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Shamelessly copied & pasted (my own work!) from another place; apologies if you've seen it elsewhere. I thought it might be of interest here too.
The upsides and downsides of LEDs have been endlessly dissected here and elsewhere. It is really difficult to find meaningful brightness / power comparisons online though. That's intrinsic, of course - the technologies are completely different and the manufacturers have no interest in publishing any such data.
I've recently had chance to do my own tests - in a somewhat non-scientific way - so here's the results.
The test was conducted in my darkened living room - so not an ideal test space, and not pure blackout.
I used a Sekonic L558 with the dome extended, 1m from the source to measure the brightness of a couple of different Rotolight configurations and a Godox AD600Pro. I didn't try running the Rotolights in their overdriven flash mode; ISTR that doubles the output.
It's a bit tricky to compare constant lights with flash via guide numbers so I settled for doing the comparison at 1/125s & ISO100. That's the slowest that most people would photograph a human subject so realistic for my usage.
The ambient light in the room measured f0.7 at 1/125s & ISO320 - so essentially negligible (the meter wouldn't go below f0.7 to give a figure at ISO100). Here's the results:
Rotolight Aeos, no diffuser, pure white, max power: f3.6
Rotolight Aeos, no diffuser, CTO, max power: f2.8
Rotolight Aeos, no diffuser, CTB, max power: f3.2
Rotolight Aeos, standard diffuser, pure white, max power: f3.2
Rotolight Neo, no diffuser, pure white, max power: f2.5
Rotolight Neo, standard diffuser, pure white, max power: f2.0
Then I moved on to the AD600Pro.
AD600Pro, bare bulb, max power: f29
AD600Pro, basic dish reflector, max power: f36
This last configuration is probably the closest to the light pattern coming from the Aeos with no diffuser. So there you have it:
at 1m, 1/125s the Aeos manages f3.6 and the AD600Pro is f36. Assuming that the supplied measurements are accurate that would put the AD200Pro at around f20 give a take a bit depending on which head is fitted.
In other words an AD600Pro is 6 2/3 stops brighter than a Rotolight Aeos; an AD200Pro is 6 stops brighter than a Neo at 1/125s. Remember 6 stops = 64 times brighter
I also performed some tests to see whether the Aeos diffuser made much difference in a +/- 45 degree range of the central axis of the lights. The light spread was remarkably even with or without the diffuser, as measured on the L558 with the dome retracted. That seems to belie one well known LED advocates' claim that LEDs fixtures inherently produce collimated beams of light which have 'superior quality'.
Whether any of that matters in the real world depends entirely on how and what you shoot. For me they work as an accent light, to give a little shape to the face when the ambient is fairly flat. And they're useful in a completely dark space, bounced off silver brollies and without the diffuser fitted.
The upsides and downsides of LEDs have been endlessly dissected here and elsewhere. It is really difficult to find meaningful brightness / power comparisons online though. That's intrinsic, of course - the technologies are completely different and the manufacturers have no interest in publishing any such data.
I've recently had chance to do my own tests - in a somewhat non-scientific way - so here's the results.
The test was conducted in my darkened living room - so not an ideal test space, and not pure blackout.
I used a Sekonic L558 with the dome extended, 1m from the source to measure the brightness of a couple of different Rotolight configurations and a Godox AD600Pro. I didn't try running the Rotolights in their overdriven flash mode; ISTR that doubles the output.
It's a bit tricky to compare constant lights with flash via guide numbers so I settled for doing the comparison at 1/125s & ISO100. That's the slowest that most people would photograph a human subject so realistic for my usage.
The ambient light in the room measured f0.7 at 1/125s & ISO320 - so essentially negligible (the meter wouldn't go below f0.7 to give a figure at ISO100). Here's the results:
Rotolight Aeos, no diffuser, pure white, max power: f3.6
Rotolight Aeos, no diffuser, CTO, max power: f2.8
Rotolight Aeos, no diffuser, CTB, max power: f3.2
Rotolight Aeos, standard diffuser, pure white, max power: f3.2
Rotolight Neo, no diffuser, pure white, max power: f2.5
Rotolight Neo, standard diffuser, pure white, max power: f2.0
Then I moved on to the AD600Pro.
AD600Pro, bare bulb, max power: f29
AD600Pro, basic dish reflector, max power: f36
This last configuration is probably the closest to the light pattern coming from the Aeos with no diffuser. So there you have it:
at 1m, 1/125s the Aeos manages f3.6 and the AD600Pro is f36. Assuming that the supplied measurements are accurate that would put the AD200Pro at around f20 give a take a bit depending on which head is fitted.
In other words an AD600Pro is 6 2/3 stops brighter than a Rotolight Aeos; an AD200Pro is 6 stops brighter than a Neo at 1/125s. Remember 6 stops = 64 times brighter
I also performed some tests to see whether the Aeos diffuser made much difference in a +/- 45 degree range of the central axis of the lights. The light spread was remarkably even with or without the diffuser, as measured on the L558 with the dome retracted. That seems to belie one well known LED advocates' claim that LEDs fixtures inherently produce collimated beams of light which have 'superior quality'.
Whether any of that matters in the real world depends entirely on how and what you shoot. For me they work as an accent light, to give a little shape to the face when the ambient is fairly flat. And they're useful in a completely dark space, bounced off silver brollies and without the diffuser fitted.
