Leica R4 Program mode slight overexposure battery / film question (XP2)

RezaLoghme · 2026-01-23T15:01:14-0500

Hi all,

I’m looking for some experienced R-series input. I’ve noticed that my Leica R4 tends to produce slightly overexposed frames in Program (P) mode, consistently by what looks like roughly ½ - 1stops. Some context / data points:

Film: Ilford XP2 Super, rated at ASA 400
Lens: Summilux-R 50/1.4
Conditions: Sunny December morning, fairly high contrast (low winter sun, light sky/backgrounds)
Battery: modern PX28 substitute (not original mercury, obviously)

Highlights look a bit flat and scans come out brighter than expected. The behaviour is consistent rather than random.

I’m aware that:

The R4 uses centre-weighted TTL metering
Program mode is fully dependent on meter logic
Modern replacement batteries can have slightly different voltage characteristics

So before assuming anything is “wrong”, I’m trying to decide on the most sensible way forward.

Two options I’m considering:

Option A: keep shooting Program mode, but rate XP2 at ISO 500 or 640 to compensate
Option B: keep ISO at 400, but use –0.5 EV exposure compensation (or switch to A mode with compensation)

For those with long-term R4 experience:

Is this behaviour typical in Program mode?
Any preference between A or B in practice?
Anything else I should sanity-check (ASA dial contacts already exercised)?

Appreciate any real-world input. Thanks in advance.

miha · 2026-01-23T15:41:01-0500

RezaLoghme said:
Battery: modern PX28 substitute (not original mercury, obviously)

This worries me a bit because the Leica R4 uses silver oxide batteries, not mercury ones. Could you specify exactly which battery you’re using as a substitute?

RezaLoghme · 2026-01-23T15:49:22-0500

Maybe I got that one wrong. So the ones originally prescribed are not available anymore, I bought what is available today (some Duracell), and I read that the voltage of modern batteries differs, not much, but enough to create a wobble in the system.

MattKing · 2026-01-23T17:25:17-0500

The 6V silver oxide batteries remain available - it is just that their commonly used designation has changed.
In addition, the silver oxide versions are a lot harder to find on a shelf than the alkaline versions.
There are also newer lithium versions, but only some cameras designed for the PX28 can be used with the lithium ones that came out later.
AI has it right:
The PX28 is a 6-volt battery (often used in vintage cameras and pet collars) with primary, widely available, and inexpensive replacements being the 4LR44 (alkaline) or 4SR44 (silver oxide).
Back in the day, the silver oxide ones were closer in price to the cheaper alkaline ones, so I always recommended the longer life silver oxide versions.
I now install the silver oxide ones in my Mamiya 645, but keep a few alkaline ones in my bag as inexpensive backups.

RezaLoghme · 2026-01-23T17:41:54-0500

Ok I have put SR44 into the R4, as I just checked. So its not the voltage then.

If its not the batteries what else could have let to the overexposure?

Two options I’m considering:

Option A: keep shooting Program mode, but rate XP2 at ISO 500 or 640 to compensate
Option B: keep ISO at 400, but use –0.5 EV exposure compensation (or switch to A mode with compensation)

koraks · 2026-01-23T17:51:43-0500

RezaLoghme said:
Highlights look a bit flat and scans come out brighter than expected.

RezaLoghme said:
The R4 uses centre-weighted TTL metering

RezaLoghme said:
So before assuming anything is “wrong”, I’m trying to decide on the most sensible way forward.

The most sensible way forward at this point is to not assume anything, forget about the clues you think you're seeing on your scans, and in case of doubt, compare the meter readings of your camera to those of a known good meter. In doing so, be ware of differences in metering patterns and between incident and reflective measurements.

Scans are a poor basis voor judging whether a camera meter works well, and "a little flat" in the highlights is not what XP2 would typically do with as little as half to one stop overexposure under the conditions you describe.

I bet your camera meters just fine within the inherent limitations of the concept.

RezaLoghme · 2026-01-23T18:13:00-0500

ok, checked

R4 meter shows same values as other cameras and my phone app.

koraks · 2026-01-23T18:39:58-0500

Great to hear, have fun with the camera!

RezaLoghme · 2026-01-23T18:51:47-0500

Still, the 36 photos were all overexposed.So my question is: what has gone wrong?

koraks · 2026-01-23T18:58:47-0500

In don't doubt the scans don't look like how you had imagined them, but whether they were overexposed is still up for debate.

Going out on a limb:
Meter works fine, but wasn't used optimally.
Metering was fine, but scans came out too bright due to disadvantageous scanning settings/profile.
Odds are 95% that either or both of the above cover the issue. To figure out which it is in this case, let's have a look at the actual negatives (photo of backlit film, not scans) and particularly the shadow areas. If those are unusually dense, overexposure is a part of the issue. If not, it's mostly the scanning/digital post processing part.

RezaLoghme · 2026-01-23T19:09:08-0500

The scan was done by "my" usual lab which has so far delivered extremely consistent results. unfortunately I dont have the negatives.

What I cannot prove is if I might not have set the lens aperture fully to "22" (required when using R in automatic modes). And it the ASA or exposure correction wheel was not 100% set.
Or if the camera's meter works fine,but the link to the lenses aperture does not work 100% correct. Either on the camera's side, or because of the lens (came from CLA, but you never know=.

