580EX II vs 430EX II Power Comparison Question

I know the 430 is less powerful than the 580 but how does that relate to real life shooting. Like, what would you be able to do with the 580 that won't be possible with the 430 in terms of power output?

not really sure, to be honest from my tests I've determined the 580ex only outputs 1/3rd of a stop more light. The one thing is the ability to attach and external battery pack for faster recycle times.

*
The 580EX II flash head rotates 180 degrees in each direction. The 430EX rotates 180° in the counter-clockwise direction only (90° clockwise).

*
The 580EX II wheel on the back allows very fast power level changes.

*
More power on the 580EX II.

The 580ex should have twice as much power as the 430ex. I've been in situations where my 580ex wasn't enough(when bouncing usually), depending on what you use it for you might not find the 430ex or even the 580 to be enough.

58 divided by 43 equals 1.35

That means that at a given power setting, zoom setting, aperture and ISO, the distance range of the 580EX will be 1.35 times greater than the 430EX.

According to the inverse square law, one stop translates to a distance factor of approximately 1.4 (actually the square root of 2). So the 580EX is nearly one stop more powerful than the 430EX.

Curtis N wrote in post #8535860
58 divided by 43 equals 1.35

That means that at a given power setting, zoom setting, aperture and ISO, the distance range of the 580EX will be 1.35 times greater than the 430EX.

According to the inverse square law, one stop translates to a distance factor of approximately 1.4 (actually the square root of 2). So the 580EX is nearly one stop more powerful than the 430EX.

Maybe I need to retest but when i measured the full power output of both the 580 wasn't even close to an extra stop of power.

How did you measure it?

Curtis N wrote in post #8535971
How did you measure it?

Sekonic l-358, and I just tested it again both at the same distance and same power and the same zoom setting and I got f/14 off of the 430 and f/16 off of the 580

Just curious, how did you do your test?

Ahh they beat me to it while the window was sitting here, my bad.

i own both and i would say go with the 580. it has a guide number of 190. compared to 141, and recycles faster

Firotechnics wrote in post #8536016
Sekonic l-358, and I just tested it again both at the same distance and same power and the same zoom setting and I got f/14 off of the 430 and f/16 off of the 580

Switch the L-358 to give you 1/10 stop readings and report back.

Also, it will depend some on what zoom setting you use. When you look at the whole spectrum of guide numbers for the two units, the 580 has a greater advantage at 105mm than it does at some of the wider zoom settings. I don't have a clue why.

Ok so i switch over o 1/10 stop increments and I have my results

580ex

Z-24mm f/11.6
Z-28mm f/11.7
Z-35mm f/16
Z-50mm f/16.6
Z-70mm f/22
Z-80mm f/22.2
Z-105mm f/22.4

430ex

Z-24mm f/11.2
Z-28mm f/11.5
Z-35mm f/11.9
Z-50mm f/16.1
Z-70mm f/16.4
Z-80mm f/16.5
Z-105mm f/16.7

so yes my original tests were inaccurate and at the higher zoom settings the 580 has the 1 stop advantage.

though on average, and please correct me if I'm wrong since I suck at math the 580ex averages about 2/3 of a stop more powerful.

Here's a table with direct comparisons of guide numbers at all zoom settings.
http://photonotes.org …sh2=canon580exi​i&flash3=*

Note that the proportional difference is not the same at all zoom settings.

Considering the various things that can limit the precision of meter readings, which include everything from meter position to recycle time, I think your results are plausible and reasonably consistent with published specifications.

Great topic! I was about to ask the same questions. I want to know the power of my strobes compare to studio strobe such as AB800. How much more power is an Alien Bee800 compare to a 580exII?

Also, how is the Vivita 285hv compared to a 580exII. At full power which has more power??