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12-07-2013, 04:00 AM   #1
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K-5iis multizone metering - blown highlights

I took a few photos of kangaroos in the evening sun, and made the mistake of leaving the camera in multizone metering mode instead of center weighted. Here's an example of the result:




It's beyond me why the camera would over expose the highlights like this. This is actually one of the less blown out examples - I already deleted the worst. I understand that the multi-segment metering is trying to get a balance, but to blow out the highlights irretrievably seems bizarre. The camera was in Aperture Priority at f6.3 but with the shutter speed at only 1/320s it had a long way to go before running out of shutter speed. There was no exposure compensation set. Has anyone had a similar experience with the multi-segment metering? A bit of under-exposure can be fixed, but blown highlights are gone forever.

12-07-2013, 04:35 AM - 1 Like   #2
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No matter the brand, when you use a tele lens, use center or center weigted metering.

The background is often darker/brighter than what's in focus, and that's fooling the multi metering system.

Even the so praised Canon system have this flaw so far in the 40/50/60D.
12-07-2013, 04:45 AM   #3
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Yep. Welcome to Australia!!
I call highlight correction 'Australia mode', because if shooting outdoors, the difference between bright areas and dark is so great in Oz, you will get a part of every photo overexposed, no matter what.
I think highlight correction is pretty good: "60% of the time, it works every time."
IMHO, just leave it on unless shooting at night.
12-07-2013, 05:18 AM   #4
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QuoteOriginally posted by aurele Quote
No matter the brand, when you use a tele lens, use center or center weigted metering. The background is often darker/brighter than what's in focus, and that's fooling the multi metering system. Even the so praised Canon system have this flaw so far in the 40/50/60D.
Interesting! I usually do use centre weighted metering with telephoto lenses but I didn't expect this. I expected that the metering would be programmed so that dark areas didn't cause highlights to be blown out. It's surprising.

QuoteOriginally posted by calsan Quote
Yep. Welcome to Australia!! I call highlight correction 'Australia mode', because if shooting outdoors, the difference between bright areas and dark is so great in Oz, you will get a part of every photo overexposed, no matter what. I think highlight correction is pretty good: "60% of the time, it works every time." IMHO, just leave it on unless shooting at night.
Also an interesting suggestion. I have avoided highlight correction since I discovered that it has a tendency to adversely impact noise - actually, shadow correction is worse because it tries to bring shadow detail out of the noise floor. So highlight correction impacts the raw image?

12-07-2013, 05:56 AM   #5
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No offense, but - there's a reason it's called "multi-zone average" metering. And Pentax DSLRs already underexpose a bit compared to most other brands.
12-07-2013, 06:29 AM   #6
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Yes - give it a go. Even with my k-7 extra noise is a none issue in daylight.
12-07-2013, 06:30 AM   #7
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QuoteOriginally posted by RobG Quote
I expected that the metering would be programmed so that dark areas didn't cause highlights to be blown out.
QuoteOriginally posted by Giklab Quote
there's a reason it's called "multi-zone average" metering
the multi metering is associated with green mode usualy. It's not so bad for everyday shots, when there is no shadow or harsh light.

Outdoor, just forget multi metering because the difference in exposure between light area and shadow area is really really wide.
here is an example :

i took it with film, i metered the shadow because film never blow highlights (or almost never).
On this picture, with multi metering i get that :


Average mesure : the sum of dark shadow and highlight = average exposure.
12-07-2013, 11:04 AM   #8
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QuoteOriginally posted by RobG Quote
multizone metering mode instead of center weighted. Here's an example of the result:

The image is generally exposed correctly, so I think the issue is not with the metering "mode" itself. If it was simply a metering issue everything would be over-exposed. I also have had those terrible over-exposed areas in otherwise normally exposed shots.

12-07-2013, 02:27 PM   #9
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Instead of saying the camera got it wrong--you got it wrong because you did not properly interpret the needs of the scene as you wanted to capture it. No offense please--most of time most of us simply let the camera decide--but that cannot be fool proof--as the logic of what the proper exposure is is not so simple (remember the example of a black cat and a white wall, or the white cat and the black wall).

