Building a huge shutter for large format lenses

[kuvaharrastaja]

Hi.
I thought it would be good time to make a big shutter, so that big large format lenses could be used outside.

I drawed some plans but its still a work in progress, lol.

It should be a leaf shutter, with spring steel leafs. Inner diameter of the opening should be 14cm. Electronically controlled. Also it would be nice to get short enough shutter time for portraits. So 1/30s or shorter. And flash sync should be easy to do with a switch.

Ive seen that many shutters use 5 leafs, but some early ones use only 2 specially shaped leafs. Maybe i can just learn for some shutter how blades are shaped, and scale it up.

For moving the shutter leafs, maybe have rotating ring around the shutter barrel, that has attachment points for the leafs, and leafs also have attachment to shutter frame, so that rotating the ring, would make the leafs pivot and work.

You are welcome to see if this works out, also can share ideas and opinions and comments of course.

 

[ic-racer]

I'm curious as to what lens you have that takes such a large shutter.

 

[kuvaharrastaja]

I'm curious as to what lens you have that takes such a large shutter.

Of course! Aerial lens telemar-2. Its 75cm f6.3, here is good info link to same lens: http://www.photohistory.ru/1207248189928449.html

I wanted to make shutter big enough to fit that, so it also fits everything smaller too. Not sure if I am going to be using that 9kg telemar-2 very much, but there's plenty of barrel lenses that are too big for 55mm regular shutters like copal 3 and shanel 5. But yeah, the telemar is the big lens.

 

[Dan Fromm]

I take it that you're going to hang the lens in front of the shutter or the shutter in front of the lens, not try to put it inside the lens. I've done both. The largest shutter I've done this with is an industrial (no diaphragm) Compound #5 that goes in front of a 900/10 Apo Saphir.

I'm all for the joy of tinkering, but if a single (usually) speed air-driven shutter will do what you need you should look into Packard shutters. https://packardshutter.com/

 

[Nicholas Lindan]

I would have picked a focal plane shutter type as in a Speed Graphic, just mounted at the lens. Unless, of course you are using the lens on a 4x5 camera. The speec shutter covers 4x5" or ~10x13 cm, and is a bit under your goal of 14cm square/diameter. You can probably pick up a trashed Speed for not much on ebay & Co. and adapt the shutter mechanism to your goals. And advantage here is that you can use slit width to achieve high shutter speeds.

And, as Dan suggests, a Packard shutter would be a good candidate - if nothing else as a design idea.

I think the inertia of a leaf shutter mechanism that size might be a real problem. Anything that minimizes moving mass would be a good idea.

 

[Richard Man]

Unless you require faster than 1/20th, lenscap/hat or a Packard would be an easier choice. The main problem is the timing for faster than 1/30. Otherwise, a Guillotine shutter is great if you don't need to tilt your standards more than 5-10 degrees. I have 3-D printed Guillotine shutters and they are fine, but now I use a Sinar Copal. It only covers around up to 3 1/2" diameter though.

 

[reddesert]

There's someone who has posted to the LF forum who made a leaf shutter electronically controlled by a servo motor and Arduino, with 3D printed parts. It could only do as fast as 1/8 sec due to the low capacity of the small servo, and it wasn't as big as you are thinking. But you might want to look at the project. Making a large shutter that operates quickly is going to be rather difficult due to the inertia of the parts as Nicholas mentioned.

LFPF thread: https://www.largeformatphotography....ntrolled-large-format-3d-printed-leaf-shutter
Github project with thingiverse link: https://github.com/hackaninstant/Servo-Shutter

 

[abruzzi]

I remember a camera (I don't remember which) that had a "leaf" shutter with two blades. They were made with a pair of wedges: < > They moved horizontally apart and then back forward creating essentially a square opening that opened and closed. I don't know if that was simpler than a traditional leaf shutter that opened and closedby rotating a rind the blades were all attached to.

I think the biggest issue you'll run into is with an opening that large, your top speed will be pretty slow, not just with inertia, but also for the distance the blades will have to travel. Some leaf cameras in the past avertised faster shutter speeds only available at smaller apertures, because the blades didn't have to move near as far as when the aperture was wide open. On small 35mm shutters the effect of distance is going to be much smaller than on a 140mm / 5.5 inch opening.

Good luck. I'll be curious to see your progress (though the Sinar/Copal shutter will be sufficient for me.

 

[OAPOli]

I think the simplest solution in terms of costs and design would be a guillotine shutter.

 

[mshchem]

Old process cameras had big solenoid operated shutters. Very simple, not sure who made them

 

[bernard_L]

A long shot, but could something be designed using the rotating arm (bearing R/W heads) in a discarded disk drive?

 

[grain elevator]

Seems difficult. Why not a curtain shutter?

 

[kuvaharrastaja]

I take it that you're going to hang the lens in front of the shutter or the shutter in front of the lens, not try to put it inside the lens. I've done both. The largest shutter I've done this with is an industrial (no diaphragm) Compound #5 that goes in front of a 900/10 Apo Saphir.

