Gossen Luna Pro...

Discussion in 'Exposure Discussion' started by ChrisJarisch, Oct 11, 2010.

  1. ChrisJarisch

    ChrisJarisch Member

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    Hello all. I have a question about metering in general, and MY light meter specifically...

    I have a Hass. 500C. I purchased a Gossen Luna Pro about a year ago. Now that I've had it for a while, I think I sorta have it figured out- by that, I mean I generally have to add 1 to 1 1/2 stops to the reading to get a good exposure. I have checked the batteries, and even replaced them...

    My question is, is this normal???

    It seems somehow not right to me... Maybe this is a newbie question or mistake, but it seems like I should be getting a correct exposure with the suggested EV... assuming all is "normal"... I know that night photography, or a high key subject, etc., will be difficult to meter. I'm mainly talking about an average, normal subject... I guess I want to know if I'm asking for too much from my light meter, and if you'se guys have a similar experience...???

    Also, I have a bit of $$$ burning a hole in my pocket... Would you'se guys suggest buying the Hass. exposure meter winding knob contraption (sorry- it's early, the correct name is escaping me :sad: ), OR... a spot meter... Or, is my Luna Pro good enough???

    I was thinking either of these might be best, tho I'm not 100% sure, so I thought I'd ask my fellow APUG'ers...

    Thanks in advance, all... I love this site :smile:
     
  2. BrianShaw

    BrianShaw Member

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    Which version of the LunaPro do you have, the one with PX-13 cells? If so, it originally ran at 1.3 volts. Did you replace with batteries that are 1.3 volts? If you put in 1.5 volt batteries that could be the cause of the difference.

    I use a Luna Pro, with the Gossen battery converter, with Hassy all the time. It's a good combo.

    If you really have money burning a hole, look into getting a meter that will increase your versatility to include flash and spot metering. I also use a Sekonic L-558. It, too, is a great combo with Hassy, and view camera too. For one of those , or the newer version (758) plan on becoming about $500 lighter. You did use three dollar signs when you mentioned money. :wink: It hurts to pay that much for a meter, but once the sting of writing the check or paying the CC bill is over you'll feel better, and probably not be tempted to buy another meter for a long, long time.
     
  3. ChrisJarisch

    ChrisJarisch Member

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    I don't see a model number on it, but it DOES have the PX-13 batteries.... When I use the battery check function, the needle goes PAST the area in red... If it didn't get to the red, I'd assume the batteries were dead, or dying. But, like I said, mine goes PAST...

    And I do have some $$$ burning a hole in my pocket, but I can't see spending $500 on a light meter... I guess I was wondering if it was a common thing, to ALWAYS have to add a stop or so to the suggested reading...
     
  4. ChrisJarisch

    ChrisJarisch Member

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    And... I just opened the battery compartment. The batteries both say PX625A...
     
  5. wiltw

    wiltw Subscriber

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    Have you tried the 'Sunny 16' method to validate that the issue is meter inaccuracy, and not shutter speed inaccuracy in the Hassy lens?

    Aiming the meter at the sky at an angle to the sun should net 1/ISO f/16 or close to that. Or if you have an 18% gray card in bright sun, you should get the same result.
     
  6. wiltw

    wiltw Subscriber

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    PX625A is the alkaline chemistry form factor, and that is nominally 1.5v (and progressively declining in voltage as the battery is depleted, down to 1.25v) and not the constant 1.35v associated with the older mercuric oxide battery chemistry.

    Unfortunately I do not have sufficient familiarity with the Luna Pro to know if its circuit design is tolerant of alkaline cell variability (compared to mercuric oxide), as some meter designs are and others are not tolerant of non-mercuric oxide batteries.
     
  7. ChrisJarisch

    ChrisJarisch Member

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    Wow... that's alot of technical info.. Thanks! I do think it's the meter... I have several lenses for my Hasselblad, and I use the meter with my Richoflex VII as well... All in all, I guess it's not a big deal, right? I mean, one way or the other, I'm able to consistently expose my negatives properly... It just rubs me the wrong way, for some reason. I think I'll just stick with what I have for now. Maybe I could use another lens instead :smile:
     
  8. wiltw

    wiltw Subscriber

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  9. CD55

    CD55 Member

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  10. ChrisJarisch

    ChrisJarisch Member

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    Thanks all... I appreciate your help very much :smile:
     
  11. BrianShaw

    BrianShaw Member

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    Whichever 1.3v adapter/battery approach you, I urge you to try it. The LunaPro is a fantastic meter and should serve the vast majority of your needs, if your needs are anything like mine. With the adapter I see the same battery check phenomenon that you mention... the needle goes past the batt check markings. The meter gives me good exposure reading and I've never had any reason from looking at results to think that it has been steering me wrong. Good luck whichever way you go.
     
