View Full Version : Help On Luminars
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.
thank you very much or your help. That is exactly what I needed to know.-
Ciao
Paolo
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.
Cheers,
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