Can anyone describe this lens please ?

[HouseMachine]

I bought this objective / lens for $2 lol few months ago... It is projecting the pictures on 5" Psone screen very sharply, however I' m not sure, if it will project 7" Lilliput.

I mean can I get sharp edges when using this objective and 7" screen.

Actually I will try to understand via acetate paper but I don' t have time to find acetate printing paper until weekend. So I need your opinions / inputs 😉

Also, is there any way to understand / find its focal length ? ( there is no info / text on it... )

You can find its dimensions on the attached photos.

 

[HouseMachine]

and here is the other photo

 

[HouseMachine]

ok

ok guys I think I found some useful info. Mine is probably same with this one;

BRAUN Ultralit PL 2,8 / 55 mm MC
A wide-angle lens for the projection of miniature format and half-frame slides or for cases where a large projected picture has to be achieved at a short projection distance.

http://www.braun-phototechnik.de/E/Products/Accessories/objektive.htm

So I am very very very very lol happy. Because I saved some $$

 

[Jolly]

IMO, if my calculations are correct, either
this lens has a very wide field angle (in
your case of projecting of 5" Psone screen
it will be at least 96 deg.) or you got its focal wrong.

 

[HouseMachine]

thanx jolly for the info, I' m thinking this lens is a bargain 🙂 and it is probably a triplet lens. btw how did you calculate its focal length ? I did a research on google but I couldn' t understand those numbers 😛

I don' t understand physics 😀

 

[dnsey]

The easiest way to (roughly) find the f/l is to take the lens outside and point it at a distant object. Hold a piece of paper, etc. on the other side of the lens, and move it to get a sharp image. The lens to paper distance = f/l, or near enough for our purposes.