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rrodex99

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About rrodex99

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  1. Fascinating project. I hope all goes well. You discuss the pressure capability and possible deflection. What looks right often is right, but there is a free Finite element analysis program Z88 Aurora which will give you the answer in seconds. If you have produced the model for the 3D printer I think you could feed it straight in and check the stresses and deflections. Not at all difficult. One question, you do not show any springs on the buttons, does the camera alone release the button or have you just not shown them? Rod
  2. Here is my latest take on this topic. I have played around with acrylic light pipes but as the density of acrylic is close to that of water I reasoned that the effectiveness would be much reduced. My concept is a piece of 20mm acrylic with appropriate edges cut at 45 degrees in prisms to take part of the inbuilt flash output and distribute it to the two bottom corners around the housing. To achive total internal reflection I needed to put small covers over each reflective surface to achieve an acrylic/air face. I made this for a friend's housing and only took one underwater photo before handing it over, but am making a second unit for myself which will sit inside a diy housing. Photos show the unit on and off the camera, and photos with and without the unit. As it is held on by the original diffuser it can be easily fitted and removed underwater and uses the camera's TTL metering. Rod
  3. Hi guys, As this thread has been brought back to life and ‘ring flashes’ are a regular topicI thought I would post the results of my endeavours. I have now built and used the camera housing I proposed, with a few refinements but quite a change to the housing. The housing now is based on a 10mm aluminium sheet on which the camera and leds are mounted and forms the base for an acrylic sandwich. The front cover is acrylic, recessed to make space for the leds and drivers; the camera lens passes through a black Perspex tube (to prevent light pollution) with a flat port of 4mm Perspex. The back of the housing is made of two sheets, 25 and 20mm thick. All the sheets are sealed by 4mm O rings made to measure from cord, and the whole thing clamped together with 5mm bolts. By milling out of solid sheet the only glued joint is the lens port for which I used super glue. Camera and light control is via four ‘hall effect ‘sensors activated by a small (3mm) magnet within the white bobbin which runs within a cruciform guide. The signal from the hall sensors is processed by an 18M Pickaxe chip which controls the lights and also the camera using the usb socket and CHDK hack. At present the lights come on for a second to allow the camera to adjust, once focus is achieved 5 shots are taken in a burst before the lights go off. In low light dives the leds can be set on but at a low level as a general purpose torch. The 4 XM-L leds are driven at 2.8A by AMC7135 boards, each board has 8 x AMC 7135 and by having both leds and batteries as 2S2P only two driver boards are needed. The only penetrations are for one diy conventional push button to turn on/off the camera, and a hole to operate an on/off switch for the micro processor with a matchstick which is sealed with an o ring and screwed plug. The whole thing has been designed ‘on the hoof’ as proof of concept and working test bench so is still undergoing development before I make a more polished and smaller Mk 2. Current development plans are to replace the sprung battery holder (4 no 18650 Li-on) with a soldered Li-Po battery pack and fit some optics to the leds to gather the light better. I have taken it down to 30m without problems and also confirmed the design of some of the components to be good for 100m by finite element analysis. If anyone want to try finite anaysis, it can be done for free with Z88Aurora. I modelled the back cover in SketchUp (free) and used a plug-in to export in .STL. My photography skills still need polishing but the camera is up to the job it was designed for. At present I have used the Powershot in P Mode, the camera seems to chose f2.6 and exposures between 1/1000 at iso400 and 1/125 at iso 125, depending on the subject, so there seems to be just about enough light being generated and it is nice and even. Since last diving I have fitted some 60 deg optics which appear to give me extra stop or two but the light does not cover the full field of view in wide angle. I have also extended the programme to give full control in Aperture priority or any other mode. February is not a good time to dive in Scotland so it will be a few weeks before I can test it further. Rod
  4. Hi, Thanks for you comments. I dive open circuit air so 45m is all I need. My major dimension will be 120mm as that seems to be readily available and a reaonable size. I am not too worried about the O ring as I plan to get cord and make them up to suit. I have not done this before, but it seems do-able for this application where it is really just a gasket rather than a moving seal. Interested that 3/8" was not enough, this is just the information I need, I will look for 1/2" or next size up. It is the port that concerns me most. Presumably it is easier to get the strength from acrylic vs glass , but will be be good enough optically, or are ther special grades? I am afraid my budget will not stretch to one of your nice domed models, so I am just planning a flat port for now, but if everything else goes to plan I may look at upgrading in the future. Cheers Rod
  5. 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
  6. Packhorse, Great project. I have been inspired to start my own version. Rod
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