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Old March 27th, 2005, 07:41 AM   #1
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Condenser Lens

Do you know where can I read about condenser lenses?

If condenser lens large, it will cover whole 35 mm frame even if not close to the ground glass. How close does condenser lens need to be from ground glass screen? What happens if it is 1 cm, or about 1/2" inch from screen? Does image look bad?

Do you put flat side to ground glass?

Can you put condenser lens on front of lens? Why is behind lens better? Would 2 condenser lenses be better? One in front, other behind.

I think that condenser lens performance will change with focal length of 35 mm lens. The angle will change. Did anyone of you tried the adapter with extreme long telefoto and extreme short wide angle? Does one of them produce more hot spot?

Where you buy condenser lens?

How you find out which focal length you need?
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Old March 29th, 2005, 03:12 AM   #2
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Re: Condenser Lens

Sorry for all english reader, but I just put all what I wrote in past to one clear czech answer :)

Jako condenser čočku jsem použil starou čočku ze zvětšováku. Před pár dny tu o tom proběhla diskuze. Vypadá naprosto šíleně a má obrovskou aberaci, ale když se skrz kouká kamera, všechna aberace je pryč a vinětace taky.

V podstatě je jedno jak daleko condensor umístíš, spíš je to o testování. Kameře vyhovuje být dál od matnice a použít zoom než být blízko.

Condenser musí být až za matnicí, jinak to nefunguje.

Jinak mraky otázek :)
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Old March 29th, 2005, 11:11 AM   #3
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Daves,

Thank you. So condenser does not have to be very close to GG, 1 cm or 1/2 inch away is fine then? Can someone else confirm, please.

I also wonder why condenser could not be before ground glass.

I want to buy new one. Where can you order them from in USA or Europe?

Radek
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Old March 29th, 2005, 11:38 AM   #4
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<<<-- Originally posted by Radek Svoboda : Daves,

Thank you. So condenser does not have to be very close to GG, 1 cm or 1/2 inch away is fine then? Can someone else confirm, please.

I also wonder why condenser could not be before ground glass.

I want to buy new one. Where can you order them from in USA or Europe?

Radek -->>>

No, I have it about 5cm far and its fine. But maybe this is because Nikon GG contain condeser too (I guess). Also my cam has to be as far from condenser as possible. If its closer, more hotspot is visible.

My condenser does not work on Maxwell GG...

I tried to turn Nikon GG condenser side to primary lens and it works. But If I take GG and condenser (2 pieces), it does not work...
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Old March 29th, 2005, 12:34 PM   #5
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Daves,

Thanks. That is interesting. What Nikon GG with condenser you use? Where did you get it? How much it cost? Where you get the Maxwell screen?

Radek
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Old March 29th, 2005, 12:56 PM   #6
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5cm? If you are using still photography lenses, the distance from the GG to the lens alone is less than 5cm, right?

The problem is, what do you mean with 'before the GG'
It has to be before the GG, if you mean the DV camcorder is behind the GG(last in row)
My setup is this:
DOF adapter lens - few cm space - condenser lens - little space - GG - DV cam.
The condenser has to spread the light before it hits the GG, otherwise (behind GG) I think it'll just function as a bad macro lens, but maybe I'm wrong.

A GG with condenser would mean a static GG, I think, than you have the grain problems.
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Old March 30th, 2005, 05:07 AM   #7
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The condenser has to be be placed as closely as possible behind the gg as possible, before the camera. If you place it in front of the gg, than it does not do what it is supposed to do which is condense the light which is scattered by the gg.
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Old March 30th, 2005, 05:17 AM   #8
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<<<-- Originally posted by Radek Svoboda : Daves,

Thanks. That is interesting. What Nikon GG with condenser you use? Where did you get it? How much it cost? Where you get the Maxwell screen?

Radek -->>>

I see opinions are different... So again - I used Takumar primary lens, then Nikon GG with condenset in itself, then condenser and then camcorder. Works well, no hotspot, very little vignetting. Little grain, probably unusable as static GG. Takumar lens 70-200mm costs me 1000CZK, NIKON GG 300CZK. I bought it used for testing in Prague at SKODAfoto (Vodičkova). Im shooting whole 36mm, not juse 24 or less...

This is the GG :
http://web.datriware.com/gfx_photos/articles/p859.jpg

This is what I shoot...
http://web.datriware.com/gfx_photos/articles/p878.jpg
http://web.datriware.com/gfx_photos/articles/p886.jpg

With Maxwell I fall into problems. But I hope I will solve it by increasing camera distance from GG... Take a look...
http://web.datriware.com/gfx_photos/articles/p947.jpg
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Old March 30th, 2005, 09:39 AM   #9
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Daves,

Thank you. Are you spinning heavy Nikon assembly with ground glass and a condenser, or is it stationary adaptor? The Maxwell screen has Fresnel lens built in, doesn't it?

Has anyone compare Beatie and Maxwell GG's?

So you have about 5 cm distance between GG condenser and your large condenser and works fine? Does the distance affect color aberation?

Nicholas,

You're saying condenser must be placed as close to GG as possible. What happens if you place about 1 cm, ot 1/2 inch, away? How it affects picture quality? Do you get color fringing, which means separatiion of color; black lines become couple color lines, etc.? What is diagonal of image on your GG? What is your condenser diameter?

Everyone,

Are all condensers you're using flat on one side? Do they have to be?

Thanks,

Radek
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Old March 30th, 2005, 09:58 AM   #10
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<<<-- Originally posted by Radek Svoboda : Daves,

Thank you. Are you spinning heavy Nikon assembly with ground glass and a condenser, or is it stationary adaptor? The Maxwell screen has Fresnel lens built in, doesn't it?

Has anyone compare Beatie and Maxwell GG's?

So you have about 5 cm distance between GG condenser and your large condenser and works fine? Does the distance affect color aberation?

Radek -->>>

No, Im not spining anything yet. Im not so far. But in next 14days I will get parts to my "spiner" so I will build it up and try to spin or vibrate with Maxwell GG. And yes, both Maxwell and Beattie have fresnel surface...

I do not use condenser for Maxwell because its not working with it. But with nikon it was almost perfect. If I do not get perfect results with Maxwell, I will return to Nikon GG and vibrate with it.

As I said and you saw, my condenser works well for nikon. I do not have vignetting even in lowlight (Two 60W bulbs in room).

Im pretty sad of results with Maxwell, but I believe I will found the right way soon.
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Old March 30th, 2005, 10:04 AM   #11
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Note that in the shot which I did with Maxwell I was shooting 40mm on GG. Also the tube from primary lens to Maxwell was not large enought, so it rip me out corners... Also I had just one hole in my holder, which was setup for Nikon GG. I found, that if I will increase distance between Maxwell and camcorder, I have clear image over all 60mm surface on Maxwell... Next monday I will bring new results :)
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Old April 12th, 2005, 06:01 PM   #12
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Thanks for information.

What diameter of condenser is needed? If condenser diameter is couple milimeters larger than diagonal of ground glass, is it enough to prevent darker corners? How much larger it needs to be?
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