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06-24-2019, 04:43 AM   #1
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KP bug or KP Broken, Av Mode and Red Blinky Warning Text in LV

So I've noticed this a couple of times now and having a K-1 to test with as well can see the two cameras doing something different even when in the same configuration modes (at least I think they are identical).

This evening I placed the 20-40 on my KP, I'm in Av mode, Auto ISO (ISO Parameters set at 100-3200). I'm in a dimly lit room, with light sources only from lamps at various corners. If I aim the KP with the 20-40 in this mode at a lamp (in Live View mode) I get white text, as I pan around the room to darker lit areas I can see that white text jump around (as it should as it compensates etc), when finally landing at quite a dark area the white text begins to blink red. Fine I think... it's warning me, I need to adjust a setting for correction exposure, so I adjust ISO, significantly so, in fact I max it out at 819200 and get a shutter speed of 1/1600 and its still blinking red! Then it dawns on me... wait up... Av mode... red blinky text.. that actually shouldn't happen at all period! Even if I max to 3200 ISO (from my AUTO ISO Parameter) it should just then keep lowering the shutter speed, perhaps blinking red when I exceed 30 sec exposure?!

So I take the lens off the KP and put the 20-40 on the K-1, and pan it around the same areas of the home, it never blinks red, the white text stays white and drops shutter speeds to very low levels if need be, but never goes red.

So I try another lens with the KP, an F28, and it's doing the same problem as mentioned before, blinking red again in Av mode.

So at least I know this isn't a lens issue, it seems my KP is somewhat broken, bugged or confused.

I put it in Manual Mode, and once I panned it ever so slowly from a nicely lit area to a darker place and it started blinking at me, I pressed the green button (bind to Tv Shift) and it adjusted the shutter speed accordingly.. BUT STILL STAYS BLINKING RED.

FWIW at any time i take a shot in Av mode or after I green button, despite the red blinky text the shot is still exposed correctly.

Has anyone seen this before?

TIA

BB

06-24-2019, 05:14 AM - 3 Likes   #2
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Blinking exposure values like that are the camera's way of saying the light levels are out of the range of the metering sensor or live view AE software -- either far too dark or far to bright too meter accurately.

Last edited by photoptimist; 06-24-2019 at 01:57 PM. Reason: typos
06-24-2019, 05:20 AM   #3
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QuoteOriginally posted by photoptimist Quote
Blinking exposure values like that are the camera's way of saying the light levels are out of the range of the metering sensor or live view AE software -- either far to dark or far to bright to meter accurately.
So I have a K3 owner confirming this same behaviour too. Just the K-1 can handle it. So it's a sensor issue? Are we saying it's deliberate, like it's blinking red saying "Um... don't trust me too much ok pal... I might be getting this wrong but I'm trying here"?

However K-1 is like boss man and can handle it all with no red blinky text with the SAME lenses in the SAME room (mind you different FoV with the lenses granted)... but still...

---------- Post added 06-24-19 at 10:31 PM ----------

QuoteOriginally posted by photoptimist Quote
Blinking exposure values like that are the camera's way of saying the light levels are out of the range of the metering sensor or live view AE software -- either far to dark or far to bright to meter accurately.
So the KP handles light metering worse than the K-1, despite being a later model?
06-24-2019, 06:12 AM - 1 Like   #4
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QuoteOriginally posted by BruceBanner Quote
So the KP handles light metering worse than the K-1, despite being a later model?
Are you using the same metering mode on both cameras? Lenses with the same field of view (so that the areas being metered for are consistent)? Standing in the same place and pointing at exactly the same point in the scene?

06-24-2019, 06:23 AM - 1 Like   #5
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QuoteOriginally posted by BruceBanner Quote
So I have a K3 owner confirming this same behaviour too. Just the K-1 can handle it. So it's a sensor issue? Are we saying it's deliberate, like it's blinking red saying "Um... don't trust me too much ok pal... I might be getting this wrong but I'm trying here"?

However K-1 is like boss man and can handle it all with no red blinky text with the SAME lenses in the SAME room (mind you different FoV with the lenses granted)... but still...

