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Hi

Currently setting up a FP25D 35mm projector in my garage and in the need of a short throw lens for the following:

Distance from lens holder in projector to screen: 12 feet

Screen size: height 3.5 feet, width 7 feet

Found this on eBay: Werbung: https://www.ebay.co.uk/itm/Short-throw-3...c3c10%7Ciid%3A1

Do you think this will do the trick?

Thanks :)

Steve

Steve
I've looked at the March 1979 copy of the projection manual of the British Kinematograph Society. It gives a formula for focal length of lenses in relation to screen sizes at a given throw.
The standard 35mm film frame has a width of 0.825". The formula is :-
Throw in feet multiplied by the frame width in inches, then divide total by picture width in feet. The final total gives the lens focal length in inches.
Using this formula for your desired lens for a picture width of 7ft at a throw of 12ft shows you need a lens with a focal length of 1.4".
The manual also states that "Focal lengths usually range from 2" to 6", in steps of one quarter of an inch."
So the lens to which you refer would probably seem to be OK for your needs.

Hi Maurice

Brilliant, thanks for your reply.

Really useful information that's good to know.

I've purchased the lens :)

Steve

Well done, Steve.
The gold coloured lenses in earlier times would have been quite expensive items.