View Full Version : can I use a closeup lens with a 300mm lens?

bill zelinski
12-Jul-2000, 22:00
I have a 300mm Fuji lens that I would like to use on my old speed graphic at som ething other than infinity. I've seen prevous posts reccomending using a nikon T series closeup lens (5T/6t) with a Nikon 300mm. Does adding a diopter somehow "decrease" the focal length? HOw does that work? The nikon catalog is little he lp. I need a 52mm size diopter and does B&W or Rodenstock or Canon or anyone els e may a good quality one in that size or is nikon the only one? Your help would be appreciated.

12-Jul-2000, 22:48
Yes a "close-up lens" does decrease the effective focal length. Think about we poor unfortunates who wear glasses, the dioptric correction that we require performs the same function (changes the focal length of our optical system so that we can focus on infinity - or closer as needed). Nikon and Canon both make 2-element lenses (not sure if 52mm is a "standard" thread size for Canon, but it is for Nikon). Kodak used to have information in their books on the change in focusing distances with different dioptric corrections. Try this link for more info: http://www.smu.edu/~rmonagha/mf/diopter.html

Paul Schilliger
13-Jul-2000, 08:06
The Nikon 5T&6T are 62 mm. The 3T&4T are 52mm. I have had reports that they are fine.

Paul Schilliger
13-Jul-2000, 08:25
If I remember well, a 1,5 diopter lens (3T&5T) will focus at 1:1,5=0,66 m (26") when your lens is placed at infinity and a 2,9 diopter (4T&6T) will focus at 1:2,9=0,34 m (14").

Scott Walton
13-Jul-2000, 10:34
No need to use the Nikon... look at the B+W filter line also. Scott

bill zelinski
13-Jul-2000, 11:45
Thanks alot, has anyone used the B&W ones?

Ellis Vener
13-Jul-2000, 23:44
The better diopters seem to be two element diopters, like the Nikon.