Bought me a Graphex Shutter for my Century Graphic with 101mm Graflex Optar Lens by Wollensak, SN# 289565. Shutter has speeds to 1/400 (no flash sync)...Lens is 4.5. Aperture adjust wouldn't work. Removed rear lens elements and it works. If I tighten rear lens elements, it presses against leaves of iris. If I back it off 1/4 turn, it's ok. Is this the correct lens for this shutter? OR, should there be a thin washer/spacer under the rear elements to prevent it from contacting the iris? Any advice most appreciated. Fred.

With lens wide open, will it focus sharply with rear element tightned and at 1/4 turn loose?
Charles

Charles...this was my main concern...how critical is the relationship between the front and rear elements. It appears that backing-off the rear elements just enough to free-up the iris, approx. 1/4 turn...has little effect on the focusing...still sharp on the GG. Just don't understand why the problem exists in the first place. Fred.

Fred,
Not being a lens expert I can't say for certain, but I would just make a shim the just prevents jamming and let it go at that if images are acceptiblely sharp. Thread pitch is around .5mm or less; 1mm=.0394 inch; 1/4 of .5mm =.125mm=.004925 shim thickness.
Damaged threads from over tightning is a possible reason.
Pull out the resolution charts and conduct test to find the optionmal distance setting if absolute precision is required.
Charles

Charles...absolute precision is most desirable...but I found out a long time ago that to seek perfection is to find frustration. So, as I always say, COMPROMISE.
Your calculations on thread pitch, shim thickness, etc., are much appreciated. I am now convinced that the rear elements, although producing a sharp image, are not original to this shutter, When you thread them in...there is bright metal showing around the lens-thread stop...and it should all be flat black. In other words this set of rear elements' housing doesn't have the same diameter to cover the diameter of the housing it's being thread into as the original. I think I may just put a drop or two of Loctite red on the threads and run'em in...back'em off until it clears the iris...and go with it, as you suggested. It looks very sharp backed-off 1/4 turn, so I'll shoot some film and check it out. Thanks a lot. Fred.

Just don't use that permanent stuff that has to be heated to 500 degrees F to break loose.
Flat black paint would work well also.
C

_________________
While a picture may be worth a thousand words, a quality photograph is worth a million.

<font size=-1>[ This Message was edited by: 45PSS on 2002-11-07 18:08 ]</font>

Hey, Charles...I like the flat black paint idea...I can touch up the bright area and dab a little on the threads at the same time. I think the Loc-tite Red will break loose with a little coaxing...and the Blue takes a torch. Fred. P.S.: This is not correct...upon reviewing...Threadlocker red is permanent and blue is "medium". I think purple is the most temporary. Fred.

<font size=-1>[ This Message was edited by: clnfrd on 2002-11-12 14:57 ]</font>