Any Way To tell If Olympus om-1n Has Battery Conversion?

brent.bousquet · May 17, 2017

I just rescued an om-1n that was going to be thrown out. It looks to be in really nice shape and seems to work fine. Just wondering if there was some way to tell if its been converted. Im no stranger to a hand held light meter so its not really that much of an issue just curious thats all.

MattKing · May 17, 2017

Put a 1.5 volt silver oxide cell into it and check the meter readings.

klownshed · May 18, 2017

Take the bottom panel off. If it's converted you will see a diode inline to the lead to the battery chamber. If it hasn't been converted you will just see a plain wire.

It's possible that the diode could have been placed elsewhere in the body but next to the battery chamber is the most likely place to find it.

If you do a google image search for "Om1 diode" you will see a photo Showing the modification.

The bottom panel is easy to remove.

thuggins · May 18, 2017

MattKing said:
Put a 1.5 volt silver oxide cell into it and check the meter readings.

This.

Never ding around with trying to disassemble any part of a camera unless tou really need to.

wiltw · May 18, 2017

MattKing said:
Put a 1.5 volt silver oxide cell into it and check the meter readings.

Just recently I put a real mercury oxide cell (owned by me since before mercury oxide became unavailable, 1.34v measured) in my unmodified OM-1n (owned by me since factory new), then inserted an alkaline PX625A (1.49v measured). The reading only varied 0.5EV (at the light level in which I was testing)...IOW, due simply to normal meter variation between brands, having the real voltage vs. wrong voltage might NOT BE a conclusive difference with only 0.5EV difference!!!

I would depend only upon the VISIBLE evidence of circuit modification by pulling off the bottom plate.

[edit with new observations made on May 19, 2017]

in EV3 light, I cannot tell with certainty what the observed value difference is, but it is between 0.25EV and 0.5EV
in EV7 light I verified just now the observed +0.5EV reading with alkaline voltage
in EV15 light, I observed +1.5EV reading with alkaline voltage

BTW, the reading with mercury oxide battery matched the reading obtained with Minolta Autometer Vf incident.

I reiterate with emphasis, "having the real mercuric oxide voltage vs. wrong voltage might NOT BE a conclusive difference with only 0.5EV difference seen at some ambient light levels"

CMoore · May 19, 2017

MattKing said:
Put a 1.5 volt silver oxide cell into it and check the meter readings.

Are you saying to do That, and then check it against another Camera/Meter.?
If so.....Will there be enough of a difference to notice.?
Thank You

Ricardo Miranda · May 19, 2017

CMoore said:
Are you saying to do That, and then check it against another Camera/Meter.?
If so.....Will there be enough of a difference to notice.?
Thank You

Let me just say I hate meter conversions.
They are done by so called "experts" just to make a buck or 2.

Yes, if the meter wasn't converted to 1.5V in the case presented.

Frank53 · May 19, 2017

Ricardo Miranda said:
Let me just say I hate meter conversions.
They are done by so called "experts" just to make a buck or 2.

Not very kind to say that about the very competent repairmen, who also do those conversions
Both my OM-1 and OM-1md were modified by (different, one in The Netherlands and one in Germany) very skilled repairmen, both specialized in OM camera's.
Regards,
Frank

Ricardo Miranda · May 19, 2017

Frank53 said:
Not very kind to say that about the very competent repairmen, who also do those conversions

The very skilled repairmen I know in the UK are honest enough to say that the conversion to 1.5V isn't the most desirable as there would be still variations in the exposure over the range of Low to High light.
There is a paper here that explains and shows the small variations: http://olympus.dementix.org/Hardware/PDFs/OM1DiodeVer2_1C.pdf
Besides that, what is wrong in using a proper battery like the Weinn-cell or a ZA675?
That's all I use in all my OM-1.

I was poking at a very competent repairman I know. As good as he is, he likes to exaggerate the extent of repairs.

Frank53 · May 19, 2017

Ricardo Miranda said:
The very skilled repairmen I know in the UK are honest enough to say that the conversion to 1.5V isn't the most desirable as there would be still variations in the exposure over the range of Low to High light.
There is a paper here that explains and shows the small variations: http://olympus.dementix.org/Hardware/PDFs/OM1DiodeVer2_1C.pdf
Besides that, what is wrong in using a proper battery like the Weinn-cell or a ZA675?
That's all I use in all my OM-1.

I was poking at a very competent repairman I know. As good as he is, he likes to exaggerate the extent of repairs.

When my first OM-1 was converted I was not even aware there were other options. It's maybe 25 years ago and the camera had been on a shelf for 5 years and needed a complete overhaul (prism replacement, wiring etc and during that overhaul, the converversion was done as a standard procedure). Luckily I never noticed any differences in exposure. And when someone gave me the OM-1md, that needed some work, I had the conversion done as well.
Only after posting a thread here about a OM-1n I got recently, I discovered there are other options and will probably use the Weincell.
Regards,
Frank

klownshed · May 20, 2017

thuggins said:
This.

Never ding around with trying to disassemble any part of a camera unless tou really need to.

The bottom plate comes off with 2 screws. Takes 10 secs. And you can see if there's a diode instantly. Hardly much of a disasssembly.

Edit. FWIW I don't bother with a diode. A zinc air cell does just fine.

Any Way To tell If Olympus om-1n Has Battery Conversion?

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