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10-17-2019, 07:53 PM   #1
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K 70 Exposure metering puzzle

Here's a puzzle. When using live view and all the settings are right for a properly exposed image, that is the meter is 0 or centered. But without changing settings and just switching over to view finder the meter reads +5 and still a good exposed image . Just to get my facts right, I was just playing with the bracketing reset ( the green button ) and it reset the settings so the meter read 0, but switching back to live view it read -5 and underexposed image. Any ideas out there form the more knowledgeable.

10-17-2019, 07:56 PM   #2
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Is your viewfinder metering set to something other than matrix mode?

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10-17-2019, 09:01 PM   #3
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QuoteOriginally posted by Doug Stanley Quote
Here's a puzzle. When using live view and all the settings are right for a properly exposed image, that is the meter is 0 or centered. But without changing settings and just switching over to view finder the meter reads +5 and still a good exposed image . Just to get my facts right, I was just playing with the bracketing reset ( the green button ) and it reset the settings so the meter read 0, but switching back to live view it read -5 and underexposed image. Any ideas out there form the more knowledgeable.
So, to restate your issue, originally both images were properly exposed, but EC read 0 for LV and EC was +5 was for OVF shots? {or did you have to change EC settings between the two shots, increase EC settings, to get proper exposure ??}
10-17-2019, 09:38 PM   #4
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QuoteOriginally posted by Doug Stanley Quote
Here's a puzzle. When using live view and all the settings are right for a properly exposed image, that is the meter is 0 or centered. But without changing settings and just switching over to view finder the meter reads +5 and still a good exposed image . Just to get my facts right, I was just playing with the bracketing reset ( the green button ) and it reset the settings so the meter read 0, but switching back to live view it read -5 and underexposed image. Any ideas out there form the more knowledgeable.
When I went to bed, I remembered this thread.
New K-70 - Metering issues between Live View and OVF - PentaxForums.com

Is anything familiar to you in it?

If your K-70 is still under warranty, or was under warranty until recently, you probably should contact the Pentax repair facility that services your area.

10-18-2019, 07:23 AM   #5
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It looks like this could well be a metering problem but it may be worth checking the mirror and focusing screen are clean. These are located in the light path to the view finder light meter but out of the way in live view mode. However, a 5-stop difference does sound like a much more major problem.
10-18-2019, 04:12 PM   #6
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QuoteOriginally posted by reduno Quote
It looks like this could well be a metering problem but it may be worth checking the mirror and focusing screen are clean. These are located in the light path to the view finder light meter but out of the way in live view mode. However, a 5-stop difference does sound like a much more major problem.
The thing I wasn't clear on is whether the 'EC' setting "just happened" or whether the OP had to set that difference in order to make the photograph 'work' - so I'm waiting for the OP to clarify where the 5-step EC came from.
10-18-2019, 07:08 PM   #7
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QuoteOriginally posted by reh321 Quote
The thing I wasn't clear on is whether the 'EC' setting "just happened" or whether the OP had to set that difference in order to make the photograph 'work' - so I'm waiting for the OP to clarify where the 5-step EC came from.
I had a play with my K-70 to see if I could get any clues. The OP looks to be using M mode with a lens with no aperture ring (or at least in A mode). This mode display the bar graph exposure meter with a +/-5 EC range. Pressing the green button adjusts the aperture to center the meter. Switching from optical to live view (on my camera) makes no noticeable difference and the meter remains centered.

Since the OP indicated he got a good exposure centering the meter in live view, it appears the camera sensor itself is metering correctly. When he switched over to the optical view finder the meter read +5, suggesting the viewfinder meter is overly sensitive.

10-18-2019, 08:19 PM   #8
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QuoteOriginally posted by Adam Quote
Is your viewfinder metering set to something other than matrix mode?
Sorry, if I am not up on all this gal dern fancy technical talk. What is matrix mode for view finder metering?

---------- Post added 10-18-19 at 08:32 PM ----------

QuoteOriginally posted by reh321 Quote
So, to restate your issue, originally both images were properly exposed, but EC read 0 for LV and EC was +5 was for OVF shots? {or did you have to change EC settings between the two shots, increase EC settings, to get proper exposure ??}
No changes in settings, switching over the meter reads 5 stops higher

---------- Post added 10-18-19 at 08:55 PM ----------

QuoteOriginally posted by reh321 Quote
The thing I wasn't clear on is whether the 'EC' setting "just happened" or whether the OP had to set that difference in order to make the photograph 'work' - so I'm waiting for the OP to clarify where the 5-step EC came from.
Sorry for being dense. What is OP?

---------- Post added 10-18-19 at 09:06 PM ----------

QuoteOriginally posted by reduno Quote
I had a play with my K-70 to see if I could get any clues. The OP looks to be using M mode with a lens with no aperture ring (or at least in A mode). This mode display the bar graph exposure meter with a +/-5 EC range. Pressing the green button adjusts the aperture to center the meter. Switching from optical to live view (on my camera) makes no noticeable difference and the meter remains centered.

