Mcd to microeinstein

1. May 24, 2010

taupune

Hi all.

I have been looking around for a while and done quite some research, however i couldnt find an answer. The one I found were quite complicated ones.

My question is of how to convert mcd to microeinstein.
I know it depends on wavelength. I am using LEd with 30deg angle and 1500mcd and near 660 wavelength (red color).

The closest I could get was using info from this website:
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/lumpow.html

however einstein is in /m^2*s.

S how can i transform the watt to einstein?

I just need a close approximation not exact answer.
Could you give some tips/hints?

Thank you

2. May 25, 2010

alxm

It's tricky, candelas are a perceptual unit, you need to know the luminous efficacy of the LED.

I'd suggest starting at the other end; don't you know the power of the LED? That's usually easier to find out (and I suspect the luminous intensity was calculated from it anyway?. LED's are pretty efficient and pretty monochromatic. So if you assume 100% efficiency and purely monochromatic light, then you should be able to convert watts directly into Einsteins/second using Planck's constant.