Film-Tech Forum ARCHIVE: Cooked Scope Lens

This is topic Cooked Scope Lens in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=006845

Posted by Ian Bailey (Member # 1752) on 01-10-2005, 02:35 AM:

I have a Kollmorgen Scope backing lens that started to give us big problems achieving acceptable focus.I removed the lens from the Anamorphic attachment and looked through it to find a round brown spot in the middle of the lens.So I assumed it had somehow overheated to cause the damage.This lens was second hand when I bought it,nothing has been changed with the lamphouse/projector since installing this lens apart from the installation of a new Xenon a few months ago.What I am confused about is how this could have happened,unless someone has left the projector running with the douser open with no film in the projector.The other thing I am unsure about is whether the Anamorphic attachment would be damaged also?I replaced the backing lens with the old original that never gave good focus(but was just acceptable to use)and now we still have the problem of a major compromise between getting the centre of the picture in focus compared to the extremities of the picture.
Lamphouse-Super Lume-X
Projector-Simplex 35 model 1050
Could a heat shield be installed to reduce the chance of this happening again.If so where is the heat shield normally installed?
I appreciate any advice given.

Posted by Monte L Fullmer (Member # 2797) on 01-10-2005, 03:55 AM:

quote: Ian Bailey
unless someone has left the projector running with the douser open with no film in the projector.

That's usually the biggest reason for the burnt elements, especially in the middle of the element: leaving the douser opened with no film running to contain some of the heat from the bulb.

And it could have been caused by the lamp being on without the machine running as well, (someone used the lamphouse/projector assembly as a floodlight of sorts..I've seen that happen before) for that'll cook a lens real quick.

Definitely have to have a new front being the lenses are burnt, but a heat shield isn't necessary.

good luck - Monte