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Old December 11th, 2005, 07:23 PM   #1
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Condenser Placement

Alright, I know that DIY 35mm adapters have been done to death, especially since so many quality products are availible and on the way.... but I'm still going to ask.

I'm about to build an adapter based on Richard Mellor's design and need to know the best order/placement my condenser(s) should go in and what focal length(s) they need to be.

I've heard of people use various options and focal lengths....

slr - (| - || - cam or....

slr - || - (| - cam or....

slr - || - |) - cam or.....

slr - || - |) - (| - cam and even.....

slr - (| - || - |) - cam



What have been your experiences? Are the focal lengths even important, since I'm focusing on the ground glass? Any suggestions?

Thanks in advance for you help!
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Old December 12th, 2005, 05:55 AM   #2
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slr - || - |) - cam....seems to be the best arrangement, althought oscar Spier is using slr - (| - || - |) - cam

I used slr - || - |) - (| - cam , but this causes alot of distortion and chroma aberation.

The focal length does mater, the shorter the FL, the more it will prevent vignetting, but also the more distortion and colour seperation. Aim for around the 85- 120mm FL area.

Also, you may find my previous thread useful:

http://www.dvinfo.net/conf/showthread.php?t=50884


Hope that helps...
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Last edited by Wayne Kinney; December 12th, 2005 at 05:23 PM.
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Old December 12th, 2005, 04:44 PM   #3
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Just to clarify, is || the GG? Thanks.
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Old December 12th, 2005, 05:18 PM   #4
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Yes. || is the GG. And the setup SLR (| - || - |) camcorder was actually an idea of Frank Ladner. It is also used in the MovieTube. If you get it right, it is the best setup to correct aberrations of all kinds.
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Old December 13th, 2005, 12:22 PM   #5
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In the condenser sandwhich (| - || - |) setup up, what focal lengths shuold be used and is there any distance between the conders and the gg?
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Old December 13th, 2005, 12:46 PM   #6
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I think for that particular setup, aim for around the 120 - 160mm FL mark, with the condenser lenses touching the GG on either side.
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Old December 23rd, 2005, 12:32 PM   #7
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Wayne, can you explain the focal lengths? Are these numbers based on math/theory or experience? I ask because I'm intrested on theory side of things... for instance, is there a reason why in the sandwhich set up that 120 fls work best and what would be the result if shorter or longer fls were used. Or why is it that moving the gg 11 mm corrected the barrel distortion in the example you site on a previous thread.... Or is all this trail and error?

Thanks.
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Old December 23rd, 2005, 08:13 PM   #8
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How much hotspot correction you need depends on what lens and camcorder you have (and the GG). Shorter focal length = more correction, more distortion and aberration. I experimented with 70mm, 80mm and 120mm FL. Also the shorter focal length magnifies the image more, hence smaller image area.

Putting the 70 or 80 between the GG and SLR lens caused the edges of the image to blur. 2x 80s ||-|)-(| corrected the hotspot but had too much colour separation. The 120s still had a very slight hotspot but minimal distortion or aberation (|-||-|) or ||-(|-|), the latter seemed to work the best.

Another solution that was posted was a 120FL PCX combined with 250FL DCX like this ||-|)-() GG PCX DCX. I put GG/condensers as close together as poss with my set up.
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