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08-08-2017, 06:35 AM   #1
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K-70 Exposure issues

I shot this scene on Sunday. As you can see, it's clearly underexposed. I feel like I play exposure roulette every time I take a Pentax out for a day's shooting. Half the pictures come out like this, for no apparent reason. My K-50 was just as bad. What causes this?

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08-08-2017, 06:42 AM   #2
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Most obvious reason would be the use of spot metering as shown in the exif. The K-70 is very accurate with exposure but you can intentionally throw it off, as shown here.
08-08-2017, 06:42 AM   #3
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Easy to answer. The exif says you used spot metering, which would be right where the sun is shining on the white of the boat. Your camera has done exactly what you told it to.
08-08-2017, 06:58 AM   #4
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I figured someone would "spot" that but I can tell you, that has no effect on the metering. I get this sort of random exposure with all metering modes. Here's another pic of the same boat in nearly identical light. This is just bizarre - shutter priority, and the auto ISO sets itself to 1600 and an aperture of f25???

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08-08-2017, 07:08 AM   #5
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There is even an easy solution even if you shoot jpegs and not in RAW. Post processing can deal with underexposure much more readily than overexposure. I routinely shoot -1EV in bright sun outdoors for this very reason. If you didn't crop, the spot used is right on the junction of the white and dark side by the seat.

Anyway, your picture cleans up nicely with Silkypix's EV and HDR tools even as a reduced jpg. I'm sure if you shoot in raw you could get a much better output using your own software.



---------- Post added 08-08-17 at 11:47 AM ----------

QuoteOriginally posted by Wolfeye Quote
I figured someone would "spot" that but I can tell you, that has no effect on the metering. I get this sort of random exposure with all metering modes. Here's another pic of the same boat in nearly identical light. This is just bizarre - shutter priority, and the auto ISO sets itself to 1600 and an aperture of f25???
Re. 2nd pic...Center spot here appears to be the reflection off the blowup tube near the girl's left elbow.

Use another metering mode. I tend to use center-weighted outdoors. For me, spot metering is for specialized uses like getting a bird inside a thicket in my experience. And shooting the moon at night.

Last edited by jgnfld; 08-08-2017 at 07:22 AM.
08-08-2017, 07:18 AM   #6
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QuoteOriginally posted by Wolfeye Quote
I figured someone would "spot" that but I can tell you, that has no effect on the metering. I get this sort of random exposure with all metering modes. Here's another pic of the same boat in nearly identical light. This is just bizarre - shutter priority, and the auto ISO sets itself to 1600 and an aperture of f25???
I think you may be confusing "metering mode" with "exposure program". This one too is shot with spot metering and with shutter-speed priority exposure program. No wonder it's all over the place. Why aren't you using center-weighed with shutter-speed priority on a shot like this? There seems to be little reason to go to spot-metering on a evenly-lit scene such as this.
08-08-2017, 07:20 AM   #7
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QuoteOriginally posted by jgnfld Quote
There is even an easy solution even if you shoot jpegs and not in RAW. Post processing can deal with underexposure much more readily than overexposure. I routinely shoot -1EV in bright sun outdoors for this very reason. If you didn't crop, the spot used is right on the junction of the white and dark side by the seat.

Anyway, your picture cleans up nicely with Silkypix's EV and HDR tools even as a reduced jpg. I'm sure if you shoot in raw you could get a much better output using your own software.
I do shoot in RAW and yes I can "fix" all these weirdly-exposed shots, but I shouldn't have to. I have no issues with any other camera than Pentax. I think I'll send the camera in for Precision camera to look at, since it's still under warranty.

Maybe the gods of fate will smile kindly on me.
08-08-2017, 07:26 AM   #8
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QuoteOriginally posted by Wolfeye Quote
I do shoot in RAW and yes I can "fix" all these weirdly-exposed shots, but I shouldn't have to. I have no issues with any other camera than Pentax. I think I'll send the camera in for Precision camera to look at, since it's still under warranty.

Maybe the gods of fate will smile kindly on me.
I give up! Why send the camera in if you haven't excluded user error yet?

08-08-2017, 07:32 AM - 1 Like   #9
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QuoteOriginally posted by Wolfeye Quote
I do shoot in RAW and yes I can "fix" all these weirdly-exposed shots, but I shouldn't have to. I have no issues with any other camera than Pentax. I think I'll send the camera in for Precision camera to look at, since it's still under warranty.

Maybe the gods of fate will smile kindly on me.
Before doing this, try the suggestions to use center-weighted or multi metering modes (middle and top icons in camera menu screen 1 "AE Metering" suboption).

It is possible that Ricoh's not including text with these icons was a point of confusion. Reading this article may help as well and shows examples of what you are seeing. Camera metering modes explained

That said, when you use spot metering outside, "exposure roulette" is precisely the game you are playing.

