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Photocell counter

Posted on Tue, 27 Dec 2005 at 5:43



Hello,
Advice please!
Photocell: The photocell of an Exposing light should be fixed (1) Anywhere (even on the edge of a 84x72 inch vacuum frame) or (2) On the edge/very close by of the coated area (30x24 inch small screen), to get the correct counting of needed UV light emission?
Thanks in advance for he time.

Thomas

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Comments

Anonymous says: If it is movable, it is better to be closer to the centre for a correct reading off a point light source that is centered on the entire vac frame. However, if you are not moving the lamp, and you have ...

If it is movable, it is better to be closer to the centre for a correct reading off a point light source that is centered on the entire vac frame.
However, if you are not moving the lamp, and you have tested with the cell to the outside to get your exposure numbers, then it can remain in that position and you will get a consistant exposure.
You definately don't want it over the emulsion or you will have a hole in your stencil!

posted on: Sat, 12/31/2005 - 4:21pm
Anonymous says: Thanks for the advice Andy. Its movable. Doubt is: close to emulsion catches actual rays. But same time I have to shift it every time I expose different size of images; right? If I fix on edge of frame ...

Thanks for the advice Andy.
Its movable. Doubt is: close to emulsion catches actual rays.
But same time I have to shift it every time I expose different size of images; right?
If I fix on edge of frame and find correct time by trial & error method, I can keet it fixed on same spot forever.
Am I correct, or not ?

posted on: Fri, 01/06/2006 - 2:47am
Anonymous says: Yes as long as your lamp doesn't move too close. It is reading the dose where it is situated - so if the lamp is too close, it is not getting dosed properly with what is actually hitting the screen posted on: Sun, 01/08/2006 - 9:54pm

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