Hello, I've been following the Mini35 adapter threads for about two weeks and have begun the process of making my own.

Last week, I went to a local photography flea market (Only a once a year event). While there, I got a nice used lens for my Nikon, and I also found a Bosscreen.

http://www.edwardflinch.com/images/boss1.jpg
http://www.edwardflinch.com/images/boss2.jpg
http://www.edwardflinch.com/images/boss3.jpg

It measures 57mm square, and appears to be designed for a Hasselblad. There were a few others, but they had gridlines in them.

I made a simple setup and took a few pictures with a digital camera:

http://www.edwardflinch.com/images/bosssetup.jpg
http://www.edwardflinch.com/images/bosstest1.jpg
http://www.edwardflinch.com/images/bosstest2.jpg
http://www.edwardflinch.com/images/bosstest3.JPG

I apologize for the quality of the pictures; the camera I used was an old Cybershot with a broken LCD. My GL2 is out at the moment, when I get it back I'll do some better tests.

Anyway, I've been trying to find resources on the internet for these screens, as I know others would find them useful. Unortunately, I haven't found anything yet. I'll keep looking, but at the moment I can only recommend looking in camera shops and at events such as the one I went to.

Thanks for the post. There are other links available with in these threads. I'll post them again when I get my own computer back up and running.

Anyways did you also make your own GG with aluminum oxide? If so what grit rating did you use? And most importantly how did the results stack up to the Bosscreen? Which one is less grainy? I know what the manufactures say but what have you found?

-Brett

Yes, I actually started on a GG before I found the bosscreen. I ordered most of my grit from gotgrit.com; SIC 120, 320, 500, and WAO 5 micron; and I also got some 3 micron diamond spray from the Graves Company (http://www.gravescompany.com/polishin.htm).

I've ground a 58mm UV filter to a very nice grind with no scratches up to the WAO 5; but the diamond spray appears to scratch it. I believe that the problem is that I've been applying too much pressure and the diamond is clumping with the glass particles and cutting the glass too easily. I have to go back to get the scratches out, then I'll try again.
Scratches aside, the grain of the 3 micron seems to be finer than the 5 micron from what I can see under a magnifying glass. (Also, when I rinsed it, it was so clear I thought I had begun to polish it!)

However, I still have not been able to create a full setup to do any comparisons to the bosscreen vs GG. I still need a condenser lens and a way to mount the bosscreen.

Michael, thaks for the post. That's great that you found some Bosscreen and are putting it to the test. Everyone on this board has been curious about how it compares to ground glass. The only Bosscreen I've been able to find has been much bigger (and more expensive) than required. Did you cut the Bosscreen down to that size? or did it come that size?

Way back in the beginning of all these threads, this webpage (http://www.phototechmag.com/previous-articles/2003/mj-dokas/dokas.html) is what got everyone started on homemade ground glass. The author mentions, Chips of glass removed from the blank were larger in comparison to the texture of the surface. This is because these grits are made of silicon carbide, which is only slightly softer than diamond. As you grind with these extremely sharp, hard grits, chips of glass flake out—much like what happens to flint in arrow making. That means, according to his observations, diamond is too hard for grinding glass (diamond is intended more for harder surfaces such as rock and diamond) which backs up your experiment. It sounds like you did a good job grinding, but the diamond was just hacking up the glass, so you might want to avoid that entirely and just stick with the 5 micron WAO.

I'm sure 3 micron WAO powder is available somewhere, maybe that gotgrit.com guy will get some once he realizes so many people here want it. The article above mentioned that he purchased his finer grit from Willmann-Bell, Inc. (800-825-7827). Maybe they have the much sought after 3 micron WAO?

Great job getting the Bosscreen. I'm very curious to see the results from your tests. I'm sure everyone is.