Help: Seiko shutter hole diameter for lensboard fujinon 250 f/6.7

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Originally Posted by Chuck Pere

It was still WS in the Copal shutter model.

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. Interesting, live and learn. I tried to put my WS in a Copal 1 and did not fit. My WS is couple of millimeters wider to fit. I guess they made several types. According to the D.O. Industries, it is possible that the latest version (after return) could have been placed in a Copal 1.

Here is a copy of the the W only:

I happened to find a Fujinon lens in one of these Seiko shutters that looks like a #1 but isn't, and I took some measurements, in the hope that it helps future perplexed people.

The lens is a Fujinon-WS 210/5.6 (older kind with inside writing), not the 250/6.7, and it's in a Seiko shutter that is the same body diameter as a Copal #1, but both the mount threads and the lens threads are different. It had no retaining ring, so this could have been a PITA, but turns out the mount thread is M46x0.75, which is the same size as a 46mm filter. So I got a 49->46mm step-down ring to make a retaining ring. This screws right on, but is too deep to clear the rear element, so I'll have to file it down a little. I'm sure skgrimes.com could make a true retaining ring for this size.

Dimensions comparing Seiko (measured) to Copal #1 (from skgrimes table):

Dimension	(Fuji)Seiko	Copal #1
front thread	M42-0.75	M40-0.75
back thread	M42-0.75	M36-0.75
thickness	~21.8 mm	20 mm
front to shutter	~12.2 mm	10.75 mm
mount thread	M46-0.75	M39-0.75
lensboard hole	~48 mm or larger	41.6 mm
iris diam	30 mm	30 mm
body diameter	73 mm	73 mm

Here's a pair of photos where I compare it (left) to a Nikkor 210/5.6 in a standard Copal #1 shutter (right). The photos have some distortion, but you can see how the Fuji lens has larger elements that fit into the larger threads of the Seiko shutter.

Attachment 195389

Attachment 195390