multi-viewfinder focal length training?

[drazin]

is there anything like a directors view finder for 35mm cameras? id like to train my eye and determine which focal lengths i should be using.

i know voightlander makes a 15-28-35 viewfinder and it is very expensive... is there something like this for lengths of like 15-90 which i can use to train my eye?

 

[stephengilbert]

Yes. There are several brands, with widely varying prices. Most have a 35mm setting and a wide range of lens choices.

Just Google "director's viewfinder."