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05-14-2007, 02:12 PM   #16
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QuoteOriginally posted by Beej80 Quote
I just want to add that on my K10D the picture appears to be overexposed, or certainly very bright when view on the LCD monitor (on cam). But when I get it on to my computer, and view it on that monitor/prints the image, the exposure is usually spot on.

I had a bad day with this, checking the images on the LCD, figuring they were overexposed (Didn't look at the histogram), and compensated for the imagined overexposure.

Ended up underexposing 60-70 images.

Now, I've learned to trust my K10D. If it says the exposure is fine, then most likely it is.

Regards,
Beej80
I found that you can change the camera display brightness, but be careful as you can be easily misled. I have the camera set now to display the histogram with the view function

05-14-2007, 02:12 PM   #17
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QuoteOriginally posted by Gimbal Quote
The histogram window can be found in photoshop under window/histogram (at least on a PC with photoshop version CS2.)

I tried it with my K10 and it comes out with fairly low numbers compared to your chart.

Results from 2 shots of a white A4 paper, multisegment metering.

Mean/median the whole picture.
93/94
94/95

Mean/median in center of picture (obviously heavy vignetting with kit zoom)
106/108
106/108

It’s quite common that I add 0.5-1 EV without blowing the highlights, but in the end it turns out just fine.
110 is arguably the correct answer for RGB color space and gamma 2.2...
(do't ask )
Early reports of the K10 had alluded to the 126 (ala Canon) peak/average/mean. Actually one of my points for asking is to see if this is correct. I gave up asking at dpreview because it led to all sorts of in-fighting. Goes back to the "old D" days.....
BTW: My re-calibrated D is usually at the above numbers (85-87 on a well behaving lens for all aperatures except the extremes), a bit lower than when I originally bought it. In theory this is withing their tolerances for recalibration. Wish I could do this minor tweak on my own..
Baseline meter calibration SHOULD be built into the camera menu. but then who would pay those high priced repair co's.......
05-14-2007, 04:20 PM   #18
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QuoteOriginally posted by JohnV3 Quote
Thanks everyone for your replies and suggestions. To answer a few questions:

My testing was only done in the P mode.

The underexposure was confirmed by viewing the photos on the computer monitor (19" screen). It is also apparent in the LCD screen which is of little value with the bright Arizona daylight unless you view it in a dark room.

I've tested with both center weighted and multi segment metereing. It made no difference. I have done a white wall test indoors and the results were the same.

I haven't viewed the histograms but the colors look good after just brightening in an editing program. It takes very liitle eyeball scrutinizing to determine the under exposure.

I will do further testing, as suggested, using a fixed ISO and other metering modes. If there is no difference noted, I will upgrade the firmware to 2.0. I will also call Pentax support but done expect much help or knowledge from call centers.

Thanks again everone. I will report back the resilts of further testing.

John
Hi John,

The lcd on the back of the camera will fool you badly if not set to approximately match what you will see later on your monitor, and more importantly, if it does not more or less match what the exposure really was. Your monitor may also not be the best tool to judge exposure unless it is calibrated.

As you noted, differing ambient light conditions will make using the lcd review as an exposure guide even more difficult and less accurate.

So, the best bet is to do the following:

Make sure you are in multi-segment metering mode. Center-weighted is ok too.

Turn on the instant histogram display in your K10D menus if you have not already done so (I do not have the K10 in front of me right now, but it is easy to find or just consult the manual). This will show you the in-camera histo right after you shoot, which will give you a much better idea of exposure than the lcd image on the back of the camera. Shoot some test shots and get used to what you see in the histo as it relates to exposure. More on this later.

Now, turn on the highlight "blinkies" for your instant review. Once again you can find this in the menu/manual. This will show you any spots that are clipping at the highlight end by blinking little bright spots in your review image on the back of the camera. Play with this by taking multiple shots changing the exposure increasing exposure for the scene until you get "blinkies" on the review. This works best with a scene that has some highlight or bright areas.

Now, call up an image that you have already downloaded and adjust the K10 LCD brightness so that it approximately matches your computer monitor. This will not be perfect, especially if you do not have a calibrated monitor, so you should always use the histo/blinkies review on your camera as the main judge of exposure, along with the histogram in whatever image editing software you use.