Last edited by jgnfld; 08-08-2017 at 07:38 AM.
08-08-2017, 07:34 AM   #10
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QuoteOriginally posted by newmikey Quote
I think you may be confusing "metering mode" with "exposure program". This one too is shot with spot metering and with shutter-speed priority exposure program. No wonder it's all over the place. Why aren't you using center-weighed with shutter-speed priority on a shot like this? There seems to be little reason to go to spot-metering on a evenly-lit scene such as this.
Nope. I am not confused. The second shot is 1/500 sec, shutter-priority mode. The auto ISO selected by the camera was 1600, and it selected f25. Spot metering meters just the center part of the scene, as shown in this mockup. There's nothing there that suggests such a high ISO and small aperture are required. Any other camera might set this to f11 at ISO 400.
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08-08-2017, 07:44 AM   #11
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QuoteOriginally posted by Wolfeye Quote
Nope. I am not confused. The second shot is 1/500 sec, shutter-priority mode. The auto ISO selected by the camera was 1600, and it selected f25. Spot metering meters just the center part of the scene, as shown in this mockup. There's nothing there that suggests such a high ISO and small aperture are required. Any other camera might set this to f11 at ISO 400.
If you won't try the suggestions of other users to fix your problems with likely user error, there is really nothing more to say. But then don't post complaints either.

The "confusion" I was positing was confusion possibly generated by Ricoh, not you.
08-08-2017, 07:46 AM - 1 Like   #12
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If you insist on using spot metering you will get the results you are seeing. That is a simple fact and has nothing to do with any camera error. Stop using spot metering and use center weighted and your results will be different and more consistent.
Also, turn off Auto-ISO there is no reason for that in a normally lit scene. Auto-ISO in general is bad idea that causes more problems than it is worth. It can be useful if the light is changing wildly but in any sort of normal light, set the ISO manually to a value that allows your other settings to be in the range you want.
08-08-2017, 07:49 AM   #13
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QuoteOriginally posted by Wolfeye Quote
Nope. I am not confused. The second shot is 1/500 sec, shutter-priority mode. The auto ISO selected by the camera was 1600, and it selected f25. Spot metering meters just the center part of the scene, as shown in this mockup. There's nothing there that suggests such a high ISO and small aperture are required. Any other camera might set this to f11 at ISO 400.
IMO you should always have the camera in matrix metering mode unless that results in improper exposure. Even a very slight misalignment in spot metering mode can throw the whole balance off. Certainly that was the issue in the other photo, but this one seems like it at least got a proper exposure reading.

I would check the auto ISO range, as it sounds silly for the camera to willingly choose those settings unless it was forced into a minimum ISO of 1600.

Unlike more advanced Pentax bodies, the K-70 lacks the ISO program line and general program line settings, so you can't control the behavior without turning to the camera's scene modes. However, the default should still result in "typical" settings rather than what you're seeing here.

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08-08-2017, 07:49 AM   #14
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Curious, applied the same overlay to the first picture, and the "metered" area is dominated by the dark blue stripe on the boat, not the white area. Thusly, shouldn't that have metered as darker than the second pic? Why did the camera choose ISO 100? Curiouser and curiouser...

---------- Post added 08-08-17 at 09:54 AM ----------

QuoteOriginally posted by Adam Quote
IMO you should always have the camera in matrix metering mode unless that results in improper exposure. Even a very slight misalignment in spot metering mode can throw the whole balance off. Certainly that was the issue in the other photo, but this one seems like it at least got a proper exposure reading.

I would check the auto ISO range, as it sounds silly for the camera to willingly choose those settings unless it was forced into a minimum ISO of 1600.

Unlike more advanced Pentax bodies, the K-70 lacks the ISO program line and general program line settings, so you can't control the behavior without turning to the camera's scene modes. However, the default should still result in "typical" settings rather than what you're seeing here.
Thanks, Adam, this may be sound advice. I need to do more controlled testing to determine what's going on. I did switch to spot metering because matrix metering was not recording correctly either, but I'll revisit that setting and try again. My primary subject is often a black dog, and as anyone who shoots black dogs regularly can tell you, they can be a royal PITA to get the exposure right on. I just didn't expect this much difficulty on such an easy scene.
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08-08-2017, 07:54 AM - 1 Like   #15
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QuoteOriginally posted by jatrax Quote
Also, turn off Auto-ISO there is no reason for that in a normally lit scene. Auto-ISO in general is bad idea that causes more problems than it is worth. It can be useful if the light is changing wildly but in any sort of normal light, set the ISO manually to a value that allows your other settings to be in the range you want.
Or at least set it to a sensible range like 100-1200 or even 100-400. Outdoors daylight should rarely require more than 400.
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