Well, I think I found my condenser. Holding it up to the GG, very close to it, brightened up the image considerably, without distortion. I am still trying what Oscar did, put another condenser close to the lens to get a more even spread of light coming out of the lens first, but it really seems to distort everything when I try it, the focal length goes out etc. Hey Oscar, how did you combat the focal length problem with the condenser next to the lens??

What condenser are you using? I'm curious since I'm ordering one either today or tomorrow. Most importantly...what's the focal length? (I'm thinking of buying about 100mm)

Well, I think I found my condenser.Congrats. Cant wait for result... Btw - how was you eBay bids ?

Leo, I put the condensers together with the GG. Like this: http://s01.picshome.com/be6/c1.jpg
I put the GG on the focal plane, I don't think it changes with the condenser. The patent of the MovieTube shows the same setup: http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=DE10240076&F=0
I wonder what that 'field lens (5)' is about.

Awesome, thanks for the link. I am going to try that now. I was putting it close to the lens instead of the GG. Also going to try the static route with that in mind as well.

Also from the link, what does a field lens do? Any ideas?

I think we need Aaron Shaw again. The only thing I can think about is that it magnifies the image.

According to their setup, they use 2 condensers totaled +9, I think 1 is about 250mm (+4) and 1 is 200mm (+5) focal length. They are not enough to solve the hotspot problem. I guess the field lens 5 is to solve the hotspot.

Quyen

I was outbid on all accounts of the ebay for focus screens. They really went up in price on the last hour of bidding!

So 100mm would be about +10 then? I think that might work.

100mm between the lens and gg is too much. If you use fresnel, it should be OK. thick glass next to gg will push the focusing image a little further and the edge will be out of focus. I think 250mm will be the best choice there. It will do some damage but hard to see.

Quyen

I did some research on the field lens, and it looks like a condenser but thicker. If that is the case, I have one sitting around here and did a test - but you know what, the condenser I have sitting in front of the GG right now is doing such a great job, I don't think I am going to need it. I am stepping down on my GG to my own homemade one with fine sandpaper. I coudn't use it before because of the hotspot, but the condenser seems to have evened it out completely, which is cool - but still more tests are needed.
Better than all of this, I don't need the achromat anymore, but the condenser spreads out the light enough that I don't get vignetting anymore. I am still trying to place another condenser on the other side of the GG

(LENS (| GG |) DV) (thanks Oscar!)

but the extra one I have seems to make it more blurry around the edges. So far, I think I might be able to get away with the one condenser. After I run some tests, I am going to build the full DOF machine and get rid of the prototype - after that, it is wax and static! (god, how many times have I said that!)

Well, testing brings out the worst in us, doesn't it?
I found that without the achromat, I am getting barrel distortion from the condenser - just at the edges. I wouldn't have noticed it but for the window pane being curved! Oh well, back to the drawing board. I am going to throw a achromat in the mix and see what happens.
Also, I have noticed that stepping down on both my DV and the lenses seems to eliminate the hotspot, but then it doesn't let as much light in either, leading to a darker scene.

I think I am going to order a large diameter Condenser as well. This one is nice, but not large enough, so I am still getting very minimal vignetting with it.

Also, it is interesting that on the micro35 board, some guy has put up footage of his micro35 adapter and you can really see the hotspot on it. He has a bunch of .tif of the footage. Overall it looks good, but at least I don't have to wonder anymore if anybody else was experiencing it.

Mandy -- what kind of condesnor do you have?

Type? I am not sure. I got it from a film strip projector - it is clear, |) about 45mm diameter and 10mm thick. It really lights up the GG when pressed close to it, but again, it is not big enough (I am guessing) because without an achromat, I sometimes see the sides of it and some minor vignetting.
On another note, it is interesting what the viewfinder sees and what actually is happening once you dump it to the computer. Vignetting that I didn't see before is actually present.

With a DCX lens between the GG and the 35mm, wouldn't there be alot of barrelling and distortion?
I know that with the m35 there is one, I am just wondering the purpose? With Oscar and others, they are putting the (| against the GG, isn't a DCX lens a double convex?