---------- Post added 06-24-19 at 10:31 PM ----------



So the KP handles light metering worse than the K-1, despite being a later model?
The official specs say the K-1 meter can handle EV -3 to 18 and the KP can handle EV -3 to 20. But that spec is probably for the meter in the pentaprism. If you were metering through the eyepeice (not live view mode), then both the K-1 and KP should be able to meter down to EV -3 which is something like 60 seconds @ f/2.8 & ISO 100 and corresponds to a scene lit by a full moon. (Note: it's a bit trickier than that because the operating range also depends on the widest aperture of the lens.)

But the camera is not using that meter when using live view. It is using the sensor. The working range of metering in live view mode would depend on: 1) the longest exposure time LV mode uses on the sensor; 2) the highest level of ISO gain that LV mode is allowed to use; 3) whether LV mode stops down the lens to the user-selected aperture. If LV mode maintains a 30 fps video frame rate, the longest shutter time it can use is 1/30 second. It's then a matter of how much ISO gain the LV mode will use and whether heavily amplified image sensor values have an accurate enough black point to make an accurate estimate. If LV mode stops down the lens (to show accurate depth of field), the low-light metering range will be significantly worse.
06-24-2019, 07:01 AM - 1 Like   #6
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QuoteOriginally posted by BruceBanner Quote
get a shutter speed of 1/1600 and its still blinking red!
The blinky indicates that the light to the meter is either out of linear range or that the metered EV is outside the available settings for auto-exposure. As noted above, live view is different than the optical viewfinder meter and apparently the image sensor used as meter has a more limited linear range.

No bug...no broken...simply how it works.


Steve

P.S. The lower sensitivity limit in live view on my K-3 is EV100 1.

Last edited by stevebrot; 06-24-2019 at 07:18 AM.
06-24-2019, 01:48 PM   #7
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QuoteOriginally posted by BigMackCam Quote
Are you using the same metering mode on both cameras? Lenses with the same field of view (so that the areas being metered for are consistent)? Standing in the same place and pointing at exactly the same point in the scene?
Nop, I can try that tho. All I could do was take the same lenses and pop them on different bodies and pan around the room to see, settling on a dark spot with the K-1 for example (with the same lens and same mode) wouldn't result in red blinking text. I could try to get the same FoV with the HD DA20-40, set to 20mm on the KP and 30mm on the K-1, that should give them similar FoV, all my other lenses are primes so can't really replicate what you need perfectly.

Point is, I usually use my K-1 in Av mode and LV a lot, I don't think I have ever seen it's text start to blink red, and in this darkened room scenario it wouldn't trigger it to doing so either (however it would trigger it for the KP).
Av mode isn't really ever supposed to blink red, it's supposed to work within it's boundaries and stay white, it would go in the red with still a lot of 'play'. For example last night I noted it go red at 1/8th of a second, not that low...

QuoteOriginally posted by stevebrot Quote
The blinky indicates that the light to the meter is either out of linear range or that the metered EV is outside the available settings for auto-exposure. As noted above, live view is different than the optical viewfinder meter and apparently the image sensor used as meter has a more limited linear range.

No bug...no broken...simply how it works.


Steve

P.S. The lower sensitivity limit in live view on my K-3 is EV100 1.
Have you any source to back this up? Not that I'm doubting you, but the K-1 has never ever went red blinky text. Same room dynamics and it wouldn't change from white text info, it simply worked within my ISO Parameters, when it hit 3200 ISO it stayed there and then when I made it worse it just dropped the shutter speed more and more but still never blinked red.
KP on the other hand would go red fairly easily, 1/8th of a second and that was it's threshold and would start blinking. If I raised ISO to 6400, then 1/15th was the trigger etc, so it definitely feels like a certain level of dim light would trigger red blinky text.

We have three cameras here to 'test' with. A K3 user reports the same findings as my KP (earlier model than K-1), and me with a K-1 which is not exhibiting this behaviour at all and a KP which is a later model doing the same as the K3. So it feels sensor related (crop vs ff).

