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08-28-2009, 12:44 PM   #16
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Almost forgot:BIG THANKS for helping,guys.
Unfortunately i dont have right now the picture available,but its nothing of unusual actually. I have chosen it to be test picture without huge dynamic range (well except a few distant lights).It was pretty much within 3-4 stops range.
Maybe after all Lowell is right. It could be the physical limit of the meter.
Or maybe a faulty meter.
I mean lets do a funny test:
1)Leave the cap on the lens.For the camera it is absolute dark (the light leakage should be very small to none).
2)Cover the lens (and the lens cap) with a thick dark cloth to ensure absolutely no light leakage.
3)Set the camera to Manual Focus so it would not bother u with autofocus motor.
4)Choose any of metering modes (i prefer spot)
5)Set to Aperture priority or full Manual and start metering.See what comes out.
6)Rub your eyes to ensure what u see is real (optional step,lol).
--->what i see is that actually my k200d's meter gets an exposure value for total darkness!!! Using common sense it should be blinking -3.0eV as it would need infinite time to expose complete darkness,to bring it to levels or neutral 18% grey.
Yet it says "10 sec with f3.5 and iso100" for complete darkness at +0eV.
----->Now what is even more funny that i have just find out is that if I change the position of the camera (lean it towards me,lean it to sides,upside down etc) still having the cap and the cloth on the lens,it starts giving different values,the values start changing rapidly!!! The values jump like crazy!!
I hope i will not end up in mental institution a trying to solve this prob.


Last edited by flamenco; 08-28-2009 at 12:52 PM.
08-28-2009, 12:57 PM   #17
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What happens if you also cover the eye piece to prevent light from leaking in that way too?
08-28-2009, 01:12 PM   #18
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QuoteOriginally posted by enoeske Quote
What happens if you also cover the eye piece to prevent light from leaking in that way too?
Doesnt make any difference actually.
08-28-2009, 01:36 PM   #19
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OK WE HAVE GOT A BREAKTHROUGH:
After playing with the camera for hours now,I have just confirmed what Ytterbium was stating.
and Lowell,i guess u r right on this one.
--->There is a "0.5s auto shutter speed limit for metering".Beyond that value and regardless of ISO no actual metering is being made.The value just freezes and blinks.
From what i observe this limit is based only on the light levels not on the actual time itself.I could get a picture of 30secs in a mildly lit conditions using f/38.
I guess it solves it.
Well then another question arises:
1)Why didnt Pentax use better meter in k200d??? I remember shooting a similar scene with an old 6mp rebel 300 and it gave correct numbers,even a compact manages better than k200d.
2)How to overcome this "peculiarity"?

08-29-2009, 02:40 AM   #20
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And now probably the best workout,without bying the light meter:
1)Set iso to 1600
2)Set aperture to smallest f possible
3)Disable dark frame substraction (long exposure NR in the adv.menu).It saves time.
4)Take pictures and review them until u get a desirable exposure.Check the exp.values (speed,aperture,iso) and convert them in order to match low iso or higher f-number or both (using the EV system,duh)
Any creative suggestions would be appreciated.
08-29-2009, 03:20 AM   #21
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Just a thought: are you using manual lenses (focus and aperture)? Particularly manual aperture.

I find the K200D doesn't meter and expose accurately when using M series manual lenses if you use any other mode other than Manual (and perhaps B).

Theoretically you should be able to use Aperture priority to take the shot with these manual lenses. However I find the camera gives the most accurate results if you set the mode to full Manual and use the green button to set the metering prior to taking the shot.

My 2c.
08-29-2009, 05:50 AM   #22
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QuoteOriginally posted by flamenco Quote
Well then another question arises:
1)Why didnt Pentax use better meter in k200d??? I remember shooting a similar scene with an old 6mp rebel 300 and it gave correct numbers,even a compact manages better than k200d.
2)How to overcome this "peculiarity"?
Switch to Manual Exposure M mode. Use the exposure meter as an exposure guide, but you will have to do the adjustment to aperture/shutter speed yourself.
The 0.5 seconds seems to be a restriction of the autoexposure/shutter control rather than the exposure meter as such. I've been able to use the exposure meter as a guide in M mode down to several seconds.

The exposure meter will still fail in VERY dim light (as it does in every dSLR I've used, including Canons).
08-29-2009, 11:08 AM   #23
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QuoteOriginally posted by flamenco Quote
2)How to overcome this "peculiarity"?
I guess I'm having trouble understanding the problem. Your description of how to reproduce it involved metering with the lens cap on?! Are there real world situtions where you are getting unexpected exposures? I shoot in very low light all the time and never have any problems. I don't trust the meter when shooting in the extremely rare cases when I am shooting in more or less *complete* darkness using a tripod and very long exposures; those I do more by trial and error. So if that's what you're asking, then I guess that's my answer - trial and error. But we're talking about real corner case situations - shooting the night sky, for example. Certainly nothing here I'd just whip the camera out and expect success pointing and shooting.

