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08-28-2009, 09:15 AM   #1
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K200d: Incorrect metering in low light conditions?

I am an (almost) happy k200d owner and just recently i decided to take some night shots with my tripod.I wanted to make some long exposures (above 15sec) at the base iso 100/200.
My problem (at low lighting only):
k200d's meter gives me faulty exposure times no matter what metering mode i use (tried all of them:frame-evaluative,center-weighted and spot).I always get a totally black picture,completely underexposed.The exposure time seem to "stuck" after a certain lack of light.
What i mean is as the scene is getting darker,the exposure time is getting higher,which is natural and expected (given same iso and aperture).
BUT:after some point the exp.time doesn grow up as it should and it stucks.
This problem seems to be known about k200d from what i hear.
Even a review at imaging-resource.com states that in the end of article.
Quoting:
"Exposure is highly variable (inaccurate) under very dim lighting".
Pentax K200D Digital Camera - Review - The Imaging Resource!
At the moment there is no new firmware for k200d and its rather unlikely there will be one to adress this problem.
1.Could any of the k200d owners confirm this problem on their cameras?
2.Is there any known solution to that?

(EDIT:
an example of the problem.
Without taking the cap off the lens and settings: iso 100,f/3.5 spot metering mode results in 10sec exposure for +0 eV !!!


Last edited by flamenco; 08-28-2009 at 09:21 AM.
08-28-2009, 09:31 AM   #2
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After a little bit of thinking i've come up with some (not so good) solutions:
- Beg Pentax to release new firmware that fixes it.
- Get a separate photographic exp.meter (dont know if they are expensive)
- Use trial and error technique: take a shot, review in camera picture (maybe checking the histogram also) and if still underexposed upper the exp.time +1 eV stop and then review the result again.Repeat until u get the result u want,hoping the initial scene has not changed and the lighting conditions remain the same.
Currently i am using the 3rd solution,but its pretty much time-consuming and also makes the whole "picture-taking" procedure less pleasant.
08-28-2009, 09:37 AM   #3
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I own k200 and never heard or experienced such a problem. Correct exposure up to 30 sec. Sorry...
08-28-2009, 09:39 AM   #4
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then i assume it could be just my camera's problem.
can anyone else confirm please?

08-28-2009, 09:40 AM   #5
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I have found that under certain low light situations, especially with high ISO, there is a limit to the ability of my *istD to meter correctly, i believe it is because the lighting conditions gall below the -1EV range of metering capability
08-28-2009, 10:05 AM   #6
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Actually i dont think iso has anything to do with it because it is a property of the sensor not the meter. Iso is applied mathematically to calculate exp.time (shutter speed) based on the meter's essential readings,which in this case are faulty.
08-28-2009, 10:13 AM   #7
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I also dont think that this sort of exposure hits the lowest limit of in-camera meter,because every other dslr can easily handle low light measuring.Even compacts can.
Based on dpreview's info on k200d:
"Exposure range: EV 0 - 21 (at Standard Output Sensitivity 100 with 50mm F1.4 lens)"
which is quite good,better than nikon d60 for example:
"• EV 0 to 20 (3D color matrix or center-weighted metering)
• EV 2 to 20 (spot metering) (ISO 100 equivalent, f/1.4 lens, 20 C)"
so, k200d has enough metering range according to the specs.
08-28-2009, 10:42 AM   #8
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Never ran into this myself but i mostly shot in manual mode. Sounds like you are trying to go less than the 30 sec exp time in which case, would think the metering would just stop changing. For example, you are at ISO 100, your lowest f stop and 30 sec. You can't change anything to brighten up your image short of changing to bulb mode.

08-28-2009, 10:46 AM   #9
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QuoteOriginally posted by flamenco Quote
Actually i dont think iso has anything to do with it because it is a property of the sensor not the meter. Iso is applied mathematically to calculate exp.time (shutter speed) based on the meter's essential readings,which in this case are faulty.
the reason it gives incorrect exposure is that 30 seconds exceeds the low light limit, especially when the meter is trying to calculate exposure with ISO set to high values.

You will probably find that by changing the ISO you can get longer calculated times.

I knopw it seems funny but you are hitting the metering limit,
08-28-2009, 10:52 AM   #10
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Similar problem

Although my night time shots do not come out black I have noticed some inconsistencies in the light metering of my k200d as well. When taking several shots of the same scene I have noticed that some of those shots will be lighter and others will be darker although I have not touched any of the settings. This seems to happen to me most frequently when using the manual settings and taking nighttime shots of the mountains across the valley. I have assumed that, since there are street lights and car lights visible in the valley below, that my camera is somehow picking up these lights and making small exposure adjustments. Since this camera is new to me, and I am a relative newbie to photography in general (other then point and shoots) I have not spent a lot of time playing with the metering options. Next time I'm out I'll try this and see if there is any difference.

I can't help but believe that, if you are getting very low exposures at night that there is something wrong with the camera. Mine seems to work quite well although, as mentioned above, there is a bit of variation.

