Pen-FT incorrect meter values

joao_ · May 7, 2021

I just picked up a Pen-FT from ebay and the meter seems to be way off.

On a sunny day it's taking me to 1/8s for the meter to show 0. It shouldn't matter, but I'm using the Zuiko 1.8

My question is: can this be the battery? If so, what battery should I buy?

Or might the meter really be broken and I should send the camera back?

I'm new at these things and any guidance is appreciated.

Les Sarile · May 7, 2021

The mercury battery was what it was originally made to use. I understand hearing air batteries can be used. There is an adapter to use other cel batteries with a diode to drop the voltage. Or, you can install that diode in the camera. I opted to have the diode installed when I had mine CLA'd so I can use the silver oxide cel batts.

joao_ · May 7, 2021

That's helpful. I see you're local, where did you have it installed?

Also, can battery be the culprit of this incorrect measurement? I'm trying to understand if I should try and find a battery or send the camera back as defective.

removed account4 · May 7, 2021

I sent mine to John Hermanson
http://www.zuiko.com/
he is the best!

joao_ · May 7, 2021

I'm seeing these batteries on amazon. May be worth a try?

WeinCell MRB625 Replacement Battery for PX625/PX13 https://www.amazon.com/dp/B07JCPG9YN

wiltw · May 7, 2021

joao_ said:
That's helpful. I see you're local, where did you have it installed?

Also, can battery be the culprit of this incorrect measurement? I'm trying to understand if I should try and find a battery or send the camera back as defective.

Yes, wrong battery voltage can be the source of error. And, if the Pen FT is like the meter circuit of the OM-1, the amount of meter error can VARY, depending upon the brightness of the light being measured! I confirmed this to be true about 25 years ago, when I still had a working PX-625 mercury battery and compared result to alkaline PX-625A in my OM-1n.

The Wein cells output the proper 1.35V, same as mercury oxide. Unlike mercury cell, the Wein will continuously deplete ittself even with a camera switch off...the chemical reaction continues nevertheless, once the seal is removed.
The alternative is to get a MR-9 adapter to change voltage from silver oxide cell.
But beware that in recent years, adapters claiming to be MR-9 are sold, and these are merely physical size adapters that use AIR CELLS just like the larger diameter Wein! These are NOT true voltage chainging adapters!

This is one of the impostors https://www.amazon.com/Acxico-Batte...?dchild=1&keywords=MR-9&qid=1620427815&sr=8-3
its description says

"The adapter fits for LR44,hm-4n or a 1.4v Zinc air battery, which are very common in supermarkets or convenience stores."

You can clearly see the HOLE in the top to let the air in!

This is an example of the original MR-9 function https://www.ebay.com/itm/323976304794?epid=8007658362&hash=item4b6e7e189a:g:TCkAAOSw1T1d5Q~A
Its description says

"This adapter converts "SR43" Silver oxide battery to "MR-9" Mercury battery appearance.
This converts the voltage of "SR43" battery 1.55V to about 1.35V.
"

MattKing · May 7, 2021

The size adapters work well with hearing aid batteries. The Wein batteries use the same battery technology as the zinc air hearing aid batteries, with perhaps a change in how those cels breath.
It is true that the Wein and the hearing aid batteries don't last a long time once opened. It is also true that the hearing aid batteries can be purchased in quantity very cheaply. So depending on your usage pattern, they can be perfect for your need.
I have used both the voltage adapters, and the physical size adapters with hearing aid batteries. At times, I have used the different types of adapters at the same time, in two different pieces of equipment. Each has their use.

wiltw · May 8, 2021

I found the original source of the MR-9 adapters!

https://shop.criscam.com/collections/mercury-battery-adapters

Huss · May 8, 2021

I use this adapter, cheaper and better made than the Cris one. Works perfectly in my PenFT, meter readings are perfect.

https://www.ebay.com/itm/130646083632

p.s there is a lot of incorrect info on the Cris site about which cameras need adapters to correct voltage. They list the Nikon FT2, Agfa 500 and 1035 in part. All those work correctly with regular batteries.

gone · May 8, 2021

Once you get the battery sorted out, it would be good to have some sort of 2nd exposure source to ck it by, like another camera that gives aperture and speed readouts. I've had cameras w/ meters that exposed properly using sunny 16 outdoors in good light, but were way off in shadowed light.

Congratulations on your new camera. These have been of interest to me ever since I saw a Warhol exhibit of his snaps using Pen cameras. The half frame has enormous possibilities for contrasty, grainy images. Just the thing for shooting in the 'loin.....during the day. I can only imagine what those streets look like post-pandemic.

Huss · May 8, 2021

I love using my Pen FT for triptychs or 'penoramas', where you can change the point of focus within the group of shots. In this one the hiker is in focus, with the background OOF, while the ones to either side of it have that in focus.

joao_ · May 9, 2021

This is awesome! Thank you all

Pen-FT incorrect meter values

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