  12. Clay2

    Clay2 Member

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  13. BrianShaw

    BrianShaw Member

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    Silver cells have a power curve more like the old merury cells than does alkaline. Silver cells are better in the Gossen adapter than alkaline for that reason.
     
  14. CGW

    CGW Member

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    With respect, I'd look seriously at getting a new meter. Anything that relied on merc cells--age-related maladies notwithstanding--is dependent on either the MR9 adapter, short-lived+pricey+bothersome zinc-air hacks, or inaccurate alkaline replacements. With film workflow not getting any cheaper, a meter with so-so accuracy seems like a false economy. The Sekonic 508 is a relative bargain now, and the newer 558 usually goes for $300+/-. In a pinch, the little Sekonic 308 does nearly everything except spot metering for a good deal less. I've got the 558 and the 308--love 'em both.
     
  15. Clay2

    Clay2 Member

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    Yes, a new metre may be in order. I still use the Gossen for sentimental
    reasons. The new mercury cells from China or Germany are a different
    chemistry and voltage from the old ones. Only in North America are mercury cells banned,
    but we are forced to buy mercury 'green' fluorescent light bulbs! Go figger???

    Best regards,

    /Clay
     
  16. BrianShaw

    BrianShaw Member

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    That's a very true and factual statement... when and if a meter really has so-so accuracy! :smile:
     
  17. CGW

    CGW Member

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    Beats me, too. Pale to think about the mercury load from fluorescents merrily tossed into landfills. Thought big corp makers like Varta stopped cranking out merc cells in 2000 due to European concerns over heavy metal pollution. Small camera stores around the GTA carried real PX625s a few years later. Have a small stash of those for the still-accurate metered finder on a sweet old black Nikon F.
     
  18. Q.G.

    Q.G. Inactive

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    Not only in North America.
    For instance: there are no (!) new mercury cells from Germany.
    And it's not just North America and Germany either.
    :wink:
     
  19. MattKing

    MattKing Subscriber

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    The adapters that permit use of silver-oxide cells work well.

    For another option, consider adapters for hearing aid batteries. Hearing aid batteries use the same technology and provide the same voltage as the special purpose zinc-air batteries, but are a lot less expensive.

    You can use hearing aid batteries if you adapt them for your meter (they are physically a different size).

    There are a number of sources for adapters for size 675 hearing aid batteries. I've been happy with the ones Jon Goodman sells. He can be found on eBay as "interslice". He is best known for his camera light seal kits.
     
  20. PSimpson

    PSimpson Member

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    Just bought one of the old meters myself for $40. It has the $20 adapter to take Silver Oxide cells (don't use alkaline LR44, use SR44 for flatter voltage curve). I've done a little looking, and you have two options if you don't choose to buy the adapter : open the meter up and tweak the trimmers to recalibrate it: http://www.graphic-fusion.com/lunapro.htm (LunaSix = Luna Pro), or get a Schottky diode (like a BAT-54) for under a buck from Digikey and solder it (or have an EE friend do it) in series with the positive battery terminal.
    Same result either way and your meter is good for many years to come.


    Regards,
    Peter

    //mine's for use with my Revere Stereo 33 inherited from my father-in-law.
     
  21. BrianL

    BrianL Member

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    This week I finally had to dump the 625s (PX13) I had for my Leica CL, Metrastar and Weston Ranger 9. About a year ago in anticipation of this I ordered 4 CHRIS MR9 adaptors from his company, no need to use eBay. The Leica only uses the battery for the meter. After inserting the adaptors I check the 3 meters and each was dead on with the other. Virtually no difference from my Bronica ETRS readings. Can not the company recalibrate the meter to use the silver/alkaline higher voltage? Either option will be less expensive than a new meter.
     
  22. M.A.Longmore

    M.A.Longmore Subscriber

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    .
     
  23. r-brian

    r-brian Member

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    Dropped and broke my Luna Pro a while back. Finally sent it off to Quality Light Metrics in Hollywood. Got it back in one week with two new parts in it, adjusted for 1.5v batteries and calibrated. Total cost was $90 but I now have a quality light meter that's good for my life, as long as I don't drop it again. Just one of 5 working meters I have.
     
  24. Greg Davis

    Greg Davis Member

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    You may have to consider the possibility that your personal EI (film speed Exposure Index) may be 1 1/2 stops slower than box speed with your camera/lens/meter/developer combination rather than a faulty meter. Unless you are just trying to find a reason to get a new one. In which case I just got a Sekonic L-758DR and love it.