Seiko LS-26 large format shutter

[inthedark_06]

I picked up a Seiko LS-26 shutter on eBay a few months ago to use with a project and would like to know what lenses it would have on it. It has apertures from f/64 to f/5.6 and shutter speeds from 1 second to 1/500th of a seconds plus Bulb mode. It did not come with lenses, and I would like to know whether I could use the glass from a similar LS-22 shutter (Fujinon SW S 75mm f/8) on it as it has a wider maximum aperture. Also, what stock lenses would it have come with?

Thanks!

 

[reddesert]

Leaf shutters for large format lenses are usually referred to by size, not by model number. Especially without a picture, it's possible that few people know which Seiko shutter is an LS-26. The numbers that you need to be concerned with are the front and rear cell thread diameters (and pitches), and the front to back depth. If these are the same as a standard shutter like a Copal #0 or #1, then you can screw in lens cells from another lens that uses the same shutter size. The aperture plate will typically then be wrongly calibrated and you'll have to measure and re-mark it (for ex, even though a 150/5.6 and 210/5.6 may use the same shutter, f/5.6 corresponds to different physical aperture diameters on the two lenses).

SK Grimes has tables of common shutter thread sizes at https://skgrimes.com/shutters/ Try looking at the table for Copal shutters. Some Seiko shutters match the Copal 0 or 1, although there is also a Seiko shutter that looks like a #1 but has somewhat larger thread diameters for lens cells and mounting ring.

 

[Dustin McAmera]

This post at Large Format Forum says your shutter is equivalent to a Copal #0:

Anti-rotation Screw Size

You know those little screws that everyone asks" What is this screw sticking out of the back of my lens and is it safe to remove?" What size are those and where can they be purchased? Alternately I would like to know a sure fire way to stop a lens rotating in the lens board. It's already over...

www.largeformatphotography.info

I guess f/64 suggests the original lens was longer than 75mm. There's a Fujinon lens catalogue of about '79 at Camera Eccentric with tables of what went in what shutter then:

Camera Eccentric

My 180mm Fujinon is not of the same age, and is in a Seiko when these tables suggest a Copal.

 

[Steve Goldstein]

LS26 identifies the aperture band attached to the generic shutter, which would have been chosen based on the specific lens originally mounted to the shutter at the factory.

I believe the lens shipped with this shutter was the "inside lettering" 150mm f/5.6 Fujinon-W. This was Fuji's first version of this combination of focal length and aperture. It was single-coated and specified an 80-degree field of view at f/22 (245mm image circle), making it usable on 5x7. It was also offered in a Copal 0 shutter. Later versions of the 150 had different designs, more advanced coatings, a slightly smaller field of view, and were sold only in Copal shutters as far as I know.

 

[Mick Fagan]

LS26 identifies the aperture band attached to the generic shutter, which would have been chosen based on the specific lens originally mounted to the shutter at the factory.

I believe the lens shipped with this shutter was the "inside lettering" 150mm f/5.6 Fujinon-W. This was Fuji's first version of this combination of focal length and aperture. It was single-coated and specified an 80-degree field of view at f/22 (245mm image circle), making it usable on 5x7. It was also offered in a Copal 0 shutter. Later versions of the 150 had different designs, more advanced coatings, a slightly smaller field of view, and were sold only in Copal shutters as far as I know.

I have two Fujinon•W 1:6.3/150 lenses. f/6.3 to f/64

Both have the coding LS 1 on the aperture band. I'm assuming that is what it is as I've never known what these two letters and number meant, until possibly now.

Both are single coated.

Both are in Seiko shutters.

Both have 40.5mm filter ring.

Both have inside lettering.

And a fun fact for me, they are only 172 serial numbers apart, even though both were purchased decades apart. Only noticed this when looking at both of them side by side today.

Not sure if this helps, but one never knows.

And in case you are wondering why I have two of these lenses, one is permanently attached to a converted Polaroid camera as a rangefinder walk around unit, while the other is permanently reversed into my folded Shen Hao HZX45-IIA as the lens you have when your camera is folded and you are travelling super light.