Since the OP indicated he got a good exposure centering the meter in live view, it appears the camera sensor itself is metering correctly. When he switched over to the optical view finder the meter read +5, suggesting the viewfinder meter is overly sensitive.
Thanks for taking the time to puzzle over my problem. I've been living with this for , oh, six months. Its livable just annoying.
10-18-2019, 09:33 PM   #9
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QuoteOriginally posted by Doug Stanley Quote
Sorry for being dense. What is OP?
Original poster.

QuoteOriginally posted by Doug Stanley Quote
Sorry, if I am not up on all this gal dern fancy technical talk. What is matrix mode for view finder metering?

This is documented in more detail in the camera manual, but basically, there are three different metering modes when shooting through the viewfinder. Here is a quick overview:
Exposure metering modes - PentaxForums.com

Spot metering mode, for example, bases the exposure just on the center of the frame. Center-weighted has a bias toward the center, but also considers the area around it. Matrix metering considers the entire frame. The latter is the default unless you change your settings.


In live view, however, the camera will meter using the entirety of what the sensor actually sees. So, if you have the viewfinder set to spot or center-weighted, then you might see a big difference between the two (and likely better exposure accuracy in live view). This will be especially apparent if the lighting in the center of the frame differs from the rest.

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10-18-2019, 10:14 PM   #10
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QuoteOriginally posted by reh321 Quote
When I went to bed, I remembered this thread.
New K-70 - Metering issues between Live View and OVF - PentaxForums.com
The original post of that thread was confirmed to be a difference in metering between the optical viewfinder and live view. Two other users weighed in stating similar problems with one turning out to be an aperture control exposure problem, not a metering issue; that problem was repaired, though it is not clear what the actual cause was (two components were replaced).

After reading through this thread, I am a little confused, but am thinking this is a difference in metering between optical and live view meters, possibly traceable to using the spot meter.


Steve
10-18-2019, 11:46 PM   #11
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Welcome to the Pentax Forums! I am late to this thread, but am willing to weigh in.

QuoteOriginally posted by Doug Stanley Quote
Here's a puzzle. When using live view and all the settings are right for a properly exposed image, that is the meter is 0 or centered.
As noted above, it reads like you are using M mode to set exposure manually.

QuoteOriginally posted by Doug Stanley Quote
But without changing settings and just switching over to view finder the meter reads +5 and still a good exposed image .
Changing over to the optical viewfinder, the display now reads +5 EV rather than being centered. That is a pretty big jump!

QuoteOriginally posted by Doug Stanley Quote
Just to get my facts right, I was just playing with the bracketing reset ( the green button ) and it reset the settings so the meter read 0,
You lost me here. I am going to assume you did not mean bracketing and just meant letting the camera meter your M-mode exposure using the green button (default is program line).

QuoteOriginally posted by Doug Stanley Quote
but switching back to live view it read -5 and underexposed image.
This would be expected given that you saw a 5 EV difference in meter reading between the two modes before.

Now, a few comments and requests and maybe a few questions:
  • As noted by Adam above, the optical viewfinder and live view approach metering differently and it is not unusual for there to be a difference on the EV scale for meter readings between the two
  • As also noted, the K-70 supports three different meter modes: matrix (the default), center-weighted, and spot metering. The icons for each mode are on page 58 of the camera manual. The icon for the current set mode will be displayed in the viewfinder and on the rear status screen
  • You can set meter mode using the menu system or the Info screen
  • Meter modes apply to both viewfinder and live view meter systems and unless you have reason to do otherwise, it is usually good to leave the mode on matrix. There are situations where both center-weighted and spot are useful, but only if one knows when and how to use them.

Now a few suggestions/requests
  • Confirm that your camera is set for matrix metering
  • Confirm that you are set up for single exposure and not bracketing. Bracketing is a nice feature, but things can get complex quickly and simple is good when troubleshooting.
  • Confirm that the camera is not set up to do HDR. (HDR is basically just a bracketed merge...see above point.)
  • Confirm that you are not set up to link AF point and metering (menu --> C1 --> 5. Link AE and AF point)
  • Confirm that Exposure Compensation is set to 0 (zero) by holding down the EC button while pressing the green button; that should clear any set EC.
  • Be aware that viewfinder metering is most accurate when one's eye is at the viewfinder. When this is not the case (e.g. using a tripod), light may enter through the eyepiece and cause a false meter reading, sometimes 5 or more EV in error. To avoid this, you can shade the opening with your thumb or something else.

Now a controlled test (will work better on a tripod or table or some other fixed support):
  1. Point your camera at a blank evenly-lit white wall. Focus is not critical except that it should be the same for the entire test. The test may actually work better with AF turned off and the lens focused to infinity.
  2. Using M mode and the optical viewfinder adjust exposure to center the pointer at zero (0) on the EV scale. Be sure the viewfinder eyepiece is not exposed to stray light.
  3. Release the shutter to take a photo using this setting
  4. Pointing at the same portion of the wall at the same distance, switch to live view and note any difference in the meter reading on the EV scale. If not the same, adjust to zero.
  5. Take another photo using the live view metering
The expected results are for the two meter readings to be very close on the EV scale with little or no difference in recommended exposure. After all, it is a blank wall. Also expected is to get two plain gray photos of close to the same brightness with almost identical centered histograms.


