Post by thread:trigger a film camera

I'd like to trigger a film camera from a pic. Also it would be nice to use a cheap auto wind type but I haven't been able to find any that have an external switch for this. I've thought about breaking into the camera to get at the switch but it's not elegant. A solenoid plunger would work if positioned over the button but any I've seen are really power hogs. Does anyone have any ideas or tips they'd like to share on being able to do this? -Ralph spam_OUTrlandryTakeThisOuThaywood.main.nc.us "If they call it Tourist Season why can't we shoot 'em?" ICQ# 19545315

|I'd like to trigger a film camera from a pic. Also it would be nice |to use a cheap auto wind type but I haven't been able to find any |that have an external switch for this. I've thought about breaking |into the camera to get at the switch but it's not elegant. A solenoid |plunger would work if positioned over the button but any I've seen |are really power hogs. Does anyone have any ideas or tips they'd |like to share on being able to do this? You probably will need to use an auto-wind camera since even cameras with electronic exposure control frequently use a 90% manual mechanism: There are two sliding shutters; one of them is closed in the cocked position and the other is open. The cocking mechanism is arranged so that the first shutter is closed before the second shutter is opened (to avoid exposing the film). The shutter button holds both shutters in the cocked position. When the shutter is tripped, the first shutter is opened and the second shutter is closed soon behind it; note that if the second shutter follows very closely after the first, there may not be any time when both shutters are all the way open; for this reason, it's usually necessary to use a shutter speed of at least 1/250-1/60 when using a flash. On many electronic cameras, there is a small electromagnet which holds the second shutter open for a certain length of time after the button is pushed. Since the magnet doesn't have to "grab" anything, but merely hold it in place, it uses much less current than a solenoid. Further, since the shutter button will hold the second shutter open until it's pushed, it's only necessary to energize the magnet for what- ever length of time the shutter has to stay open. Note that this mechanism, as used in most cameras, is very economical in its use of power, but it's not very adaptable to external tripping (other than by using a solenoid). Many of the better 35mm cameras do have, though, a connector for a mechanical shutter cable, so mounting a solenoid or similar tripping device may not be too bad. While solenoids do need a fair dose of current, a solenoid in this usage would only need it very briefly so the total energy requirement should be quite reasonable.

John Payson wrote: > > |I'd like to trigger a film camera from a pic. Also it would be nice > |to use a cheap auto wind type but I haven't been able to find any > |that have an external switch for this. I've thought about breaking > |into the camera to get at the switch but it's not elegant. A solenoid > |plunger would work if positioned over the button but any I've seen > |are really power hogs. Does anyone have any ideas or tips they'd > |like to share on being able to do this? > An RC servo would work here, they have a lot of torque, and you could even power it down when not using it at the risk of an extra picture during the powerup "twitch".

On Thu, 19 Nov 1998, Dave VanHorn wrote: > John Payson wrote: > > > > |I'd like to trigger a film camera from a pic. Also it would be nice > > |to use a cheap auto wind type but I haven't been able to find any > > |that have an external switch for this. I've thought about breaking > > |into the camera to get at the switch but it's not elegant. A solenoid > > |plunger would work if positioned over the button but any I've seen > > |are really power hogs. Does anyone have any ideas or tips they'd > > |like to share on being able to do this? > > > > An RC servo would work here, they have a lot of torque, and you could > even power it down when not using it at the risk of an extra picture > during the powerup "twitch". For some pics and good descriptions of RC servo triggered cameras look up 'kite aerial photography' on the web. 0.02 Agorot Peter

Peter L. Peres wrote: {Quote hidden}> > On Thu, 19 Nov 1998, Dave VanHorn wrote: > > > John Payson wrote: > > > > > > |I'd like to trigger a film camera from a pic. Also it would be nice > > > |to use a cheap auto wind type but I haven't been able to find any > > > |that have an external switch for this. I've thought about breaking > > > |into the camera to get at the switch but it's not elegant. A solenoid > > > |plunger would work if positioned over the button but any I've seen > > > |are really power hogs. Does anyone have any ideas or tips they'd > > > |like to share on being able to do this? > > > > > > > An RC servo would work here, they have a lot of torque, and you could > > even power it down when not using it at the risk of an extra picture > > during the powerup "twitch". > > For some pics and good descriptions of RC servo triggered cameras look up > 'kite aerial photography' on the web. > > 0.02 Agorot > > Peter Another thought, something like a sear mechanism could trigger a more-powerful spring-wound mechanism (i.e. a small movement of a catch releases a powerful plunger for one stroke, just spring wind the clockwork each time you replace the film.) Something like the way mechanical clocks work. You can have a lot of leverage with a sear (50:1 is quite a possible control ratio - i.e. 1 Lb pull releases a 50# spring etc.) Look at the way a rifle "Set Trigger" works, for one example; Also just a regular rifle sear etc. Mark, mwillisKILLspamnwlink.com