Do you worry about absolute accuracy of your meter

Discussion in 'Exposure Discussion' started by BobF, Dec 13, 2002.

  1. BobF

    BobF Member

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    Because of a recent thread about meters I have been obsessing about my meter's accuracy and metering technique. With all the inherent inaccuracies of metering and metering technique I am wondering about how many of you worry about half stop differences in different meters or in my case a reported half stop difference between my Seckonic L508 in spot vs. incident mode. I personally don't experience problems with B&W but I suppose it could be a problem with transparencies.

    In trying to see if my meter has a problem I started thinking about the problems of how to check against a standard, and we have 12% vs. 18% gray as a standard. Then of course different light cell's response to different light wavelengths. Also there is technique, such as angle of gray card or incident dome to light source and in spot mode which green grass or other surface is truly representative of 18% gray (or 12% gray depending on the meter). Which shadow is spot metered for detail and the film and development you are using. I guess we should also consider what printing method you use, contact, condenser, diffusion. To further complicate this we have new MC lenses vs. old single or uncoated lenses that may actually flare enough to effectively preflash the film. I could go on about bellows extensions etc. and I am sure you can add more variables.

    With all of the above either separately or cumulatively it is no wonder everyone seems to arrive at their own metering technique and EI for different film/dev. combinations and therefore the common advise to test for yourself with your equipment and your technique.

    So my question, do you obsess about absolute accuracy of your meter/meters (if there is such a thing) or like me have you developed a "system" with your equipment and technique that works for you and you don't sweat the half stops.

    Bob
     
  2. Prime

    Prime Member

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    I don't "sweat" the half stops, I just make sure that my exposures are more accurate than that. I primarily use transparency film, and half a stop is outside of my tolerances.

    I wouldn't be unduly concerned about a meter that wasn't perfectly accurate, as long as it was consistent. It would be useful as long as I tested it and knew how to compensate. The meters that I've seen, though, all have been quite accurate.

    I think, too, that exposure can be very subjective. Often, correct use of the meter may indicate a certain exposure, but I know that I will adjust the exposure based on the situation.

    Incidentally (ha!), my metering improved markedly once I started exposing QuickLoads, which cost me $4.00 to $5.00 each.

    I'm happy with my own system, which I've developed (ha!) after much practice.
     
  3. SteveGangi

    SteveGangi Member

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    I don't sweat it. Another factor you could add in for variability is the variation from one batch of film to the next. All I can say is, if you use something like Velvia which "wants" a narrower range of "correct" exposures, then bracket. But the qualifier here is that I shoot mostly black and white film and color print film, which are pretty forgiving. Like Prime said, even if your meter was off, that's OK so long as you have an idea how far off it is. Most are pretty darn close. Plus if you are using a spotmeter and zone system, what you see as Zone III may be different from what I see as Zone III.
     
  4. BobF

    BobF Member

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    Glad to read some agreement with my attitude, but I still have the feeling that many would not tolerate the half stop.

    Steve, your point about how we each see what is zone III is well taken and to underscore it over in the thread "Shadow Detail" Les is advocating using zone IV instead of III. In his total system it must work.

    If we could take apart several different peoples "systems" it would be interesting to see where the compensating +/- are to arrive at the same result.
     
  5. SteveGangi

    SteveGangi Member

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    I start by considering what shadow detail I want to have at Zone III. then I look at what highlight I think should be at Zone VII. This way I can quickly size up the overall scene brightness range. Once that is done, I then see what might look good as Zone V (trees or grass) or a Zone VI to Zone VI-and-a-half or so (peoples faces). But for me, it is easiest to "see" and judge the extremes (III and VII). Anything in between for me is a judgement call. Sometimes when in doubt, I will shoot one sheet as recommended by the spotmeter, and a second one as indicated by an incident meter, unless both give me the same exposure reading. Generally, I can then print to either a grade 2 or grade 3 paper.
     
  6. BobF

    BobF Member

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (SteveGangi @ Dec 14 2002, 07:38 PM)</td></tr><tr><td id='QUOTE'>But for me, it is easiest to "see" and judge the extremes (III and VII). &nbsp;Anything in between for me is a judgement call. &nbsp;Sometimes when in doubt, I will shoot one sheet as recommended by the spotmeter, and a second one as indicated by an incident meter, unless both give me the same exposure reading. &nbsp;.</td></tr></table><span id='postcolor'>
    Pretty much sums up my approach but it still leaves the question of precise meter readings when so much judgement comes into the equation. You (and I) make a judgement about anything in between but also judge what is a III shadow. My III shadow may not be the same as yours but may be the same as what Les calls a IV (or not). If you are using say HP5 have you rated it at 400, 320, 200? Just with those two factors we could have a couple of full stops of judgement (from experience?) to offset a half stop of possible meter difference.

