laser trip and electronic shutter for 8x10 Deardorff

[karlmartini]

I've an unusual project. I want to take shots of moving subjects on my Deardorff 8x10 with my Schneider Symmar-S lens wide open at 5.6!

Needless to say it's completely impossible to get the subject sharp at this aperture.

I'd like a system where I can pre-focus on a particular point and then have my moving subject trip a laser beam/electronic shutter when they get to that point.

I think the laser trip system is easy enough to come across as off the shelf home security products. There are some electronic shutters available on ebay (is Ilex 3 the same screw mount as my Compur 3?). Then there's the issue of rigging the laser trip to the shutter.

Am I mad to embark on this project? has it ever been done before?

An added bonus is if it could also activate the shutter on my Canon 5dII so I can do testing of the laser setup.

I'm a 3rd year photography degree student and I reckon I'd get extra points for originality if I pulled this off.

Opinions appreciated.

[BetterSense]

If you are trying to measure the distance to the person, it will not be feasible. There are ultrasonic rangefinding systems, but to get inches of resolution at high speed, it will be very difficult.

If you are talking about using a kind of breakbeam tripper, that can be pre-set, and the person can walk through it, that should be pretty easy with a laser and a photodiode, or with a modulated IR like this

http://www.sparkfun.com/products/10266

The motion detectors for security camreras and lights are pyroelectric sensors that measure gross changes in radiant flux and they are not suitable for something like this.

[BradS]

What a great idea!

The automatic garage door opener at home has a light beam sensor system at the base of the door - it automatically reverses the closing door if something, like a kid,interrupts the beam...

That, a battery and one of those Graflex shutter solenoids should about do the trick, I'd think.

Makes me wish I hadn't sold off the Graflex solenoids I had laying around.

[karlmartini]

Bettersense, you are correct on the breakbeam tripper and thanks for the tip. I'll stay clear of the security products. Thanks!

BradS...I did a bit of poking around on the Graflex shutter selenoids. Can I use one of these to attach to the shutter release on my existing shutter?

[BradS]

BradS...I did a bit of poking around on the Graflex shutter selenoids. Can I use one of these to attach to the shutter release on my existing shutter?


Yes. I don't see why not. They are a very simply electro-mechanical device. They simply pull on the shutter release lever the same as you would with a finger. I think that they operate at 3 VDC (maybe, 4.5VDC).

The garage door thingy might be kinda expensive to buy separately but, you get the idea.

[karlmartini]

I'm making progress. I entered a bid on ebay for a Graflex selanoid. It's only a few dollars. I'm looking into a laser trip and it seems they have one for players of Airsoft (it's like paintball) that sets off a claymore anti-personel mine. I shot off an email to ask what the output voltage is. It's likely it won't be 4 to 5VDC so I'll have to make enquiries in Maplins (like radio shack) about how to make something with a soldering iron.

[E. von Hoegh]

There will be a delay with any electromechanical gizmo, eg solenoid. Not much of a delay, but at f5.6, perhaps significant depending on the speed of the subject.

Yes, it has been done before http://americanhistory.si.edu/muybridge/
I think the Graflex solenoid ran off the flash battery?

[BradS]

an even simpler one shot device could be fashioned from a mouse trap, some string string and a small pulley

[E. von Hoegh]

Check out the Muybridge link, that isn't far from what he did. With wet plates, no less.

[jp]

There are consumer electronic items that buzz when someone enters through a door to announce a customer or visitor. (they break the beam). I know they used to use them at my local radio shack a decade or three ago. I'm sure it had relay contacts for external creative uses.

Solenoids to trip a mechanical shutter a available in a variety of styles and sources for very little money. Cars have them to lock doors. Appliances have them to operate valves for water or gas. Any good sized relays (such as the ones with the tube bases or screw terminals) can be taken apart to use the solenoid that operates the contacts) Security businesses online sell solenoids to operate door strikes.

The speed graphic solenoids might work; I've never tried them on a bigger copal-3 shutter. I guess it depends on the throw distance and resistance of the shutter.

[karlmartini]

an even simpler one shot device could be fashioned from a mouse trap, some string string and a small pulley

It may work but if I sent my subject home after 30 minutes of fiddling with mousetraps and pulleys I'm not sure if I'd get him/her back again. I'd prefer to fail and have a mysterious engineering excuse to save my pride.

[karlmartini]

Here's a link to a youtube video of the laser tripper I was thinking about.

v=3G_GnjfgLFU"]http://www.youtube.com/watch?v=3G_GnjfgLFU[/URL]

[karlmartini]

Check out the Muybridge link, that isn't far from what he did. With wet plates, no less.

