Size of Seiko #0/#1 shutter's thread?

MsLing

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Quite strange! I can't find Seiko shutter's precise data! I only remember fuzzily that Seiko#1 uses m42*0.75?

BTW, I've browsed a site which recorded sooooo many leaf shutters' data. Including but not limited to Copal, Compur, Compound, Seiko, Ilex, Bausch & Lomb, Wollensak, Parkard, Shanel and other shutters. On that website, owner also measured and mentioned that mechanical shutter can only reach 1/400s instead of literal 1/500s. He also told how a shutter use air to control leaves' releasing time. But now it disappears! Did you see the site and could you please tell me where it is? Thanks
 

BrianShaw

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You can find the dimensions in this list:

Threaded Rings for Lens Shutters

Threaded rings for #00, #0, #1, #3, #3S, Compur 2, Compound 3, Compound 4 and Ilex 5 shutters on large-format camera lensboards.
customphototools.com
 

koraks

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A few more pages of interest:

photographic leaf shutters

Sizes of photographic leaf shutters.
www.sizes.com
https://www.largeformatphotography.info/shutters.html (this link may be the page you were reading earlier @MsLing )

Thread dimensions should be the same across shutters of different brands, so e.g. data from Copal #0 shutters should apply to a Seiko #0 shutter just the same. At least, that's what Bob Solomon wrote on that last page.

I also happen to have a Seiko #0 at hand here and can confirm that its thread is 29.5x0.5mm, which is the same as Copal (etc.) #0.

T
 
OP
OP

MsLing

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Thanks for your answering, koraks. Now I can go auctioning and hunt one Seiko #0 at a low price. I also comfirm that Seiko #1's thread is 42*0.75mm(both sides). Anyway, I'll keep looking for that treasured website.
 

reddesert

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Unfortunately, this is not 100% true. There is a Seiko shutter that looks like a Copal #1 - same body size, but the Seiko has a different mounting thread and lens cell threads, slightly larger. I have a Fujinon 210/5.6 that uses one of these shutters. It requires a M46x0.75mm retaining ring vs the usual Copal M39x0.75mm. If you don't have an M46x0.75 retaining ring, customphototools lists it, or you can use something like a 49->46mm filter step-down ring.

Here is a comparison of the Seiko nearly-#1 vs a Copal #1 dimensions (Seiko numbers measured by me):

(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 41.6 mm
iris diam 30 mm 30 mm
body diameter 73 mm 73 mm
 
Last edited:

reddesert

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Reformatted into a table for readability:

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

_T_

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My seiko #1 wasn’t made with a retaining ring at all. It has its original mounting flange which is designed with 3 countersunk holes drilled 120° apart for mounting screws.

It works okay if you use it as a retaining ring but it’s got no slots for tightening or loosening it with a spanner so it can be a pain to get it back apart if you tighten it too much.

Never measured the threads and at this point I’m not willing to take it apart again unless I have to.
 
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MsLing

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Thank you! It helps a lot.
 
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MsLing

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Ok, finally I find the site I browsed. It's SK Grimes' site.

Shutters

At this time there are no new large format shutters being manufactured. There is some remaining stock, but nearly everything in the market is second hand. These links will take you to the wealth of information we have gathered on each shutter type over the decades. S.K. Grimes no longer has a...
skgrimes.com
 
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