Watts, Lumens, Lux, W/s, GN?

[terry.langham]

Is there a way to convert these to compare different light sources?

Been looking for continuous and flash light sources but it is hard to compare them when they are all in different measurements. Then to get an idea of the amount of light they are capable of putting out, I would like to be able to compare them to the compact flash units I have, but again I am not sure if or how to convert the ratings.

Cheers
Terry

[JM Tran]

tell us what flash units you are using first, and what lighting stuff you are looking at too

[terry.langham]

Currently I have a Canon 420ex and a NoName Brand of similar power (both left over from my parents film SLR days). Neither are adjustable so pretty much useless for anything except TTL.

I have been looking into portable LED light panels for on the road and continuous CFL clusters at home. I have been looking at the sort of photos I would like to be able to do on Flickr and most seem to be done with Strobes. So I was hoping there would be a way of comparing outputs of different sources even though they are all measured differently.

[terry.langham]

Here (http://protog.com.au/144-led-video-light-with-colour-adjustment-p-393.html) is what I am considering for portable light or something similar. What I would like to know is how they compare to the output of say a YN560 or Canon 580ex2?

[terry.langham]

Guess I may be having to suck it and see.

[ameerat42]

Terry. Watts don't count in the above line-up, but watt-seconds do.
Watts are units of work, but there is the efficiency of the light source to consider in producing the light output. (Think of incandescent vs compact fluorescents.)

Also, compare flash units using GN, and compare continuous light sources using lumens.

Comparing between the two sets of units would be a bit hard.

(Now what happened to the chap from NZ with all his experiments with flash units and lightery? Went back thru my posts but couldn't find him.)
Am.

[I @ M]

Terry, I haven't had anything to do with the led lights but I do know that you need one helluva lot of power from compact fluros to get results. They are best used for fairly long exposure shots on a tripod where every little detail in the subject is not going to be seen.
From what I have seen from images done with the newer led panels they appear to have quite a lot ( relative to most constant lights ) of power and the advantage of less heat output but I think they will still fall short of a strobe for outright intensity and the ability to "freeze" motion in subjects.

[terry.langham]

[snip]
Also, compare flash units using GN, and compare continuous light sources using lumens.

Comparing between the two sets of units would be a bit hard.

[more snip]

Thanks Am, you have summed up my quandry better than I could. I guess what I was really asking for is some opinion from personal experience. However I haven't seen much use of small LED panels in my searches, whether that is because they aren't capable or just not 'accepted' yet, I don't know.

Thanks Andrew. Have done a bit of experimenting with DIY CFL clusters and had some OK results. If I can find a source of more powerful bulbs, at a reasonable price I would be set. Studio shoots aren't very high on my to do list at the moment so I am happy to leave my experimenting until I have more time to dedicate to it.

I will order a couple of portable LED panels soon, as there are a few advantages over flashes for me (lightpainting being the main one at the moment). If I find they aren't strong enough, I may pick up a decent speedlite later to use as a key lite and use the LED panels for fill, hairlights etc.

Will be sure to report back when I get some conclusive results.