Started Feb 1, 2010 | Discussions thread
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MightyMike Forum Pro • Posts: 38,917

Hello everyone, I'm sure you know that for the most part shallow DOF is pretty easy with DSLRs however in the area of macros we need to stop down and we stop down so far that we need to provide our own light, this usually means a flash. i've been doing that for years now but only single shots at a time. If i need more DOF i'm going to need to burst off a number of shots and focus stack them. Note: I don't use a tripod or macro rail, a bug won't wait for that and it all gets in the way. Well from experience the flash can't easily handle that. I currently shoot with an F100mm F2.8 and extension tubes, I like F16 so with a magnification factor of 2:1 i'm actually at F48 equiv. the EF500 flash can't quite give me 13 frames of even light at 1/64th power, ISO400, 1/100th sec... i tend to lose a stop by the end.

Here comes my Extremely Bright idea, Why bother with a flash, bursting it off like that will shorten its life and be inconsistent, time for a home made macro light

the idea was to get ISO100, 1/250th sec at F16(F48) well i didn't quite get there, the problem being heat and power and sometimes few reflective surfaces around the subject, i compromised about 1 stop in a ideal situation, 3-4 stops where there aren't many reflective surfaces.

The design required a heat sink and a fan for active cooling, 3 6V 7.5Ah Lead Acid batteries, 2 bridgelux 25 die LED arrays. with the power I am feeding them I am expecting 5000 lumen... I may have got that but getting all that light to the subject efficiently still needs work.

here are some photo of the device, it weighs in a little over 1lb (it doesn't have to look good, it just has to work!)

2 switches, one for the light the other for the fan as you'd want to cool the device after you turn the light off, the temperature rise of the device is inthe ballpark of 5° - 15°C

here it is switched on, hard to give you an accurate idea of how bright it is

anyhow... the results... well i have a full gallery on the way here is the first

1 slice

12 slices stacked... each slice is F8.0(F13.7 equiv.), ISO1250, 1/200th sec, 1:1.4 magnification
the whole thing is in the DOF ballpark of F165-F175

yes its clear at F8 (not F16) and ISO1250 (not ISO200) that the design came up a little short, the light is there we just need to focus it to the right spot
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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