I want to project a picture about 7.5 feet ind was wondering if the magnification of the fresnel made any differnts? 😕
No. This will affect only the distance between your fresnel and light source from one side and the projection lens from the other.bobcat190 said:
What will do affect your projected image size is the focal length of your projection lens.
To be able to control the size of the projected image one would need a variofocal projection lens (I guess, with focal length of ~ 10"..20", need some calculation though).
Please correct me if I'm wrong.
The focal length of a fresnel used as a condenser should be the same distance as the lamp to lens distance, or slightly more if your lens is bigger than your panel.
If you have an efficient reflector system, the focal length of the lens should be measured from the focal point of the reflector assembly, (bear in mind this may be a virtual focal point).
Fresnel lenses are not suitable as objective, (projection), lenses as afan states.
If you have an efficient reflector system, the focal length of the lens should be measured from the focal point of the reflector assembly, (bear in mind this may be a virtual focal point).
Fresnel lenses are not suitable as objective, (projection), lenses as afan states.
pinkmouse said:
I think you misunderstood me. I didn't state that projection lens is the fresnel one. I meant that it is the additional projection lens that should be choosed according to the desired screen size/distance from the wall. All I said about fresnels is that their focal lengths (or magnification) influences the distance between them and light source from one side and the additional projection lense from the other side.
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