There are a few more things like linking AF and AE point, different metering modes and even the jpeg recording settings (the camera uses an imbedded jpeg in the file to display the histo so even when shooting RAW the jpeg settings play a role in the exposure analysis) to set or reset that could be causing you grief, but try getting the basic playback/histo/blinkie/brightness setting worked out and then we can go on to some other stuff.

If you already have the camera setup this way, or once you do, shoot the white wall as described above. It should be pretty close to basic grey with no exposure compensation dialed in, and the histo on the back of the camera should look a lot like the one above. which is to say clumped very close to the middle.

Let us know how that works out.

I apologize if you already know what I have written here, but I could not tell from your posts.

Ray
05-14-2007, 04:34 PM   #19
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No this is NOT normal

QuoteOriginally posted by JohnV3 Quote
I have both a Ds and a K10. The Ds requires no EV compensation but the K10 is very under exposed without a comp of +1.5 regardless of the camera's other settings. A variety of AF and A lenses were tested on both cameras in the P mode using the same subjects at the same time both indoors and outdoors in bright sunlight. The K10 has an attached grip and the ISO on both cameras is set to auto.

Is there a problem with the K10 or is it usual or common for it to under expose without compensation? I'm still learning the camera's features after a few months of ownership but just discovered EV issue with it. Could I have overlooked something?

Any ideas or suggestions would be greatly appreciated.

John
My K10Ds (both of them) meter pretty well and underexpose less than my old DS. You will get underexposure in some situations (too much sky, bright spots in the picture) but you should not get a consistent 1.5 underexposure (thats a lot).

There is a problem using the green button with old K mount lenses which underexpose. FA and DA lenses should be fine. Try shooting any uniformly coloured object (the white wall is sometimes reflective!!!) and the histogram should be dead centre.

But it sounds like you may have a metering issue.

05-14-2007, 07:07 PM   #20
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It looks like I will be learning some of the intricasies of histograms pretty soon. The LCD is worthless outdoors here in Arizona. I cannot determine exposure from it on any camera because it is so bright outdoors that the screen is all washed out. I merely check to see if I even have something of an image. My under exposure determination is strictly from reviewing the computer monitor and comparing with the Ds image.

I will get around to doing the histogram test now that I have a better idea of how it works. But, in all honesty, and with due respect to the very knowledgeable people on this forum who were gracious enough to reply to my post, the proverbial blind man could instantly notice the under exposure at first glimse. However, I find the histogram testing very interesting and will put it on top of the "test to do" list and will report the findings. I just hope that I do it right and not get meaningless or false readings but I see pretty clear instructions above .

Thank you again everyone for all the help and suggestions. It is greatly appreciated.

John
05-14-2007, 07:33 PM   #21
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QuoteOriginally posted by JohnV3 Quote
It looks like I will be learning some of the intricasies of histograms pretty soon. The LCD is worthless outdoors here in Arizona. I cannot determine exposure from it on any camera because it is so bright outdoors that the screen is all washed out. I merely check to see if I even have something of an image. My under exposure determination is strictly from reviewing the computer monitor and comparing with the Ds image.

I will get around to doing the histogram test now that I have a better idea of how it works. But, in all honesty, and with due respect to the very knowledgeable people on this forum who were gracious enough to reply to my post, the proverbial blind man could instantly notice the under exposure at first glimse. However, I find the histogram testing very interesting and will put it on top of the "test to do" list and will report the findings. I just hope that I do it right and not get meaningless or false readings but I see pretty clear instructions above .

Thank you again everyone for all the help and suggestions. It is greatly appreciated.