I always took red blinkies to meaning 'bad exposure' and you have to fix it via turning knobs etc, however in this case twiddling any know will NEVER fix the red blinky, it's almost like its blinking red for a different reason (like you suggest, metering out of range, untrustworthy recommended settings, user beware etc). Just wondered if there was an official passage in print from Pentax to back this up?



QuoteOriginally posted by reh321 Quote
Two comments to start with

1. you need to read the text - not just notice the color - it might contain valuable information.

2. you are being very very conservative with your KP; I limit my K-30 to ISO 800, but after some testing when I first got it, I usually limit my KP to 12800.
Iso 25600! - PentaxForums.com

Now for your questions ..... I lowered my ISO limit to 3200 and tried your experiment using my 18-135 {I don't have 20-40}. When I set my KP to Av mode, it keeps ISO at 100 and continually lowers shutter speed; when using LV and shutter speed gets down to 8" the three exposure parameters start flashing red, their way of warning you that you are way past reasonable hand-held values. When I set me KP to TAv mode, it raises ISO until it reaches the limit and then starts flashing that ISO value in red ..... it acts like Av mode when you get to even more ridiculous light levels.
Not sure what you mean by point 1)

My ISO limit is just an example, I vary it from job to job. Typically I am happier to handle a shutter speed drop and keep ISO under control than have unnecessarily high shutter speeds and additional grain/noise above what I needed.

If you have your KP set to ISO 100 you're not in Auto ISO but fixed for this test? I think you'll find its blinking red not because it got to 8 secs, but because it also is struggling with the meter system. Try raising your ISO to 6400, you'll get the red blinking again this time with higher shutter speeds.

I'll repeat my point before, when I pan slowly from having 'healthy' white exposure parameters (good lighting) and gently enter worse dim lighting, as soon as it turns red and starts blinking there is no adjustment that can be made to fix it and bring it back to being healthy white. No lowering of shutter speed, no widening of aperture, no bump in ISO. The only thing that will make the red blinky text go back to being white and healthy again is to pan away from that dim lit area back towards some brighter.

The K-1 however under the same scenario never goes red blinky ever.

I further tested this in Manual Mode, and typically when red blinking exposure parameters starts happening it means it wants you to change some parameters to get better exposure (the red blinking is either very badly exposed either above or below). Using the Green button (set to Tv Shift so that it adjusts shutter speed immediately to bring about proper exposure) does work, however once again the exposure parameters stay red and blinking despite being given a new safe shutter speed.

Like Steve & photoptimist says, I think this is to do with LV metering and it suggesting to the user that it's heading outside it's comfort zones so is perhaps less accurate and 'guessing' etc.
06-24-2019, 02:26 PM - 1 Like   #8
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In all honesty, I've never used Auto ISO in Av. If I want automatic ISO selection, I use TAv mode so I can choose the relevant shutter speed and aperture. I've always worked on the basis that I either shoot entirely manual, or (more often than not) select one of the modes that allow the camera to automatically adjust one of the three exposure-related variables. My most used modes are TAv, in which I select shutter speed and aperture manually, allowing the camera to set ISO; Av, in which I set ISO and aperture manually, allowing the camera to calculate shutter speed; and M, where I handle all the settings.

I don't quite understand how Av mode with Auto ISO would work... Is it supposed to use the focal length of the lens to decide what minimum shutter speed to use before bumping up to a higher ISO setting?


Last edited by BigMackCam; 06-24-2019 at 02:54 PM.
06-24-2019, 03:02 PM - 1 Like   #9
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QuoteOriginally posted by BigMackCam Quote
In all honesty, I've never used Auto ISO in Av. If I want automatic ISO selection, I use TAv mode so I can choose the relevant shutter speed and aperture. I've always worked on the basis that I either shoot entirely manual, or (more often than not) allow the camera to automatically adjust one of the three exposure-related variables. My most used modes are TAv, in which I select shutter speed and aperture manually, allowing the camera to set ISO; Av, in which I set ISO and aperture manually, allowing the camera to calculate shutter speed; and manual, where I handle all the settings.

