victorpei
07-11-2010, 03:30 AM
Hey all,
I saw a lens package, which is a 155m triplet f/1.9, together with a 85mm doublet which is said can bring the f number up to 3.25.
I dont know much about refractor. I find the normal f value is about 7-10, so 3.25 is much lower than that. Don't know what does that mean. My question is
1) Is it possible to build a superfast refrator with this lenses package?
2) How to build a refractor with 2 set of lenses, a simply digram will help a lot.
Thank you with your time and help, and, of course clear sky!
Victor
I saw a lens package, which is a 155m triplet f/1.9, together with a 85mm doublet which is said can bring the f number up to 3.25.
I dont know much about refractor. I find the normal f value is about 7-10, so 3.25 is much lower than that. Don't know what does that mean. My question is
1) Is it possible to build a superfast refrator with this lenses package?
2) How to build a refractor with 2 set of lenses, a simply digram will help a lot.
Thank you with your time and help, and, of course clear sky!
Victor