HV Battery for Honeywell Strobonar 882

Discussion in 'Lighting Equipment' started by ed_kubacki, Nov 15, 2005.

  1. I do not agree on this. I think they cheat. Because the GN always errors on the inflated side. They never deliver more power than their rated GN.
     
  2. Consistent, so usefull.
     
  3. In fact I agree with Joe that they overate them by about 1 stop.
     
  4. The GN discussion is no different than the power wars for HiFi back in the 1970s/80s where the goal was to have the highest possible number to advertise.
    So the testing, flash design and reporting are manipulated to give the highest GN.
    • Example1 - In the old days, a flash was designed just to cover a 50mm normal lens, to maximize the GN. vs. another flash that could cover a 35mm lens, but with a lower GN.
    • Example2 - GN is/was given at ASA/ISO 100, but I've seen a few done at a higher ISO, to give a higher GN. You had to READ the specs to see that.
    • Example3 - A few years ago, when I was looking at flash specs, the GN was given for the flash in max tele zoom position, where the light is concentrated the most, to get the highest GN. While they tell you that, it is up to you to figure out what the GN would be in the normal lens position, so that you can compare different flashes and determine if the "normal" GN will match your needs.
    But to be fair, your shooting environment has to be similar to the testing environment. If the testing is done in a small room, but you never shoot in a small room, but instead shoot in LARGE rooms or outside (as wedding/event photographers do), then there is little/no light reflected back to the subject. So of course the advertised GN will not match what you use.

    In the end, you have to test YOUR flash in YOUR shooting environment to determine YOUR GN.
     
  5. Again: consistent, so useful.

    And again: GNs cannot be valid in most photographic situations. The only one in which they would be, you agree they are not valid either.
    So again: they are good for comparisons. So stop complaining about they not being valid in another context. They can never be.
     
  6. I am complaining because the manufacturers intentionally inflate their GN. It's not manufacturing variation or something out of their control. They know their flashes don't put out as much light as the GN suggested.
     
  7. Yes. But whatever they say, the GN is of no practical use. So what?
     
  8. So they cheat. That's what I am complaining about not because the GN is of no use but because in fact I would pretty much know what GN it actually is.
    It's not like you buy 1 lbs of something and you may get more or less than 1 lbs. It's like you know if you buy 1 lbs you almost sure to get 1/2 lbs.
     
  9. You are missing the point.
    GN is based on testing in a standardized environment, whatever that may be, and however unrealistic you may think it is.
    Exposure in the camera depends on the environment that the flash is in.


    Inside my house, the GN exposure might be right on.
    But outside the house in the back yard, the GN exposure will be one stop low. This is because there is no walls and ceiling to reflect the light back onto the subject.
    Take the flash back into the house, and the GN exposure will be right on.

    Even inside, the GN exposure might be different.
    If I go to my friend home with a large room, high ceiling and dark walls and floors, there is less light reflected back to the subject, and the GN exposure would be less than my home with smaller rooms, an 8 ft ceiling and white walls and light floor.
    With the SAME light output, the environment is changing the exposure.

    If you shoot in a different environment, than the testing environment, the exposure WILL be different.
    And if you shoot in different environments (home, office, church, banquet hall, etc.), the exposure will be different in each environment.

    GN is an open loop concept. It is based on just the output of the flash, no consideration is given to the environment.
    Automatic and TTL flashes use feedback to attempt to compensate for some of the environmental factors.

    In your case, it seems that you are shooting in a larger/darker environment than the GN was determined in.
    This does not mean the mfg is "cheating" it just means that your shooting and the testing environments are different, so that you cannot use the mfg GN. You have to adapt it to YOUR conditions.
     
  10. Try it. It won't be. Not unless you live in a gloss-white painted packing case.

    If the "non-reflective environment" instruction stated in the standard was followed, then all other scenarios would require less exposure, not more.

    Why so eager to defend the universal hyperbole of manufacturers?
     
    Last edited: Nov 13, 2021
  11. Why so eagerly complain about the limited usefulness of something that never was meant to be more than it is?
     
  12. I think both Joe and I do not complain about the usefulness of the GN. We said the GN are always inflated and was done intentionally. A way to make a product seems better than what it is. If we during testing the GN and found they are greater than the manufacturers claim they are still not useful but we wouldn't complain about that. The fact that none of the flash I tested so far and I think Joe too would come up with a GN greater than claimed by the manufacturer.
     