So I will probably have another test shooting. Thanks for your attempt to help; maybe some R users with first-hand experience will chime in.

koraks · 2026-01-24T03:40:41-0500

Wait until you have the negatives. Scans don't say much. Don't jump to conclusions at this point. You're way too quick in trying to find fault with the camera.

RezaLoghme · 2026-01-24T04:29:31-0500

koraks said:
Wait until you have the negatives. Scans don't say much. Don't jump to conclusions at this point. You're way too quick in trying to find fault with the camera.

I always let the negatived be destroyed by the lab after scanning.

koraks · 2026-01-24T04:38:07-0500

Well, then you'll have to accept that you'll never know whether your photos were correctly exposed to begin with. All that's left is to make the best of it with the scans the lab hands to you.

Btw, I find this decision utterly incomprehensible for any serious photographer. You spend loads of time fussing over cameras, lenses etc. - and then when push comes to shove, you don't even get to see the negatives? You lost me there.

RezaLoghme · 2026-01-24T05:48:33-0500

What would I do with them?

koraks · 2026-01-24T06:02:19-0500

Scan them in an optimal way for the output you have in mind.
Print optically in a darkroom if you fancy.

Either way, take control over the imaging chain.
In terms of impact on overall image outcome and quality, you're fussing endlessly over the 5% influence that your Leica (vs. other brands) gear has on the image while you're ignoring the 95% impact of the digital scanning and post-processing choices. You're trying to bake an excellent cake by choosing the best possible oven to bake it in, but you're ignoring the fact that you're using sawdust and pond water for ingredients. It's inexplicable, illogical and entirely ass-backwards. I'm sorry, but that's the way I see it.

RezaLoghme · 2026-01-24T06:10:04-0500

Well, thanks for outlining your view. I would think that it is very ass-backward to get to so worked up over a gear setup of a 180 EUR camera body and a 180 EUR lens (135mm Elmarit-R in this case) with which I am talking occasional snaps. I surely dont want to have my own lab at home, as I am using a very good "artisan" one in my city. I understand that tinkering in the dark chamber is your hobby. But please be a bit tolerant if other people dont share your passion.

So please lets get back to my original question.

koraks · 2026-01-24T06:14:05-0500

RezaLoghme said:
So please lets get back to my original question.

The answer to your original question is that due to a lack of control over the imaging chain, you paint yourself into a corner where your problem cannot be addressed. You're setting yourself up for failure and try to find a solution in the camera. It's not going to work.

RezaLoghme said:
I understand that tinkering in the dark chamber is your hobby.

To an extent, but I'm not advocating for you to do the same. Digital space is great, too.

The way you've set up your imaging chain presently, the solution to your problem is in Photoshop/GIMP etc.

RezaLoghme · 2026-01-24T06:18:39-0500

koraks said:
(...) You're setting yourself up for failure (...)

Maybe for context: A roll of film from my new-to-me R4 (I think first time I used it) turned out to be overexposed. Delevelopment-wise, "my" lab has done well in the last 3 years. So I am asking the R owners "Could my Program Mode be wonky, or the modern type of batteries".

Really no reason to be so dramatic and start a fundamental discussion.

koraks · 2026-01-24T06:22:09-0500

I'm not being dramatic, I'm pointing out the fatal flaw in your workflow that anyone here with some experience in imaging systems will recognize. Whether you want to address that problem is up to you. It appears that you don't, which is fine, but don't blame me or anyone else for it. This is your decision and I'm only pointing out the consequence of it.

RezaLoghme · 2026-01-24T06:23:57-0500

koraks said:
I'm not being dramatic, I'm pointing out the fatal flaw in your workflow that anyone here with some experience in imaging systems will recognize. Whether you want to address that problem is up to you. It appears that you don't, which is fine, but don't blame me or anyone else for it. This is your decision and I'm only pointing out the consequence of it.

Ok, thanks.

In case any R users have actual hands-on experience with exposure issues related to camera bodies they own(ed), I would also be happy to hear from them.

miha · 2026-01-24T06:29:04-0500

RezaLoghme said:
"Could my Program Mode be wonky, or the modern type of batteries".

It could be wonky, but we really can’t tell for the reasons koraks explained. At that point we’d just be guessing ad infinitum and wouldn’t be any wiser.

For what it’s worth, my R4s Mod 2, if anything, tends to underexpose. After all, these cameras were designed and put on the market at a time when slide film was the film of choice for advanced amateurs.

runswithsizzers · 2026-01-24T06:39:54-0500

RezaLoghme said:
I always let the negatived be destroyed by the lab after scanning.

RezaLoghme said:
What would I do with them?

*IF* you had the negatives you could:
a. use them to help troubleshoot processing and scanning issues
b. rescan them if the lab scans turn out to be less than optimal
c. rescan them if better digitization options become available to you in the future
d. rescan them if your digital files get lost or corrupted
e. make optical prints (or have a lab make them), should you decide to do that in the future (people change)

RezaLoghme · 2026-01-24T08:45:12-0500

Ok thanks.

For now, I want to understand my R4.

Leica R4 Program mode slight overexposure battery / film question (XP2)

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