Comparing Metz handle flashes.

tbeaman

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Q.G. said:
If you test any flash unit against any other, with all of them in some sort of auto mode, it would be a sign of a bad flash if it didn't produce the same output as any other unit.
Click to expand...

Who do you think I am, Gomer Pyle?

Attached is the patented SuperFlash™ arrangement that I was testing. The main purpose of the test was to see if the wireless triggers I'd just purchased work (they do!), and also to see how much juice this thing could kick out in combination, with and without an umbrella (to see what kind of options I can get with 4x5 portrait set-ups). Since it was necessary to fire each flash individually as well, I took readings then too.

All four flashes were set to full manual power, and were metered with a Quantum Calcu-Flash II from about four feet away. I didn't take notes, but I think it was about f16 at 100 iso for each flash. The Canon and the two Sunpaks are all rated at GN 100 (feet), while the Metz is 120.

Now, I'm sure someone will ask about the diffuser on the Metz. Removing it didn't seem to make any difference. However, this whole thing made me curious, so I just stood the Metz next to one of the Sunpaks and the meter a measured four feet away. The readings are the same as I remember (actually f18), but it looks like removing the diffuser is now consistently giving an extra 2/3rds of a stop extra light compared to the Sunpak (so, f22).

Therefore, it looks like they perform against each other like they should after all, but that both underperform compared to their stated ratings by almost exactly one stop (calculator tells me they should have been f25 and f30), meaning my Metz rates at an actual GN of 88, and the Sunpak a GN of 72.

So I'm not sure if that accounts for everything, but it looks like I might be Gomer Pyle after all.
 

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wiltw

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A number of us, who use different brands of flash units, have found that the manufacturer stated guide numbers all seem to be about 1EV optimistic, compared to what we measure with pro grade flash meters from Minolta or Sekonic. :confused:
 

tbeaman

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True enough, and that's well known, but Metz has a reputation for being not quite so 'optimistic' with their ratings.

Also, I was a little off with the stated ratings. I don't know where I got that GN 120 from, but the Metz is actually rated at GN 148. That's almost a two stop difference, so I think mine is definitely underperforming. mgb74, maybe you're right about a tired capacitor.

In the end, it's of no real concern to me, and it doesn't negatively affect my impression of Metz and their products. Merely, it serves to remind those interested in purchasing used equipment that inspection and testing is valuable, and when possible, the price that something commands should reflect it's real value. In this case, I only paid $15, so that holds true here. In fact, I'd say it was still a bargain!
 
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MattKing

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Almost all manufacturers' guide numbers depend at least partially on there being at least some reflection off adjacent walls, ceilings or floors.

If you take your flash meter measurements from 10 feet in a room with an 8 foot ceiling painted in a light colour, you will get readings much closer to the manufacturers' predictions.
 

tbeaman

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MattKing said:
If you take your flash meter measurements from 10 feet in a room with an 8 foot ceiling painted in a light colour, you will get readings much closer to the manufacturers' predictions.
Click to expand...

You're right. Placing the two units up on top of a seven foot tall bookshelf in the corner of the room, then measuring from nine feet away gives a GN of 81 and 117 for the Sunpak and Metz, respectively. A pretty 'optimistic' way of rating them, but that's two-thirds of a stop under the manufacturer's rating for both and therefore well within the accepted tolerances.

I forgot that the cheaper manufacturers tend to make their flashes a little more directional so that they can rate higher, and therefore compete better with the more professional units. That said, the Sunpak is supposed to cover as wide as a 28mm field of view on 135.
 
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Q.G.

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There is a clue!

At the short distance, the size of the flash's reflector is considerable compared to that of the dome of a flash meter.
When that happens, things get complicated, because you are no longer measuring the full output.
Differences between source/reflector size of the various flash units may then have an effect too.

(Also, at such a short distance, the thing about reflections being assumed in guide numbers applies. There's not much cnache for light to bounce off something and still reach the meter when it's that close to the source.)


So increase the distance between flash units and meter to tens of feet, at least.
 

benjiboy

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The wide angle diffuser 45-42 you have on the Metz 45 stops one stop of light according to the manufacturers instruction book.
 
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