300mm OHP triplet

[no_-_name1337]

Hello folks!
I have 300mm OHP triplet and 15" LCD... which fresnel is better, 317,330 or 550mm ?

And my second question, is there any chance of adjusting my objective's focal lenght to about 320mm ? What shoul i do?


P.S. sorry for my lame questions and even more lame english 🙁

 

[no_-_name1337]

okay, i heard that 330 would be best, 317 usable and 550 impossible 🙂

but nothing about objective's focal adjusting...