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12-11-2009, 04:54 AM   #1
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Is it my new K20d OK?

Hi to everybody,
I've just purchased a K20 and after some releases I had the feeling that something was wrong.
So I've effected many shots to all the focal lengths, times, diaphragms and all the automatic programs.
I've posted some images (tall to the right also data and histogram) and I ask You, please, to tell me what You think about.

Above each photo there's a kink to my web site, please, use to visualize the images to high resolution (in this way it is easier to analyze them).

My feeling is that the camera underexposes a little bit (it seems to see this also from the histogram), that the focus is some inaccurate and that maybe there's an high level of noise at low ISO.
Ok, am I a beginner, do You believe that I am wrong?

Thanks to all for the answers.

_IGP0027.JPG hi res



_IGP0257.JPG hi res



_IGP0263.JPG hi res



_IGP00268.JPG hi res




..... and sorry for my broken english...


Last edited by VincenTC; 12-11-2009 at 07:08 AM.
12-11-2009, 06:12 AM   #2
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I can't see any images, only red X's.
12-11-2009, 06:34 AM   #3
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QuoteOriginally posted by audiobomber Quote
I can't see any images, only red X's.
Sorry Dan, I think in allright now.
Please, use the links above the images for the best view.
12-11-2009, 06:42 AM   #4
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I can't see it also, you might want to use ImageShack® - Image Hosting to upload instead.

12-11-2009, 07:15 AM   #5
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QuoteOriginally posted by LeDave Quote
I can't see it also, you might want to use ImageShack® - Image Hosting to upload instead.
Sorry again, I used ImageShack®, please, try again.
The link above the photo brings yourself to a page of altervista.org: to see my images needs to click the word: qui.
12-11-2009, 07:21 AM   #6
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I can see the images. ImageShack is usually the one i never see .
Well, id expect the middle two to come out as they are - the sky is bright, so the camera makes them darker, unless you meter of the buildings.

First and the last on the other hand should have been brighter, even with white paper and light couds.

Are you sure your'e not adding any negative exposure compensation?
What metering mode are you using?
....
I extracted the exif for the first and last images:

Everything seems nice, but the metering mode. I believe by iso standarts the images would be a bit darker when using it. I had to dial in 0.3 to 0.7 with Kit lens Mark I, for pleasant exposure. Are images the same when using Matrix/Multi/Auto and Spot metering modes?

QuoteQuote:
# Exposure Time (1 / Shutter Speed) = 1/30 second ===> 0.03333 second
# Lens F-Number / F-Stop = 80/10 ===> ƒ/8
# Exposure Program = aperture priority (3)
# ISO Speed Ratings = 200
# Exif Version = 0221
# Original Date/Time = 2009:12:06 16:40:13
# Digitization Date/Time = 2009:12:06 16:40:13
# Components Configuration = 0x01,0x02,0x03,0x00 / YCbCr
# Exposure Bias (EV) = 0/10 ===> 0
# Metering Mode = center weighted average (2)
# Flash = Flash did not fire, compulsory flash mode
# Focal Length = 5500/100 mm ===> 55 mm

This one really seems to be wrong. It is not common for camera to underexpose by itself. Is there anything else that could interfere with exposure (external flash mounted, weird light source -like fluorescent, heavy wear on the lens - sticky aperture, filters - UV, polarizing)

Technically, when spot metering of completely white spot you should get it correctly exposed by dialling in 1.7 (decent detail) to 2.0 (near blown out) positive exposure compensation. Have you tried it? It produced correct results with my kit lens, when some m42 lenses were underexposing.

QuoteQuote:
# Exposure Time (1 / Shutter Speed) = 1/45 second ===> 0.02222 second
# Lens F-Number / F-Stop = 45/10 ===> ƒ/4.5
# Exposure Program = aperture priority (3)
# ISO Speed Ratings = 400
# Exif Version = 0221
# Original Date/Time = 2009:12:09 10:01:26
# Digitization Date/Time = 2009:12:09 10:01:26
# Components Configuration = 0x01,0x02,0x03,0x00 / YCbCr
# Exposure Bias (EV) = 0/10 ===> 0
# Metering Mode = pattern / multi-segment (5)
# Flash = Flash did not fire, compulsory flash mode
# Focal Length = 3750/100 mm ===> 37.5 mm
Currently im using exclusively spot metering. It allows me to explore the brightness levels present in a scene, or simply make me quickly decide what is the thing i want to be correctly exposed. When with other modes, i feel somewhere in middle between me and the camera trying to decide on exposure and what to expose for.

Last edited by ytterbium; 12-11-2009 at 07:34 AM.
12-11-2009, 07:35 AM   #7
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Your English is way better than the metering on the pictures appears. I used PhotoME to review the details briefly and noted you used Photoshop, I guess to convert for posting maybe, but what caught my eye is there is no Color Space listed. Actually it is shown as "none" and should be "sRGB". Since you can't take a JPG with the K20D like that you may be converting the picture. Not sure and have to leave a the moment. Yes your pics are quite dim posted but do they appear that way on the camera LCD also?

Also, exactly what 38mm lens are you using for the calendar shot (the last picture). That information was stripped from your files

Sorry for brief look, will be back later.
12-11-2009, 09:12 AM   #8
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Hi my friends, thanks for replies.
QuoteOriginally posted by imtheguy Quote
Your English is way better than the metering on the pictures appears. I used PhotoME to review the details briefly and noted you used Photoshop, I guess to convert for posting maybe, but what caught my eye is there is no Color Space listed. Actually it is shown as "none" and should be "sRGB". Since you can't take a JPG with the K20D like that you may be converting the picture. Not sure and have to leave a the moment. Yes your pics are quite dim posted but do they appear that way on the camera LCD also?

