Chris T Loc: from England across the pond to New England

Would that honor go to a Nikon unit, or a Canon unit? .... Or, perhaps, to a Sony, or to a Pentax unit? ... Or would these all be bested by a Third Party unit, in fact?

speters Loc: Grangeville/Idaho

Who cares? (they all do what they are supposed to do)!

Chris T Loc: from England across the pond to New England

Right, S

DTran

Well Chris to answer your question I would need to know what do you mean by the most amount of light? If you go by GN then a good number of newer flashes boast very high GN but because they have zoom head and at long focal length setting they can produce very high GN. Some flashes rated their power at 200mm setting. A fairer comparison would be to compare them by the GN at 35mm setting. I think all flashes without zoom head are designed to cover 35mm and all the ones with zoom head do have the 35mm setting so they can be compared. Another way is to compare the WS output but 2 flashes of the same WS rating may produce different amount of light due to their differences in efficiency. Besides most portable flashes do not have a WS rating published.
Now I assume you would exclude the studio type flashes so
Among the handle mount flashes I think the Metz 60 series is the most powerful with GN of 197 ISO 100 and 35mm coverage. For hot shoe mount flashes I think the Quantum Q flashes are the most powerful.

CO

Profoto just introduced their new A1 TTL on camera flash. It's rated at 76 watt/seconds instead of guide number. A reviewer estimated that it's about 1/2 stop brighter than equivalent Nikon or Canon speedlights.

Chris T Loc: from England across the pond to New England

Yes, D .... I agree ... handle-mount flash units are very easy to mark, aren't they?

But this Topic Post is about the on-camera flashes ... which are dedicated to different systems, and, are thus, much more difficult to quantify .....

Chris T Loc: from England across the pond to New England

Wow, CO .... that's really saying something, huh?

Does it have dedicated modules, like the old Vivitar 285, or does it handle dedication differently?

CO

They're made in versions for Nikon and Canon cameras.

Chris T Loc: from England across the pond to New England

Just Nikon and Canon, huh ?

Nothing made, then, for Sony or Pentax?

Fuji, neither?

Olympus, Panasonic?

Shame!!!

Chris981 Loc: Pacific Palisades

I have 3rd party flash units like Bower that have higher gn numbers than my Nikon units. While the 3rd party ones have higher output they tend to lose color consistency, output consistency, don’t recycle quickly and they over heat rapidly. Build quality also lower. My next expenditure for lighting will be one of the pro photo units of minimum 1000 WS.

Chris T Loc: from England across the pond to New England

Bower, huh? ... Really, Chris?

Yes, well, there's 3rd Party Flash Units, and 3rd Party Flash Units ... know what I mean?

CO suggested earlier in this thread ... the Profoto A1 .... apparently a whole half stop brighter than top-of-the-line Canon and Nikon units. Expensive, tho ... $995 !!!

Chris T Loc: from England across the pond to New England

Chris981 Loc: Pacific Palisades

Yes, Bower was lesson learned that like in life you get what you pay for, most of the time. Good lighting equipment is expensive.

Chris T Loc: from England across the pond to New England

Bower is kind of bottom of the barrel, Chris ....

One of the better cheapies is Yongnuo .... many think well of their dedicated adaptability ... and their features ....

But, again ... you get what you pay for ....

The expensive 3rd Party Options - are, well ... expensive, and you might find better deals on Canon and Nikon top-of-the-line units - used ....

But, then - if they're available on the USED shelf - one could fairly ask - why?

amfoto1 Loc: San Jose, Calif. USA

What do you mean by "on-camera flash unit"?

If you mean the "built in" flash that many cameras have.... well those generally suck. They're quite weak, in the worst possible place for redeye and ugly shadow problems, plus they draw heavily on the camera's power source.

If you mean "accessory flash" that typically connect via a hot shoe on the camera (can be mounted in that shoe... or might be used off-camera via a cord or wirelessly).... those vary in power but all are rated by Guide Number (GN), usually at ISO 100. Some use a "telephoto" setting to determine guide number, done by a Fresnel lens in front of the flash tube that adjusts to better accommodate different lens focal lengths (such as 24mm, 35mm, 50mm, 85mm, 105mm). So long as ISO and lens focal length are the same, you CAN compare across various brands even though they're operations are dedicated to different, specific camera systems.

Guide Numbers are stated in feet or meters. It's basically the maximum distance the flash can reach (at ISO 100).

I don't know how other brands name their flashes, but most Canon Speedlite model names give an immediate clue of the flash's power (in meters):

For example, top of the line Canon 600EX has a GN of 60 meters (197 feet).

The mid-size Canon 430EX has approx. GN 47 (141 feet).

Among the smaller current Canon flash are the 270EX series (GN 27 meters/88 feet).

Even the tiniest Canon Speedlite, the 90EX, follows this naming scheme. That has a GN of 9 meters/30 feet.

There have been other Canon Speedlite in the past including 580EX, 550EX, 420EX, 380EX and 320EX. They're all similarly named.

Often third party flash for Canon use the same or very similar model names, giving similar clue to the flash's power. But even if they don't there's almost always a specification somewhere stating the GN.

For sake of comparison, the flashes built into cameras typically only have a GN of about 4.5 meters/15 feet... maybe 6 meters/20 feet or a little further at best. And, even in the hotshoe accessory Speedlites are positioned farther from the lens axis than built-ins, making for less redeye and better shadow effects. But it's also possible to put them higher up and/or off to the side on a flash bracket, attached to the camera via an off-camera shoe cord - or even off-camera entirely and control them wirelessly - to further manage and improve lighting effects. Many also have heads that tilt or rotate to bounce the light and there are many accessory light modifying devices available for them. They also have their own power source, instead of putting a heavy drain on the camera's power source. This usually makes for much faster recycling than built-ins, too.