Building a huge shutter for large format lenses

[NiallerM]

It's an amazing task. It's probably way too late to make any meaningful suggestions, but I'd probably personally opt for a solution involving a completely separate shutter for those open shots, and a more standard shutter for other use. That's purely from looking at things in a modular way. It would reduce wear to when it is necessary. Also (in the sense of the hammer-owner to whom every problem is a nail), and because I have one handy, I'd probably opt for compressed air (I mean a serious compressor) if I wanted that type of torque, both in opening and closing. Slower than a solenoid, but do you need instant response, or do you need that short exposure more? You won't be taking sport shots obviously!


It's a fascinating problem. Good luck with it!

 

[koraks]

I'd probably opt for compressed air (I mean a serious compressor)

In the field, this may look something like so:

Sorry, couldn't resist...

Welcome to Photrio! Hope to read more from you in the future!

 

[NiallerM]

In the field, this may look something like so:
View attachment 378913

Sorry, couldn't resist...

Welcome to Photrio! Hope to read more from you in the future!

Yup!!! Something like that! Just slide it in between the filters and the film frames in the case....

Thank you for the welcome. I'm about to head to the introductions sub-forum...

 

[NiallerM]

My main question here is as to how to dampen such an abrupt and weighty movement. To be honest, I'd look at a two part shutter. First, a curtain type at the rear of the lens, then the leaf shutter. The leaf shutter would need to be manually cocked under strong resistance, to the open position. Then the curtain drops (under power), to reveal the open lens with wide aperture, which, through an electric timer is timed to the appropriate delay to clang shut after the exposure.

 

[Richard Man]

My main question here is as to how to dampen such an abrupt and weighty movement. To be honest, I'd look at a two part shutter. First, a curtain type at the rear of the lens, then the leaf shutter. The leaf shutter would need to be manually cocked under strong resistance, to the open position. Then the curtain drops (under power), to reveal the open lens with wide aperture, which, through an electric timer is timed to the appropriate delay to clang shut after the exposure.

Yes, one of the problems I had with the Guillotine shutter was that it slams down HARD, and causing stress to the lens standard lock.

 

[kuvaharrastaja]

This is looking awesome. Good luck!

Thank you!

 

[kuvaharrastaja]

It's an amazing task. It's probably way too late to make any meaningful suggestions, but I'd probably personally opt for a solution involving a completely separate shutter for those open shots, and a more standard shutter for other use. That's purely from looking at things in a modular way. It would reduce wear to when it is necessary. Also (in the sense of the hammer-owner to whom every problem is a nail), and because I have one handy, I'd probably opt for compressed air (I mean a serious compressor) if I wanted that type of torque, both in opening and closing. Slower than a solenoid, but do you need instant response, or do you need that short exposure more? You won't be taking sport shots obviously!


It's a fascinating problem. Good luck with it!

Hmm, yeah probably! Compressed air would be very nice actuation method for sure. Being able to adjust and even make softer closing/opening.
It could have very light mass piston made of plastic, too. Not like iron core of solenoid.

Solenoid is so much easier to control and if its possible to make work it will be simpler, I think. That air thing could be good solution if solenoids are being too problematic for some reason.

About the shutter time, it doesnt need to shoot sports, but I want to be able to shoot portraits outside. So about 1/30s or shorter.

 

[kuvaharrastaja]

In the field, this may look something like so:
View attachment 378913

Sorry, couldn't resist...

Welcome to Photrio! Hope to read more from you in the future!

Lol That guy looks determined to use the gas! It would actually be nice idea to use co2 tank for example, if going to that pneumatic way.

 

[kuvaharrastaja]

My main question here is as to how to dampen such an abrupt and weighty movement. To be honest, I'd look at a two part shutter. First, a curtain type at the rear of the lens, then the leaf shutter. The leaf shutter would need to be manually cocked under strong resistance, to the open position. Then the curtain drops (under power), to reveal the open lens with wide aperture, which, through an electric timer is timed to the appropriate delay to clang shut after the exposure.

Yes, one of the problems I had with the Guillotine shutter was that it slams down HARD, and causing stress to the lens standard lock.

I have been thinking about this, if the shutter shake will be a problem. But this type of a shutter is known to cause minimal amount of shutter shake.

Being so far away from film, but also shutter leafs moving short distance and moving symmetrically, cancelling out some forces. Shutter and lenses will be so heavy that it will need a lot of force to make it shake.

The ring part will have some inertia that is hard to cancel out, but I will make it pretty light.

What do you think about this picture about solenoid placement, does it work like that? If the solenoids with the arrows drawn are pulling, they make the ring rotate.
But when they are kinda mirrored on opposite sides, solenoids will become to a hard stop at the same time, maybe that will cancel something out? Like in 4cyl engine, when 2 pistons are up, the other 2 are down.

 

[NiallerM]

I have been thinking about this, if the shutter shake will be a problem. But this type of a shutter is known to cause minimal amount of shutter shake.