Although your posting is about the "inadequacy of matrix/multi-segment metering' in fact the metering as special K commented--is fine. The point is if you imagine a different scene--then balancing the dark and light areas is what you want. And in another scene the same exposure range and same resulting exposure setting would be underexposed.

Actually the interpretation of the various segments exposure values is not so straightforward as to say that one proper exposure value follows. In fact the same scene can have many proper exposure settings--depending on the photographers choice--i.e., what he/she "wants to say."

Actually the camera has some kind of logic it follows (in combining the various segments into a exposure value)--indeed one problem in using this metering mode--is the photographer is never sure what the camera logic is--and thus how to fix it (this is the reason may of us choose to not use this mode--as one cannot easily "accumulate the experience" to immediately/intuitively properly bias the exposure).

The point is you must look at the scene and choose what to meter and how to adjust the meter reading you get. Since the camera uses reflected light (and not incident light) it starts of at a huge disadvantage--it doesn't even know what the exposure is to make a middle gray look middle gray! This is what you need to tell it--along with what end of the exposure range you want to emphasize or ignore.

Actually the dslr is potentially a "teaching machine" in this regard, as you can immediately look at the taken image and see what happened, unlike w/ film where you took (mental or actual written) notes, and then saw what happened, quite a bit later when the film was developed.
12-07-2013, 04:04 PM   #10
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QuoteOriginally posted by Giklab Quote
No offense, but - there's a reason it's called "multi-zone average" metering. And Pentax DSLRs already underexpose a bit compared to most other brands.
Actually, you made me RTFM. It is not called "multi-zone average" metering, it's called "multi-segment metering". If all it was doing was a simple average across multiple segments, it would be a bit pointless. The manual specifically mentions compensating for backlighting, which unfortunately is the reverse of the situation I posted. A multi-segment average would not be effective at compensating for backlighting, although an example of multi-segment metering posted in this thread seems to suggest that the camera's algorithm doesn't cope well with brightness on one side. I'll have to test whether a backlit subject with light on both sides exposes for the subject correctly. In the image I posted, the camera seems to be compensating for an OOF dark area in the top right corner, and allowing the subject in the centre of the image to blow out. It surprises me that the algorithm used allows the focal point to blow out. If I was using something other than centre spot focus, I could understand using a different weighting - and indeed having RTFM there's a setting (not the default) for the camera metering to follow the focus point (link AE to AF point). I found a thread elsewhere which suggests that the normal bias is toward the centre of the frame and linking to the AF point will only be useful if the AF point is elsewhere. I'm now curious whether linking the AF point might eliminate this over, exposure at the centre.
12-07-2013, 05:19 PM   #11
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QuoteOriginally posted by dms Quote
Instead of saying the camera got it wrong--you got it wrong because you did not properly interpret the needs of the scene as you wanted to capture it. No offense please
Maybe you could go back to what I actually said - I prefaced everything with a statement that I made the mistake of leaving the camera in multi-segment mode. Normally I would use centre-weighted. My post relates to why the multi-segment metering allowed the highlights to be blown out. If you don't want me to take offense, you could have addressed my question without referring to an error which I already admitted.

QuoteQuote:
Although your posting is about the "inadequacy of matrix/multi-segment metering' in fact the metering as special K commented--is fine.
Maybe I should post a photo for comparison of another kangaroo in full shade. I disagree that the metering is fine. Looking at the image produced, the camera has exposed for the background not the subject. I'm not sure for that equates to the metering being "fine".

QuoteQuote:
Actually the interpretation of the various segments exposure values is not so straightforward as to say that one proper exposure value follows. In fact the same scene can have many proper exposure settings--depending on the photographers choice--i.e., what he/she "wants to say."
Of course. The camera can't know what's in my head. At this point, I'm questioning the logic of the Pentax programmers who apparently decided that it's ok to let the highlights be blown out - even knowing that with a digital image, it means that the highlight detail is lost.