    I was looking for someone that does require absolute meter precision but I guess no one does.

    Bob
     
  7. avandesande

    avandesande Member

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    Are you guys saying I should dump my Weston II meter?
     
  8. SteveGangi

    SteveGangi Member

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    You mean the Model 735 Master 2? Keep it. I have 2 of them myself.
    To answer the previous question about film rating, I use the film at the Ilford suggested speed of 400 and develop at their sugested times. I probably could rate it at 320, but have not yet done it. It seemed to me that everyone had their own personal EI for every film, their own special times, and their own "special sauce". I decided to keep it simple. I might be more particular if my income depended on photography but even so, there are just so many variables and unknowns to foul up any data I might collect and I had to wonder if it was worth the effort for me.
     
  9. Robert

    Robert Member

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    Only thing that matters is if you're happy with the results. The thing about figuring out what works for you is we all do things differently. No way the film companies could check everything we might do.

    Does your Master II read ASA or weston ? Mine reads the weston system. The IV I have is rated for ASA.
     
  10. SteveGangi

    SteveGangi Member

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    Mine both read Weston.
     
  11. Robert

    Robert Member

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    Do you adjust the Ilford ASA rating to the weston then?
     
  12. SteveGangi

    SteveGangi Member

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    No, I just move the dial on the meter "about a notch". If you want, I can find the URL for a site that has a lot of info about Weston meters when I get home from work.
     
  13. Robert

    Robert Member

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    I'm just curious. 400 weston is what 500ASA?
     
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  15. SteveGangi

    SteveGangi Member

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    http://perso.club-internet.fr/ptthome/weston-man.htm

    http://www.diaxa.com/weston/westontwo.htm

    http://www.westonmaster.com/

    For mine (unless I got it backwards) if using ASA100 film, I set the meter for Weston 80. For ASA 500 I would set the meter for Weston 400.

    Here are some quotes from a Weston meter page.
    In short: Models- Master V, Master IV, Universal III and all cine models
    Sangamo/Weston Source - Use the film speed rating recommended by the Film manufacturer. OR -Cine Models only - the next lower rating is recommended.
    Ensure that the ASA or Din rating is set in the appropriate window of your Master V
    *****Regarding the Models Weston Master II universal and earlier...
    Use the next lower rating to the B.S or ASA arithmetical index recommended by the manufacturer. *****
     
  16. Ole

    Ole Moderator Staff Member Moderator

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    Nah. I don't worry at all. I picked up a Pentax Spotmeter (no modification) on Ebay for next to nothing. I meter shadows, midtones, highlights. Then I guess at an exposure which will give good shadows. If the highlights are way high I might make a note of it for the development.

    But if the meter is off, doesn't worry me at all. As long as it's consistent.
     
  17. Ed Sukach

    Ed Sukach Member

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (BobF @ Dec 13 2002, 10:14 AM)</td></tr><tr><td id='QUOTE'>Because of a recent thread about meters I have been obsessing about my meter's accuracy and metering technique.&nbsp; With all the inherent inaccuracies of metering and metering technique I am wondering about how many of you worry about half stop differences in different meters ...</td></tr></table><span class='postcolor'>
    In a previous life I was involved in calibrating "Light Meters" - in particular, those employing Cascade Photomultiplier systems. The set-up was on an optical bench, with Intralaboratory "standard lamps" calibrated by the National Bureau of Standards, and amperage-contolled power supplies. (Note 1)

    At the time, there was an idea that the Honeywell 1/21 Spotmeter could be used in some of the light measurements we were doing. Three were purchased and "wrung out" on the bench. The results were surprising, so we contacted Honeywell, and after a rather tough struggle, got them to tell us what their criteria for accuracy was ... plus or minus (+/-) one-half "stop".

    I use the Gossen "Ultra Pro" - usually with the incident attachment - for studio work . Gossen states that the operating tolerance for the UP is plus or minus (+/-) one-third "stop".

    There are so many variables involved in photography - tolerances on film speed (really difficult to pry that information from the manufacturer) - remember the information sheets on Polaroid film that directed the use of increased - or decreased film speed settings -; Tolerances on shutter speeds; aperture stops --- does anyone remember the Bell and Howell 35mm camera where the lens aperture was labelled in "T" stops, instead of "f/" - to indicate a more realistic system of controlling the amount of light (T)ransmitted through the lens?