Being so far away from film, but also shutter leafs moving short distance and moving symmetrically, cancelling out some forces. Shutter and lenses will be so heavy that it will need a lot of force to make it shake.

The ring part will have some inertia that is hard to cancel out, but I will make it pretty light.

What do you think about this picture about solenoid placement, does it work like that? If the solenoids with the arrows drawn are pulling, they make the ring rotate.
But when they are kinda mirrored on opposite sides, solenoids will become to a hard stop at the same time, maybe that will cancel something out? Like in 4cyl engine, when 2 pistons are up, the other 2 are down.

My worry would be that sudden stop. It might need dampening. You really have me thinking about this "simple" problem. It's a doozy!

I'm reminded of a camera that was given to me as an attic gift a few years ago. It was a Pentax P50 (A P5 in the US, I think). It was a cheapish SLR with similar function to the Canon AE-1. For a cheap camera, it took (and takes) absolutely superb photos. That thing has a recoil, though. Thankfully, it comes from the mirror slapping back into place, so its work is done and dusted by then. That was behind my suggestion of a curtain and a hand-cocked aperture. All the commotion will happen after the light has reached the plate. Light is faster than a compressive wave, after all.

I've had other thoughts too. Polarising filters?

It's a toughie.

 

[kuvaharrastaja]

My worry would be that sudden stop. It might need dampening. You really have me thinking about this "simple" problem. It's a doozy!

I'm reminded of a camera that was given to me as an attic gift a few years ago. It was a Pentax P50 (A P5 in the US, I think). It was a cheapish SLR with similar function to the Canon AE-1. For a cheap camera, it took (and takes) absolutely superb photos. That thing has a recoil, though. Thankfully, it comes from the mirror slapping back into place, so its work is done and dusted by then. That was behind my suggestion of a curtain and a hand-cocked aperture. All the commotion will happen after the light has reached the plate. Light is faster than a compressive wave, after all.

I've had other thoughts too. Polarising filters?

It's a toughie.

About the pentax camera, for sure, isnt it more about the lens and film used, hehe. Okay! you mean darkening with polarising filters, I wonder if anyone has tried that. Its not going to be completely dark or transparent tho.

 

[kuvaharrastaja]

I have been making a mount from an old brake disk, to get the ring part to a lathe. Its coming out pretty all right so far. Ring has lost over half of its weight already and more is still coming off.

But I have been thinking big thoughts! If the ring design is the best after all.. If it needs 4 solenoids, or 2 push/pull voice coil type actuators.


Would it be better if each of the 5 shutter leafs, would have its own push/pull voice coil type solenoid? Shutter would look like a ww2 era plane radial engine from front. Reversing polarity to all them with a single relay, would make it open/close.

It would have very small mass, single leaf weight only 10.9g, then connected to a small actuator with a rod. I bet it could go even higher shutter speed than with a ring design. And have no shutter shake issues. No ring's inertia to deal with. Only symmetrical forces acting similarly on 5 directions, within the 5 leafs and solenoids.

It would be pretty radical change of plans, lol.

That idea could also be adapted if the ring design is not good.

 

[NiallerM]

About the pentax camera, for sure, isnt it more about the lens and film used, hehe. Okay! you mean darkening with polarising filters, I wonder if anyone has tried that. Its not going to be completely dark or transparent tho.

Of course. Polarising filters will defeat the purpose. In fact, the better they are, the longer they'll push the exposure.

 

[kuvaharrastaja]

Okay I'll go with this ring style. Maybe if it doesnt work, the invidual solenoid drive leafs design may be worth doing.

Ring part now is 2.6mm thick, weights 130g. Thats exactly what I wanted. Got almost mirror finish straight out of lathe, as seen in first picture.

I took apart 2 car starter solenoids that was found from scrap. They seemed to be working still. They come much smaller and lighter when they were cut out of the steel casing and contact bits. Only coils left.
These seem to be powerful and take a lot of amps too Maybe I start with these and see if its working.

Next would be designing and making sand mold pieces for aluminium casting of the shutters frame, and when the 5mm pin material and reamer arrives, then finish off the ring.

 

[ic-racer]

Looks very nice!

 

[koraks]

@kuvaharrastaja I'm blown off my socks by your metalworking skills; really cool!

 

[kuvaharrastaja]

Thank you!

 

[grain elevator]

The idea with individual solenoids working in a radial direction sounds elegant. You could also study the Werra shutter which, I've read, closes without reversing direction of the ring travel. Or maybe I've misunderstanding, I dunno. Anyway your work so far looks great!

 

[DanyB]

Wow! Incredible project! Hold fast!

 

[NiallerM]

I have been making a mount from an old brake disk, to get the ring part to a lathe. Its coming out pretty all right so far. Ring has lost over half of its weight already and more is still coming off.

But I have been thinking big thoughts! If the ring design is the best after all.. If it needs 4 solenoids, or 2 push/pull voice coil type actuators.