Oscar,
Has you (or someone on this forum) tried arranging lenses the same as shown in the movietube patent, minus the prism?

e.g. 35mm-(|) () (()

oops, clicked submit...

so anyway, with this
35mm (|) () (()
I was trying to show lenses in this order...
35mm, pcx, gg, pcx, field lens, achromat

That is what the movietube shows. Anyone tried it?

This site shows why a field lens is used in optical tube-like systems, it seems to be able to fix the hotspot, but i dont know optics well enough to translate this info into our adapter design.
http://www-optics.unine.ch/education/optics_tutorials/field_lens.html

Also, according to this page we should be doing this )|(
http://www-optics.unine.ch/education/optics_tutorials/plano_convex_lens_aberration.html

Interestingly enough, the second picture with the right and wrong way shows that after the light has hit the PCX lens from the flat side, it would come out flat on the other, which is untrue and I can attest for that with the distortion and blurriness I am getting with a condenser. So what is the deal?

oops, clicked submit...

Also, according to this page we should be doing this )|(
http://www-optics.unine.ch/education/optics_tutorials/plano_convex_lens_aberration.html

Actually, the second example there represents the hot-spot scenario. Light from the ground glass is scattering off the glass in many directions, being most intense where it lines up with your eye (or video lens).

We don't see such hot-spots in film because every crystal on film receives the same amount of light proportional to the scene. The film is a "slice" across the focal plane, getting an accurate representation of the photographed scene's lighting. But we aren't working with slices. We're dealing with projectors.

In the adaptor scenario, the gg is a projector, and creates the hot-spot problem. To act as a projector, it must diffuse light (heavily). This diffusion/scattering causes light to be "lost" as it gets further away from the center of the picture -- your eye never gets to see it since it bounces off in some wild direction. Apparently, the second PCX (PCX2, between gg and video) works by getting that scattered light to refocus along the lens axis to the video camera -- bringing the "lost" light back into the path of the lens, and thus brightening what was once dark.

So, the second example in the link you posted represents a situation where the PCX is trying to refocus the scattered light into a parallel stream, in effect, removing the hot spot.

The first PCX (PCX1, located between 35mm lens and gg) is probably more purposed to reverse any distortion caused by PCX2, since the light entering it has already been focused onto the ground glass at a pretty extreme angle and probably doesn't have any "hotspot" issues in this section of the pipeline. I haven't been able to experiment with it, however.

So I would interpret your link as supporting the (|) configuration that others have been finding to be successful.

Sorry for being so verbose. I can't help it.

I am also curious about the first PCX in this way - when I have tried it, it makes the image smaller - is this what it is supposed to do? Or is it more a fact that it concentrates the light into one spot instead of the graduated light spread you regularly get from a lens onto a GG?

My guess is that the first PCX is compensating the second.
One thing that bothered me about the second PCX is that it enlarges the image, and I thought it was simply getting rid of the hot spot by enlarging the bright portion of the screen and ignoring the darker areas. Do this too much, and you completely lose any reason for using an adapter at all (remember, you can get shallow DOF in video just by using a real long lens, or "magnifying" the image).
Now I realize the second PCX is actually redirecting the light back toward the lens, correcting a problem created by the diffusion of the ground glass.
With the second PCX close to the GG, there's not going to be a lot of magnification, but by having the first PCX on the other side, it seems that it would "reverse" or reduce whatever magnification/distortion was created by the second PCX.
Again, I don't have a rig set up to carefully experiment with these ideas, but "thought experiments" can help.

FYI,
I tried this setup and it has given me the best results yet, no noticable hot-spot and no distortion or blurring towards the edges. Also, I set a two tripods up, one with a still camera, and the other with my vx2000 and the lens adapter. I tried my 50mm lens on both to make sure I was getting the same frame and angle of view. "a" OK!

camcorder ) (| 35mm lens

I was concened about putting one of the pcx lenses between the 35mm lens and the GG, so I tried this and it works great for my setup. the two pcx lenses are fl 150mm. And I put as much space between them as I could. Hope to post pics soon.

It will be interesting to see what the PCX lens will do for quality of the image. Did you get them at Surplusshed?