What about gluing some black velvet or felt inside the tube? My Canon AE-1 was lined with black velvet on the inside...

I also got a shipment of lenses from ASS (chuckle) and yes - the condenser(s) make a huge difference. Additionally - it didn't seem to matter much what I had as a condenser (single-element vs. achromat) as long as my macro was achromatic... seemed to fix any abberations that crept in from the first lens.

Jonathon- Thanks for the info about your condenser. Would you mind answering the questions about FL, diameter, working space.

Velvet will be the best material for soaking up any scattering light BUT your likely to see small pieces of the material come off once in a while and ruin your shots. You have to remember that these adapters are totally unforgiving to even the smallest speck. Our ground glass is in focus and not moving. Anything touching it will also be in focus. Personally Im going to get around this problem by putting standard UV filter between my 35mm lens and the ground glass. The other side of the adapter has the macro len on it so theres no way for dirt to get on or close to the focus plane of the ground glass.

-Brett Erskine

I don't have them in front of me (still at work :-( at 12:30 am, blech). From the limited experimentation I did, It seemed like the focal length of the condenser didn't matter nearly as much as the diameter. The diameter of the condenser absolutely must be larger than the 36x24 (or whatever you plan to captuer) image on the GG.

With the three or so I tried (which all had different FL), I had a large amount of latitude as to where I could position the macro and still get good focus, and nice bright light all the way out with no abberations. I could get out-of-focus images, but I *really* had to move...

This was much much more true with an achromat as a macro. I tried some single-lens elements as Macros and they worked but tons of chroma and spherical distortion.

likely not tonight (will be hitting the sack immediately upon reaching the homefront), but when I get my next free cycle, I'll take some real FL measurements and try to find an 'optimal' position for the macro given those focal lengths and post 'em.

Hear you on the velvet - that makes sense... we definitely need to minimize potential debris in there... Good idea on the additional filter.

Johnathon W - Im REALLY looking forward to thoughs numbers. They will tell everyone alot! When you find out the focal length of each condenser check and write down whats the best distance to have your camera with the macro lens. If you do that for all three there should be a relationship with a noticeable patern (ie. A ratio with the a given distance between condenser and macro lens being X the focal length of the condenser should be Y).

Its good news to hear that its likely we dont have to be extremely picky about the focal length for our condenser for our adapters.

BTW did you ever try doing this setup?:

(l ll l)
<Condenser, Ground Glass, Condenser>

Im curious because thats basically what SLR's have. Instead what we are doing look like this:

ll l)
Ground Glass, Condenser>

Thanks again. Cant wait to hear thoughs numbers.

-Brett Erskine

just a few months ago i heard that there was a "paint" type coating surface invented in england that absorbs about 98% of light that hits it, apparently it makes the surface about 25% more black than traditional matte black paint. If it makes it to the consumer market it'd be perfect for the inside of the adapter.

Nail Polish
 

For the outside, people were discussing they couldn't find a paint that adheres to the PVC pipe. I would think nail polish would do the trick.

I was looking around for a PVC paint solution and found this:

http://www.azcentral.com/home/garden/articles/0125patio25.html

Excerpt from the article:
---------------------------------------------------------------------------
"Krylon, the aerosol-paint maker, has developed a Fusion line of spray paint for use on plastic surfaces such as patio furniture, kids' play equipment and - should you care to paint them - PVC plumbing pipes.
.
.
.
DETAILS: 1-800-457-9566 or www.krylon.com. "
---------------------------------------------------------------------------

May not be the solution, but I don't think it has been mentioned yet. (Someone mentioned Krylon plastic furniture paint, I believe, but this 'Fusion' line may be different.)


Also, here's another link for a different product:
http://www.qbmdistributors.co.uk/H&SCOSHH/Tech%20PVC%20Paint.htm


,Frank

why not just use black pvc pipe?

A lot of people want the 'flat black' look, as opposed to the shiny plastic.
Still, I think that using black PVC, as you suggest, but sanding and painting it flat black, would be better than painting white PVC.

I'm going shopping for some today (currently, all my stuff is held together by duct tape - HA HA!), so I will try and find some black pipe.

Thanks!

Black PVC pipe is better than white for sure but all of the pieces may not be available in black. Not to mention we need a FLAT black finish. Im still going with flat black aluminum but for everyone thats doing PVC starting with black tubing may be a real good idea because you only need to lay down a very thin layer of flat black paint. Just make sure your threads are consistantly hold the adapter together firm enough after you find focus. If it flexs at all you will have moments of out of focus shots.

Plus - the main reason for all of this painting is optical. If you have too reflective a surface on the *inside* of the pipe (even shiny black plastic), the light bounces around in there and 'milks-out' the image. Just like when you look at your ground glass before you put it in the tube... all of that extra light coming in the side really screws things up.

We want the insides of all of these tubes to be a non-reflective as possible - very very flat, roughened black surface, or better - cloth like velvet. The insides of some cameras are lined with black velvet for this reason.

Of course, the outside has to look cool :)

Also, as mentioned, it has to be a lint-free solution (the inside part). I think Brett mentioned his workaround for this, which sounds like it will work well.

Absolutely - as Brett mentioned - our sensitivity to dust and crap is very high... any kind of fabric is likely to be a problem. His idea of hiding the GG behind another filter sounds good to me-

After R&D is over, I hope to go with aluminum tube. But PVC for now, with the black rubber/plastic coating seems to work well.

For now I'm having more trouble getting quality GG. I have tried the grit and polish that comes in a rock polishing kit. It puts very fine chips in the glass which comes across as dark spots. I will order the aluminum oxide and give it a try. I wish I knew of a place to order 2" round GG. I think this will be the biggest obstacle to a quality image.

Did anyone remember where those threaded aluminum tubes can be found?

Also has anyone found a specific condenser which works on the camera side of the GG for getting rid of the hotspot? What I have (a close up lens 10+) is ok, but not quality. I still have a hotspot.

Brett seems to be the only one with alumunim tubes, but his sources remain unnamed :) (he said he had them fabricated).

Here's the best I've found...

http://www.northcoastmetalmart.com/60altu2odx1w.html

They specialize in 'hobby' projects, so they don't mind orders in the 1 foot range.

Not threaded, but an approach to this is what I'm doing with PVC - get a step-up ring which male side is the same diameter as your ground glass uv filter (I'm using 52mm) and the female size wraps snugly around the 2" outer-diameter tube... (50.8mm is the official inches-mm conversion, but pipes vary somewhat - my 2" pvc coupling is much bigger and works best with a 58mm step-up).

At any rate, you can JB Weld the step up to the end of the unthreaded tube and presto - fine-threaded metric threads as if designed for cameras :)

Other advantage - is you can easily unscrew it to clean/replace your ground glass.