Here is my imitation of Packhorse’s ‘Ring of Light’, but not having an existing suitable camera and housing I decided to make it a composite light and camera housing.
I have used 4 XM-L leds driven at 2.8 amp to give something approaching 4000 lm and a combination of Hall sensors, a Picaxe microprocessor and Cannon CDHK to control the lights and a Cannon A590is camera, with no penetrations of the housing. The whole thing at present is a working test bed, so apologies for the rough appearance. When I first started there were many yet to be solved details and the current build still shows the scars of a developing design and the learning curve of production techniques. There are 4 Hall sensors; the 3mm magnet is mounted in a ptfe bobbin which runs within a cruciform slot, an elastic band snaps it back to the centre position. The controls are grouped into 4 modes with two smallc oloured leds indicating the status. Mode 0 is power management with battery check, camera display on/off and picaxe sleep.
Mode 1 is photo with zoom in and out, and shoots.
Mode 2 controls the macro mode on/off and shooting takes five photos with focus bracketing.
Mode 3 is lights and turns the led’s on/off and ramps up and down the power. The camera is controlled by the length of pulse sent by the picaxe to the camera via the usb cable. Since the picaxe controls both the lights and the camera they can be synchronised so that when shooting, the lights go from a low level to full powers whilst the photo is taken, then turn off, as a pseudo flash plus focus light. With the picaxe and the camera (via CDHK script), both fully programmable (in Basic), the custom options are endless. (inc options to shootin RAW, custom white balance etc etc) The leds are wired 2S2P as are the 4 18650 batteries. Two 8x 7135 drivers power the xml’s using ‘downloads’ technique to share one driver between two leds. The AMC7135 chips also act as the power switch, the pwm output from the picaxe into Vdd directly controls both on/off and brightness. The housing has a ‘chassis’ of a 10mm aluminium plate which acts as the heat sink with the front and back covers milled out of thick Perspex sheets, 20mm at the front for the XML and two 25mm sheets for the camera. The Perspex sheets are bolted to the chassis with ss bolts and sealed by 4mm O ring cord in a peripheral slot. Light pollution into the lens port (4mm Perspex, and the only bit glued on) was at first a problem, requiring the port to be set on a sheet of black Perspex with a black plastic tube set into the lens tunnel and taped external edges. So far I have tested it to 3.4m in the swimming pool, but there is plenty of meat left in the Perspex so I am willing to risk it down to whatever depth I chose to dive. There was nothing in the pool to judge the performance by, but dry test shots are promising. Mark 2 ideas include two more leds to give a slightly directional light option, increasing the lens tunnel and port to accommodate closeup lens and filters, and powering the camera from the Li-ions. Sorry if I am off topic in parts but I thought it would be the kind of project to interest you guys. I’ll be posting some underwater shots just as soon as I can.
IMHO, that is an awesome build! As a fan of super LEDs, custom machining and micro-controllers your build ticks all the boxes.
How do you take a photo? Move it to 0 and hold for a set amount of time?
Are you using the LEDs as a flash or a flood light?
Glad you like it.
To take a photo, or carry out any action, I just flick the magnet across, or up or down, (the white bit in the third photo down in the previous post) and let go. Looks a bit 'Heath Robinson' but actually works well. The chip then send a Pulse of up to 300msec (separate length pulses 50msec apart give different instructions)
If you look in the full size piture, the white ptfe bobbin has a wide bit at the bottom, a narrow bit that runs in the slot and holds the rubber band and a broader bit at the top which just (with a push) passes through the slot at the intesection but holds it all in place.
A 500ms delay in the programme ensures that only one action occurs.
Flicking the switch in the photo mode, turns the leds on full, pauses 100ms to let the camera adjust, takes the photo, leaves the light on for a second, then switches it off. The timings could be played around with but for now I am just happy that it works.
The weight is 2.2kg and the principal size is 210mm x 125mm and 70mm thick. 210 is the dimension of the length of a A5 sheet or the width of A4 which is the size I buy the acrylic in.
Also it just about fits my milling table which only has 220x100 travel.
The batteries are in dx battery holder( rewired from 4s to 2s2p) which sits underneath the circuit board in photo two above.
The photos are; lens port, camera back without cover, camera back with cover and top view. (or bottom to be honest, one small drawback is that when operated righthanded the camera is upside down, so photos two and three are actually upside down).
If you could mount that to a tray and handles, shrink down the enclosure to the minimum and mount the controls remotely on the handle you'd have a great setup for easy and quick photo taking. The handles could even house the batteries, probably 2x18650 each.
Sorry guys if I have had you looking in vain. The secret to controlling the camera is Canon CHDK, and not Cannon CDHK. ( if I cannot get a post right you will understand how long it took me to sort out the programming). My success is all due to the guys at CDHK and all the other forum posters and bloggers, not least CPF who have shared their secrets and let me put it all together.
MSP430's come in very low-power packages, with one and a transistor/mosfet the world's your oyster. They're also dirt cheap, the full launchpad (Arduino type platform) is only about £3 over here and comes with 2 MCs!
I was typing with a capacitive switch, though I'm not sure how they're affected by water yet.