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View Full Version : Screw at rear of Fujinon 450 C ?



Ken Lee
27-Dec-2005, 11:09
My Fujinon 450 C has an odd screw on the rear of the lens. It seems to be in there rather snugly.



http://www.kenleegallery.com/images/personal/fujiscrew.jpg



Is this normal ?



Because it sticks up, it prevents the lens from sitting flat against the lens board. The result is a permanent "tilt", which throws focus off.

BrianShaw
27-Dec-2005, 11:19
It's a positioning screw... to keep the lens from spinning onthe lensboard. You either need to remove it or drill a blind hole in the board so the lens will lay flat on the board.

Rory Roopnarine
27-Dec-2005, 12:45
My Fujinon 240A had one. I removed the screw so that the lens would seat properly on my Arca Swiss lensboard.

Bruce Watson
27-Dec-2005, 12:46
What Brian said. It's there as a stop to keep the lens from rotating relative to the lens board. My understanding is that it's safe to remove it.

Ron Marshall
27-Dec-2005, 12:54
My Fujinon 300mm f8.5 had one. I took it out rather than drill the hole.

Brian Vuillemenot
27-Dec-2005, 15:17
My 110 SS XL has one of those. I just cut a small slit extending out from the lensboard hole so that it could lay flat. I actually didn't notice it until after I had been using the lens for about a year, so the small "tilt" did not seem to result in any significant focus shift.

Tim Hyde
27-Dec-2005, 15:47
I would be very very cautious about drilling any holes in the lens board. Good way to get light seeps that are not particularly obvious but deleterious nonetheless. I always remove them and have never had a lens wobble as a result.

BrianShaw
27-Dec-2005, 16:27
The important part of drilling a hole for the positioning screw is to make sure the hole is "blind", meaning that it doesn't go all the way through. Otherwise, you're right... it would leak light.

Jack Flesher
27-Dec-2005, 18:08
>> The important part of drilling a hole for the positioning screw is to make sure the hole is "blind", meaning that it doesn't go all the way through. Otherwise, you're right... it would leak light. <<

Actually, this isn't true... The alignment screw hole discussed here will not leak light any more than the shutter hole itself will. You see the notch regularly in older boards. A quick search on the Bay revelaed these.

Here's one where somebody could not decide which orientation they wanted the shutter in ;) : http://i22.ebayimg.com/04/i/05/ca/fc/2f_1.JPG

And here's one where the screw was not removed prior to mounting the lens in a board without the screw-hole, creating the bright "rub" area. Of course this situation CAN allow light leaks since the lens is not fully seated on the board ;) : http://imagehost.vendio.com/bin/imageserver.x/00000000/kiler/ebay07449.JPG

BrianShaw
27-Dec-2005, 20:15
"Actually, this isn't true... "

At the risk of seeming argumentative... I drilled one board through for a Fujinon 250 in Copal 3 since I couldn't remove the alignment screw (in VERY tight). It leaked light. Maybe your experience has been different, but mine definitely leaked light. A piece of lelectrical tape cured the situation. A second board was drilled blind and there was no light leak. As is often said: "you're mileage may vary".

Ken Lee
28-Dec-2005, 06:48
Many thanks - I removed the screw and all is well.