Another question please. I have several of these. Again, I am doing some zero-budget film making. In one short crime thriller movie I helped on, they had a scene with a crime scene photographer taking pictures. The director wanted the flash from the camera to be seen in the background while the characters talked about the crime in the foreground. However, there's a problem with that. The electronic flash is so brief (1/1000 of a second or faster) that half the times it doesn't even register in a video frame. (many higher end video cameras can imitate film camera's "shutter angle" which traditionally is 180-degrees. This means that for 24 frames per second, the video sensor records light for 1/48 of a second and does not record light for the other 1/48 second of the 1/24 second frame. This can be important for achieving that "film look" when shooting video.) So there's a 50/50 chance that the 1/1000 electronic photo flash will be recorded.
So, my idea is this. I have a couple old electronic flash units. I am considering removing the electronic flash guts from them, along with the xenon flash tube, and replacing them with the guts of a cheap (like $1) LED flashlight.
Problem 1, is that the flash unit has a battery compartment (which I intend to keep) for 4-AAs whereas the flashlight is powered by 3-AAAs. So my question is would over-driving the LEDs with the extra voltage from 4 batteries be fatal to the LEDs made for 3 batteries? A couple solutions come to mind. One is to put a conductive battery placeholder, like a metal rod cut to fit, in place of one of the 4 batteries. Or, use rechargeable 1.2v lithium AAs who's voltage would add up to 4.8v instead of 6v. Or don't I need to worry at all? Would 6v for a fraction of a second be harmless to the LEDs?
Issue 2. Most camera flash triggers close the trigger circuit for the duration of the exposure. So by setting the shutter speed of the prop camera to something like 1/8 of a second would allow 2-3 frames of video to record the "flash." This might be important for addressing another video problem called "rolling shutter" which I won't go into. But again, there is a voltage concern. I read that modern electronic cameras (DSLRs) should not have flash trigger voltages exceeding 5v. So, should I put somekind of isolating transistor circuit in the flash prop rather than just wiring the batteries/LEDs directly through the prop flash hotshoe? I want to keep this as simple as I can. I'm guessing that the 5v limit might be conservative and the circuit will easily handle 6v rather than 5v. Again the 1.2v 4-lithium battery idea above would provide only 4.8v. But I can't be sure that someone on set wouldn't replace the batteries with 1.5v ones.
This sounds trivial, I guess, but I don't want to be accused of damaging someone's $1000+ DSLR.
Thanks again.
So, my idea is this. I have a couple old electronic flash units. I am considering removing the electronic flash guts from them, along with the xenon flash tube, and replacing them with the guts of a cheap (like $1) LED flashlight.
Problem 1, is that the flash unit has a battery compartment (which I intend to keep) for 4-AAs whereas the flashlight is powered by 3-AAAs. So my question is would over-driving the LEDs with the extra voltage from 4 batteries be fatal to the LEDs made for 3 batteries? A couple solutions come to mind. One is to put a conductive battery placeholder, like a metal rod cut to fit, in place of one of the 4 batteries. Or, use rechargeable 1.2v lithium AAs who's voltage would add up to 4.8v instead of 6v. Or don't I need to worry at all? Would 6v for a fraction of a second be harmless to the LEDs?
Issue 2. Most camera flash triggers close the trigger circuit for the duration of the exposure. So by setting the shutter speed of the prop camera to something like 1/8 of a second would allow 2-3 frames of video to record the "flash." This might be important for addressing another video problem called "rolling shutter" which I won't go into. But again, there is a voltage concern. I read that modern electronic cameras (DSLRs) should not have flash trigger voltages exceeding 5v. So, should I put somekind of isolating transistor circuit in the flash prop rather than just wiring the batteries/LEDs directly through the prop flash hotshoe? I want to keep this as simple as I can. I'm guessing that the 5v limit might be conservative and the circuit will easily handle 6v rather than 5v. Again the 1.2v 4-lithium battery idea above would provide only 4.8v. But I can't be sure that someone on set wouldn't replace the batteries with 1.5v ones.
This sounds trivial, I guess, but I don't want to be accused of damaging someone's $1000+ DSLR.
Thanks again.