Not Telling
Hi.
I am new hereso first let me introduce myself. I am a diver first and a photographer second,and have been very pleased with the modest results obtained from my now ancient Olympus mju 400, but now see the need of updating.
Key requirements to improve on the shortcomings evident to me are, I think, bettermacro-focusing,( the visibility in Scotland, where I do most of my diving lends itself to shooting nudibracts etc); a lighting system to illuminate macrosubjects; RAW format to allow post shooting white balance adjustment, and imagestabilising for good measure.
All to beproduced on an affordable budget.
I have a minilathe and small milling machine and love to dabble so my first thought was tobuild my own housing. I have successfully built and modified led dive torchesand fancy a built-in ‘ring of light’ and shown by Packhorse here and on CandlepowerForums.
My initial thoughts are to follow a well trod path with a piece of aluminium tube, round or square, say 120mm dia with Perspex end plates and O rings.
Sitting 15mm behind the front cover I will fix a sheet of aluminium to act as a diaphragm and heat sink for a collection of LED’s and AMC 7135 regulators.
A hole willbe needed for the camera lens. To avoid all the reflected light the lens would be extended through a hole in the front Perspex sheet to a separate lens cover,with an aluminium cover tube.
All this should be straightforward to produce in a watertight manner.
About now youshould be saying, yes, but the tricky bit is waterproofing the controls.
By using a CanonPowershot camera and CDHK I can get all of my requirements for a camera and the ability to control all the functions via the usb socket.
By using a PICAXE microprocessor I can generate control pulses, using ‘schoolboy’ Basic programming.
To interfacethe picaxe I propose to use Hall effect chips. I have used these very successfully in my torches. A small 3mm magnet can precisely activate it through 3-5mm of aluminium without bother and can generate an input signal to the chip.
At its simplest I am thinking of having the magnet on a small finger ring and having 4 recesses on the outside of the housing. By placing the magnet in each of these in the required sequence I can run through a full menu of camera and light controls. An additional display screen could be added to aid navigation.
A bonus will be that the leds can be at a low power level and ‘flash’ at full power for focus and shooting
I hav ealready bought a cheap A590IS off ebay so can afford to experiment without fear.
My questions are
How thick do the end plates need to be?
How big does the lens cover need to be, should it be glass or acrylic and how thick?
How much illumination do I need? I am thinking in terms of say 4 Cree XM-L giving me around 1000lumen each. (quite often there will be zero ambient light)
Anyone see any insurmountable pitfalls?
Anyone already been down this route and can offer any short cuts?
Thanks
Rod
rrodex99
Member Since 03 Mar 2012Offline Last Active Apr 07 2013 06:16 AM
