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06-15-2022, 03:37 AM   #1
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K-70 exposure problems in Auto mode

[Thread title should read K-70, not K-20]
I've been into photography for nearly 40 years, and still consider myself to be not much more than a novice. I started out in 1984 with a Pentax ME Super, then augmented that with a used Pentax MX, and had those cameras for a long time, and sold them to finance the purchase of my first digital camera, the Olympus Camedia 2040 Zoom. In 2004, I bought the Pentax *ist-D, and used that camera until last summer, then had it professionally cleaned and inspected, and gave it to my daughter when I bought my new Pentax K-70 .I am using it with the Pentax 18-55mm F1.3 lens that came with it, as well as an older Sigma 18-200 F-3.5 lens.

Much of the photography I do is of cars, mostly at Cruise Nights, as we call them here in eastern Ontario, Canada, known elsewhere as Cars & Coffee. I also take pictures of old and interesting cars wherever I see them. I have an archive of car pictures that currently numbers about 1500.

The problem I am having is that, too often, when shooting in full-auto mode, with ISO set at 100 with the Sigma lens, some pictures are coming out overexposed, almost washed out, as if the camera chose too slow a shutter speed, or too big an aperture.

Is anyone else experiencing this? Is this the camera not functioning properly, or am I doing something wrong?

The accompanying photo was taken at my local Cruise Night last Wednesday evening at 5:39 with the sun obscured by a passing cloud. It was taken at 26mm focal length, f/8, 1/125-sec shutter speed, ISO 100 in Auto shooting mode. Note how the building in the background blends into the sky.

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Last edited by gearjammer63; 06-15-2022 at 03:48 AM.
06-15-2022, 03:58 AM   #2
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QuoteOriginally posted by gearjammer63 Quote
[Thread title should read K-70, not K-20]
Fixed.......
06-15-2022, 04:34 AM   #3
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QuoteOriginally posted by gearjammer63 Quote
The problem I am having is that, too often, when shooting in full-auto mode, with ISO set at 100 with the Sigma lens, some pictures are coming out overexposed, almost washed out, as if the camera chose too slow a shutter speed, or too big an aperture.
Is anyone else experiencing this? Is this the camera not functioning properly, or am I doing something wrong?
I've replicated a similar fault by accidently pressing the AE Lock button when gripping the camera.
If the camera is pointed to the ground or somewhere relatively dark when AE Lock is activated, the camera will over-expose if the subject is somewhat lighter.
Check if pressing the AE-L button on your camera causes the 'asterix' indicator next to the ISO rating in the viewfinder to illuminate.
If so, you may want to try allocating a different function to that button see Menu 'Camera' 5 "Button Customisation".
Not a perfect solution, I know, but maybe better than over-exposed pictures
Hope this helps good luck
06-15-2022, 04:52 AM   #4
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Maybe shooting in landscape mode as EXIF reveals causes this problem? On my K-01 shooting in landscape mode without there being a landscape does not give a satisfactory picture...
On the other hand I feel that 1/125 exposure time with the light being as it is, is perhaps a bit long, or the aperture too far open, or a bit of both. Have you tried setting the values yourself as you did with your mx and super me?


Last edited by AfterPentax Mark II; 06-15-2022 at 12:52 PM. Reason: Changed KP to K-01
06-15-2022, 07:52 AM - 1 Like   #5
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QuoteOriginally posted by AfterPentax Mark II Quote
Maybe shooting in landscape mode as EXIF reveals causes this problem? On my KP shooting in landscape mode without there being a landscape does not give a satisfactory picture...
On the other hand I feel that 1/125 exposure time with the light being as it is, is perhaps a bit long, or the aperture too far open, or a bit of both. Have you tried setting the values yourself as you did with your mx and super me?
My KP has no SCN Modes and thus no landscape mode?
You seem to have a unique version of the KP?

@gearjammer63:
You write AUTO-MODE (which would be the worst) but EXIF does reveal SNC (Scene) = almost AUTO but a little bit better....
yet... it is not really the way to go with such a wonderful camera.

