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http://metku.net/hwforum/viewtopic.php?f=65&t=6947
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Author:  japala [ 15.11.2009 23:19 ]
Post subject:  Question / Comments?

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Questions, comments?

Kysymyksiä, kommentteja?

Author:  Jipa [ 16.11.2009 00:30 ]
Post subject:  Re: Question / Comments?

I'm so building my own one! ;)

(no kidding, I already ordered the rings...)

Author:  Jyrchi [ 16.11.2009 01:57 ]
Post subject:  Re: Question / Comments?

Hmm, sounds like a pretty good idea and wouldn't do any harm in my Sony either. I wonder how one of those rings would look in a case fan...

Author:  AK [ 16.11.2009 02:06 ]
Post subject:  Re: Question / Comments?

I thought of making a ring light too after I saw those pop up in the latest additions at DealExtreme. My main usage will be with my macro lens so they seem to give enough light for that purpose. I'm hoping to get my rings next week as they should have left HK already.

Author:  gregdowning [ 17.11.2009 00:26 ]
Post subject:  Re: Question / Comments?

Great ring light! Anyone know where I could get rings like this in red, green and blue LEDs? I am using a retroreflective screen for "greenscreen" shooting. The LED rings hotlights they sell for this are 1000s of dollars. Would love to do it with a $6 part! Also have any suggestions about building a dial to adjust the brightness?

Author:  japala [ 17.11.2009 02:20 ]
Post subject:  Re: Question / Comments?

Easiest way to control the brightness would be to use a rheostat / potentiometer. Better solution would be using a LM317 adjustable regulator.

And sorry, at the moment they do not carry other colors. :(

Author:  richardsan@mac.com [ 17.11.2009 06:53 ]
Post subject:  Re: Question / Comments?

coloured LED's might not be available but coloured perspex™/lexan™/plexiglas™ certainly is available...i'm using a low-tech solution at present, but i am eager to make this project. i am a jewelry fabricator and this looks like it will fill the light around the small metal objects i make.
i currently use a white glass [milk glass] lamp shade. it is truncated and fits around most of the small objects i photograph. i can get my nikon 950 right in there to shoot. in ambient light, it works quite well, scattering light all around.
with the light ring, i'll be able to use a larger digital slur.

Author:  japala [ 17.11.2009 08:47 ]
Post subject:  Re: Question / Comments?

Lamp shade is a good choice for this kind of small objects. I've also seen cones made out of paper to scatter the light coming in from the sides. This method has a dual purpose as it controls the reflections too.

Author:  IainMcClatchie [ 17.11.2009 10:44 ]
Post subject:  Re: Question / Comments?

How much actual power do these ring lights have? I'd like to build a 10W to 20W light, but I'm going to guess that the decorative ring around a headlight is more like 2 watts.

Author:  japala [ 17.11.2009 14:13 ]
Post subject:  Re: Question / Comments?

The smaller ring alone:
P=U*I = 12 volts * 120 milliamps = 1.44 watts.

With the larger one:
12 volts * 330 milliamps = ~4 watts.

If you want more but can't increase the size of the light, perhaps cold cathodes are the way to go. Sure, there are more powerful leds out there but they product quite a lot of heat and one should need several of them to make the light appear more uniform.

The ones that I used offer a steady light but they are not that bright so that you could shoot hand held with very small apertures etc. This just offers a cost effective way to make a usable ring light. I would suggest a tripod but for example the photo from my wife's eye was shot 1/200, f6.3, ISO160 and 50 mm. So it all depends on one's needs.

Author:  maurice [ 17.11.2009 14:29 ]
Post subject:  Re: Question / Comments?

I’d really like to know how much light this produces. By this I mean at a distance of 3 ft what is your shutter speed if an fstop of 5.6 and an iso of 200 is used? Even an estimate from the author would be fine. I just don’t want to build this to find it’s so underpowered that it’s not useful for my uses.

Author:  japala [ 17.11.2009 15:18 ]
Post subject:  Re: Question / Comments?

Maurice, read the post above your question.

Author:  maurice [ 17.11.2009 16:38 ]
Post subject:  Re: Question / Comments?

Thank japala. I missed that comment. Just to be clear there was no cropping done on that photo, correct? My guess would be that you were about 20 cm away from the eye, right? Since light dissipates by the reciprocal of the square of distance you probably need a tripod for all picture taken from 50 cm or more. Do my guestimations seem reasonable?

Author:  japala [ 17.11.2009 18:26 ]
Post subject:  Re: Question / Comments?

No cropping. I believe you are right about the distance. For example that photo of my daughter's eyes is already 1/25 with ISO125 and f7. For some reason I managed to keep it steady even without a tripod but with that slow shutter speed that was a near miracle. :)

Author:  nismode [ 17.11.2009 21:04 ]
Post subject:  Re: Question / Comments?

Japala, I saw your mod via a tech blog, and I am very impressed. I would like to make something similar, or I'd be willing to pay you have you make me one, since I'm not really adept with soldering and such.

Also, you say that you used a motorcycle battery to power these...Is there any other way to get these powered? Possibly via the hotshoe?

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