Large shutter design - help for project

[m1tch]

Hi all,

I am currently in the process of building a 5x4 camera and my own lens, everything is going well except I will be in need of a shutter, due to the f number on the lenses I am building even ISO 3 paper negatives would need to still have quite a fast shutter speed.

I am ok in some instances to stop the lens down to say f11 or a smaller aperture for landscapes, however I am also thinking of using the camera for portraits as well so would shoot fairly wide open which is where the issue comes.

I am unable to source/afford a shutter that is big enough for some of the lenses I am designing so I will need to make my own, I would need it to be very simple to make - I am thinking about something like a spring loaded guillotine or rotary disk with a slot cut in it.

I am thinking that if I can produce something with a fixed speed then I could simple stop the lens down slightly or use ND filters on the lens to make sure that its properly exposed - I would want to shoot quite wide open for the shallow DoF on portraits.

Is there a simple design I can use to produce a shutter? I was thinking about making a double iris/clapperboard shutter of my own design which would allow for variable speeds, however I would want to go with something simpler.

Could I produce something simple like a spring loaded flap infront of the lens something like:

Spring loaded flap in front of lens with small arm sticking out of shutter assembly
A dark slide infront of the lens and infront of the shutter
Open the spring loaded flap to put it under tension
Let the dark slide fall and also release the spring loaded flap
The gap between the falling slide and time take to flap closed would equal the shutter speed
The flap would be sprung to flip downwards to counteract the fact that the slide exposes the top of the negative first.

Can I have some other simple ideas for shutters that can be made, the design would need to be scaled up or down depending on the lens I would be shooting.

[Tim Meisburger]

simplest I know of is the guillotine shutter. There is a design on the front page of the large format site. They do not seem very popular though. Most people use a hat, or use what is known as a "Galli shutter", which is two 5x7 dark slides held in a "v" shape and rapidly shifted across the lens (if you search the site you should find a better description).

I would be quite interested in designs for an adjustable mechanical shutter. I think the roller blinds are fairly simple, and if I was hacking something I would probably look at that, and use a reversible and variable speed motor instead of a spring.

[m1tch]

Thanks Tim, yeah I saw the guillotine shutter, its quite simple and you can adjust the shutter speed depending on the slot gap, however it would also need to be 3 times the width of the lens which in my case is pretty large which is why I was looking at alternatives. I did see that 'Galli shutter' which would be a cool idea, but I would want something a bit more repeatable although I like the low tech and low cost idea!

I will post up the idea a bit later, its really simple but might take a bit of time to calibrate properly, I will have a think about roller blinds, although there might be quite a bit of mechanism behind making those work properly, im trying to keep it simple as possible.

I guess I could look at doing something electronic where I just get a simple solinoid/linear actuator and use that to open and close the shutter - more modern tech but on an older camera - might be interesting as I could look into using a timer - I also guess that this could be done like the Packard shutters with a vacuum/air input.

[DannL]

I've been using a 3.0 ND filter (10x) and a lens cap on my barrel lenses with paper negatives. Rating the paper at ISO/ASA 3-6 depending on the filters used has been typical. This is very manageable under normal daylight conditions with the iris at f/32 44 64 etc. Any faster than that is too unreliable for my hands. I wanted a shutter or to design one for the longest time. I finally acquired one, a Thornton-Pickard front mounted shutter, as part of a outfit I purchased recently. Now that the shutter has been restored I'm perty sure it will give the speeds needed for larger iris openings. I just need to get out and give it a test.

[m1tch]

I've been using a 3.0 ND filter (10x) and a lens cap on my barrel lenses with paper negatives. Rating the paper at ISO/ASA 3-6 depending on the filters used has been typical. This is very manageable under normal daylight conditions with the iris at f/32 44 64 etc. Any faster than that is too unreliable for my hands. I wanted a shutter or to design one for the longest time. I finally acquired one, a Thornton-Pickard front mounted shutter, as part of a outfit I purchased recently. Now that the shutter has been restored I'm perty sure it will give the speeds needed for larger iris openings. I just need to get out and give it a test.

Thanks for that, I think using an ND filter for a longer exposure for landscape should be good, however I think I would still want to shoot it wide open and would need a fast shutter speed for portraits so that there isn't a blur etc.

[Jim Galli]

Consider a design that works like a Cine camera shutter. Look at my "galli shutter" which is indeed a bit of silliness thanks very much to Eddie Gunks. But the idea is sound. Shutter angle and speed of revolution. So if you had 2 pieces of light material on an axle with an adjustable fulcrum and something as simple as a rubber band you could duplicate most of what a Graflex curtain shutter can do. You can simply adjust shutter angle to get the same effect that the different size openings in the focal plane on the graflex were giving you.

[jp]

If 1/10 or 1/30 is a good slowest shutter speed, you could use a speed graphic.

[Jac@stafford.net]

I can tell you what does not work - at least for me. The pneumatic (bulb and hose) barn-doors front shutter. I'm sure they were good with slow plates, but are too slow for general work (I do not like to use ND filters), and have too much vibration.

I can make a snap-shot of the unit if you wish.

Here is another version of the Galli shutter.

[TheToadMen]

Ddid you see this website?
http://re-inventedphotoequip.com/Site/Shutters.html
Maybe this is an option that isn't too expensive?

[m1tch]

Ddid you see this website?
http://re-inventedphotoequip.com/Site/Shutters.html
Maybe this is an option that isn't too expensive?

The front element on the lens is over 4", which is why I will have to go with a DIY option, plus the camera is a 'cheap and cheerful' trial to see how cheaply you can make a 5x4 camera and lens.

The larger lens I am making would be something like a 150mm f1.3, a slightly smaller lens I am also making would be a 71mm f0.87.

I might simply use the faster wider lens on the speed graphic and use the focal plane shutter but I would like to shoot wide on my DIY camera and I would also need quite a fast shutter speed (ish) for portraits on either.

Here is my issue, with ISO 6 paper in brightest sunlight shot fully open I would need a shutter speed of 1/2000s, in shade it would probably be something like 1/125s which is where the issue is.

I am perhaps thinking about a fast blade shutter, pivot at one end, blade covers, uncovers and then recovers the lens powered by a spring or band, could make that like a half moon or something.

I am thinking making a rotary shutter powered by a rubber band might be good,