Need condenser advice
 

Hi!

Here's the deal, I'm refining my cd-spinner and need a condenser. I've disassembled various projectors in search of optics, but I haven't found anything that give me satisfying results yet. So my question to you expert is what exact condenser should I buy?

The lens is a fast Canon FD1.4 and the camcorder type that will be mostly used is the 3CCD Panasonic NV-series (37mm optics). Groundglass will be a transparent Nivea-coated cd-r.

I would really appreciate if you could point out specific condensers, preferably within the EU, but US shops are ok too. I guess glass condensers are the best.

if you are just going to coat a clear cd with nivea without grinding it first with a 200 or 300 grit i doubt you will get enought diffusion to avoid hotspot. in that case, you also wont get much of a shallow dof, if its too transparent.

but as for condensers, this one works alright:
http://www.surplusshed.com/pages/item/l3385.html

it was used in early versions of the Letus and Sg35

For me, i was lucky to snag a 35mm sized condesner out of an old SLR camera. it was coupled with the focus screen. I like to use that, and this may sound odd, but i found that if you put the condenser between your SLR lens and the GG. with the flat side facing your gg, place the condenser about say 20mm in front of your gg, and if you are using a 35mm condesner like i am, you will get a perfect 35mm sized image on the glass (slightly larger perhaps) but without any falloff, it is bright throught the frame until it ends and then its just dark like the cd. very cool and good for reference. It plays with the optics when you do this so back focus changes, but once you find backfocus again, it wont vary from slr lens to slr lens. it works really well.

I forgot to mention the grinding. You're right, without any grinding I could as well skip the GG... :)

I disassembled an 8mm camera and used that "condenser" (or was it a condenser? - don't know) between the GG and SLR and it worked quite well, the image projected was a bit smaller though than without the "condenser".

Thanks for the advice and link to the condenser, exactly what I was looking for. Is that condenser some kind of "generic" condenser that works well with most adapters?

/Carl

I think that condensor is sold out. I took a chance with this one instead. Waiting for it to arrive. http://www.surplusshed.com/pages/item/l3600.html

Ok, would you please tell me if it worked when it's arrived?

Will do. They seem to be a bit slow though. It's been two days and I still haven't been billed or receive any shipping info.

I recommend placing it between your GG and Camcorder with it very close to the GG:

SLR-----GG| |)-----cam

That wasn't possible because the "condenser" was only around 18 mm in diameter :). I believe the placement you suggest is the best, but it requires the condenser to be in good condition, which is not the case with all my scratched optics.:( And that's a reason why I have to buy one!

OK cool.

That one from surplus looks ok, just note that alot of lenses from there arrive scratched.

It arrived. I take back what i said about them being slow. Anyhow, it does what it is suppose to do but it might be too strong. The center of the lens is over 1/2 inch thick. There's quite a bit of distortion. I took a pic so you can see for yourself.

http://www.ocf.berkeley.edu/~mdlee/condenser.jpg

Yes, it does indeed look quite distorted. I have a condenser that is 2/3 of an inch, which is way too much. Have you tried filming with that condenser?

I'm actually still putting my adapter together so no, I haven't shot any footage. I still need a macro. The distortion is mainly around the edge and my camera has a 37mm lens so it doesn't really pick it up so much. I still get some vignetting but not nearly as bad as before. A new problem though is that the area in the center is a bit soft. I notice this everytime I move a object off center and when I tried to focus on a ruler. Any solutions to this?

I've been looking in Surplussheds catalouge for a PCX that has similar specs as the suggested "L3385" (52MM X 44MM, 100MM FL).

What do you think about those?
STOCK#, TYPE, DIA, FL,COATED,$
L4336 PCX 52.5 80 Y $4.00
L6260 PCX 51.5 103 N $4.00
L8081 PCX 35.0 103 Y $4.00
L5705 PCX 38.0 101 Y $4.00

Unfortunately I can't find the product pages for those lenses.

What about achromats? Aren't those the same thing as a pcx, but with an extra lens cemented on that prevents chromatic aberration?

Does anyone know about some other supplier that has a pcx or achromat that has been tested to work?

/Carl