Discussion in 'Lighting Equipment' started by ed_kubacki, Nov 15, 2005.
I am the most pesmimistic person around. I know when they cheat and when they don't know.
So your pessimistic nature will be why you see something to complain about where there isn't anything to complain about.
A very good question!
After searching through my extensive collection of flash instruction manuals - from Nikon, Metz, Sunpak, Nissin and the like - I can find no claim of adherence to ISO or other recognised standard apart from use of ISO in reference to film/sensor speed.
With one exception; an old Braun manual quotes this: "Specification of the
Braun F 900 Professional
(ln accordance with DIN 19011)"
Which is printed next to a table of Guide Numbers.
DIN 19011 was a superceded German standard for the determination of flash output, and nothing to do with the current DIN/EN/ISO 19011 standard that waffles on about auditing management methods.
Nothing more modern seems to even hint at adherence to a standard, outdated or otherwise. So I guess, as suspected, that makers' Guide Numbers are worth less than the virtual paper they're printed on.
Except to be divided by 1.5 as a realistic starting point.
No! Do not use Guide Numbers as a starting point for whatever.
So? What? In the absence of a flashmeter we stick a wet finger in the air and guess at a flash exposure?
Empirical experience shows us that nearly all published Guide Numbers are exactly one stop short of a picnic. So why not use a figure that's proven itself in practise to be a good starting point?
I.e. Divide the maker's lying and connived figure by 1.4 or 1.5, and you're pretty much good to go.
Joe I am sure they conform to a standard which we don't know about.
And by their ridiculous pricing and policing of the Internet, those Swiss ISO gnomes are determined that all of their standards remain 'secret'.
Naively, I used to think that national standards were there for the public good, like checks on weights and measures. The ISO have proven that to be a totally misguided view. It's not like they even bother to create the 'standards' themselves these days; they just leave it up to a committee of bean-counters experts employed by large corporations.
I just go by deduction. As you find out you can pretty much tell the real GN of a flash by its published GN so they must be following a standard somewhere. Now for the ISO I found it's a very silly things. It seems to exist only to allow manufacturers the ability to claim that they follow the standard.
ISO, as far as quality standards are concerned, allowed or still allows companies to set their own standards. A certificate was/is no more than a promise that the company receiving the certificate would aim for that standard. Not that the standard was high.
Anyway, this entire thread is one complaint about a certain number that represents something so well that it is deemed rather usefull.
I would complain about such a thing too, if i had nothing else to do. Maybe.
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