08-30-2009, 07:19 AM   #24
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QuoteOriginally posted by Marc Sabatella Quote
I guess I'm having trouble understanding the problem. Your description of how to reproduce it involved metering with the lens cap on?! Are there real world situtions where you are getting unexpected exposures? I shoot in very low light all the time and never have any problems. I don't trust the meter when shooting in the extremely rare cases when I am shooting in more or less *complete* darkness using a tripod and very long exposures; those I do more by trial and error. So if that's what you're asking, then I guess that's my answer - trial and error. But we're talking about real corner case situations - shooting the night sky, for example. Certainly nothing here I'd just whip the camera out and expect success pointing and shooting.
The whole "lens cap on" was just an experiment to see that camera actually gives u exposure values for complete darkness,which should not be happening.
Again the problem is "real world" metering in dim light conditions.For example:
I am in a small village in a place lit by a few street lights (commonly positioned at 15-20meters(50-65ft) from each other) and no extra lights,the moon is low.I get away from this scene at a distance of 50-70m (165-230ft).Then I set up my tripod.There are virtually no light around me,but the distance as u see is not that big.Using my kit 18-55mm II, i set it to 18mm,f/3,5 to capture the whole scene including the lights.I use spot metering off the grass just under those street lights,always in manual.The exp.values are too low(the whole picture exposes black).Then i notice the exp.values blink and i suspect 30sec exposure is not enough.But as i dont have a release cable,i start changing iso for lower times (I am already on lowest f of the lens).Even at iso 1600 the exp time is wrong.Thats it.
I guess thats just my meters limit as the others posters suggested.
However i dont give up,i am getting alot quicker on my trial-error technique.
08-30-2009, 07:32 AM   #25
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Your camera will meter accurately to EV0. EV0 is f/1 for 1 second at ISO 100.
If you are trying to meter past that, you won't get accurate metering, and the closer you get to that threshold the more likely your metering will be off.
Also, you mentioned you use spot metering. I presume you know how a spot meter works and that you can't just blindly dial in what your spot meter is giving you for settings?
08-30-2009, 08:29 AM   #26
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QuoteOriginally posted by Wheatfield Quote
Your camera will meter accurately to EV0. EV0 is f/1 for 1 second at ISO 100.
If you are trying to meter past that, you won't get accurate metering, and the closer you get to that threshold the more likely your metering will be off.
Also, you mentioned you use spot metering. I presume you know how a spot meter works and that you can't just blindly dial in what your spot meter is giving you for settings?
I am pretty much familiarized with spot metering,as i use it all the time and i know exactly where to meter and on what +/- and checking highlights/shadows.On 95% of the pictures i take the exposure is correct.
The spot i was trying to measure on was +1 EV,calculated based on the correctly exposed picture's speed/aperture/iso combination and the center point being really close to neutral grey (based raw without +/- exposure settings,no auto adj. in the converter).
Given that the electronic sensors (CCD,CMOS) are not susceptible to reciprocation as films, my calculated values are really close to scene's actual EV.
Conclusion:scene's EV +1 or below ---> metering impossible (at least with my kit lens).
I will post update when i will find +2EV scene.
P.S. maybe the thread should be renamed to "Discovering my built-in light meter's limit". LOL.
09-05-2009, 07:24 PM   #27
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I have only had my K200D since last November, but I have taken a dozen or so night shots and have not had any problem. Hope you find a solution.
11-26-2009, 05:13 AM   #28
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Same problem with K20D

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.


I know exactly what you mean. I have just bought a K20D, and I discovered that it behaves the same way. I had a Nikon D60 previously, and that measured the lighting correctly under those same kinds of conditions. It seems to me that Pentax' engineers didn't do their homework on both these models.

Pentax should correct this problem with a firmware update. How can we get them to do this?
11-27-2009, 10:29 AM   #29
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I don't think it's a firmware issue - more likely it's inherent in the meter itself. It's not an issue in practice 99.999999% of the time, so don't sweat it.

Last edited by Marc Sabatella; 11-28-2009 at 12:57 PM.
11-28-2009, 02:50 AM   #30
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It was suggested that the reason is that metering starts at EV 0 on these cameras, while it starts on EV -1 on the Nikon D60. However, according to dpreview, the Nikon D60 starts metering at EV 0 too, same as K20D. So that can't be the root cause of this.

Maybe it's not an issue for you, but it is for me and others, as you see. I like taking pictures under such light conditions and do it quite often. I was used to relying on the Nikon D60s metering, and was therefore surprised and disappointed when I discovered that the K20D isn't capable of it. In other respects it is a great camera, though, and I enjoy using it. But I can't understand why they have cut short the metering range. Maybe there is a technical reason or other reason, anyway I'd like to know.
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