Jump to content

Can 4k and 2,5k HMI's give the same light output?


Recommended Posts

I have acquired some old 2,5K and 4K HMI's. Both are dedicated 2,5k and 4k ballasts. 4k ballast is twice as big as 2,5k.

When testing them I noticed that 2,5K LTM HMI gives the same light output as 4k Sirio HMI.

I don't have a light meter to do the accurate test, but to my eye and on the camera it seems to give the same light output on spot and flood setting, see pictures attached.


What could be the reason? Why 4k is not brighter?

Both lights has new Chinese bulbs now, but the output was the same with used Osram bulb on 4K. Can it be the bulb? Ballast? Or something else?

post-73760-0-28699500-1511511054_thumb.jpg

post-73760-0-81562900-1511511060_thumb.jpg

post-73760-0-76020300-1511511065_thumb.jpg

Link to comment
Share on other sites

Output also depends a lot on the reflector and (not as much) on lens diameter. And Sirios have smaller lenses than old-school fixtures like LTM Luxarc - but that doesn't make them 2x less in output, of course.

Check if the reflectors are clean, make sure the ballass are set to correct mains voltages (big magnetic ballast have separate primary winding taps for 250, 230, 200V, etc).

I won't trust my eyes in such a test, lights are something like 50 000 and 30 000 lux spotted, kind of hard to distinguish in a dim room.

Edited by Michael Rodin
Link to comment
Share on other sites

  • 2 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...