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Old February 21st, 2005, 05:19 PM   #31
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Ok, for 8 bucks it isn't a bad deal. I saw another condenser one that looks like this :

http://www.surplusshed.com/pages/item/l3136.html

It says it is a : Glass aspheric condenser lens, 1-3/4" diameter by 1 inch back focal length. Aspherics offer superior aberration correction for light concentration that would normally require several spherical elements.

I don't know enough about optics to figure that out - I actually don't know achromatics do, but I think Condensers spread the light out evently - now, what does asperic condenser do?
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Old February 21st, 2005, 05:43 PM   #32
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Aspherics typically help with corner distortion.

It may be just me, but that 1 3/4 diameter is going to be too small, I'd think. The abberations are worst nearest the edges of the lens. If I were buying a new condensor (which I will be soon), I would go larger -- probably something in the 60mm or larger size. This way, you're using a more central part of the glass. With 1 3/4, you're barely (if even) going to cover a 35mm image. Also, I'd recommend a focal length fairly near to the distance between your camcorder and the condensor. In other words, if your camcorder is 60 mm back from your condensor (6cm), then get a 60mm F.L. condensor. Frankly, I haven't found this to be critical, but its a good rule of thumb. If its a very short F.L. the lens is much more curved and you'll get a lot of curvature distortion (straight lines will bow). If its a very long F.L., the lens is much more flat -- and just doesn't offer as much correction. I believe perfect is exactly matching your distance from the condensor.

Try anchoroptical.com. Something along the lines of:
http://www.anchoroptical.com/Product....cfm?catid=255 Item number: AX75359 (coincidentally also $8) would be pretty good. Vary the f.l. as listed above. At that price, you could try a couple.

Frankly, I haven't bought from anchor, but they're overs from Edmunds Optical which makes absolutely beautiful (and expensive) scientific glass. I'd think these would beat the heck out of those found at surplus shed.
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Old February 21st, 2005, 05:46 PM   #33
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Thanks Jonathon, I think I am going to get that one. I also was looking at Prism at the Surplus shed which had prices that were very reasonable considering the prices of DOVE prisms that have been floating around the forum lately. I am very out of my league when it comes to optics, so maybe the surplus shed ones are too cheap to be any good?

By the way is the Anchor one a Achromatic or just plain condenser?
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Old February 21st, 2005, 05:51 PM   #34
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Good luck, and let me know how the Anchor stuff works out. Again -- I haven't purchased there, so buy at your own risk :)

I've never come across a dove prism with a large enough entry/exit face -- sure the long sides are plenty big, but most have like 10mm end faces.

Are you sure you don't want to simplify and just flip the image in some sort of alternate viewfinder solution? The extra optics are going to reduce the amount of light and be yet another area needing precise alignment, etc... I'm not sure what kind of cam you have... but most others have found that by carefully placing a magnet (somewhere) near the LCD -- it trips the inversion circuitry (which happens when you rotate the LCD away from you), such it's rotated when facing you. This completely solves the problem. It doesn't work for my cam -- so you'll have to dig the other threads to find the location of the magnet.

Also - you can add a separate viewfinder and rotate that. Old b/w pro-CRT viewfinders are beautifully sharp and cheap on ebay (I bought one for $9 and its fantastic). I _much_ prefer it to the LCD - even if I could flip it.
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Old February 21st, 2005, 05:53 PM   #35
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Sorry - missed your question. Those anchor PCX lenses are straight up PCX, not achromats. Occaisionally they have achromats -- but again, if you can stay in the middle of the glass, it may not be a problem for you... it'll take experimentation.
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Old February 25th, 2005, 07:42 AM   #36
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Has anybody tried to build a DIY remote focus mechanism for the DOF machine? It isn't that bad to focus with your hands, but would be much easier to focus using a motor-cycle handle based focuser (sorry I am not sure what these are called, I used then when I worked in a TV station).
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Old February 25th, 2005, 07:48 AM   #37
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Follow focus:
http://www.cinetechonline.com/FF01.html
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Old February 25th, 2005, 07:54 AM   #38
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Is that the one that you created Dan? I remember seeing something on your site that was a focus follower...
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Old February 25th, 2005, 03:47 PM   #39
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No, that is just a follow focus by cinetech.
What I have done is a visual feedback for the focus puller to "SEE" where he is focusing the camera.
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