  13. Quote:
    FWIW. The GN testing methodology described in the freely available Indian Standard (and probably lifted directly from the 'secret' ISO standard) specifies that measurement should take place in a "non-reflective room". This wording is open to wide interpretation. It could mean anything from a matt black painted large hangar, to a small matt white painted wardrobe. Just as long as it didn't have a mirrored surface.
    End quote

    So what is the reference "non-reflective room?"
    Absent any specifications and definition, as you say it could be anything from not mirrored to MATT BLACK with light absorbing panels, or a hanger.
    Unless you have enough details of the measurement requirements, you cannot duplicate the test conditions. So you cannot evaluate how the test conditions compare to a real life environment.

    What I am saying is that the exposure from the flash depends on the environment.
    So if the GN is based on some representative "indoor" situation, you will not get the same exposure inside your house and outside in the backyard.
    So if you primarily shoot outside, you WILL need more exposure, because there are no walls and ceiling to reflect the light back onto the subject.

    And yes, IF the GN is based on near zero reflectance, then that is more representative of shooting outdoors.
    So if you then go indoors, you will overexpose because of the light reflected back from the walls and ceiling.

    Now to take this discussion from theoretical to real.
    My real world experience when I shot film with manual flashes, for many years, was:
    • Indoors, in an average size room in a house (say 15x10ft with 8ft white ceiling), the GN on the flashes that I used, was close enough for a good exposure.
    • Outdoors or in a large banquet hall, the GN was 1 stop low, and I needed another stop more exposure.
    • This was consistent for ALL my manual flashes.
    • This was based on film exposure, not a flash meter test.
    When I switched to digital, I used first an Automatic flash, then a TTL flash. So, with digital, I do not use the GN calculator.
    So, for today's flashes, I have no idea how close or far the mfg GN is from reality.
     
  14. You feel cheated by a number known to be meaningless other than as a thing to use to compare different flash units.
    That (provide a comparison) they do well. Where's the deception? What wrong was done to you?
     
  15. The cheating is obvious and intentional and the number is in fact not meaningless.
     
  16. You take it for more than it is.
    And then feel cheated because it isn't.
     
  17. It's obviously meant to be literally totally non-reflective, and as close to free-space as possible. Such that only the direct light from the flash is measured. Otherwise it wouldn't be much of a standard - and it obviously isn't!

    However, weasels will seek out weasel-wording and use it to their own advantage.

    In any case: The difference between a direct-flash exposure and a fully-bounced exposure is about 2 stops in a room with an 8' 6" high and matt white-painted ceiling at a distance of 2 to 3 metres from the subject. (see examples below) Therefore, even in those fairly optimum conditions, the reflected light only contributes at maximum about 25% to the directly-lit version. Making a difference of +1/3 stop compared to a free-space exposure. This is a long way short of the 1 stop exposure difference from the maker's Guide Number when measured, or found empirically.

    45CT-4_compare.jpg

    Guide Numbers are 'only' a guide, agreed, but there's being in the right ball park and then there's not even being in the same city! That's the difference.
     
  18. [QUOTE="rodeo_joe|1, post: 5929083,
    Guide Numbers are 'only' a guide, agreed, but there's being in the right ball park and then there's not even being in the same city! That's the difference.[/QUOTE]

    They said it's only a guide and not accurate OK but if something is not accurate it can err on either side but as you found out it only err on the low side so that I say the error is intentional.
     
  19. Fwiw I doubt that the room layout has much effect on those little hot-shoe flashes. They get good power efficiency by putting most of their light into a narrow zone that the lens is looking at. So what I'm suggesting is that there is not much extra light to be spilled onto the walls of the room, reflective or not. (No, I haven't tried this to see, but I have, in the past, had a look at the flash illumination patterns at various zoom settings; the more recent "dedicated" hot-shoe flashes set their zoom settings to match the camera lens.)

    A note in defense of the ISO standards... in the past I've used a number of ANSI standards (the ISO standards seem to be essentially the same, or at least very similar). And I've found them to be pretty good, without loopholes for the most part. I suspect what is going on here is not an ISO issue, but rather people presuming that their flash unit guide numbers conform to ISO standards.

    So here's a question for the users of overrated flash units... does the manual for your flash say it uses ISO-based guide numbers, or in any way conform to ISO?
     
  20. It could be that you consistently have too optimistic expectations of something, and like to blame that on someone else.
     

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