With your ME Super and your MX you must have learned about aperture and exposure-time?
There is something which is too sad if one just uses AUTO or SCN.

At least learn P-Mode, which first is AUTO but you can override it either to Tv or Av!
06-15-2022, 10:32 AM   #6
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Looking at the shot the DOF seems more shallow than it should be at f/8 using 26mm focal length. So it may be that the Sigma lens has a problem stopping down the aperture, and the shot may be using wide open aperture.

If you try to capture the same shot using same focal length, stopped down to same f-stop and using same shutter speed using your Pentax and Sigma lenses to you notice other differences other than brightness when you compare these images?
06-15-2022, 11:39 AM   #7
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QuoteOriginally posted by photogem Quote
At least learn P-Mode, which first is AUTO but you can override it either to Tv or Av!
Not quite - in ‘AUTO’ mode you leave all aspects of the initial ‘triangle’ to the camera body - although apparently {although I’ve never photographed in ‘AUTO’ mode, I set up my KP to use that mode just now} you can override the ISO choice. In ‘P’ mode, you do control ISO and I routinely override shutter speed or aperture if I don’t like the initial choice. I use ‘P’ mode all the time, because often I don’t care what the initial choice is.


Last edited by reh321; 06-15-2022 at 12:57 PM. Reason: Added parenthetical expression about trying ‘AUTO’ mode
06-15-2022, 01:04 PM - 1 Like   #8
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QuoteOriginally posted by photogem Quote
You seem to have a unique version of the KP?
I stand corrected! My unique version of the KP is the mirrorless version of it: K-01! Getting confused between the two brilliant installments of camera's labled Pentax.
06-15-2022, 02:36 PM   #9
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I think Fogel70 has figured it out. I bet that Sigma has a slow iris.
06-15-2022, 02:38 PM   #10
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QuoteOriginally posted by photogem Quote
My KP has no SCN Modes and thus no landscape mode?
You seem to have a unique version of the KP?
"Landscape" with the KP could only be one of the Custom Image categories- but this would have little or nothing to do with the camera's setting of exposure. Something else has to be causing this problem, and you are right, having a SCN mode would be improper with an advanced model such as the KP.

---------- Post added 06-15-22 at 02:42 PM ----------

QuoteOriginally posted by photogem Quote
At least learn P-Mode, which first is AUTO but you can override it either to Tv or Av!
That would also be my suggestion. In the "Auto" mode, the camera has control over many aspects of operation with no control by the user, whereas in "P" mode the user has access to all adjustments as well as Tv or Av operation in switching to the exclusive and very useful Pentax Hyper Program. Trying AE modes other than the green "auto" would be a good idea.

---------- Post added 06-15-22 at 02:51 PM ----------

QuoteOriginally posted by reh321 Quote
Not quite - in ‘AUTO’ mode you leave all aspects of the initial ‘triangle’ to the camera body - although apparently {although I’ve never photographed in ‘AUTO’ mode, I set up my KP to use that mode just now} you can override the ISO choice. In ‘P’ mode, you do control ISO and I routinely override shutter speed or aperture if I don’t like the initial choice. I use ‘P’ mode all the time, because often I don’t care what the initial choice is.
I too never use the "Auto" mode except sometimes if handing to someone who knows nothing about cameras to take a picture with me in it, so they don't accidentally touch a control that might bring unwanted results. I work very much as you do, often using "P" mode.

Like Fogel70, I also think the real problem could be the lens, so trying the same shot with the Pentax kit lens might reveal the cause being the Sigma lens. However, if there is a control available in "Auto" mode, perhaps it is set wrong.

Last edited by mikesbike; 06-15-2022 at 03:41 PM.
06-16-2022, 11:15 AM - 1 Like   #11
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Thank you, everyone. I will try P mode and see how that works out.
06-16-2022, 03:14 PM   #12
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QuoteOriginally posted by gearjammer63 Quote
Thank you, everyone. I will try P mode and see how that works out.
Good luck! And let us know!
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