I'm all for the joy of tinkering, but if a single (usually) speed air-driven shutter will do what you need you should look into Packard shutters. https://packardshutter.com/

Yes, just like that. No need of modifying/adapting lens groups to fit each side of shutter, just have the whole barrel lens mounted front or back of shutter.
Omg that compound 5 shutter looks sweet from google search!

Okay, so that packard shutters look like a simple design. I have to look into it, and other designs too.

 

[Kino]

Old process cameras had big solenoid operated shutters. Very simple, not sure who made them

Yup. I have one of those. Contacted Packard and they could not confirm or deny if they built them in the past. Said the records for third party builds were practically non-existent.

The one I have looks just like a Packard Bulb shutter, but uses a lever attached to the solenoid and it takes a good bit of pressure to move the blades.

Maybe with the new Lithium battery packs being so cheap now, I could find a powerful DC solenoid and try to make it functional.

Kinda low on the priority list now, though...

 

[kuvaharrastaja]

I would have picked a focal plane shutter type as in a Speed Graphic, just mounted at the lens. Unless, of course you are using the lens on a 4x5 camera. The speec shutter covers 4x5" or ~10x13 cm, and is a bit under your goal of 14cm square/diameter. You can probably pick up a trashed Speed for not much on ebay & Co. and adapt the shutter mechanism to your goals. And advantage here is that you can use slit width to achieve high shutter speeds.

And, as Dan suggests, a Packard shutter would be a good candidate - if nothing else as a design idea.

I think the inertia of a leaf shutter mechanism that size might be a real problem. Anything that minimizes moving mass would be a good idea.

Thanks for the idea, i am sure it would work okay, but I want to make a shutter project from scrap.

I agree on minimizing moving mass. Not sure which design would be good for that. Also maybe its not so bad if there's some inertia to leaf drive mechanism, because that can be overcome with a stronger drive motor/mechanism.

 

[kuvaharrastaja]

Unless you require faster than 1/20th, lenscap/hat or a Packard would be an easier choice. The main problem is the timing for faster than 1/30. Otherwise, a Guillotine shutter is great if you don't need to tilt your standards more than 5-10 degrees. I have 3-D printed Guillotine shutters and they are fine, but now I use a Sinar Copal. It only covers around up to 3 1/2" diameter though.

I do want faster than 1/20s. Guillotine shutter is something that ive wanted to build some years ago. But never started to build it because it seemed so hard to get good light seal, with low friction. And the big piece of plastic i got for a slide, was all bend, like in a bit of tension -not good for light tight gravity operated slide x.x

Ive been looking sinar copal db shutter pics, it has interesting design with square body and 4 shutter leafs.

Btw something I thought about guillotine shutter, maybe it could be operated by a weight tied to a string and a pulley. That would maybe allow tilting the camera because the hanging weight would always be pulled staight down.

 

[kuvaharrastaja]

I remember a camera (I don't remember which) that had a "leaf" shutter with two blades. They were made with a pair of wedges: < > They moved horizontally apart and then back forward creating essentially a square opening that opened and closed. I don't know if that was simpler than a traditional leaf shutter that opened and closedby rotating a rind the blades were all attached to.

I think the biggest issue you'll run into is with an opening that large, your top speed will be pretty slow, not just with inertia, but also for the distance the blades will have to travel. Some leaf cameras in the past avertised faster shutter speeds only available at smaller apertures, because the blades didn't have to move near as far as when the aperture was wide open. On small 35mm shutters the effect of distance is going to be much smaller than on a 140mm / 5.5 inch opening.

Good luck. I'll be curious to see your progress (though the Sinar/Copal shutter will be sufficient for me.

Hmm, that's interesting idea, I wonder if the wedge with square shutter opening, had any benefit over packard shutter's slit or v-shaped opening.

That is true. I have fairchild k-20 aerial camera leaf shutter that can go 1/500s time with 30mm opening. It has very strong spring and release of that in 1/500s is violent and loud It doesnt a have ring controlling the blades, but a little levers going from blade to blade, if i remember correctly.

Ive been thinking just that inertia and distance of the blades. Traditional 5 leaf shutters would allow the blades travel shorter time, but also be lighter. It seems for a best design at this point.

The ring would be pretty heavy tho, but blades light and small. K-20 shutter's lever approach looks more complicated.

 

[Nicholas Lindan]

The 2-blade square opening shutter is common in point&shoot cameras. The shutter blades do double duty as the camera's aperture - the opening size is controlled by the camera's exposure system.

 

[kuvaharrastaja]

Okay so I will do similar design that shanel 5 (50.8mm opening) shutter has. It actually is very basic and just like i described in the start post. Pictures are from that shutter.

Similar geometry but just larger. Shutter leafs are 0.1mm steel and the hole and slot doesnt have any support. I mean that the pivoting "bearing" surface is also only 0.1mm thick.