John
Actually there is more to this than meets the eye, literally. If your monitor is not correctly calibrated it can be fooling you as well. Actually short of a lot of calibrating/testing it is all "smoke and mirrors". Post an image (doesn't matter which one) and that will give us a chance to see exactly what you are seeing. The beauty of numbers is they are absolute regardless of monitpr/printer ect. Theres a school of thought that you should be able to color balance an image (to exact standards) even using a B&W monitor and the eyedropper tool in Adobe or any editor. This applies to exposure as well as "colors"" that your monitor would be incapable of showing you.
It's actually quite fascinating. When I find I'm printing something and the color is not as expected I go back to the eyedropper tool.
BTW: the camera has a histogram display and it's easy enough to check. some scenes absolutely require human intervention (exp comp) to get them "right". The meter is d u m , dumb. l..............................................
Adobe Photoshop Help
Each pixel in an image document has a set of color numbers that describe the pixel's location in a particular color mode--for example, red, green, and blue values for the RGB mode. However, the actual appearance of the pixel may vary when output or displayed on different devices, because each device has a particular way of translating the raw numbers into visual color......................
This applies somewhat equally to "exposure" which is why I even bother to mention it and why the numbers and histograms are so important to a discussion. To say "all my images are underexposed" is really not enough on a forum level to target any help. More variables than meet the eye.....
Photoshop CS3
Also should add there is camera underexposure and user underexposure..and without hard numbers it's almost impossible to seperate the 2.

Last edited by jeffkrol; 05-14-2007 at 08:17 PM.
05-15-2007, 08:27 PM   #22
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Test Results

I did further testing in AV, TV, and M modes and it was still (in my opinion) under exposed.

Histogram readings were taken on a white board (artist type), indoors, in a bright (as opposed to dark) room in P mode:
K10: mean-78, median-77; +1 EV: mean-148, median-150; +.5EV: M/M-115/116
Ds : 0 EV:Mean-138, median-142

Readings outdoors on an orange tree in bright sunlight:
K10: mean-122, median-102
Ds : Mean-179, median-180

Reaings outdoors on a white utility trailer against a tan wall:
K10: mean-134, median-121
Ds : Mean-110, median-88

It appears that some reading contradict my eyeball rerading, but, overall, the Ds readings are higher. There was also a small variance with the white board when taken later in the day.

I don't know if this informantion helps any, but I think I'll be using EV+1 most of the time. Tomorrow, I will upgrade the firmware to 2.0.

John
05-15-2007, 08:29 PM   #23
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QuoteOriginally posted by JohnV3 Quote
I don't know if this informantion helps any, but I think I'll be using EV+1 most of the time. Tomorrow, I will upgrade the firmware to 2.0.
Or 1.2. Whatever. ;-)

WP

05-16-2007, 04:40 AM   #24
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QuoteOriginally posted by JohnV3 Quote
I did further testing in AV, TV, and M modes and it was still (in my opinion) under exposed.

Histogram readings were taken on a white board (artist type), indoors, in a bright (as opposed to dark) room in P mode:
K10: mean-78, median-77; +1 EV: mean-148, median-150; +.5EV: M/M-115/116
Ds : 0 EV:Mean-138, median-142

Readings outdoors on an orange tree in bright sunlight:
K10: mean-122, median-102
Ds : Mean-179, median-180

Reaings outdoors on a white utility trailer against a tan wall:
K10: mean-134, median-121
Ds : Mean-110, median-88

It appears that some reading contradict my eyeball rerading, but, overall, the Ds readings are higher. There was also a small variance with the white board when taken later in the day.

I don't know if this informantion helps any, but I think I'll be using EV+1 most of the time. Tomorrow, I will upgrade the firmware to 2.0.

John
DS looks way high. Not sur of the anomoly w/ the trailer though where the pattern reverses. So your DS meter is over and the K10 is under. Quite a spread.....
I'd send them both in if those figures are accurate....
A +1 exposure of a white board should add about (roughly) 40 points to the mean not 70.
05-16-2007, 02:30 PM   #25
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QuoteOriginally posted by JohnV3 Quote
Histogram readings were taken on a white board (artist type), indoors, in a bright (as opposed to dark) room in P mode:
K10: mean-78, median-77; +1 EV: mean-148, median-150; +.5EV: M/M-115/116
Ds : 0 EV:Mean-138, median-142
Those numbers are strange. Can you elaborate a little? How did you measure the light when taking he white board (or grey card or anything neutral in color)? How did you get the numbers?

From your measurements the DS overexposes while the K10D underexposes. For the exposure checks I have done with my cameras I have used spot metering, taking care that the grey card/neutral wall has filled the frame and then read the numbers in ACR after having white balanced the picture. Did you do something similar?

