35mm Adapter Condenser | Shedding some light

I tried it both with the convex side facing the GG and the flat side facing the GG but didn't really notice a difference. Is there a correct way?
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It would make sense that the plano-side of the PCX to face the ground glass as this is the side that would produce the parallel stream as the diverging light from the 35mm lens is converged by the convex side of the PCX, but if it also produced desirable results the other way then who can argue that?

It is my feeling that the problem lies AFTER the GG, so putting a PCX lens between the 35mm lens and the GG is the wrong approach.
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I think this is where focal length of the lens matters. I would say the focal length should match (as close as you can) the distance of the gg to the 35mm lens....then my guess is it can be placed pretty close to the ground glass. Your focal length is pretty long, I would guess this is why that particular placement provided results. I do know that the closer you get to the camer lens and/or achromat all your doing is adding to more magnification and no longer correcting hotspotting...at least not in the same way (as more magnification can be thought of as a correction).
 
Which way do the commercial adapters orient the condeser lens, and how close is it to the GG? Any owners out there?
 
I'm curious about this myself. If anyone who owns a Brevis, Redrock, Letus, etc can chime in that would be awesome.
 
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David at the HV20 forums provided this information:

SGPro - yes, uses a condenser - it's between the ground glass and the achromat
Brevis - yes, uses a condenser - it's built into the imaging element. I think it's on the front, but I'm not 100% sure and I don't think I could be positive without touching the ground glass to feel the fresnel rings
Letus - yes, uses a condenser - it's behind the ground glass but in front of the flip

Seems like you are on to something with having the condenser between the GG and achromat. I still feel placement depends on focal length of the condenser lens...
 
Dingles said:
David at the HV20 forums provided this information:

SGPro - yes, uses a condenser - it's between the ground glass and the achromat
Brevis - yes, uses a condenser - it's built into the imaging element. I think it's on the front, but I'm not 100% sure and I don't think I could be positive without touching the ground glass to feel the fresnel rings
Letus - yes, uses a condenser - it's behind the ground glass but in front of the flip

Seems like you are on to something with having the condenser between the GG and achromat. I still feel placement depends on focal length of the condenser lens...
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That's great!
But which way is the condeser oriented? Flat side towards the GG or towards the achromat?

I did notice that the closer I moved the conderser to the GG, the less distortion I would get (kind of a reverse barrel distortion where the top and bottom edges bowed IN slightly)

Because of my design of the GG nut that holds it to the hub/shaft I'm not able to put the flat side very close to the GG, but if the curved side was facing the GG, I could almost touch it.

I just finished making a circular glas disc and managed to drill a hole in it too, now my plan is to make the ground side as smooth as I can without having a hotspot. I'll post updates as they occur.
 
Unsure of orientation right now...my guess is the convex side faces the 35mm lens and the plano side faces the camera...but that is a guess
 
The Plano-convex lens (PCX) should ALWAYS go behind the GG, as close as possible to it, if not touching, then 1/2 mm away, with flat faces together.

The Achromat should be as close to the Video camera lens as possible also.

The 35mm lens should cast a "perfect" image onto the GG, without vignetting or hot-spotting, just as you would expect it to project this image onto the film frame.

The close proximity of the video camera lens to the GG, focussing at short range through a thick achromatic lens, is a primary cause of hotspotting, and that is why we need a PCX lens to correct this aberration.

The NIkon F series GGs have a PCX built in, which is very useful for this purpose, either with the Nikon D screen or a GG of your choice.

The farther your GG/PCX are from the video camera/acromat, the more likely you will avoid hotspotting.

I hope that helps!
 
Won't this present a problem for vibrating gg holders as you really can't position anything between the camcorder side of the gg and the gg holder (which is probably a good 1.5 to 2 inches from the gg itself?
 
sek0910 said:
Won't this present a problem for vibrating gg holders as you really can't position anything between the camcorder side of the gg and the gg holder (which is probably a good 1.5 to 2 inches from the gg itself?
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In that instance, the gg and the pcx have to be held within the same vibra unit. That's how mine is. My advice is to buy a Nikon F type gg with D type matte - you get a nice gg, a pcx and a housing for them both to fit in one of Daniel's vibra-holders. It works a treat, believe me.
 
Actually, when you put the pcx lens in between the ground glass and slr lens, convex side facing the gg, the pcx acts as a condenser. When you put it in between the gg and the achromat, the pcx is now a magnifier.
 
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