QuoteQuote:
Actually the camera has some kind of logic it follows (in combining the various segments into a exposure value)--indeed one problem in using this metering mode--is the photographer is never sure what the camera logic is--and thus how to fix it (this is the reason may of us choose to not use this mode--as one cannot easily "accumulate the experience" to immediately/intuitively properly bias the exposure).
If indeed nobody knows the logic used by the camera in multi-segment metering, my question becomes moot and I'll simply avoid it. I'm trying to figure out what the logic may be, obviously not precisely but at least to get a better idea of it. In the example I posted, the exposure chosen by the algorithm seems to have exposed correctly for everything in the background, while allowing the foreground in the middle to be blown out and overexposed. The thing which shocked me wasn't that the middle was overexposed, but that it was blown out and detail was lost.

On pages 117 and 118 of the manual, the only specific difference mentioned with respect to the multi-segment metering "interpreting the scene" is backlighting. The manual specifically states that centre-weighted metering doesn't compensate for backlighting. That actually suggests the opposite of what I imagined for backlight compensation - it appears that the camera will underexpose the shadows so that it doesn't overexpose the highlights. If that's the case, and you had a person in shadow in front of a bright background, the multi-segment metering will probably result in a silhouette. Ordinarily, I would think that "backlight compensation" meant correcty exposing the subject and ignoring the backlight. I'll have to try it and see. I've used a combination of multipoint AF and multipoint metering on a Nikon (oh no, I mentioned the "N" word) which somehow correctly identified the person in the photo, correctly focussed on them and exposed for them.

QuoteQuote:
The point is you must look at the scene and choose what to meter and how to adjust the meter reading you get. Since the camera uses reflected light (and not incident light) it starts of at a huge disadvantage--it doesn't even know what the exposure is to make a middle gray look middle gray! This is what you need to tell it--along with what end of the exposure range you want to emphasize or ignore.
I'm perfectly well aware that I have options like the use of the exposure lock, centre weighted and spot exposures. Please focus on the subject. If the intention of multi-segment metering really is simply a multi-segment average, and the metering algorithm doesn't care what detail is lost in the highlights and shadows, its usefulness seems questionable unless it's based on an assumption that each scene doesn't contain a wide range of brightness. It may be useful on a dull day, but not in the full glare of the afternoon Australian sun. It could have been far more useful if the exposure chosen limited over-exposure in a situation where the middle of the image was bright and the borders were dark. In the reverse situation it would make more sense to allow the highlights to be blown out to avoid a dark subject with a bright background being lost in the shadows.
12-15-2013, 01:07 AM   #12
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QuoteOriginally posted by RobG Quote
I took a few photos of kangaroos in the evening sun, and made the mistake of leaving the camera in multizone metering mode instead of center weighted. Here's an example of the result:




It's beyond me why the camera would over expose the highlights like this. This is actually one of the less blown out examples - I already deleted the worst. I understand that the multi-segment metering is trying to get a balance, but to blow out the highlights irretrievably seems bizarre. The camera was in Aperture Priority at f6.3 but with the shutter speed at only 1/320s it had a long way to go before running out of shutter speed. There was no exposure compensation set. Has anyone had a similar experience with the multi-segment metering? A bit of under-exposure can be fixed, but blown highlights are gone forever.
I disagree, as I find the multizone metering is better for high contrast scenes. With that said, turn your Highlight Correction "On", raise your High/Low Key Adjustment, reduce your Contrast, and lower your Contrast Highlight Adjustment. Also, learn how to use histograms and "blinkies". That alone would have allowed you to prevent the issue of blown highlights.

Incidentally, when you lower your Contrast, the Saturation will generally need to be increased a tad.

Edit: I took a look at your EXIF info. for the shot, and again I will say - lower your contrast. That is what is causing your blown highlights. You are forcing the camera to expose with the maximum extremes between light and dark, and not giving it a chance to expose the shot in a more natural way. Incidentally: 1) Increasing your contrast does not really improve the sharpness of a photograph. & 2) You lose a lot of detail with higher contrast. The real world is not so stark all the time..