I ask as the DS results tells us that you hardly have been able to take any normal pictures without blowing a lot.
05-16-2007, 06:26 PM   #26
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Jonas:

The white board was in a well lighted room and a full frame shot was taken in the P mode. the metering was center weighted. The photos were loaded into PS7 and the numbers wre read from the histogram window. I did not do a white balance.

I upgraded the firmware today to ver. 1.2 and got some differnt reading from the white board but the outdoor photos requied a +1 EV comp. The readings on the white board after the upgrade on the K10 increased to mean-92 and median-94. I didn't test any other modes or the Ds.

I'm just becoming somewhat familiar with histograms but I did notice that the histogram on the K10 LCD appeared different than what PS7 was showing but not significantly.

I would again to thank everyone for their comments and suggestions. I will just work with EV +1 and take test photos in different outdoor locations. But, IMHO and regardless of my possibly faulty inconsistent readings, the Ds seems to meter better than the K10. But, I realize that there are a lot of variables involved.

John
05-16-2007, 08:07 PM   #27
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QuoteOriginally posted by JohnV3 Quote
Jonas:

The white board was in a well lighted room and a full frame shot was taken in the P mode. the metering was center weighted. The photos were loaded into PS7 and the numbers wre read from the histogram window. I did not do a white balance.

I upgraded the firmware today to ver. 1.2 and got some differnt reading from the white board but the outdoor photos requied a +1 EV comp. The readings on the white board after the upgrade on the K10 increased to mean-92 and median-94. I didn't test any other modes or the Ds.

I'm just becoming somewhat familiar with histograms but I did notice that the histogram on the K10 LCD appeared different than what PS7 was showing but not significantly.

I would again to thank everyone for their comments and suggestions. I will just work with EV +1 and take test photos in different outdoor locations. But, IMHO and regardless of my possibly faulty inconsistent readings, the Ds seems to meter better than the K10. But, I realize that there are a lot of variables involved.

John
Thank you.

As you say, there are a lot of variables here. It is puzzling that the numbers changed when you updated the firmware. i haven't seen any other reports that the exposure changed after a firmware update. It seems as nothing happens to the outdoor pictures? Maybe we can neglect this change, perhaps it comes from more or less reflections from the white board that fooled the meter. The K10D still underexposes considerably.

I indirectly mentioned that I took my test pictures in raw format. In ACR everything was set to zero, or neutral, or default and straight curve. Then the white balancing was made and I got the numbers from a sample point in the center of the picture.

The histogram in the camera is based on the JPG that is embedded in the raw file. To make the histogram reading to at least loosely match the saturation levels on the sensor, sort of speaking, you can set the WhiBal to K5000 all the time (assuming you shoot raw, otherwise just disregard this). For my take on the incamera histogram check this thread over at DPR:
K10D, WB and color histograms

Now what? I guess you either have to live with the underexposure and compensate for it yourself, or send the camera in. The DS is probably out of warranty but it clearly overexposes.

just my thoughts on the matter,
06-08-2007, 10:47 PM   #28
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Hi, JohnV3,
I have been using / experimenting with HDR images since getting my K10D. Let me share my finding:
I shoot in RAW for this always (PEF to save space on SD card. I use the AdobeRGB colour space which allows a greater dynamic range without blowing highlights.
I use a bracket setting of 2 stops between images ( the most available).
I find that 3 shots frequently works well although 5 is obviously better.
I do NOT convert to JPG as this discards 3 stops or more dynamic range before I start. Besides this provokes a warning from CS2.
PS CS2 and 3 are both happy to work on RAW files although you need to save in another format.
If you use the camera hand held you must allow PS to attempt to align the images (almost always successfully, but time consuming)
The 32bit image must be converted to 16 or 8. I usually work in 16 TIFF so I can adjust the image without banding developing. When satisfied you can save in JPG (8 bit)
The ony other thing to know is that there is a choice to be made for the conersion to 16 bit. the best choice for the beginner who doesn't want to use the levels in the histogran is the Equalise option. This works best when the image has 2 separate high points in the histogram graph.
I dont always like the result but I rate 2 of the images as the best I have produces in 60 years out of hundreds of thousande if not millions of images (retired professional).
Photog
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