Topic: Minox GT exposure woes

[mcduff]

(Note I edited this a few times as I was having a bit of a dyslexic moment wrapping my head around over/under exposure as u am juggling between its built in metre and my handheld one!)

 I was going to post this under the minox group in Flickr, but since jojonas is one of the main contributors to that discussion group, I thought I would post it here where the signal to noise ratio is so awesome  In fact, I was just going to PM jojonas about this but thought I would open it up as I think there are a few other minox users here.

That lovely Minox GT I recently purchased is really off on the exposure, and it seems to be doing so in a somewhat non-linear manner. In really low light (say 2.8 @ 1/30th) it is underexposing a bit  (less than a stop) and in normal it is probably 2 stops under.

Is this just due to me using modern, non-mercury batteries? I am trying both LR44 and SR44 sandwiches of 4 stacked together, which is of course kicking out bit more juice than the 5.6 volts that the nasty merc batteries did. As I usually shoot FP4+, I can live with just setting the ISO at some love value (25-50?), but I am wondering if this behavior is typical of the Minox living in a post-mercury world. I have swapped modern batteries for mercury batteries before and the difference is usually not that dramatic -- much more predictable and linear. So I am wondering if it is something else? Is this a normal behavior for a minox GT running modern batteries or did I get a lemon? Its probably the non-linear nature of the problem that most problematic.

I have only put one roll through it (at the rated ISO of 125) and will try one at somewhere around 25-50, to see if that works. However I am looking for any tips before I waste a roll (and I mean 'waste' in the bad way, not the good way that we are supposed to waste it, haha). I have heard that a superior battery solution is using 2 of the lithium CR1/3N batteries. Has anyone tried them? I can pick up a few of them locally, but they are not super cheap and I dont want to grab them if they will not make a difference. As they will also kick out 6 volts when stacked (like the SR and LR batteries) I am dubious - but there must be some difference as I have read where they are NOT recommended as a replacement for 2 SR44 batteries.

So should I
1) Waste another roll of FP4+ set at something like ISO 25-50?
2) Waste some money buying some CR1/3N batteries?
3) Waste some money seeing if a technician can adjust the metre?

I really hope I can come to an understanding with this light metre, as I love the Minox35. Even tho I was not happy with the outcome of the first roll, I really like the way this camera works. I know there are a lot of Rollei 35 users out there (and I have been one in the past) but I think this may be a plastic camera that I love as much as my metal ones!

[Francois]

Hard question since I never handled a Minox. But I had a similar problem with a Konica T3 that didn't even like the WeinCells!
I think your best bet would be to either make or get an adapter for your silver cells. It's just a diode that drops down the voltage slightly so that it matches that of the Hg cell. Butkus has a nice document explaining it all.

[gsgary]

What battery are you using ? Does it need 1.3v if so you need an adaptwr or wein cell batteries

[SLVR]

I just did a little google snooping this morning. I'm impressed that such a small camera needs such a big battery. It needs almost the exact same battery as my Pentax 67 and bronica!

I googled px27 battery to see if they were extinct or not. The mercury ones are long gone but there are silver oxide ones still available it looks like.

You would be surprised how big of an effect the wrong voltage has on a cameras meter. I didn't think it was a big deal until I got my m5. I thought the meter was bunk until I got the silver oxide batteries you recommended. In conjunction with the adapter i have too the meter performs flawlessly.

I'd look at getting a "proper" v27px or  s27px battery.

Likewise, does the minox show you what it's meter is doing? Just go out and compare what it's saying to a camera you know works well, that's what I ended up doing when I was sorting the m5's meter out.


Sent from my iPad using Tapatalk

[gsgary]

If it has the correct battery and the meter is still out you could try different voltage batteries to bring it more in line

[mcduff]

Yes tintin is is funny that such a tiny camera uses so much battery! Prob half the weight is battery ;-)

I think a minor adjustment to the iso dial more or less brings it in line (it seems like a stop will do so setting for 64 for 124 iso film). It still is non-linear tho, it seems like it likes different compensation if it is low light than full sun.

I would still like to know from jojonas and any other minox users if the CR1/3N lithium batteries are worth it.

[Francois]

I know Lithium will have a much higher voltage than the Hg cells it was designed for...

[mcduff]

I know Lithium will have a much higher voltage than the Hg cells it was designed for...

I am wondering if this is why Lithium may be suggested. While it does not have as flat of voltage curve as mercury or silver, it is flatter than alkaline, and more importantly, it looks like its real voltage (once it burns in) is closer to a value that would make it a good mercury replacement. It looks like it is 2.8 volts (give or take) for much of its life so 2 could give you 5.6 volts (the same as a merc battery). Whereas it looks like 4 silver oxide batteries (@ 1.55v each) would kick it out at 6.2 volts. Hmmm.


That link is from http://rick_oleson.tripod.com/index-111.html

More data sheets for the nerdy
a CR1/3N lithium - http://www.tme.eu/en/Document/3254059e85ac28c1ea2ffeeaed274ead/BAT-1_3N-GP.pdf
an SR44 silver oxide - http://www.gpbatteries.it/allegati/datasheet/specialistiche/silver-oxide/1101_GP303.pdf

[Pete_R]

Reading around the net it seems metering problems are common with the Minox. One reference I found said the meter in the viewfinder uses a different circuit to the actual metering system and they can differ by a couple of stops so, first question is, are you just comparing the displayed exposure setting against another meter or are you saying the results of the film you put through it were underexposed?

You would be surprised how big of an effect the wrong voltage has on a cameras meter.