Last edited by zekewhipper; 12-15-2013 at 01:22 AM.
12-15-2013, 02:47 AM   #13
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QuoteOriginally posted by zekewhipper Quote
I disagree, as I find the multizone metering is better for high contrast scenes. With that said, turn your Highlight Correction "On", raise your High/Low Key Adjustment, reduce your Contrast, and lower your Contrast Highlight Adjustment. Also, learn how to use histograms and "blinkies". That alone would have allowed you to prevent the issue of blown highlights.
It would have been helpful if you had read my previous response. Thanks for your suggestions, but I wasn't actually looking for this sort of response. What I was trying to better understand was how the multizone metering is intended to work. In particular, I don't understand why the people who programmed the multizone metering didn't attempt to limit the loss of detail in blown out highlights. I was expecting the algorithm to be a lot smarter - as I have observed in another brand of DSLR, where the camera exposed for the subject not for the background. While the adjustments you suggested may well overcome the problem with that particular situation, what I'm trying to understand is what the Pentax programmers expected the default settings to achieve with multizone metering. For most photos I actually take, centre weighted metering works best for me, but a lot of work has gone into multizone metering, so it would be good to better understand what it really is capable of doing and what its limitations are. Sadly, I find the spot metering mode of limited usefulness as well.
12-15-2013, 09:05 AM   #14
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QuoteOriginally posted by RobG Quote
It would have been helpful if you had read my previous response. Thanks for your suggestions, but I wasn't actually looking for this sort of response. What I was trying to better understand was how the multizone metering is intended to work. In particular, I don't understand why the people who programmed the multizone metering didn't attempt to limit the loss of detail in blown out highlights. I was expecting the algorithm to be a lot smarter - as I have observed in another brand of DSLR, where the camera exposed for the subject not for the background. While the adjustments you suggested may well overcome the problem with that particular situation, what I'm trying to understand is what the Pentax programmers expected the default settings to achieve with multizone metering. For most photos I actually take, centre weighted metering works best for me, but a lot of work has gone into multizone metering, so it would be good to better understand what it really is capable of doing and what its limitations are. Sadly, I find the spot metering mode of limited usefulness as well.
I did read your response, and again I disagree. I also shoot Olympus, Nikon, and Sony; and I don't see them as being any more capable than Pentax. What I do see however is that some cameras have better dynamic range than others. That can give the impression of not metering correctly, because not everything can be exposed at the same time. Doing what I recommended will draw in the exposure distribution of the visual elements. With that said, the K-5 has as good a dynamic range as your going to get. If you are unhappy with the way Pentax's algorithm works, then like with any camera's shortcoming, you need to work around it besides just recognize it and grumble. Some folks like yourself worry about blown highlights, while some other photogs obsessed with noise hate too dark regions. Pentax probably tries to make both types of photographers happy by trying to keep the whole exposure distribution as centered as it can. That logically will lead to blown highlights and too dark regions when the spread is too great. That is why the camera is as customizable as it is, so that you can prioritize its functions around what is important to you and how you want your images to look.

I too shoot center-weighted (about 85% of the time), but you have to remember that you still need to analyze the elements in your scene and apply exposure compensation when you think you need to.

Giklab commented that Pentax underexposes a bit. I found that to be -sometimes- true with my K20D, But I definately find the opposite to be true with my K-5. That is why with my bracketing mode I have it set to do just two exposures (under & right on).

Do you have AF divorced from the shutter release? That matters too when it comes to getting the right exposure. If you don't, then everytime you AF it can change the exposure settings to something other than the subject's when you recompose.

Also, don't worry about noise so much. High contrast drives dark areas to be darker. The more dark something is the more noise shows up. Try exposing to the right, and then dropping the exposure in post-process.
12-19-2013, 10:41 AM   #15
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Gentlemen,

A novice here;

I use Spot Metering for Portraits, Macro & Point objects.

Center weighted metering - I just ignore. I don't have enough experience for using it. Neither do I have the experience to handle. It mentions in the manual this mode does not automatically compensate for backlit scenes.

Multi segmented Metering for Landscapes.

Having said that, I could be wrong, but usually before taking a picture in blown out sun I take digital preview, it helps me make last minute adjustments. Also using a Polaroid filter has helped.

I saw a friend of mine was spot on focus and exposure using a different brand (Entry level DSLR) at a concert, I had to go through several settings. What can I tell you, I felt I have to learn my camera better. The decision is mine to use a professional camera, where I don't have things like scene mode - Eg. Sports mode.


Cheers!
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