Canon QL17 + 1.5v battery - adjust ISO or invest in MR9?

darinwc · Feb 19, 2013

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?

Chan Tran · Feb 19, 2013

darinwc said:
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.

Cold · Feb 19, 2013

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.

madgardener · Feb 19, 2013

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.

davidmasek · Feb 19, 2013

darinwc said:
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.

E. von Hoegh · Feb 19, 2013

davidmasek said:
I thought that the Schottky diode is mostly used to drop the voltage by 0.15V.

Correct.

Arvee · Feb 19, 2013

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!

David Lyga · Feb 19, 2013

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

E. von Hoegh · Feb 19, 2013

David Lyga said:
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.

nwilkins · Feb 19, 2013

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.

Arvee · Feb 19, 2013

The only problem with adjusting ISO is that the meter circuitry may not be linear vs. supply voltage. It might now be good in sunny 16 but off when measuring in low light. Most circuits are non-linear but it depends on the camera.

Bill Burk · Feb 19, 2013

Of course the strength of the QL17 is its manual mechanical shutter that you can use with any meter.

nwilkins · Feb 19, 2013

Very interesting. I should add that although I have had no problems I am using b/w film, where there is quite a bit of margin for error. If the OP is going to be using E6 then maybe the converter is the best answer. Also for what it's worth I find I most often use the camera in manual mode anyway.

E. von Hoegh · Feb 19, 2013

Fred Aspen said:
The only problem with adjusting ISO is that the meter circuitry may not be linear vs. supply voltage. It might now be good in sunny 16 but off when measuring in low light. Most circuits are non-linear but it depends on the camera.

Some meters can be recalibrated to use the silver oxide cells, it's well worth doing if you have such a meter.

Cold · Feb 19, 2013

Fred Aspen said:
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. ... 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.

Compared to these results, my little Canonet is downright current-ravenous! I can expect maybe 2-5 outings of life from one 675 zinc air cell. I'm guessing/hoping that there's some sort of fouling/shorting/issue with the circuitry that a good CLA will fix, and that I'll get plenty of life from a silver-oxide, once it's been converted.

E. von Hoegh · Feb 19, 2013

Bill Burk said:
Of course the strength of the QL17 is its manual mechanical shutter that you can use with any meter.

Yes, but it's sometimes very handy to have a camera with built-in metering. I've been using #675 hearing aid cells in my Nikkormat, blocking off three of the four airholes makes a huge difference in cell life, they last a year or more for me.

Arvee · Feb 19, 2013

E. von Hoegh said:
Yes, but it's sometimes very handy to have a camera with built-in metering. I've been using #675 hearing aid cells in my Nikkormat, blocking off three of the four airholes makes a huge difference in cell life, they last a year or more for me.

Now there's a great idea! I haven't given that a shot yet. My concern was that when using two of the cells piggyback, how do you block the holes and still maintain contact between the cells? Perhaps you have solved that issue? I would be most grateful to hear how that is accomplished. Definitely a great idea!

E. von Hoegh · Feb 19, 2013

Fred Aspen said:
Now there's a great idea! I haven't given that a shot yet. My concern was that when using two of the cells piggyback, how do you block the holes and still maintain contact between the cells? Perhaps you have solved that issue? I would be most grateful to hear how that is accomplished. Definitely a great idea!

I fill the holes with glue, then scrape it off the contacting surface. The 'mat takes one cell, the FtN finder for my F as well as my Gossen meters take two cells. You can use O-rings as bushings to keep the cell centered.

The cell in my camera is still active, I installed it April 2011.

mgb74 · Feb 19, 2013

Cold said:
Compared to these results, my little Canonet is downright current-ravenous! I can expect maybe 2-5 outings of life from one 675 zinc air cell. I'm guessing/hoping that there's some sort of fouling/shorting/issue with the circuitry that a good CLA will fix, and that I'll get plenty of life from a silver-oxide, once it's been converted.

Do you use a lens cap? As I recall, the meter is always on.

Arvee · Feb 19, 2013

E. von Hoegh said:
I fill the holes with glue, then scrape it off the contacting surface. The 'mat takes one cell, the FtN finder for my F as well as my Gossen meters take two cells. You can use O-rings as bushings to keep the cell centered.

The cell in my camera is still active, I installed it April 2011.

Thanks for the instructions! I do use the O rings when necessary.

E. von Hoegh · Feb 19, 2013

Fred Aspen said:
Thanks for the instructions! I do use the O rings when necessary.

You're very welcome. Pass it on, I dislike seeing folks ripped of on those Wien cells.

madgardener · Feb 19, 2013

E. von Hoegh said:
You're very welcome. Pass it on, I dislike seeing folks ripped of on those Wien cells.

My Konica Autoreflex TC uses 2 batteries, Stacking them blocked the air holes and I didn't get a current. I ended up buying 2 adapters so I can use the hearing aid cells. All the adapter is, is a cleaned out alkaline px13, which leaves a hole for the hearing aid cell. It works very well in my Konica. Why did I buy the adapter? Because I don't want to mess with the chemicals in the battery, it was worth it to me to buy them already cleaned out.

nwilkins · Feb 19, 2013

mgb74 said:
Do you use a lens cap? As I recall, the meter is always on.

The meter is only on in auto exposure mode, so moving the aperture ring off the "A" setting should turn it off. At least I think so. I always do this when not using the camera.

Cold · Feb 19, 2013

nwilkins said:
The meter is only on in auto exposure mode, so moving the aperture ring off the "A" setting should turn it off. At least I think so. I always do this when not using the camera.

This is correct.

This is where I think mine may have a problem, as the battery appears to be draining in mine regardless of being on "A" or not, capped or not.

darinwc · Feb 20, 2013

OK, after using a light bulb to compare my QL17's meter to another QL17, four other SLR's, and five meters.. I am confused.
I will try again during daylight when I can use a grey card.

Canon QL17 + 1.5v battery - adjust ISO or invest in MR9?

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