Full Version: Cutting Fresnels
Hi i have a question about cutting fresnels I have tried searching but cant find what im after. i know HOW to cut the fresnel but im unsure about this, if i want to shorten the fresnel by 40mm can i just take 40mm off one side or do i have to take 20mm of both sides?
You'd want to cut off equal amounts from both sides.
The important thing is that you keep the focal center in the center.
The important thing is that you keep the focal center in the center.
I suppose that it depends on how you need to shorten the fresnel. If you take 40mm off of just one side, then the center of hte lens will be 20mm out. If you just need room for airflow, for example, and the 40mm is okay to keep the principal axis of hte projector in line, then that works, too.
Still, it's definitely recommended to take 20mm from both sides, it's much easier to construct that way.
Still, it's definitely recommended to take 20mm from both sides, it's much easier to construct that way.
QUOTE (SupraGuy @ Feb 23 2009, 09:59 AM) 
I suppose that it depends on how you need to shorten the fresnel. If you take 40mm off of just one side, then the center of hte lens will be 20mm out. If you just need room for airflow, for example, and the 40mm is okay to keep the principal axis of hte projector in line, then that works, too.
Still, it's definitely recommended to take 20mm from both sides, it's much easier to construct that way.
Still, it's definitely recommended to take 20mm from both sides, it's much easier to construct that way.
Sweet thanks that clears it up
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