Questions about Flymo
Posted 23 February 2010 - 11:13 PM
This is my first post so I will apologize in advance for any and all silly questions that are surely to follow.
I have recently started flying an Eyemo variant on my large radio controlled helicopters. I have been doing this for several years now (with HD cameras like the HVX/HPX, EX1/EX3, 5D Mk2 and most recently the Red One) but have always wanted to give film a try so I just dove right in. I have done much research but still have several unanswered questions.
I have the video assist image downlinked to my camera operators ground station who can start/stop rolling the camera remotely by DC motor. My question is, how might I get indication that the camera is actually rolling and also end of reel indication?
Where can I find other gearing? I have 8, 30 and 48 fps but would like a few others?
I have many other questions but I'll hold back the floodgates for now.
Posted 24 February 2010 - 05:16 PM
Posted 24 February 2010 - 07:47 PM
Posted 24 February 2010 - 07:59 PM
Posted 24 February 2010 - 08:08 PM
You could do an OSD of the amperes coming out of the battery. When the camera starts you should see an increase to a more or less constant level, indicating the camera is rolling. That will not give you any indication if the camera is at speed, or if the battery voltage has dropped (perhaps due to altitude induced temperature change) and the film could run slow, overexposing the image, or the camera might shut down all together. You might be able to do that with over the shelf parts, but it wouldn't be ideal. I figure this is a commercial project and you need proof positive feedback of the cameras performance?
With a bit more info on your particular camera I could propose a solution to sample the feedback and provide an OSD data providing film accurate film speed monitoring. For film roll out you could place a paddle micro switch somewhere in the film chain. Place it so the paddle is depressed when the film is threaded. Once a roll out occurs the paddle switch is released and an OSD event alerts you to the roll out. be sure the paddle doesn't scratch and contacts the base side, not emulsion of the film. The hard part here is to get that signal out of the camera in a light-tight way.
I know nothing of the eyemos or their controlling mechanism. What kind of motor do you have on it? Is it crystal synced or wild? Standard electronics or an upgraded model? If your looking for a custom setup I could put something together to include OSD film speed monitor, footage counter, battery meter and roll out alarm. I don't know of any over the shelf parts that would give you positive feedback of camera conditions in a flyable weight for a model size heli. I would have to price it as a one off, but I think I have most of the libraries needed to make the development quick and easy. Weight could be as little as a few ounces. When do you need this to work by? or is it a side project?
Posted 24 February 2010 - 08:52 PM
Posted 24 February 2010 - 09:42 PM
How stock is your Eyemo? Is it a Northridge? A stock Eyemo with a B&H motor? Etc? I'm thinking that a tach signal derived from something in or on the camera radio'd to the ground would give you what you needed to calculate speed and footage with a pretty simple program running on a laptop. Depending on budget a program like National Instruments Lab View could handle calculations and show a nice GUI display.
To make the camera flyable everything must be compact and lightweight. The camera is bare bones/non reflex no electronics based on 1920's technology. It has a external CCD video camera with the same FOV as the prime that is downlinked to a receiver/video goggles to frame the shot. I am looking to add film to our existing commercial service so yes it needs to be very dependable. I don't have a deadline at the moment as it is really in development stage. The motor is 30vdc that is not crystal sync at the moment. I would prefer sync obviously if it could be had without adding to its size or weight significantly. I have come up with an LED indication of power to the camera that I think will work but I would still love to have speed, footage, battery and roll out indication. I would think it would have to be a one off arrangement. I can send photos if that would help.
Tach pulse rate per unit time gives you speed, total tach pulses added is proportional to footage. If you know total footage, you know when you're about to run out.
PS: I love "Flymo".
Posted 24 February 2010 - 09:52 PM
It would cost more than a CP upgrade, but 90% of the system is the same. I would be surprised if pushing data to a OSD chip is much more difficult than sending it to an LCD. There is a chance they are even compatible models out there that would reduce the cost of the modification.
weight could be as little as an ounce or less. The board could be as small as 2x3". I would have to add the work to the end of my design cycle for the CP. I have two months left, but some of that will be delay time waiting for the manufacturers and vendors to turn around the various parts, in which time I could start designing it. I would have to be done with it fairly quick, because there is no way I'm going to be cooped up inside programming and designing during Alaska's summer! My hibernation phase is wrapping up.
Send any pictures you have of the camera and the motor especially. If you have the model of the motor that would help as well.
Posted 25 February 2010 - 08:51 PM
As for you roll out problem, I can see 2 very simple solution. One, a stop watch. If you hit the switch, the camera should run, if not, you'll know as soon as you check it. Film shot at 24 FPS shoots at 90 feet per minute so with ramp up, that would be close to your run out time because if I'm not mistaken, an Eyemo holds an internal hundred foot daylight load (if it's a 200 foot load, that 180 ft for 2 minutes OR around 2 min 14 sec. for 200 ft.). I know they made models that could take exterior mags of 400 and 1000 ft, but I doubt because of the weight you would use those on an R/C helocopter. Now if you're shooting at a different frame rate, the Camera Assistant Manual has a chart with FPS/times in it otherwise you could always just use a calculator, unless, you're one of those wizz kids who can do it in your head like me (yeah.....right, I need a calculator to figure out my age)
The second low tech solution would be to mount another camera/transmitter with a small book light on the chopper so you can see the camera mag and tac readings, maybe use a mirror if one is not in the field of view for any reason. The cam wouldn't have to be all that fancy, it's not like you're going to pull focus with it. ME. I would go with a stop watch.
Posted 26 February 2010 - 04:35 PM
Michael, I will send some photos. Let me know what you think.
We have a fleet of various helicopters. The ones we use for the larger cameras are 52-80cc twin cylinder gasoline models that are custom built and have been highly modified for this type of work. They have payload capability of over 15 lbs. They fly much better with a 10 lb. load so that is my target weight for this set up.
My LED indicator in front of the video assist is on the same circuit as the camera power so it should be reliable indication that the camera is rolling.
Posted 26 February 2010 - 07:30 PM
For pilot data I would use something like this:
With that I should be able to interface through what normally would be the EXT jack on the CP, hopefully allowing me to use the same board as the CP, with a custom program running to work with your camera and the OSD. That would be able to feed down the measured FPS, battery voltage, roll out, and footage counter in real time. And because the board is already designed and built, it would drastically reduce the amount of customization needed to get it to work for your situation.
Send some pics of your motor, I'll try and look up info on it and see if there is a good point where we can get that feedback. Optical is ideal, but hall effect would work in a pinch. Find a main wheel and attach a few magnets around the circumference then place a hall effect sensor just above that.