix to the Thorlabs tube? Does a C mount screw directly on?

parts list
 

I was happy to find when the thorlabs tube came in .that it
is the same as a 52mm camera filter thread so common step up and step down rings will work. the key is the tube. the first one I made was with 52mm filter rings I never was able to get the focal distance from the slr lens to the ground glass perfect or place the plcx directly on the ground glass.I did try the thorlabs groundglass the opto sigma is better. and when you build this dust is your enemy start with the 35mm lens then c mount then tube insert ring at about focal length the ground glass comes dust free
adjust threaded ring untill sharp focus don't let your fingers touch the ground glass. gently place plcx on top and thread the ring down with your finger nail if you didn't trap any dust the glass surface will stay clean. one trick I used is to use a poor ground glass attempt to set the focus . then took the pristine ground glass and set it in.

Thanks again Richard, that's exactly what I'm going to try.

But just to clarify if I may - does the C mount adapter fit directly to the 2" thorlabs tube? Sorry if this is obvious.

I'm using Nikon lenses so I want to attach this:
http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=77558&is=REG

Best

parts list
 

this is a link to some pictures of step up rings. http://www.cs.mtu.edu/~shene/DigiCam...ead-rings.html the tube is 52mm you would need a ring 52mm to whatever the thread size is in the adapter . and a second one 52mm to whatever your camera thread is

Do you have any footage with this setup rich?