1.35 volt Button Cells

[Cliffy13]

I have just picked up a gorgeous Minolta SRT 101b but the battery for the meter is flat,anybody know whetre I can get one of these batteries in the UK

 

[sangetsu]

I got a couple Wein cell batteries which are adapted to use in old cameras on eBay. They fit in without adapters, and work fine in my old Canon and Olympus. The seller is located in the US, but he ships internationall (I live in Japan).

 

[Terry Again]

I asked about the same question on page 24 and was going to convert my Minolta to use Silver oxide batteries but the thread also covers the wein cell use and how it'd be cheaper to just buy the zinc air batteries and a rubber O ring to fit around it! This subject should be made a sticky to stay at the top of the page to be easy to find!! Or you could convert to a certain type of silver oxide battery to mimic the discharge rate of the old mercury batteries, Steve Smith is a nice guy and can give you the info you need to convert.He lives in the UK
Cheers
Terry

 

[Steve Smith]

Steve Smith is a nice guy and can give you the info you need to convert.He lives in the UK

Thank you.

If you want to go down the route of modification so you can use modern silver oxide cells then you will need to put a schottkey diode in series with the battery line as per this website: Dead Link Removed

This is a similar description for the same modification to an Olympus OM: http://www.google.co.uk/url?sa=t&so...6-3ECA&usg=AFQjCNEZLyYYqHVjdEkQBKdT7nRW6luSrg

And our previous thread on this subject is here: (there was a url link here which no longer exists)


Steve.

 

[Cliffy13]

Many thanks for that guys and Steve I may go down the Wein cell route as I am technically a total pillock so the mention of adapting cameras scares me rigid

 

[Terry Again]

Your welcome Steve! The truth is true!!
Cliffy do your wallet a favor and just get a zinc air battery and a #9 O-ring to go around it and that's the same as the Wein cell battery!! IF you don't use the camera for weeks at a time then to make the zinc air last longer you can place a piece of tape over the air holes to seal them up while not in use. Check out the link to the old topic steve provided and then make up your mind? Perhaps there is a camera shop you could have do the conversion for you? Or Someone maybe? It's up to you!
Cheers

 

[Cliffy13]

Actually guys just picked up a Weston Master 2 off ebay for 99p so I think that will do the job

 

[wiltw]

Disadvantage to the Wein is that it is air activated, so once activated one cannot try to suspend its lifetime.

One alternative is to go to www.zuiko.com and buy the MR-9 adapter, which you insert a silver oxide 386 battery and then put the MR-9 into the battery compartment; it fits the spot an PX625 or PX13 would otherwise fit.

 

[monochromeimages]

As far as I know this camera uses a moving needle type meter similar to my Canon F1 (first version). If so I have found a silver oxide battery is fine, the increased voltage just causes it to show a bit 'more light' than there actually is. Setting the ISO to half the actual ISO of the film compensates and gives correct exposures. The same also worked for my Canonet QL17 GIII. I'd be surprised if it doesn't work for you.

 

[wiltw]

As far as I know this camera uses a moving needle type meter similar to my Canon F1 (first version). If so I have found a silver oxide battery is fine, the increased voltage just causes it to show a bit 'more light' than there actually is. Setting the ISO to half the actual ISO of the film compensates and gives correct exposures. The same also worked for my Canonet QL17 GIII. I'd be surprised if it doesn't work for you.

The Olympus OM-1 has a needle, too, which one centers in a permanently positioned scale. Its needle swings to one side when power is off. I have conducted direct test of Mercury Oxide vs. alkaline, and have found that the amount of error depends not only upon the actual voltage of the alkaline cell (which varies throughout its lifetime), but is also dependent upon the levels of light being metered, so it is impossible to compensate simply.


I have heard that if a meter needle is centered in a permanently positioned scale AND its meter needle stays centered when power is off, it uses a Wheatstone bridge circuit and is not subject to devialtions caused by different voltage (alkaline cell).

 

[Steve Smith]

I have heard that if a meter needle is centered in a permanently positioned scale AND its meter needle stays centered when power is off, it uses a Wheatstone bridge circuit and is not subject to devialtions caused by different voltage (alkaline cell).

That is correct. If the needle position for correct exposure is the same as the position the needle rests in with the power off and that position is the centre then it is a bridge circuit. As this circuit shows correct exposure when both sides of the meter are at the same voltage i.e. zero voltage difference across the meter then the actual voltage of the cell cannot alter this.


Steve.

 

[monochromeimages]

Agreed that alkaline cells are not suitable. Silver oxide have much more stable voltage over their life and I have found that the above works, well enough at least, in sunlight and for very low light shots.

 

[Steve Smith]

Agreed that alkaline cells are not suitable.

It still depends on the circuit. Alkaline is fine for a bridge circuit but probably not too good for the SRT.


Steve.

 

[benjiboy]

Actually guys just picked up a Weston Master 2 off ebay for 99p so I think that will do the job

Cliffy The Weston Master 2 has no I.S.O. speeds ! it's only calibrated in Weston speeds which was their own way of rating film although you can get a conversion chart this is a very old meter from the 1940s. I f you buy a Weston buy a IV, V, or a Euro-master they are cheap enough these days, and make sure you get the Invercone incidental light attachment with it.

 

[Zuikopath]

1.4v Zinc Air (Wein-type) batteries can be bought at Boots the chemist - I picked up a six-pack recently for £3.75. Look for Boots 675ZA batteries.

It's also worth keeping an eye on Ebuy - I managed to grab a 60-pack of 675 batteries (dated 2013) for £2 including postage

 

[wiltw]

As I wrote before, one alternative is to go to www.zuiko.com and buy the MR-9 adapter, into which you insert a silver oxide 386 battery and then put the MR-9 into the battery compartment; it fits the spot any PX625 or PX13 would otherwise fit.

 

[benjiboy]

If anyone has a Canon EF although originally designed for 1.35 V Mercury cells you can quite happily use 1.5V alkaline or 1.55V Silver Oxide button cells in it because it has a self regulating circuit that will accommodate the voltage difference, but not batteries with rubber "O" rings round them because they need to make electrical contact all the way round.

 

[Steve Smith]

it's only calibrated in Weston speeds which was their own way of rating film although you can get a conversion chart

No need for a chart. The Weston number is 80% of the ISO/ASA. e.g. ISO 100 is Weston 80, ISO 400 is Weston 360, etc.


Steve.

 

[Craig Swensson]

another option which will work without modification is a VARTA V625U 1.35, but, it is alkaline and you need to check/change often, i have an SR7 and use these batteries.
regards
CW

 

[Vincenzo Maielli]

See at www.smallbattery.company.org.uk based in London, they have the best and large options to replace the old outlawed PX625 1.35 mercury batteries, PX400, PX32, PX675, PX27 ecc ecc. Personally, i have bought some Kanto MR9 adapters to replace the PX625.
Ciao.
Vincenzo

 

[Steve Smith]

Many thanks for that guys and Steve I may go down the Wein cell route as I am technically a total pillock so the mention of adapting cameras scares me rigid

If you have a friend who knows which end of a soldering iron to pick up, I can supply you with a suitable diode.


Steve.

 

[Cliffy13]

Thanks for all the advice folks I have got a Wein cell as well as the Weston and the results from trhe cameras meeting are superb as per the following

 

[Vincenzo Maielli]

Nice picture!
Ciao.
Vincenzo