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Thread: Help with G1 underexposure with 20mm 1.7

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    Unhappy Help with G1 underexposure with 20mm 1.7

    Hi,

    Got the G1 yesterday and tried out the Pana 20mm 1.7 with a lot of excitement. Big disappointment When exposing under artificial light (WB set to auto and incandescent) most of the photos look clearly underexposed by at least a couple of stops ! I do not see the same behavior when using the 14-45 zoom and the photos are correctly exposed. Is it a problem with the 20mm and the G1 ? How does one fix it?

    My G1 has firmware 1.4 if thats of any help and I was using the matrix metering.

    Thanks
    Dipankar

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    Subscriber Member Streetshooter's Avatar
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    Re: Help with G1 underexposure with 20mm 1.7

    Check your EV setting. I find it best to keep it at -.3
    That sounds like the problem.
    Where is your ISO set? That could be it also.
    I'm in Philly if you want to call...
    We can work thru it...
    Don... 267-784-4042

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    Re: Help with G1 underexposure with 20mm 1.7

    Don,

    Thanks for the inputs. Checked the EV settings - no issues with that, in fact have to compensate by a couple of stops to get the correct exposure. ISO is set to Auto . Also the underexposure is only for those areas where there is a mix of well lit and shadow areas or overall dark areas. A well-lit room for example exposes fine. And with the other lenses there is no problem

    Dipankar

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    Re: Help with G1 underexposure with 20mm 1.7

    Maybe it's time to post a few images with exit data.
    Then maybe you'll get some constructive feedback.

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    Re: Help with G1 underexposure with 20mm 1.7

    Don,

    Adding couple of underexposed images for reference

    Dipankar

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    Re: Help with G1 underexposure with 20mm 1.7

    On googling found that this has been raised as a known issue but with no resolution !

    http://forums.dpreview.com/forums/re...ssage=33476563

    Did any of the G1 users on this forum with Pana 20mm face this and can help?


    Dipankar

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    Re: Help with G1 underexposure with 20mm 1.7

    Quote Originally Posted by dipgang View Post
    Don,

    Adding couple of underexposed images for reference

    Dipankar
    Hi,

    I believe both those images are underexposed - but only if your reference is for more light. The camera is compensating for the bright stuff in those images. I guess some weird light metering method is used?

    You need to learn your new equipment. What does it do in different situations? For example, AutoISO and AutoExposure systems, in particular intelligent and artificial evaluative modes can trick a photogrpaher.

    I don't know of any problem with exposure and the G1 and 20/1.7 combo so you can probably make things work for you:

    Turn off AutoISO, turn off evaluative metering and set the camera to A mode, manual ISO, manual White Balance and Center weighted metering only. That's a good starting point as you are in control. Shoot a plain ordinary boring wall or something with no specular highlights or light sources in the image. Use a tripod, check different aperture openings, switch lens to the kit zoom and if you are lucky you'll see the images look pretty much the same. Rule out the problem having a possible problem with the equipment.

    Take a lot of images and you'll learn how to adjust the EV comp to get it right in different situations.

    Good luck,

    /Jonas

    EDIT: I see you found a problem by searching... OK, then there is something. I haven't run into this. I still think you should try it out as described above.
    Last edited by Jonas; 27th August 2010 at 11:25. Reason: a slow typist found another post agyer having posted...

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    Senior Member Y.B.Hudson III's Avatar
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    Re: Help with G1 underexposure with 20mm 1.7

    In A mode...put the meter in the spot meter mode, take the reading of the area your interested in and use the AE lock to hold the reading.


    I would recommend a basic photography course...

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    Senior Member Peter Klein's Avatar
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    Re: Help with G1 underexposure with 20mm 1.7

    I recently had the same thing happen. Some indoor photos were grossly underexposed. It was in a restaurant with very reddish light, almost no blue in the histogram at all. ISO 800, lens set wide open, evaluative metering. I never have this trouble with my M8, I just aim the center at a medium tone, lock the exposure, recompose and shoot. I may have to do this with the G1, rather than rely on its supposedly more advanced computerized metering. :-)

    Different people have proposed that the reason is color temperature, or that the lens is wide open (meter angle of acceptance is greater than the sensor wells), or that highlights are being over-aggressively protected, which is exactly what you want in bright light, but exactly what you don't want in available darkness with light sources in the picture. All of which are plausible. It would take a lot of testing to figure out which is the real culprit.

    I suspect that because the G1 is designed primarily for slow zooms, its metering may be misreading the light from a fast lens. I had similar issues with Olympus 4/3 cameras and fast manual OM prime lenses. These lenses metered oddly at their widest and narrowest stops, and correctly at middle stops. If this is indeed the issue, the good news is that once you know how much to compensate when the lens is wide open, that factor always works.

    If it's the lack of blue light in tungsten light that's throwing the metering off, you'll just have to learn to compensate when you're in tungsten light. Again, easy once you know to watch for it. Mr. Histogram is your friend. :-)

    As others have suggested, you can try spot metering and/or AE lock. Another thought is that at maybe in available darkness, you have to set the exposure compensation to plus 1 stop or so, rather than the -0.33 it should be set to most of the rest of the time.

