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Member Since 03 Mar 2012
Offline Last Active Jul 01 2014 12:56 PM

Posts I've Made

In Topic: DIY housing for E-M5

18 January 2014 - 01:49 PM

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?



In Topic: DIY Housing ideas

12 February 2013 - 01:58 PM

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.

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