Will I be the first to do 8x10 action photography since Muybridge? I doubt it. I am amazed there was optics and chemistry available to make film sensitive enough to shoot at these speeds all the way back then. I read he actually had the horse go through a series of strings attached to a long line of cameras in series. I'm not sure if my budget will extend to purchasing 20 Deardorff cameras!

[el french]

Well, if you really want to do it right :) http://www.flickr.com/photos/fotoopa_hs/sets/72157625073020642/

[karlmartini]

Thats pretty impressive!

[E. von Hoegh]

Will I be the first to do 8x10 action photography since Muybridge? I doubt it. I am amazed there was optics and chemistry available to make film sensitive enough to shoot at these speeds all the way back then. I read he actually had the horse go through a series of strings attached to a long line of cameras in series. I'm not sure if my budget will extend to purchasing 20 Deardorff cameras!

I have held 8x10 negatives of bobsleds going through "Shady", a banked turn at the Mt. van Hoevenberg bobsled run in Lake Placid, NY. Looked like '50s vintage. A couple of the shots were panned.

[johnielvis]

i got a polaroid miniportrait with the ultrasonic focus--it focuses like a bigshot but the rangefinder is untrasonic and electronic--a green led lights up when it's in the focus zone

I was thinking of adapting that for a similar purpose...the green light lighting can trip the shutter...very fast the ultrasonic focus on polaroid....

HEY--great idea--get a junk sx70 with the autofocus...the lens moves FAST boy on that ultrasonic focus...like push the button and ZAM..it's THERE...

I've seen these things hacked--all kinds of diy for robots----you can use this system to trip the shutter--a hacked sx70 or miniportrait...or some of the old one-steps...there were a few that had the ultrasonic focus on it...even some with no moving glass..it set the flash aperture I believe

[Ivan J. Eberle]

Hopefully you've got a repeatable motion or relatively steady speed. Triggering systems designed to capture fast-moving subjects at a particular point in space (in this case the plane of focus) are typically positioned to pre-trigger on the subject shortly before it gets to the capture spot, with a variable delay lagging device in the circuit to dial in the correct amount of delay so that the photographic capture hits that spot. There is usually a lot of wasted polaroid stock when doing this with film.

(This is essentially the task predictive AF must do in an SLR as the mirror is flipping up out of the way, incidentally.)

Most of this work in LF done with open shutter and electronic flash, because it takes the mechanical shutter variability out of the calculation, and greatly shortens the lag interval.

[John Koehrer]

There will be a delay with any electromechanical gizmo, eg solenoid. Not much of a delay, but at f5.6, perhaps significant depending on the speed of the subject.

Yes, it has been done before http://americanhistory.si.edu/muybridge/
I think the Graflex solenoid ran off the flash battery?

Muybridge 1830-1904= no Graflex solenoid

[karlmartini]

I do have a repeatable motion that I can test with digital in advance of the event I want to capture using a sheet of 8x10. The issue I'll have is that I need to trigger the digital camera as well as the Deardorff. I may need the help of a local amateur electronics buff who will take photography services in lieu of pay. You are right about using a strobe in a dark room with an open shutter. Unfortunately I need to shoot outdoors in the daylight.

[E. von Hoegh]

Muybridge 1830-1904= no Graflex solenoid

The OP commented that he thought the Graflex solenoid ran on 3 or 4.5 volts. I THINK it ran off the flash battery, which I THINK was 3 "D" cells.
I'm well aware Muybridge didn't use Graflex solenoids.;)

[Ivan J. Eberle]

How fast are your subjects moving? If more than very slowly, shutter/solenoid circuit lag time will require some sort of compensation. If it's a consistent speed you might move the sensor back and forth until the lag time hits the spot where you're prefocused. I'd try to do this without film but with flash to test; the strobing via the X-sync terminal on your view-camera lens, with even a Strobist-type flash on the very lowest power setting could get you in the ballpark. Alternately you might use an open shutter DSLR mounted behind the 8x10 lens to test. Either may save you a lot of expensive film.

You're most likely going to need a variable lag-delay device to dial back tripping the shutter of an 8x10 on a solenoid circuit to let the DSLR to catch up. If by digital camera you mean you're using another view camera lens with a digital back you might get away without one. The mirror/shutter delay of DLSRs ranges from about 39ms to a lot longer. Most recent Nikons are in the range of 39 to 42. Medium format cameras are slow unless there's a mirror lockup provision as on some of the the Rollei 6000 series (which can be as fast a 2ms). But the delays will all be additive.

I have some really small sensors. These are low draw, waterproof infrared beam interrupt triggers and are reasonably fast for enclosed units with a 1amp switching relay, but even these have a 10 milisecond (1/100s) switching time. The ones I've got also trigger off red LED laser-pointers.


An electronic-oscillator controlled shutter may prove more consistent on the lag time. An SLR could be consistent within a milisecond or so.