Would it be better if each of the 5 shutter leafs, would have its own push/pull voice coil type solenoid? Shutter would look like a ww2 era plane radial engine from front. Reversing polarity to all them with a single relay, would make it open/close.

It would have very small mass, single leaf weight only 10.9g, then connected to a small actuator with a rod. I bet it could go even higher shutter speed than with a ring design. And have no shutter shake issues. No ring's inertia to deal with. Only symmetrical forces acting similarly on 5 directions, within the 5 leafs and solenoids.

It would be pretty radical change of plans, lol.

That idea could also be adapted if the ring design is not good.

Hey! If nothing else, you could end up with the most expensive cat flap ever made. Also the most dangerous! Imagine it with a proximity detector.

I jest. It looks like a monster, and I'm amazed at your work so far. Everything about it screamed "No way!" at me, so it is fascinating to see it take shape.

 

[kuvaharrastaja]

The idea with individual solenoids working in a radial direction sounds elegant. You could also study the Werra shutter which, I've read, closes without reversing direction of the ring travel. Or maybe I've misunderstanding, I dunno. Anyway your work so far looks great!

Hmm, i couldnt find any examples of Werra shutter with quick search. But maybe if the ring had a lobe for each leaf instead of slot, and each leaf would have some kind of return spring. Maybe then it could close without ring reversing.. hehe, just thinking how it could be done. Thank you!

 

[kuvaharrastaja]

Hey! If nothing else, you could end up with the most expensive cat flap ever made. Also the most dangerous! Imagine it with a proximity detector.

I jest. It looks like a monster, and I'm amazed at your work so far. Everything about it screamed "No way!" at me, so it is fascinating to see it take shape.

Thank you! Lol that cat comment It could look like some scifi space ship air lock door thingy.
I try to get this ready and moving, but it remains to be seen if its possible to made go 1/30s and not shake the camera too much.

 

[kuvaharrastaja]

Here is some progress, with the ring part I searched the center point, marked the leaf drive pin hole locations, every 72 degrees. Then 4mm holes were drilled, and the part could be attached to lathe from those holes (second pic).
There inner surface is machined to be perfectly round, because it had gone 0.2mm out of round from all the welding mountings and machining earlier. Now its ready for trimming outer shapes and riveting the pins to it.

The wooden box with 2 halves and locating pins, is made for sand casting the shutter frame out of aluminium.

In last pic, box is ready and there is parts that's going to be the wooden model, that will be used for the mold making and casting.

Its pretty bulky because I want to have good amount of material when machining the aluminium piece. It helps with attachment to lathe, room for defects in casting etc..

 

[NiallerM]

Here is some progress, with the ring part I searched the center point, marked the leaf drive pin hole locations, every 72 degrees. Then 4mm holes were drilled, and the part could be attached to lathe from those holes (second pic).
There inner surface is machined to be perfectly round, because it had gone 0.2mm out of round from all the welding mountings and machining earlier. Now its ready for trimming outer shapes and riveting the pins to it.

The wooden box with 2 halves and locating pins, is made for sand casting the shutter frame out of aluminium.

In last pic, box is ready and there is parts that's going to be the wooden model, that will be used for the mold making and casting.

Its pretty bulky because I want to have good amount of material when machining the aluminium piece. It helps with attachment to lathe, room for defects in casting etc..

Just wow.

 

[kuvaharrastaja]

Okay, I did this kind of side project/ testing solenoid for shutter controll. Wollensak verito lens shutter is controlled electronically with a cable. Lens and shutter is unmodified of course. So nothing old is ruined.

Minolta slr camera's flash sync is used as a clockwork for solenoid, and its connected to diy circuit board.
Circuit takes 13v from battery and puts it trough a 12k ohm resistor, to minolta camera, and it comes back to drive a mosfet, and the mosfet then takes battery voltage also, and drives the car's relay (orange part).
There's also safety diode between relays coil, and a resistor from mosfets gate to ground to keep it stable.

The solenoid is taking a juicy 25 amps from the litium ion motorbike battery, voltage being 9.9v at the solenoid. So its 250w power. I dont want to use any stronger wires or the power will go up even more.

Solenoid simply pushes the wire release and return springs pulls it back when solenoid is not energized anymore. Shutter, solenoid and cable release has their own return springs as well.

I am pretty happy with performance of this thing. It works, and i got linear exposure in test photos taken every stop with times 1/2 to 1/30s on minolta slr.

I tried 1/60s but the pulse was so short that the relay didnt have enough strenght to open shutter fully. So 1/30s is shortest. BUT the actual time may be shorter since the wollensak shutter doesnt open imediadly when minolta slr sync time starts.

Solenoid does kick a bit for sure, but the remote mounting and cable drive takes it away quite nicely.

Maybe something like this could be used to drive the big shutter as well. Delete or help shutter shake problem with bicycle brake cable actuation method