Hi to old friends! Sorry I've been away so long -- one of my periodic lapses! I've been building bows, so only woodwork this winter.
Lately I was thinking I'd really like to see what a bow and arrow was doing when it releases. I'd like to know what changes in design do to arrow speed at multiple moments during release. There are high speed consumer grade video cameras out there made by Casio that can shoot 1000 fps -- but the quality of the video isn't too great, and the price for a used one imported from japan is $120 -- on up. Unsure of quality and out of my price range at present.
I don't know what's available super cheap for multiple flash stop-action strobes either, but I suspect they aren't cheap. They'd have to charge a pretty big capacitor (I assume) to flash like 10 frames in maybe a 50th of a second. And some kind of programmable sophisticated interval timer circuit.
So then I was thinking of good old Muybridge with his multiple cameras fired by strings across a race track way back in photo history. Only could I do something similar with say, a bunch of old fashioned hot shoe camera flash units from ebay triggered by an Arduino board. I was thinking I could program in the intervals wanted, that way.
Does this seem feasible? I don't remember exactly how the flash shoe triggering worked, but I think it was just a switch -- is that right? Or was there a signal from the camera? "Hot" shoe does seem to imply a voltage. Anybody know specs if so?
I figure the time interval of interest -- might not be totally accurate, but here it is.... A very fast arrow from a wooden bow might reach 200 feet per second terminal velocity, and is about 28" long. Since it starts from zero, it averages about 100 ft/sec through the bow, and is about 2 feet long -- so as a guess roughly 1/50 second in the bow. Let's say 1/60th to be more conservative -- I don't know actually.
It would be nice to have an image every tenth of that -- ten images total -- so the intervals between flashes might be about 1/600 second. The flash duration itself should be as short as possible. I don't know how short a used flash unit can flash for, but a tenth of the interval would be nice. That's a duration of say 1/6000th second. No idea if that is possible -- anybody know?
That would mean the arrow traveled about 1/4" (if I'm figuring right) during the duration of the flash. At that rate the phot will be a little blurry, but maybe good enough to get a measurement of the distance from release, which is the main thing I'm interested in. Faster would obviously be better -- if you think that's possible....?
I think most of the automatic thyristor flashes for SLRs of the past adjusted the flash length -- which isn't something I want. Ideally it would just flash for one set duration, and flash as short as possible to still register on my digital camera set to a time exposure. The bow would be set against a black background and the distance to subject would be quite short. The arrow would have an automatic release.
I'm thinking an Arduino Uno R3 board (I have a few) and an interface digital switching board like this 8 channel job (well I guess that's 8 frames per photo, but acceptable). But I don't know if it would be fast enough:http://www.ebay.com/itm/New-8-Channel-5V-Solid-State-Relay-Module-Board-OMRON-SSR-4-for-Arduino-/321866921038?hash=item
It seems possible to get older flash units in the $5 range on ebay:http://www.ebay.com/sch/Flashes-/48515/i.html?_sop=15&Compatible%2520Brand=Universal
To me this whole idea seemed like a total maddmodder approach, so I just had to come back and ask you guys if this seemed feasible to you, and if you had any suggestions or recommendations.
It is nice for me to tie bowmaking with this, my old favorite forum. I've felt kind of out of touch with you.