Thornton Pickard shutters - a query

[IanG]

I have one or two (20++) TP shutters but need some help/info.

First does anyone have one of the small high speed front (lens) mounted roller blind shutters ? If so what size and what's the aperture slit size ? These have a top speed of 1/1000th of a second.

Second question is does anyone have a half plate TP focal plane shutter, if so what's the slit width and speed range, and can I have a photo of the speed dial (if there is one) ?

The reason for asking is I have many spare shutters and want to make two front mounted high speed versions, the only difference is the slit width. Oh and I bought a half plate focal plane TP shutter here on this forum last month, I need to make new a shutter curtain but it's a high speed model, I want to convert it to a usable shutter.

Thirdly out on a real limb - I have a rare TP studio shutter if anyone has one I can't fathom out what's missing, can you help.

Ian

[thomas ciulei]

Hi Ian,

got a couple but not front mounted.
They are different sizes.
On the smaller one, the hole is 60mm, so the slit is about 80mm.
I have replaced the fabric on both.
speeds range from 1/15 to 1/80.

if you want to build a high speed shutter,
you need to narrow the width of the slit-as you know.

how much exactly, I cant tell, but a speedgraphic shutter for 1/1000
is about 4mm wide. how much of a difference it makes if the shutter is in front of the film
or in front of the lens I cant say. I imagime there to be a difference though.

interested in this too, so keep posting your findings

[IanG]

Thanks Thomas, actually I want to convert a high speed focal plane TP shutter in to a more practical 1/15th to 1/90th range, that probably means a slit width slightly over 12cm the current slit is 2.4cm. I'll make two setts of curtains and run some tests. The shutter as it is is impractical as there's no T setting and it would be difficult to use, it has the "Snapshot" type ratchet (similar to the one on the right). It does have a Speed indicator dial though.



There's quite a difference in slit width compared to a Graflex shutter but they do run at a higher tension at the top speed. The actual speed is going to depend on how well it runs at lower tension, and what's the minimum for reliable use. It'll need a shutter speed test to calibrate.


The smaller lens fitting shutters shouldn't be difficult to adapt for high peed, I'll use one that fits on the front of a lens so I can take it off for focussing, I've just bought some more shutters. I'm thinking that 1/10 the full slit width should be a good starting point, I'll let you know.

Ian

[thomas ciulei]

the maximum slit width is such, that its slightly larger than the hole, plus "a small reserve".
obviously if the slit is smaller than the hole, you loose B and T

One of my TP's got a little larger slit than factory wise, meaning that the exposure interval is
more limited- meaning that the adjustment of the initial spring (where the dial is) simply
cannot compensate enough for the faster speeds. so be careful with that.

anyhow, initial spring tension should just about get you that 1/10th, that would be the way to go.
i use a shutter tester (with a fotosensible cell) hooked up to my microphone jack on the laptop along with the sound app "audacity".
on the other side i use a LED-flashlight. when shutter opens, the fotosensible cell sends an impulse to Audacity.
Since this is a music app(free), you can measure down to 1/1000 of a sec quite accurately.
there are diagrams on the net for building this thing, but i also have a ebay contact who can make you one.
cost me 10euro.

[IanG]

The problem with my TP Focal plane shutter is the Snapshot type mechanism has no T setting, although you could half cock the shutter so that it's open but you'd have to do this visually. I've just found a reference in a Watson advert to my TP Focal plane shutter, they were adapted to order and you had to supply a dark slide and preferably also the camera, I'll have to adapt it to fit the Half plate TP Triple Imperial I'm restoring, it only need bellows now. TP were already selling a more advanced shutter in their own adverts (1898).

I've rebuilt a lot of the lens fit TP roller blind shutters and there's very little consistency in manufacture, particularly of the cases and the slit widths vary quite a bit as well, seems to have been a lot of sub-contract work. It's not generally realised that they were still being made around 20 years after the Thornton Pickard company itself ceased trading, and were sold by Watson, The Altrincham Rubber Company, production ceased around 1960. B&J were the US importer/distributor and their imports carry the B&J name, the aluminium bodied versions seem to have been more popular in the US.

I'm still stuck with my TP studio shutter, I'm missing a crucial bit aside from the bellows part that open/close it, however I'm begining to think it's a relatively simple metal/wire hook, there's no indication looking insde the shutter that anything is missing, no empty screw holes, no room for a mechanism.

These TP shutters were at the fore-front of roller blind shutter design, and the variable slit width versions pioneered the way for later high precision LF, MF and later 35mm versions.

Ian

[DannL]

Just checking to see if you found all the data/dimensions you needed? I have a front-mounted Thornton-Pickard shutter like that pictured above, on the left. 1/15th-1/90th sec. I just finished replacing the curtain on it. Seems to work just fine. I just need to test it in the field.

[IanG]

Just checking to see if you found all the data/dimensions you needed? I have a front-mounted Thornton-Pickard shutter like that pictured above, on the left. 1/15th-1/90th sec. I just finished replacing the curtain on it. Seems to work just fine. I just need to test it in the field.

I've rebuilt another two since starting this thread but am waiting to acquire some more before experimenting, I'm looking for a larger TP shutter to use with a Petzval, I want to use one for speeds between 1/15th and 1/90th and the other for higher speeds. Other restorations have taken priority at present.

In adition I've picked up a spare TP SLR shutter, these work outside a camera body as a module so could be very adaptable.

Ian

[DannL]

Sounds good. I verified the slit opening size on the original curtain to be 70mm wide. I will post a drawing of the curtain with dimensions for reference.

[IanG]

I've found that the slit width isn't standard for the same size shutters, there's some variations in the two set points on the main gear wheel. It's easier when you have the original curtain as a pattern but many of theshutters I buy are a bit challenged and missing bits, and often have no curtain left.

Sometime soon I'll write an article about them, and the variations.

Ian

[DannL]

I had to fabricate three curtains and test each one before I learned what I was doing wrong. Shellac is a wonderful resin for coating the curtain. And in the end I simply removed the gear wheel and reinserted it to properly align the slit. Finding a pull cord of a proper material that wouldn't fly off the wheel was also a challenge.