Trondsi, go here http://www.largeformatphotography.i...to-look-for-information-on-LF-(mainly)-lenses for links to manufacturers' catalogs and other useful information. The catalogs show lens cross-sections.
Plasmat types are roughly symmetrical, each cell has three elements. From the outside in, a cemented doublet (two elements), an air space, and a singlet (the third element). For some reason we tend to refer to Fujinon Ws as plasmats even though some (six elements in six groups) aren't. The typical LF plasmat is f/5.6 or slower.
The Xenotar you're thinking of is a five element double Gauss type. It is a variant of the six element double Gauss type, sometimes called planar type. Roughly symmetrical, each cell has three elements. From the outside in, a single, an air space, and a cemented doublet. Five element double Gauss types (Xenotars, some Zeiss Oberkochen Planars) replace one of the cemented doublets with a singlet. All are good lenses, but with less coverage than the typical plasmat of the same focal length. Six element double Gauss types, starting with the TTH Opic and Dallmeyer Super Six are (f/2.0 and f/1.9 respectively) are faster than plasmats. Five elementers are typically f/2.8.
I take it you're dreaming and haven't shopped yet. 135/2.8 Xenotars and Planars are much more expensive than 135/5.6 plasmat types.
That is correct. I'm a little low on cash right now, but I will be looking for a new lens for the Crown Graphic in the near future. Any specific recommendations for plasmat-type lenses?
Rodenstock Sironar-N, Schneider Symmar-S, Nikon Nikkor-W, Fuji Fujinon-W
....but none of these is going to be extraordinarily better than the Optar that you already have.
The Rodenstock APO Sironar-S is significantly better but, the price is also considerably more. The Schneider APO Symmar might be comparable to the Sironar-S but, I'm not sure that it is.
That is correct. I'm a little low on cash right now, but I will be looking for a new lens for the Crown Graphic in the near future. Any specific recommendations for plasmat-type lenses?
At the same aperture, the plasmat types will have somewhat better image quality off-axis. The farther off-axis, the better.
..... the first generation convertible Symmar, which isn't quite as good as the successors.
Plasmat, not planar. Fast double Gauss types have less coverage than the equivalent plasmat, cover little more than their focal lengths.Thanks for clarifying this folks! I think that lack of coverage is what has sometimes annoyed me with my current lens, so the plantar lenses sound very interesting.
I have read through all your post in this thread and nowhere do you state which rangefinder you have.Follow up question: I'm assuming that if I get another 135mm lens I don't need to do much adjustments to the range finder. Is adjusting the range finder for a different focal length an easy task? Can it be adjusted to, say 203mm?
I have read through all your post in this thread and nowhere do you state which rangefinder you have.
Lens are rarely their marked focal length, they are .1mm to 3mm either side of the nominal marked focal length on adverage.
Hugo Meyer side rangefinders are for one focal length and adjust for the variation of that focal length.
Kalart side rangefinders are adjustable for a verity of focal lengths from 101mm for 2x3 cameras to 165mm for 4x5 cameras.
Graphic top rangefinders use cams machined to the lens focal length.
With any rangefinder 2 lens of the same marked focal length that are .1mm to .2mm in actual focal length will focus correctly with the rangefinder up to the closest distance which will be off an inch or two.
Any 2 or more lens of the same marked focal length .5 to 1mm different in actual focal length will be in focus up to about 10 feet then the focus error will increase the closer the subject is.
Lens with more than 1mm difference in actual focal length will have focus errors starting around 15 feet subject distance.
A clean, smooth operating side rangefinder will adjust easily, a dirty, sticky, sluggish one will be a PITA.
There is no procedure for making new cams for Graphic top rangefinders on Pacemaker Graphic cameras.
http://www.graflex.org/speed-graphic/kalart-adjustment.html
http://www.graflex.org/technical-information.html
Follow up question: I'm assuming that if I get another 135mm lens I don't need to do much adjustments to the range finder. Is adjusting the range finder for a different focal length an easy task? Can it be adjusted to, say 203mm?
Adjusting the Kalart is a long process which one would not want to do very often. Regarding a 203mm lens, I think the answer depends on whether it is a telephoto design or not, as the Kalart maxes out at a certain amount of bellows extension. The literature cited in this thread from graflex.org suggests that the maximum focal length that can be calibrated depends on which version of the Kalart you have (and I don't know how you tell the version).
https://graflex.org/helpboard/viewtopic.php?t=5254&sid=c153455129b701f2d063073a57c55cf3
Another basic question: Maybe I'll buy an additional lens board, but if I want to use the one I have, how do I take the Optar off from the lens board? It seems to be firmly attached to the board, and I don't want to use too much force here.
EDIT: and just wanted to check: a European lens, like a Schneider Kreuznach will fit on the original Crown Graphic lens board, right?
... and just to further clarify... that mm difference doesn’t matter. A “0” shutter fits the hole just fine.The 135 Optar has a 1.325 inch/ 33.6mm mount thread.
A Copal/Prontor/Seiko #0 has a 32.5mm mount thread.
Lens retainer rings that have not been loosened for a long period of time become fused to the lens and require a lot of force to remove.
Get a spanner.
Actually the Copal 0 shutter will have a little play in the mount hole and the lens will need to be centered on the board to prevent unwanted rise/fall or left/right shift.... and just to further clarify... that mm difference doesn’t matter. A “0” shutter fits the hole just fine.
Sure. That’s very easy to do. But 1 mm off axis really doesn’t equate to a movement.Actually the Copal 0 shutter will have a little play in the mount hole and the lens will need to be centered on the board to prevent unwanted rise/fall or left/right shift.
In what book, amateurs guide to general camera use?Sure. That’s very easy to do. But 1 mm off axis really doesn’t equate to a movement.
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