Film-Tech Forum ARCHIVE: Okay..what's a slit lens?

This is topic Okay..what's a slit lens? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Kathy Roberts (Member # 1410) on 08-18-2003, 04:17 AM:

I've been trying to find this out for the past couple weeks and I'm having no luck. I have century projectors from 1983, I think. Can anyone help me here? Thanks if you can..i'm going insane thinking this item does not exist...

Posted by Michael Schaffer (Member # 1204) on 08-18-2003, 04:31 AM:

It is the lens which projects a thin band of light onto the solar cells in the analog sound pickup. You find it in the tube which begins at the exciter lamp compartment.

Posted by Michael Cunningham (Member # 210) on 08-18-2003, 04:32 AM:

A slit lens is a small, tube shaped lens assembly that carries light from the exciter bulb to the film's soundtrack. It focuses the light into a narrow band through a slit so that only a small portion of the photo cell is lit. You don't see these much anymore as most of the industry has converted to reverse scan, red LED light sources for analog sound which use a different sort of lens.

- Mike

Posted by Ken Layton (Member # 133) on 08-18-2003, 10:35 AM:

A slit lens is located in the soundhead not in the projector head. It comes in several types original, narrow, or extra narrow. The narrow and extra narrow give much better high frequency response. A slit lens is found in soundheads with an exciter lamp or one that has been upgraded to a Jaxlite (red) replacement.

Posted by Kathy Roberts (Member # 1410) on 08-19-2003, 07:07 AM:

Hmm..okay..i'm going to search that area today at work....thanks a lot for the help!