Yes, for an FP shutter you'd need something moving linearly at right angles to the shutter opening, and you'd get a diagonal trace which you'd have to measure the length of in the shutter movement direction. Doable, but not so easy.
Neil
Yes, for an FP shutter you'd need something moving linearly at right angles to the shutter opening, and you'd get a diagonal trace which you'd have to measure the length of in the shutter movement direction. Doable, but not so easy.
Neil
Your eye will retain an image of the shutter blades frozen by the electronic flash burst for 1/10 sec. Look through the shutter (cells removed) as the flash illuminates a wall. You will see the position of the blades as the synch contacts close. If you have a Ghostmaster you can see their position when the contacts open. Many large studio strobes can have a flash duration of close to 1/300 sec. You can easily cut off part of the burst if you use a high shutter speed like 1/250 or 1/500. The tail end of the EF burst is where most of the red component is, so by cutting it off you can end up with a colder color rendition.
Originally Posted by Randy Moe
I got a PM to elucidate. Perhaps this explanations fails, but it's what i am thinking about.
The old iPhone app works fine, sort of. Very crude. What I want to see is actual shutter opening dimensions and exact sync time with duration compared to the shutter opening, resting or closing. 2 dwell times. 2 frozen scope traces.
Particularly a Packard has an odd set of leaves that obstruct light differently than leaf or FP shutters.
Additionally studio strobes have very short duration, perhaps 1/8000th second. Flash bulbs designed for FP shutters such as Speed Graphics, have long light production duration in seconds to accommodate synchronization with slow or fast moving slit shutters. The area opened to the film is a moving target. So is a leaf shutter, but they worked/perfected those longer, i.e. M, X settings and solenoids. Beat the Reaper methods. I also need that method.
Some Packards are tri-leaf shutters, others have 4 moving leaves, that have something in common with moving slits, however exposed Packard shutter light area changes radically in shape and speed. I see this shape on my incorrectly exposed film.
Maybe what I want is high speed video of whats happening.
Thank you for the cogent explanation, Drew! It is an intriguing project. By gosh, I might even have a use for my Busch film pack adapter!
Peter De Smidt suggests I use my D750 at 60P and record the action from the rear.
Good idea.
Perhaps tonight.
Video at 11.
I use a photodiode in photoconductive mode and an old Tek466 storage oscilliscope.
the p/d is arranged to receive a narrow beam, of scatter from the ground glass, usually.
This link should be Dir of scope traces and a summary sheet of
RB67 50mm shutter tests including variation over frame
https://app.box.com/s/6d06x1j0n6dm5et3jmypxpijpscdym8a
Here is Graflex Graftar f/4.5 103mm. The narrow spike of light is the electronic flash firing
http://www.largeformatphotography.in...0&d=1422319890
Lovely demonstration, Wombat. The traces clearly show the opening and closing delay, the fact that it's faster on a small aperture (though I did not expect it to be quite so large a ratio), and the difference in signal height with iris.
It's clear that an automatic system will have to do some thinking.
Thanks.
Neil
My video below of my problem.
During the video notice the flash is a quick white line across the DSLR field or lens, but not coming from the View Camera taking lenses, despite the strobe pointing at the view camera. The orange glow is the modeling lamp.
I deliberately operated the Packard slowly, also notice the PCB radio is on upper left and the red led always blinks late, just as it does when syncing with a DSLR. So ignore that.
I think I need to move the upper right micro switch lower to contact the piston sooner. This used to work, but perhaps has worn...
https://youtu.be/jzeLQES4XUE
We are getting pretty far afield from the original idea I proposed, but it is good to have a complete understanding of X-synch challenges. One that I have encountered recently is that the new Norman power packs, 24/24 and newer may not have sufficient synch voltage to reliably operate older radios and IR sets. The guys at Holly Enterprises are aware of this and can change some resistors to increase synch voltage enough to operate these older remote sets but not damage other digital do-dads that may be attached.
I know we are pushing this thread, but we may as well have one conversation. imho
I am going to make a better video that demos a few options.
Need a couple days for that.
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