Screw at rear of Fujinon 450 C ?

[Ken Lee]

My Fujinon 450 C has an odd screw on the rear of the lens. It seems to be in there rather snugly.







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]

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]

My Fujinon 240A had one. I removed the screw so that the lens would seat properly on my Arca Swiss lensboard.

[Bruce Watson]

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]

My Fujinon 300mm f8.5 had one. I took it out rather than drill the hole.

[Brian Vuillemenot]

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]

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]

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]

>> 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 :

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 :

[BrianShaw]

"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".