    Your best bet is to shoot a few test shots in the environment, adjust the exposure compensation accordingly, and then shoot happily.

    --Peter

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    Re: Help with G1 underexposure with 20mm 1.7

    Hi, I have the same problem with my G1+20/1.7 underexposing indoors using pattern metering.

    The shots you posted though don't highlight the problem very well since they contain bright light sources.

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    Re: Help with G1 underexposure with 20mm 1.7

    I've made upwards of 5000 exposures with the 20/1.7 on my G1. I doubt I've seen more than a dozen underexposed photos and all of them were my fault (manual exposure mode that I'd forgotten to switch back to Aperture mode ...).

    - Learn to use the Live Histogram.
    - Learn to look at the scene and judge what's required with EV Compensation.

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    Re: Help with G1 underexposure with 20mm 1.7

    Perhaps the most useful thing I have done to my G1 is to set up a Custom setting with spot metering, AE toggle on/off and spot focus.

    Then all I need to do is to turn the top dial from P to Cust and I have those three changes.

    I use it a lot. Especially with the 20/1.7 indoors when a room might have extremities of light and shade. Those two examples from dipgang would have been killers for anything other than spot metering - no wonder he had poor results.

    Tony

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    Re: Help with G1 underexposure with 20mm 1.7

    Thanks to all for your suggestions. Using Spot metering to handle the very contrasty scene solved the problem which is what was expected. Specifically my question was to understand why the same scene (with extreme highlights and shadows) is properly exposed when I use evaluative metering and a 14-45 kit lens , whereas with the 20mm I had to use spot metering to expose it right( and the evaluative metering did not work).

    Dipgang

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    Re: Help with G1 underexposure with 20mm 1.7

    Quote Originally Posted by dipgang View Post
    (...)Specifically my question was to understand why the same scene (with extreme highlights and shadows) is properly exposed when I use evaluative metering and a 14-45 kit lens , whereas with the 20mm I had to use spot metering to expose it right( and the evaluative metering did not work).
    You didn't have to use spot metering to get it right. You had to avoid the stupid automatic thing to get it right.

    So, have you confirmed that the scene was the exact same when the camera gave you different exposure values? With tripod, the kit lens zoomed to the exact same FL and nothing changed between the images?

    Now I never use the evaluative metering but if everything is exactly the same I would expect two very similar images from the two lenses. If it doesn't work, well, then it doesn't work.

    If that was your specific question I actually didn't understand it. I'm sorry if my reply was offending. But... who cares about mystery i-modes or evaluative mode?

    /Jonas

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    Re: Help with G1 underexposure with 20mm 1.7

    Jonas,

    Yes the question was not on how to meter a contrasty scene but on the vagaries of modern evaluative metering with the added dimension in this specific context since the metering was behaving differently for different lens reading the same scene. And I used a a tripod and the zoom lens at the same fl as the 20mm. Have been using cameras and making photographs for last 20 years or so - have gone the OM to rangefinder (BESSA) to digital (20D to 5D) and now the four third way and still s get occasionally surprised when unpredictable technicalities still come in the way of the act of seeing and making a photograph. Thanks for getting back and I love the little G1.

    Dipgang

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    Re: Help with G1 underexposure with 20mm 1.7

    Did you ever come up with a fix for this metering problem? Although I'm willing to set up a custom metering setting for this lens and inside shots, it would be nice to hear that a firmware fix solved the problem (although all I see on the Panasonic site is a firmware update from a year ago).

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    Re: Help with G1 underexposure with 20mm 1.7

    Hi

    Quote Originally Posted by Peter Klein View Post
    ... or that the lens is wide open (meter angle of acceptance is greater than the sensor wells),
    except that with all "auto lenses" (read all lenses since the 80's which are not working in stop down mode and certainly all electronic controlled lenses) they always meter and focus "wide open"

    they stop down moments before exposure ... a quick look at the front of your camera while taking a picture will confirm this as you'll see the iris stop down on all lenses

    the G1 (as do some others) has one exception to this and that is to operate with "shutter speed effect" happening

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    Re: Help with G1 underexposure with 20mm 1.7

    FWIW, the G1 and 20mm lens meters accurately when I use the spot meter, and then the live view is pretty close to the captured image even with images that are problems for the other metering modes. It's as if, with some lighting and composition combinations, the metering mechanism in evaluative or center-weighted modes "sees" the edges of the frame as brighter than they are, even though the live view represents the scene accurately. This can be observed by pressing the shutterspeed preview when framing the troublesome compositions. The view immediately darkens by an amount equa to the underexposure that occurs when you take the shot. It's hard for me to understand how this is even possible, since I would imagine the live view and exposure metering are working with the same data. Also hard to understand why this doesn't occur with spot metering or other lenses or with all compositions and lighting with the 20.

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