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  1. #1
    darinwc's Avatar
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    Canon QL17 + 1.5v battery - adjust ISO or invest in MR9?

    Hello all! I just replaced the seals on a Canon QL17.
    This is the smaller model with the 40mm f1.7, but with the plain QL17 nameplate before they updated to GIII.

    I also cleaned the rangefinder, and wow what a difference that makes! It's like 2x as bright as any other viewfinder ive seen.

    OK, so here is my question.. I was planning to just use a silver-oxide 1.5v battery but I was reading about the MR-9 adapter.
    It reduces the voltage from 1.5v to 1.35. But does it actually have a voltage regulator circut to keep the voltage steady or does it just have a resistor that flatly reduces the voltage?
    Go not to the elves for counsel, for they will say both yes and no.

  2. #2

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    Quote Originally Posted by darinwc View Post
    Hello all! I just replaced the seals on a Canon QL17.
    This is the smaller model with the 40mm f1.7, but with the plain QL17 nameplate before they updated to GIII.

    I also cleaned the rangefinder, and wow what a difference that makes! It's like 2x as bright as any other viewfinder ive seen.

    OK, so here is my question.. I was planning to just use a silver-oxide 1.5v battery but I was reading about the MR-9 adapter.
    It reduces the voltage from 1.5v to 1.35. But does it actually have a voltage regulator circut to keep the voltage steady or does it just have a resistor that flatly reduces the voltage?
    If I were you I would try the 1.5v battery and see if it's accurate enough. If not I would use the camera without battery as the QL17 can be used without battery.

  3. #3

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    From what I remember, it's a fairly simple in-line resistor to reduce the voltage, but the silver-oxide batteries have a surprisingly flat discharge voltage anyway, rivaling that of mercury.

    If you're shooting B&W negative, I'm sure you could get results 'close enough for government work' shooting at the rated speed. After a few rolls, if you notice consistent over-exposure that is problematic (I've come to appreciate a touch of overexposure in my negs), a simple adjustment of ISO on camera would probably be sufficient.

    Of course, it's worth noting that eventually, I'm planning on sending in my own QL17 for a CLA soon, at which point, I'll be having the shop convert it for the silver-oxide cells...so take that for what you will. :P

  4. #4

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    Another alternative is to purchase an adapter, and use standard hearing aid cells. They provide almost the exact voltage your camera needs, downside is that they don't last that long. I'm using them in my Konica Autoreflex TC.

    If you do a search on Ebay you can usually find them, or if you are handy you can find plans on the internet to build your own adapters.

  5. #5

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    Quote Originally Posted by darinwc View Post
    But does it actually have a voltage regulator circut to keep the voltage steady or does it just have a resistor that flatly reduces the voltage?
    I thought that the Schottky diode is mostly used to drop the voltage by 0.15V.

  6. #6

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    Quote Originally Posted by davidmasek View Post
    I thought that the Schottky diode is mostly used to drop the voltage by 0.15V.
    Correct.

  7. #7

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    I found the best solution for these cameras that use the old PX625 mercury batteries is to make a quick trip to Costco and go the pharmacy and buy a card with 30 ea. 675 hearing aid batteries. These zinc-air batts are about 1.4v nominally and last a couple of months. The batts on the card don't get activated until you remove the blue foil tab. I believe I paid about $10 for the card. I have been running my old cameras on these batts for 4-5 years now. I think it is the best solution for these old cameras. Yep, you have to change them more often but you don't need an adapter, circuit changes, or recalibration of the light meter circuit.

    If you are really frugal, you can remove the batts from the camera after use, re-install the little blue tab and put them away. This stops the chemical reaction and discharge of the battery. Like I said, I have the original card from 4-5 years ago and still have a few left. I think the card has a 5-6 year 'use by' date on it.

    If your camera is a current hog, take a couple of extras with you when you shoot.

    You simply can't beat this solution!
    -Fred

  8. #8
    David Lyga's Avatar
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    Correct me if I am wrong here but when a 1.5V button cell starts to lose power, doesn't its power drop from 1.5V? Is there really such a big deal between 1.35V and 1.5V? - David Lyga

  9. #9

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    Quote Originally Posted by David Lyga View Post
    Correct me if I am wrong here but when a 1.5V button cell starts to lose power, doesn't its power drop from 1.5V? Is there really such a big deal between 1.35V and 1.5V? - David Lyga
    It's only a "big deal" if you want an accurate meter.
    Mercury oxide cells were used because of their flat discharge curves. Silver oxide cells also have a very good discharge curve, nearly as flat as mercury cells. Alkaline cells do not have a flat curve, their voltage falls constantly over the life of the cell.

    Hearing aid zinc-air cells are the best low cost solution, a Schottky diode adapter is the deluxe solution as it allows you to use long life silver oxide cells.

    .15v doesn't sound like much, but it is better than 10% of 1.35v and yes it does make an observable difference in readings.
    Last edited by E. von Hoegh; 02-19-2013 at 09:47 AM. Click to view previous post history.

  10. #10

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    I am using a non mercury battery in mine and I just found a surface of uniform brightness to take meter readings. I simply adjusted the ISO until the Canonet meter agreed with the meter on my FM2 (around half a stop difference). The AE setting has worked fine since then.

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