Yes it can, but not always. I have no personal experience of the Minox but did some research into batteries for a Yashica Electro 35 (you can read about it at http://www.z0g.eu/monopix/gtbattery.shtml) and found that the Yashica is very tolerant of battery voltage. It depends on the design of the metering circuit. The Yashica uses a bridge circuit which keeps the circuit 'in balance' for a range of supply voltages.

Also worth mentioning (and more of this at the link above) is that replacement batteries need to be more than just a voltage match. They need to be a match in terms of the current they can supply and/or internal resistance. Murcury batteries generally have a low and constant internal resistance and can maintain their voltage under load better than some more modern batteries. A voltage output of a battery that is struggling to deliver the current may fluctuate and that can be a reason why the effects may not be linear.

[gsgary]

How many batteries are you using ? Just been reading you can stack 2 or 4

[jojonas~]

haha, and here I almost ignored this post because my bad mood over my most recent roll in my latest buy, a PL, ran out of juice mid roll without me noticing. (do a bettery check every day you use it!)

that aside though, I think your camera is working fine
I've tried four LR44's and they drift in exposure more noticably in this camera than in others so I recommend four SR44's with some electrical tape or thin cardboard around as per usual to not get the short fuse or whatever it does.
with that I meter against a plain wall and adjust the aperture so the needle settles on a shutterspeed indicated and then check the iso against another camera. one stop or 2/3 adjustment is usually fine.

now to your problem with the underexpuse... that's just how she works
really, I've noticed that this camera more than any other I've used really reads by the highlights. so just have that in mind and remember that the x2 esposure compensation switch is your friend and learn when you need to use it
it seems they tried to adjust this in later models like the GT-X so the meter was a bit more average-ing. but the GL and early GT I've used acted like this.

it's cool to see that you've got the sunshade btw! that should help with the worst cases with sun hitting the cell. I hold mine upside down from time to time to let the door block some light. I bet it looks funny for people but I don't mind

but yeah, x2 and be there. or if you'd rather not worry as much about it, rate the film down a stop and process normally
let me know how it goes!

[mcduff]

Thanks guys. Yes peter some cameras can handle the change in voltage from mercury better than others and I think this is NOT one of them! I did find the silver oxide seem to be less wonky (as jojonas confirms) and I bet that has to do with the whole voltage under load issue. I might try to get some lithium batteries and see how they work.

Between that and the point jojonas alerted me to (of it having a light metre that is a bit over reacting to highlights), it is a bit of a handful in such a tiny package! ;-) But aside from this issue I really like this camera. I always loved my balda/voigtlander Vito (a minox clone from the same factory) but it is just a bit to automatic (it sets speed and aperture and does not even let you know what is going one). It does take modern batteries and seems to have a less wonky battery tho.

So I will pound a roll through at a stop less and see how that works and be mindful of times to use the 2x button!

[Paul H]

A bit late with this reply.....

I used silver oxide cells in my 35GT for years without any problems, even when using slide film.  I always found the metering to be really accurate, especially under low light & for night shots. In fact, the only problem I had with night shots and longer exposures was that the shutter was so quiet it was really hard to tell when the exposure was complete.

I took apart an old mercury battery, and retrieved the plastic tube that held the mercury cells.  You can then put the 4 x SR44s / LR44s, or 2 x CR-1/3N cells into the plastic tube, and pop it into the battery compartment.

Now, these cameras often suffer from sticky shutters - IIRC, the electromagnetic bits stop working correctly. That does play havoc with exposure!  My 35GT's shutter is now sticky intermittently, which has lead me to stop using the camera.  The real nuisance is that it always seems to dry fire correctly, but when actually shooting with film in it the shutter plays up 

If I shot a scene with strong overhead light (in landscape orientation), I'd just turn the camera upside down, using the door as a shade. 

It was a fantastic camera, with a great lens in a tiny package, and for years accompanied me everywhere.  It should glow in the dark with all the trips it took through the x-ray machines 

[mcduff]

It was a fantastic camera, with a great lens in a tiny package, and for years accompanied me everywhere.  It should glow in the dark with all the trips it took through the x-ray machines 

Paul, I really love this camera. I am also playing with my old Rollei 35 (now owned by a friend) and while I appreciate the Rollei 35, I think the Minox fits what I am looking for, except for perhaps the durability issue. I know of the shutter issues with them, for example. And this one looks absolutely MINT and yet I just cannot get the light metre under control. I know the Jojonas did mention that the metre is strongly influenced by the highlights and he suggests liberal use of the backlight button.

But my particular example is incredibly twitchy. I have set the light metre ISO quite low (eg a few stops below film speed) and even using the backlight button the metre goes through the roof if there is any sunny spots in the scene. I might take it in to see if there is a cheap fix but I fear a full CLA is going to be more than these cameras are worth.

The Rollei 35 I am using has a dead light metre and I appreciate that it can be functional in this state whereas this poor little minox is making it really hard for me to use 

[jojonas~]

my love/hate relationship with these lil buggers continues. I loaded my minox gt-e with fresh sr44's and it ate through them in a couple of days(!)
I even used the do-not-advance-the-film trick but it didn't seem to work on this one.

next I think I'll try the battery holder from the gt-e in my pl. I don't mind the program mode on something that I want to use quick anyway and it has the clear/annoying lights on top so you know it's working.

[johnha]

I have a a GTS and have only had one problem with it, I'd left a roll in it for a while, and when developed it had images at both ends but what looked like unexposed frames in the middle. At first I thought this was a battery problem (maybe I'd swapped the batteries at some distant point in time), but it could also be related to the 2x switch. I remembered that some of the missing shots had been taken with 2x exposure comp. and I'd turned 2x off about the time the shots on the end of the roll started working. Since then I've used 2x again, but not had the film developed yet.

John.