Doctorseyes Macro LED Kit

Harold Gough · Post by **Harold Gough** » Wed Mar 12, 2008 3:40 am

This is the latest:

http://www.kauserinternational.com:80/P ... rseyes.htm

The power is to be increased from 40,000 to 70,000 lux. According to my calculations, that is about four times the intensity of sunlight in temperate latitudes.

cannyman · Post by **cannyman** » Wed Mar 12, 2008 6:27 am

Just lately there has been a lot of interest on using superbright LED`s for front flash. Now I read about this German model and very high lux values. One from the U.S has shown a lot of interest. I enclose a shot of same for you to judge. An electronics store here in the UK has a multi LED model on sale,so I tried it out. I would say its about the equivalent of a 40 watt lamp. Was it Barnum or Bailey who said, "Theres one born every minute."

Harold Gough · Post by **Harold Gough** » Wed Mar 12, 2008 7:37 am

I note that you say "front flash". We must be careful to differentiate between the scope of steady, continuous illumination, of whatever intensity, and that of electronic flash.

With the latter, the shutter speed is largely irrelevant, in determining the exposure, provided it is synchronised with the flash. The very brief duration of the flash, say <1/20,000 second, freezes movement, even at tiny effective apertures. Getting even four times the intensity of sunlight to give a fast enough shutter speed to freeze action at an effective aperture of f90 or f180, even with 800 ISO is probably not going to happen.

I can see that such very bright diodes offer great potential as cold (as in temperature at the subject) light for "modelling" prior to the real work being done by flash.

puzzledpaul · Post by **puzzledpaul** » Wed Mar 12, 2008 7:48 am

<< I can see that such very bright diodes offer great potential as cold (as in temperature at the subject) light for "modelling" prior to the real work being done by flash >>

Not quite the same thing, but I've been using a home-made 'focussing' light, using 4 leds to provide sufficient light to obtain a brighter v/finder image - for the last 3 months or so.

Clips into the same groove around the end of the lens (mpe65 / 100mm macro) as the Canon specialist macro light rigs use (I use a 550 ex, so groove is free)

Total cost less than a quid

pp

cannyman · Post by **cannyman** » Wed Mar 12, 2008 1:14 pm

Harold Gough wrote:I note that you say "front flash". We must be careful to differentiate between the scope of steady, continuous illumination, of whatever intensity, and that of electronic flash.

With the latter, the shutter speed is largely irrelevant, in determining the exposure, provided it is synchronised with the flash. The very brief duration of the flash, say <1/20,000 second, freezes movement, even at tiny effective apertures. Getting even four times the intensity of sunlight to give a fast enough shutter speed to freeze action at an effective aperture of f90 or f180, even with 800 ISO is probably not going to happen.

I can see that such very bright diodes offer great potential as cold (as in temperature at the subject) light for "modelling" prior to the real work being done by flash.

Sorry, just a slip up to mention flash. When talking about duration 1/20000 would hardly ever be used. My balloon bursting shots are at a normal flash speed.

Harold Gough · Post by **Harold Gough** » Thu Mar 20, 2008 6:36 am

Just to give a figure: on full power, a flash duration is likely to be 1/350 of a second or so. The 1/20,000 second would be for a flash, fully discharged, on 1/32 power. However, if the flash duration is controlled by metering then the duration will come somewhere in between those values, with proximity to the subject giving a shorter duration, a greater distance giving a longer one. Quite what the shortest duration, controlled by quenching by the meter, might be is something to which I have no access.

Harold Gough · Post by **Harold Gough** » Mon Mar 31, 2008 2:48 am

A fellow photographer gave me this link.

http://www.mtixtl.com/index.asp?PageAct ... ProdID=636

It is meant for microscope work but, with a 48mm mounting thread, could probably be adapted for use on a camera for much less than the cost of the Doctorseyes units.

Harold