Steve

Last edited by stevebrot; 10-18-2019 at 11:55 PM.
10-19-2019, 06:19 AM   #12
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QuoteOriginally posted by Doug Stanley Quote
Sorry for being dense. What is OP?
Depending on context, it is either Original Post or Original Poster {i.e., you or what you said initially}.
10-19-2019, 08:03 PM   #13
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QuoteOriginally posted by Adam Quote
Original poster.




This is documented in more detail in the camera manual, but basically, there are three different metering modes when shooting through the viewfinder. Here is a quick overview:
Exposure metering modes - PentaxForums.com

Spot metering mode, for example, bases the exposure just on the center of the frame. Center-weighted has a bias toward the center, but also considers the area around it. Matrix metering considers the entire frame. The latter is the default unless you change your settings.


In live view, however, the camera will meter using the entirety of what the sensor actually sees. So, if you have the viewfinder set to spot or center-weighted, then you might see a big difference between the two (and likely better exposure accuracy in live view). This will be especially apparent if the lighting in the center of the frame differs from the rest.
Thanks Adam. I have used all three exposure modes over the last few months and it does not make a difference. I was just unaware of the term 'matrix'. However I was unaware that Live view was unaffected by these modes. Good to know. Thanks again.
10-19-2019, 09:07 PM   #14
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QuoteOriginally posted by stevebrot Quote
Welcome to the Pentax Forums! I am late to this thread, but am willing to weigh in.



As noted above, it reads like you are using M mode to set exposure manually.



Changing over to the optical viewfinder, the display now reads +5 EV rather than being centered. That is a pretty big jump!



You lost me here. I am going to assume you did not mean bracketing and just meant letting the camera meter your M-mode exposure using the green button (default is program line).



This would be expected given that you saw a 5 EV difference in meter reading between the two modes before.

Now, a few comments and requests and maybe a few questions:
  • As noted by Adam above, the optical viewfinder and live view approach metering differently and it is not unusual for there to be a difference on the EV scale for meter readings between the two
  • As also noted, the K-70 supports three different meter modes: matrix (the default), center-weighted, and spot metering. The icons for each mode are on page 58 of the camera manual. The icon for the current set mode will be displayed in the viewfinder and on the rear status screen
  • You can set meter mode using the menu system or the Info screen
  • Meter modes apply to both viewfinder and live view meter systems and unless you have reason to do otherwise, it is usually good to leave the mode on matrix. There are situations where both center-weighted and spot are useful, but only if one knows when and how to use them.

Now a few suggestions/requests
  • Confirm that your camera is set for matrix metering
  • Confirm that you are set up for single exposure and not bracketing. Bracketing is a nice feature, but things can get complex quickly and simple is good when troubleshooting.
  • Confirm that the camera is not set up to do HDR. (HDR is basically just a bracketed merge...see above point.)
  • Confirm that you are not set up to link AF point and metering (menu --> C1 --> 5. Link AE and AF point)
  • Confirm that Exposure Compensation is set to 0 (zero) by holding down the EC button while pressing the green button; that should clear any set EC.
  • Be aware that viewfinder metering is most accurate when one's eye is at the viewfinder. When this is not the case (e.g. using a tripod), light may enter through the eyepiece and cause a false meter reading, sometimes 5 or more EV in error. To avoid this, you can shade the opening with your thumb or something else.

Now a controlled test (will work better on a tripod or table or some other fixed support):
  1. Point your camera at a blank evenly-lit white wall. Focus is not critical except that it should be the same for the entire test. The test may actually work better with AF turned off and the lens focused to infinity.
  2. Using M mode and the optical viewfinder adjust exposure to center the pointer at zero (0) on the EV scale. Be sure the viewfinder eyepiece is not exposed to stray light.
  3. Release the shutter to take a photo using this setting
  4. Pointing at the same portion of the wall at the same distance, switch to live view and note any difference in the meter reading on the EV scale. If not the same, adjust to zero.
  5. Take another photo using the live view metering
The expected results are for the two meter readings to be very close on the EV scale with little or no difference in recommended exposure. After all, it is a blank wall. Also expected is to get two plain gray photos of close to the same brightness with almost identical centered histograms.


Steve
Thanks Steve for the step by step to eliminate possible variables and the control test. ..... Results- View finder at 0 resulting image - black. ... Switch to Live View meter reads -5 resulting image - black. ... Set meter to 0 on Live View image grey , histogram centered. ..... Switch back to View finder meter reads +5 , image grey, histogram centered.
Thanks Again for your time and expertise.

---------- Post added 10-19-19 at 09:10 PM ----------

QuoteOriginally posted by reh321 Quote
Depending on context, it is either Original Post or Original Poster {i.e., you or what you said initially}.
OP , I thought it might be a camera setting I was not aware of. Thanks for the clarification on posting lingo.
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