Maybe I have to rivet some alumium piece to the small end of the leafs to make it stronger, so that the leafs dont start to cut into drive pin and support pin within use.

Id like to make cast alumium frame for the shutter, with about 15cm diameter threads on each end for attachment. Over all diameter of the shutter will be huge, 30cm, or so. Good thing that my camera can fit it no problem.


Thanks for suggesting guillotine and roll shutters, but really i found those a bit problematic and not nessesarily easier to do right. If i get this working, it will be easy to work with, having flash sync at all speeds and relatively compact size.

Oh and I took my fully working shanel 5 shutter apart for the exploration, hope it goes back together nicely, lol.

 

[koraks]

I've thought about this for a few minutes a couple of weeks ago. More like, daydreaming. The main thing that stuck with me is that I'd probably build this around a solenoid. With a proper linkage, this should be capable of opening and closing a shutter fast enough for slow to moderate shutter speeds. It'll beat the heck out of the servo approach linked to on LFPF (it's beyond me why someone would use a servo in this application; it doesn't make any sense to me). Solenoids are plentifully available; pick something reasonably fast. It doesn't have to have a very long stroke or be particularly powerful.

 

[kuvaharrastaja]

I've thought about this for a few minutes a couple of weeks ago. More like, daydreaming. The main thing that stuck with me is that I'd probably build this around a solenoid. With a proper linkage, this should be capable of opening and closing a shutter fast enough for slow to moderate shutter speeds. It'll beat the heck out of the servo approach linked to on LFPF (it's beyond me why someone would use a servo in this application; it doesn't make any sense to me). Solenoids are plentifully available; pick something reasonably fast. It doesn't have to have a very long stroke or be particularly powerful.

Nice! That solenoid approach is probably what is going to be used for this. Servo's are good putting out a constant torque on the whole movement range, but that precise control is not needed in shutter.
One thing that might become problematic with solenoid, is that the pull force will be very strong at certain point of the stroke, but then drop off quickly. But that probably will be possible to overcome with bigger solenoid and fitting linkage that utilises the strongest part of the stroke.

Also with this big shutter there's no way around that if it needs to open and close quickly, it needs a lot of force to do that. I think the shutter leafs alone weight about 80g. Then there will be that rotating ring, and linkages etc. Friction, too. Its hard to estimate.

 

[Nicholas Lindan]

To refine your ideas you may want to see if you can get an inside view of Sinar's behind the lens shutter. It is always a good idea to first find out how those who have gone before solved the problem.

A few seconds of web search turned up https://www.uniblitz.com/product-category/optical-shutters/ - they make a 15cm shutter and will sell it to you for a mere $12,250. Opening and closing times are 200mSec - so the top speed is ~1/2 second. A peek at the obstacles in making such a gadget.

You may want to do a patent search on the subject. The patent office is the publisher of record for technology - the engineering equivalent of a scientific journal.

 

[Dan Fromm]

Hmm. OP, are you aware of the AGI F.135 aerial camera? It uses 5" roll film, has two very strange leaf shutters that hold 38/4.5 Biogons. Not a stereo camera, the shutters fire alternately, the film is advanced after two shots. The shutters embody a few ideas that you might want to consider.

The shutters' blades are metallized mylar, are probably lighter than the equivalent steel blades. Less inertia.

The shutter is opened/closed by a pair of opposed solenoids that extend when energized. The open solenoid whacks a lever that opens the blades, the close shutter whacks the lever to close them.

 

[Donald Qualls]

One thing you might consider is a guillotine type shutter, but using your electric driver (stepper motor with ,lead screw or solenoid) instead of the gravity fall common in homebuilt guillotine shutters.

This doesn't absolutely require a very fast travel; like a focal plane shutter, exposure time is mainly governed by the width of the slit -- but if you drive with a stepper, you could have a fixed width slit and vary the drive speed instead.

 

[kuvaharrastaja]

To refine your ideas you may want to see if you can get an inside view of Sinar's behind the lens shutter. It is always a good idea to first find out how those who have gone before solved the problem.

A few seconds of web search turned up https://www.uniblitz.com/product-category/optical-shutters/ - they make a 15cm shutter and will sell it to you for a mere $12,250. Opening and closing times are 200mSec - so the top speed is ~1/2 second. A peek at the obstacles in making such a gadget.

You may want to do a patent search on the subject. The patent office is the publisher of record for technology - the engineering equivalent of a scientific journal.

You mean that square body sinar db shutter? Ive googled some pics from insides of that, but coudnt find pics of the mechanism how is the shutter leafs moved in that.
But ive already kinda gone with this 5 leaf desing that seems to be most popular in shutters.

Wow, that 15cm shutter is crazy expensive. That 1/2 second speed is probably because it is designed for long shutter life and that stepper motor driving it, is not build for speed.

Maybe I will run to some issues when it comes driving the shutter fast enough, but ill worry about that then. That should be possible to overcome with power and reduced shutter life. But i dont need a half million actuations anyway. lol.