View Full Version : Help On Luminars

17-Mar-2008, 14:08
Hi there. Anyone can help? How does the diaphram work on Luminars? I just got a 63 and a 40mm 1:4.5.-
Does it mean that the position indicated on the barrel as 1 equals F4.5, 2 F5.6, 3 F8 and so on?
Please help......

Dan Fromm
17-Mar-2008, 14:39
That's how mine work. The number indicates the exposure time, relative to wide open. 1 is wide open; 2 is twice as long as 1, i.e., 1 stop down from wide open; 4 is twice as long as 2, i.e., one stop down from 2, 4 times as long as, 2 stops down from, 1; and so on.

David Millard
17-Mar-2008, 15:57
To add to Dan's post, the series would be f/4.5, f/6.3, f/9, f/12.5, f/18 . . .

Dan Fromm
17-Mar-2008, 16:23
Dave, thanks for the added explanation, which applies to the f/4.5 and f/6.3 (Paolo, that's the 100) Luminars but not to the 25/3.5 or 16/2.5. If I wasn't clear, the steps are in whole stops.

Paolo, you might want to buy Brian Bracegirdle's book Scientific PhotoMacrography or Lester Lefkowitz' book The Manual of Closeup Photography.

17-Mar-2008, 23:09
thank you very much or your help. That is exactly what I needed to know.-

Dr Klaus Schmitt
18-Mar-2008, 15:48
Or you might simply look in up online in my macro lens database, even the various Luminar types are mentioned: Macrolenses online database (http://www.macrolenses.de/objektive.php?lang)

There are a few neat (Zeiss) documents how to use them efficiently, send me an email if you like that.