Also, exactly what 38mm lens are you using for the calendar shot (the last picture). That information was stripped from your files

Sorry for brief look, will be back later.
Maybe I saved the pictures without color space, on camera I use AdobeRGB only.
Yes, on LCD I see the images as You can see on monitor.
38mm lens is my kit lens 18-55.
QuoteOriginally posted by ytterbium Quote
I can see the images. ImageShack is usually the one i never see .
Well, id expect the middle two to come out as they are - the sky is bright, so the camera makes them darker, unless you meter of the buildings.

First and the last on the other hand should have been brighter, even with white paper and light couds.

Are you sure your'e not adding any negative exposure compensation?
What metering mode are you using?
....
I extracted the exif for the first and last images:

Everything seems nice, but the metering mode. I believe by iso standarts the images would be a bit darker when using it. I had to dial in 0.3 to 0.7 with Kit lens Mark I, for pleasant exposure. Are images the same when using Matrix/Multi/Auto and Spot metering modes?




This one really seems to be wrong. It is not common for camera to underexpose by itself. Is there anything else that could interfere with exposure (external flash mounted, weird light source -like fluorescent, heavy wear on the lens - sticky aperture, filters - UV, polarizing)

Technically, when spot metering of completely white spot you should get it correctly exposed by dialling in 1.7 (decent detail) to 2.0 (near blown out) positive exposure compensation. Have you tried it? It produced correct results with my kit lens, when some m42 lenses were underexposing.



Currently im using exclusively spot metering. It allows me to explore the brightness levels present in a scene, or simply make me quickly decide what is the thing i want to be correctly exposed. When with other modes, i feel somewhere in middle between me and the camera trying to decide on exposure and what to expose for.
I haven't used any exp comp. nor flash for these shots, only I used center and multimode. Do I have to compensate the exposure from 1.7 to 2 stops in metering mode? Do I understand right?

And for focus and noise what do You think?

12-11-2009, 10:12 AM   #9
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The offset i mentioned is for completely white subjects. Just for testing.

Meter something completely white and add 1.7..2 stops - you should get it completely white.

Because now, that there is no daylight shining on my LCD monitor, the shots may as well be 18% gray.

About the noise - when exposure is too low, you will get increased noise - same as in dark parts of picture.
As for focus, it seems to be ok, at least as much as you can tell from such DOF, image size and subject.

Here, i did a fast test with my k200d, to illustrate, although for my surprise it didn't came out was bright as expected with +2EV. So your cam is probably all right.
Attached Images
 

Last edited by ytterbium; 12-11-2009 at 10:58 AM.
12-11-2009, 10:49 AM   #10
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It's a known fact that the K20D exposes very conservatively to avoid blowing highlights. It's not a problem once you're used to it, but it does require photographer input to a greater extent than most cameras. In the photos with a lot of sky, I would probably have added +.3 to +.7Ev with my K20D. That would not have been sufficient to expose your photos correctly. I didn't use the kit lens for long, but my copy did underexpose by half a stop. The sharpness also was not quite up to scratch with the high resolution of the K20D.

The calendar photo is a mystery to me. I would try another lens first to see if the problem is the camera or the lens, but it appears to me that something is off to create such underexposures.
12-11-2009, 01:38 PM   #11
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So do You think that it could be a malfunction of the lens?
12-11-2009, 02:21 PM   #12
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I'd say dial in +0.3 EV, meter of objects a bit darker than plain gray and the images should come out fine. It's most likely just the Pentax metering behaviour.

If your'e certain that there is a problem, then better get to more serious testing - constant subject, constant lighting (GOOD lighting - so that you get 1/125@f/8...16 at iso100).
Start by making sure that you get the same reading in all modes, if not - think why and write down the difference.
If you have several lenses try with more than one.
Then take pictures of black and white subjects. Two pictures for each - at 0EV and +2 for white, -2 for black. Make sure that the black is really black compared to the rest of the scene.
See what dynamic range you get - what are the RGB values when black has -2EV, white +2EV and both of them are exposed as 18% gray (0EV).
And so on...

Otherwise we can only guess what we are seeing here.
12-12-2009, 02:52 AM   #13
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QuoteOriginally posted by ytterbium Quote
I'd say dial in +0.3 EV, meter of objects a bit darker than plain gray and the images should come out fine. It's most likely just the Pentax metering behaviour.

If your'e certain that there is a problem, then better get to more serious testing - constant subject, constant lighting (GOOD lighting - so that you get 1/125@f/8...16 at iso100).
Start by making sure that you get the same reading in all modes, if not - think why and write down the difference.
If you have several lenses try with more than one.
Then take pictures of black and white subjects. Two pictures for each - at 0EV and +2 for white, -2 for black. Make sure that the black is really black compared to the rest of the scene.
See what dynamic range you get - what are the RGB values when black has -2EV, white +2EV and both of them are exposed as 18% gray (0EV).
And so on...

Otherwise we can only guess what we are seeing here.
Yes my friend, now it's time to learn the correct use of my new camera and to make some serious test to exclude issues.
Thanks to all!
12-12-2009, 10:40 AM   #14
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I looked at some of your pics closely as a K20D owner IMO they are fine, take IPO0263, this is a hard scene for the auto metering you still have some brightness in the sky about 60% of the scene is bright and when the K20D meters and does not blow out any of the sky and cloud detail the bottom become dark. The best way for now is just use exposure compensation to deal with it when it happens I do all the time. As for the noise I don't see any problems but(!) for lowest noise don't use too much sharpness or fine sharpness at least if you go over ISO400. But nice job so far I like that first pic
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