Leica SL - Exposure problem or settings not right?

[DaveS]

Hi all, I just got the SL and like it.

I bought it initially for just manual focus lenses, since I have so many of them. (Leica M, R, Olympus OM, and Canon FD/LTM all with adapters.) Which is proving to be fun to revive so many of my 'keeper' lenses from my film days.

The problem I need help with is metering exposure errors in 'A' mode when I stop down below F8 on any lens I test so far. (M and R with the Leica brand adapters)

The problem for me is as follows:

- Point camera at static subject with a manual focus lens on Leica adapter (M or R) in 'A' mode
- Start out wide open, then take picture or just look at meter reading, and stop down one stop at a time
- The shutter speed cuts in approx. 1/2 every stop until around F8 - then it doesn't really go down after that much, it under exposes every F Stop after that (from F11 to F16 or F22 depending on the lens)

When I pointed it at a blank wall it seemed to work today with my Leica 35-70 F4, in room light, but fail in outdoor light

So it seems to need:

- complex subject. (anything but a blank surface)
- Brighter EV (light) ?
- Auto ISO fails
- Fixed ISO fails
- Center weighted or complex metering pattern fails
- In Fixed ISO (pick any ISO) it seem to get slightly better turning off 1/focal length or 1/2focal length setting from Auto ISO menu
(which is really weird since Auto ISO wasn't on to make it fail)


It seems to be roughly OK till F8 and then exposure gets all confused and stays about the same so every picture gets darker and darker.

One more problem:

Lastly problem 2, taking pictures the joystick 'magnify focus' got stuck in the upper right and it took a battery removal to let the camera work again. I even turned it off, and it stayed on!


Any help on the exposure problem or settings is greatly appreciated. (I think problem 2 is a random bug)

thanks all!

Dave

 

[Godfrey]

You're running into the metering range limits, which is typical for stop down metering TTL situations with all cameras to greater or lesser degree. The SL response is worse than some others, but I've seen it with all my 'mirrorless' cameras and adapted lenses: Below about f/5.6-f/8, metering falls off and accuracy suffers unless you're metering very bright circumstances, leading to underexposure.

There aren't many good workarounds. Going to Manual exposure and using a fixed ISO as well as Exposure Simulation mode (two shortpresses on the FN button) will restore accurate metering up to a point, but you have to give the camera time to collect all the exposure data. This means, for instance, if the required exposure is two seconds, the camera cannot read out a correct histogram and exposure for at least two seconds.

In most normal, average day-lit circumstances, this problem does not surface. But in indoor room light, etc, it can be problematic. I've just taken the tack of making a few test exposures (Manual mode) and then guesstimating when I know the metering will be compromised. Or carrying a meter.

This situation almost never surfaces with the SL's dedicated lens because then the camera has control of the lens opening—it has much more information to work with as well as much more light at the sensor.

I've written about this before. Few people either noticed or responded.

G

... BTW: I've found similar issues with the Sony A7, with the Olympus E-M1, and with the Panasonic G1. ...

 

[DaveS]

Thanks Godfrey, I didn't know about that phenomenon. (I did a search and couldn't find anything, but I might not have used the correct key words)

So I will probably just stop at F8 or use exposure compensation and the histogram view to adjust it after that. (It is strange that the turning off the auto ISO settings seem to give it one more F Stop of room before failure, even if I am in fixed ISO settings. So either I am not reproducing the problem correctly, or there is some slight interaction on the ISO settings that don't make sense to me.)

But that is helpful,

thanks for the quick reply.

all the best,
Dave

 

[jonoslack]

HI Dave
Sorry to come to this so late - Godfrey's answer is a good one.
It does also depend on your Auto ISO settings - I can't remember what the camera defaults to, but it's important to understand the shutter speed options. I think it defaults to 1/fl (1 times focal length).

This is fine . . but if you put on a lens via an adapter and you don't choose a lens in the M or R menus, the camera doesn't know the focal length, it's clearly trying to do something, but i'm not sure what! (it puts 0mm into the exif information).

If you haven't already done so try setting a maximum shutter speed in Auto ISO settings (depending on the focal length of the lens). I have both Lens Profiles and Auto ISO settings in my favorites menu.

As far as the magnify getting stuck . . . and then the camera not turning off, I think I've seen that . . . basically it's hung! (damned computers). I must say though, considering it's an entirely new camera with entirely new firmware I think it's remarkably stable - hang ups are few and far between.

All the best

 

[scott kirkpatrick]

Godfrey and several others spotted this problem a while back. Auto ISO prefers to let you underexpose rather than violate the maximum ISO or minimum shutter speed that you select. If you set a minimum shutter speed of 1/f or 1/2f and then present it with a lens of very short focal length, or unknown focal length, or zero focal length (all of which can occur in our slightly immature firmware), the minimum goes to 1/30 sec. To get slower shutter speeds, I set fixed ISO, and I seem to have no lower limit on the shutter speed. I don't see f/8 as a boundary point. My auto ISO settings are max ISO = 3200, max exposure time = 1/f and floating ISO ON (I believe that gives values between the full stop or 1/3 stop settings. YMMV and there may be additional settings that I have made which have an effect.

Let's calibrate our exposures. My old GossenPro meter and the Weston meter that I learned about in Ansel Adams The Negative have a natural exposure scale in EV. A light level that produces zone 5 on ISO 100 film with an exposure of 1 sec at f/1 is called EV 0. Sunny 16 for ISO 100 (f/16 at 1/100) is EV 15 (using 1/125 as the exposure). A good analog meter could give me readings down to EV -2 to -4.
With auto ISO on, I'm focused on a dark corner in the office (and it is night outside), giving me 1/80 at ISO 400 with f/1.4 set on the lens. The amount of light from the wall is about EV 6. The minimum shutter speed is 1/80, so f/2 gives me ISO 640, f/2.8 gives me 1250, f/4 gets 2600, and around f/5 we hit the wall. f/5.6 and smaller apertures all produce my max ISO, 3200. I've set Exposure Preview ON, so I can see what is happening when I half-press the shutter. The screen darkens and the histogram shifts to the left. In this case, my AutoISO settings confine me to operating at EV 3 and above -- the amount of light that is seen inside the camera with the lens stopped down a bit more than three stops.

Now let's set exposure to ISO 100, not changing any other settings. f/1.4 gets me an exposure of 1/15. f/2 likes 1/12, f/2.8 is 1/6 second, f/4 is 0.3, f/5.6 is 0.5, f/8 is 1 sec, f/11 is 2.5 seconds, and f/16 will get 5 seconds. The screen does not darken when I half-press, the histogram does not shift. I take a picture of the boring office corner and it is properly exposed. This means that the exposure calculation inside the camera was operating at a light level of 0 to -1 quite successfully. So using fixed ISO works for me.

scott

 

[DaveS]

Thanks Godfrey, Jono, and Scott, those responses helped me figure this out.

Still enjoying it a lot, will try and set up some favorites for common lenses and settings.

Three samples so far.
- night time = Leica R 35-70 F4
- Watering girl = Canon FD N 85mm 1.8
- houses - Canon FD 17mm

All three are light and well balanced on the SL, and amazingly the SL/lens combos do a very good job of resolution corner to corner - wow.

take care,
Dave