BTW I'm usually shooting from a tripod in manual or AV and I always shoot RAW, if that has anything to do with it. I have used the Pentax 28-200mm FA zoom, the Pentax 80-320mm FA zoom and my 18-55mm kit lens and the type of lens doesn't seem to make a difference.
08-28-2009, 11:05 AM   #11
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QuoteOriginally posted by enoeske Quote
Never ran into this myself but i mostly shot in manual mode. Sounds like you are trying to go less than the 30 sec exp time in which case, would think the metering would just stop changing. For example, you are at ISO 100, your lowest f stop and 30 sec. You can't change anything to brighten up your image short of changing to bulb mode.
That is not the problem. Maybe i didnt explain it right. I always shoot in manual and always meter using spot metering to get perfect exposure.
Here is the problem explained again: when i meter in very low light conditions on,lets say grass for example and i want it to be neutral grey, i measure for +0eV on grass.Given the iso 100 for example and f3.5 and 3 sec exp.time when i meter to the grass i see "+0" for +0eV.My metering is done.I say OK,lets take the picture.Then i take the picture.On the picture i have just shot i expect the grass to be neutral (meaning not too bright and not too dark). BUT INSTEAD ALL I SEE IS A BLACK PICTURE IN WHICH NOTHING IS DISTINGUISHABLE.
Then i continue and i say to myself "screw the meter,lets try with greater exp.times"
and i set the time to 25sec (which according to the meter should overexpose by 3 stops,but screw the meter). What i see is a picture with distinguishable shapes but still underexposed. Then i decide to give it another stop by doubling the iso (dont have cable,otherwise i would use the same iso and doubled the time,which cannot be set past 30secs).Then i review it again and i get a well exposed night shot.
Looking again at the meter it says +3.0 and its blinking,saying i have extremely overexposed,but thats not true because my pic is just well exposed.
08-28-2009, 11:15 AM   #12
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QuoteOriginally posted by Lowell Goudge Quote
the reason it gives incorrect exposure is that 30 seconds exceeds the low light limit, especially when the meter is trying to calculate exposure with ISO set to high values.

You will probably find that by changing the ISO you can get longer calculated times.

I knopw it seems funny but you are hitting the metering limit,
Please take a look on my prev. post and u will see what is happening.
Just for the record, i took my 2.5-year old compact camera (which has spot metering) and it measures the grass just correctly. It gave me 30sec with iso 200 (as i would double it) and f3.5.Thats why i dont think its the hardware limit.
What is really strange is that in not that dark conditions,like indoors,the metering is just perfect.
08-28-2009, 11:15 AM   #13
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QuoteOriginally posted by flamenco Quote
That is not the problem. Maybe i didnt explain it right. I always shoot in manual and always meter using spot metering to get perfect exposure.
Here is the problem explained again: when i meter in very low light conditions on,lets say grass for example and i want it to be neutral grey, i measure for +0eV on grass.Given the iso 100 for example and f3.5 and 3 sec exp.time when i meter to the grass i see "+0" for +0eV.My metering is done.I say OK,lets take the picture.Then i take the picture.On the picture i have just shot i expect the grass to be neutral (meaning not too bright and not too dark). BUT INSTEAD ALL I SEE IS A BLACK PICTURE IN WHICH NOTHING IS DISTINGUISHABLE.
Then i continue and i say to myself "screw the meter,lets try with greater exp.times"
and i set the time to 25sec (which according to the meter should overexpose by 3 stops,but screw the meter). What i see is a picture with distinguishable shapes but still underexposed. Then i decide to give it another stop by doubling the iso (dont have cable,otherwise i would use the same iso and doubled the time,which cannot be set past 30secs).Then i review it again and i get a well exposed night shot.
Looking again at the meter it says +3.0 and its blinking,saying i have extremely overexposed,but thats not true because my pic is just well exposed.
can you show a photo of the scene

Please note, I think you and I are discussing the same thing.

I have found in low light and in manual mode, the meter simply cannot produce a correct calculated exposure for these shots.

I ran into this as I said with my *istD a long time ago
08-28-2009, 11:41 AM   #14
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My K200d does the same. It's not a problem. Can you calculate (from the correctly exposed scene) what EV value the grass has?
I think it stops calculating actual exposure when automatic shutter value drops to 0.5" or below. Then it shows +EV if it's manually set longer than that or -EV if it's faster.
Metering values blink - indicating that some limit has been reached (lens, speed, metering).

I think this can be found in manual no one bothers reading.

Practically it is hard to get "correct" exposure in the dark anyway, because dark scenes have huge dynamic range, so you must make a decision what to keep and what to blow or underexpose. So often it is error and trial anyway to get best results, or some bracketing and stacking.
I usually use bright portions of the scene to get initial readings, and then extrapolate from them.

Last edited by ytterbium; 08-28-2009 at 11:47 AM.
08-28-2009, 11:45 AM   #15
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QuoteOriginally posted by ytterbium Quote
My K200d does the same. I think it stops actually calculating actual exposure when automatic shutter value drops to 0.5" or below. Then it shows +EV if it's manually set longer than that or -EV if it's faster.
Metering values blink - indicating that some limit has been reached (lens, speed, metering).

I think this can be found in manual no one bothers reading.
I think the actual shutter speed it calculates changes as a function of ISO, but yes, this is what I am referring to.
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