    Add to all this the human element -- the subjective judgement involved in metering the "scene" - and the finely exposed film that is routinely turned out is a tribute to the skills that "involved" photographers have mastered.

    In sum, I avoid making the statement, "I always expose within "x" fraction of a stop." I can't tell - all I really have to determine that is the equivalent of a rubber ruler.

    Note 1: The primary voltage in the first stage of one of these Cascade Photomultipliers is usually fairly high -- about 1800 volts. I took a "belt" from one of those once - not really dangerous - but a real eye-opener.
     
  18. David Hall

    David Hall Member

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    It seems like half stops would mean almost nothing to BW users, but would be pretty critical to people who use transparency film, ESPECIALLY people who photograph people on transparency film.

    And for that, it seems like you could do a simple test once to make sure the meter meters uniformly relative to itself, and then you're done. It doesn't really matter if it matches other meters or not, unless you have to use more than one meter in differing situations.

    As for BW, I can't imagine a situation in which a half stop would mean the loss of anything. As a practical matter, it seems it would only mean that you expose your paper a second or two longer or shorter, or MAYBE burn or dodge for a second or two in some highlight or shadow.

    Am I missing something?

    dgh
     
  19. benjiboy

    benjiboy Subscriber

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    It seems to me it's an unwritten truth about exposure meters, that no two ever give the same reading, either in reflected or incidental methods, but somehow give correct exosure, I wonder why that is.
     
  20. jovo

    jovo Membership Council Council

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    When I dropped my Adorama (Soligor) one degree digial spot meter a year ago, I bought a replacement of the same thing (only an earlier model) on ebay never expecting I could bring the broken one back to life. Since then I've had it repaired and calibrated by Richard Ritter (in Vermont) to whatever absolute standard it is that he uses. Now, the two meters disagree by about two or three tenths of an EI and I'm sorely tempted to send in the second meter to be 'standardized' with the first. Thing is, with a very small compensation, the two work splendidly and my exposures are just fine. So....the anal urge for perhaps unnecessary precision is in a precarious balance with common sense practicality. I think, for the time being at least, I'll spend the cost of calibration on film. Or maybe not....;-)


    BTW...I encountered Richard Ritter at the View Camera LF conference in Springfield last month. The guy looks like a Vermont 'character' poster boy, but man does he know his stuff. If you need view camera or spot meter (Pentax or Soligor under its' own brand or rebranded like Adorama) work done, this dude's got it goin on!! Highly recommended!!
     
  21. Claire Senft

    Claire Senft Member

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    I am of the upiinion that there is nothing made that is absolutely accurate. There are only differences that matter and do not matter.
     
  22. Michel Hardy-Vallée

    Michel Hardy-Vallée Membership Council Council

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    I'm really not that experienced with slides, but I just started shooting some expired Ektachrome 100S (which I got thanks to the kind sale of a fellow APUGger) with my Yashica-D (yashikor lens, not the better yashinon one) and I use a Metrastar 30degrees meter that's older than me. I can see differences in one stop overexposure, but otherwise I'm blown away by what's coming out of my rudimentary equipment.

    I meter for the highlight, put it on a relevant zone, try to keep the light source at my back, and shoot happily. Even without bracketing I haven't had problems. I suggest you put more effort than that only when you face a situation that you can't solve easily, otherwise you'll be stuck into considering gamma rays but not actually shooting. Learn when the needs happen: you can't prepare for everything.

    Happy sliding!
     
  23. eric

    eric Member

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    Like my meters, I have 3 darkroom thermometers. Each one has a different reading. I put all 3 in and average it out. Somewhere in there, is the right temperature.
     
  24. Canuck

    Canuck Member

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    I find that as long as the meter is consistent, I can live with it as far off as a 1/2 stop. Besides, my meter is far more consistent than me and my selection of what to meter at times :D
     
  25. Loose Gravel

    Loose Gravel Member

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    I don't worry about absolute calibration either. If one has more than one meter it is nice to have them match.

    A friend of mine and I recently had occasion to have a bunch, maybe 8, meters together at one time. Some were spot, some were cameras, this and that. It was amazing how close they all were. There was maybe 1/3 stop between them, except one that was 1 stop out. That one we disregarded completely and called the others good.
     
  26. Flotsam

    Flotsam Member

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    Toss out the high and low, average the rest ogether and BINGO!