Condensers - what do I look for?
 

Ok, after many many months of frustration, successes and challenges - I am finally going after the condenser to evenly spread out the hotspot. What should I look for when getting one of these optical masterpieces?

You should get something with least 20% larger diameter than diagonal of the image on ground glass, focal length maybe 75 mm, then find what distance to camera will give you most even ilumination. I haven't built mine yet, just read these threads. I'm sure others will give better information.

Radek

Thanks Radek,

Also, since I am sticking another piece of glass in the mix, will it increase warping, abberations, colour distortions etc?

I have curious experience... I took piece of glass (in fact some low quality light condenser from photo enlarger) and if I looked through it, it was terrible. Very strong abberation and warping. But If I used it together with Nikon GG, all these bugs were gone... No color abberation (Ok, very small in fact, but I think it caused by camera), no warping, no vignetting. I shoot 36x24mm and take a look :

http://web.datriware.com/gfx_photos/articles/p878.jpg
http://web.datriware.com/gfx_photos/articles/p873.jpg
http://web.datriware.com/gfx_photos/articles/p877.jpg

That looks great Dave! I can't see any abberation at all - I just don't want to spend money on a condenser and find out it sucks. But I guess trial and errors is the only way

Condenser position?
 

I've ordered a couple of condensers to try out, I was just wondering where things should be positioned. I'm guessing the condenser has to be located on the 35mm lens focal plane, then the position of the GG is not critical because the light coming out of the condenser is parallel? What difference does the focal length of the condenser make?

Cheers
Andy

Hard to say... my setup was :

Primary lens - GG - condenser - DV camera

My setup was
Primary lens - condenser - GG - DV camera
That works very good too, I use the same condenser from the photo enlarger the Daves are talking about, I mean Daves is talking about.

Yeah, we are using the same :)

I would have thought the condenser in front of the GG like this :
action >> condenser >> GG >> camera
because this would distribute the light evenly before it hit the GG, but I haven't got one yet, so I could be wrong.

Also I noticed a few photoenlargers on Ebay and they are plano-convex glass lens - isn't there some distortion because of this? I get blurring around the edges and fisheyes with some of my macro that I have found because of the convex shape - how can you guys fix that?

I don't know, but most condensers somehow only affect the light and doesn't distort the image. You can also look in other kind of projectors.
The way you describe it: action >> condenser >> GG >> camera
That's the way I used my condenser. You've seen my footage, it has a good enough spread of light. You also get a brighter image.

I agree with you Oscar, you get some great images and the light spread is even. I am going to look into buying a cheap plano-convex to see if it works.

Also, how is the anamorphic prism system going? Haven't seen any new footage in while!

A cheap lens could work just fine I think. Good luck.
Also keep in mind that a good light spread also depends very much on the lens on the adapter. I have a 135mm lens which reduces the hotspot completely, but a 50mm lens that gives annoying dark edges. I don't really know what causes the difference. Maybe bigger lens diameters.

Everything works pretty good with the anamorphic lenses, thanks. I'll post new footage when I have something useful.