Speed Light / Monolight Comparison

[neuroanatomist]

Is there a more user friendly way to compare my speed light to a mono light

We wish. [:P] Guide numbers don't work that well, because AoV coverage is also a factor. You can see that because the GN changes as the flash head is zoomed (and Canon specifies GN at the longest zoom, inflating the number). The specs for the Dynalite Uni 400 indicate a GN of 110, but they don't say what reflector. Assuming a 'standard' coverage of 75-85°, that could be compared to the 580EX II at a zoom setting of ~28mm, where the GN is ~30.


Because of reflectors and modifiers, monolight power is usually rated in Watt-seconds (Ws), but that's a measure of electrical power, not light output. Not too useful for comparing them to Speedlites, an analogy might be comparing cars where you have the 0-60mph time for one and the horsepower for another. But, most estimates place the 580EX II at somewhere between 60-80 Ws. Your monolight is 400 Ws, so assuming the 580EX II is putting out the optimistic estimate of 80 Ws, your monolight is 5 times more powerful. If you want to compare in f-stops, that's a base-2 log scale, so as a rough estimate, your monolight provides about 2.33 stops more light than a 580EX II.


Hope that helps...


--John

[iND]

Thanks


So buying a battery pack for my monolight will give a much greater bang for the buck than buying another speedlight and a dual light stand head.


Now that begs the question on batterypack technology.


Jack rabbit? 140 flashes at full power for $400+

[Sean Setters]

I have the Innovatronix Explorer XT, and I've been decently impressed by it. It isn't small, but it has two plugs and the build quality is fantastic. Checking the compatibility chart, it looks like you'd do fine with the XT rather than having to pay more for the SE model. For the same money, I think it'll give you more bang for your buck. It's definitely worth looking into...

[freelanceshots]

interesting information.

[clemmb]

that could be compared to the 580EX II at a zoom setting of ~28mm, where the GN is ~30.
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Interesting[:^)]


I do not have any experience with mono lights but have often wondered about them. I would be interested in a test of a 580EX fired into an umbrella at 28mm zoom at full power compared to a mono light of ??w/s at full power fired into the same umbrella, all other things held constant, to see the difference in exposure setting. Anyone done this?


Mark

[Sean Setters]

Ok guys, just for you. I set up a controlled experiment in my bonus room. I placed a light stand in one corner of the room, and my camera on a tripod on the other. On top of the camera I had my PCB Cyber Commander. The CC features a light meter--handy for measuring relative exposure differences for our little test. On the light stand I placed a monolight firing into an umbrella. The monolight was set to 394 w/s (because the CC wouldn't let me choose 400 on the nose). I used an umbrella swivel to place the umbrella in exactly the same place as it was with the monolight. I tested out a few shoe-mount flashes with the CC set at 100 ISO and the results were...


Ultrazap 1600 set to 394 w/s f/8.0'2


580EX full power, 24mm zoom f/2.8'9


YN560 full power, widest zoom f/2.0'2


285HV full power, widest zoom f/2.8'2





So, relatively speaking, the monolight at 400 w/s equals a little more than (4) 580EXs at full power.

[clemmb]

You are the man Sean,


thanks


Mark