I don't quite understand how Av mode with Auto ISO would work... Is it supposed to use the focal length of the lens to decide what minimum shutter speed to use before bumping up to a higher ISO setting?
Yes basically, you can control some of that limit in the Menu 1>ISO Auto Setting>Minimum Shutter Speed (KP)/Auto ISO Parameters (K-1)>Slow, Normal or Fast. Slow meaning it will allow the shutter speed to get quite low for that focal length before raising ISO, Normal... normal... and Fast being the opposite, faster shutter speeds before bumping the ISO.

Example, FA50/1.4 attached, Slow might mean 1/25 before it raises ISO, Fast means 1/200th before raising ISO.

None of this pertains to the thread issue however, and I quite often fix ISO in Av mode, it just depends on dynamic lighting. One scenario I found Av better than TAv was shooting in Australia's dynamic climate. I was covering a school event, outside I was shooting wide open at 1/8000 shutter speeds, but then if a kid enters the shade or indeed we move inside the classroom I am now subjected to drastically different lighting conditions. TAv forced me to continually adapt to these conditions whereas Av mode I could walk in and out of dynamic lighting and never worry about changing a setting, all I needed to do was specify what kinda minimum shutter speed I was willing to accept for that shoot, and thus when it encountered that shutter level it would raise the ISO. I basically could focus more heavily on aperture, composition and focus, rather than dwell on whether I had decent enough shutter speeds, or was taking shots with unecessary high ISO etc.

Like I said tho, none of this matters, this issue I'm getting can happen in any mode, even full manual.
06-24-2019, 03:25 PM   #10
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QuoteOriginally posted by BruceBanner Quote
Yes basically, you can control some of that limit in the Menu 1>ISO Auto Setting>Minimum Shutter Speed (KP)/Auto ISO Parameters (K-1)>Slow, Normal or Fast. Slow meaning it will allow the shutter speed to get quite low for that focal length before raising ISO, Normal... normal... and Fast being the opposite, faster shutter speeds before bumping the ISO.
Thanks - that's useful info!

QuoteOriginally posted by BruceBanner Quote
Like I said tho, none of this matters, this issue I'm getting can happen in any mode, even full manual.
My apologies, I didn't read your initial post fully, then. Not wanting to seem picky, but the thread title had me concentrating on Av mode, when in fact you're saying the issue is with Auto ISO in any mode? In which case, it has to be a metering thing, IMHO. I would start by tripod mounting each camera, with a lens of (or set to) equivalent field of view, aimed at exactly the same point in a controlled-lighting scene, cameras in TAv with same metering mode, same shutter speed and aperture, and see what ISO each camera selects. Assuming they're the same or pretty close, switch to Av with Auto ISO and repeat the test...

Last edited by BigMackCam; 06-24-2019 at 04:57 PM.
06-24-2019, 03:33 PM   #11
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QuoteOriginally posted by BruceBanner Quote
Not sure what you mean by point 1)
the camera is trying to tell you something, and that something is conveyed by the text as well as by the color.

QuoteQuote:
If you have your KP set to ISO 100 you're not in Auto ISO but fixed for this test? I think you'll find its blinking red not because it got to 8 secs, but because it also is struggling with the meter system. Try raising your ISO to 6400, you'll get the red blinking again this time with higher shutter speeds.
I was in Auto ISO, but because I was in Av mode, I was also in Auto Shutter Speed .... aperture is the only parameter the camera had to keep fixed, so it chose to vary shutter speed and keep ISO at the lowest possible value,
06-24-2019, 03:47 PM   #12
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QuoteOriginally posted by BruceBanner Quote
One scenario I found Av better than TAv was shooting in Australia's dynamic climate. I was covering a school event, outside I was shooting wide open at 1/8000 shutter speeds, but then if a kid enters the shade or indeed we move inside the classroom I am now subjected to drastically different lighting conditions. TAv forced me to continually adapt to these conditions whereas Av mode I could walk in and out of dynamic lighting and never worry about changing a setting, all I needed to do was specify what kinda minimum shutter speed I was willing to accept for that shoot, and thus when it encountered that shutter level it would raise the ISO. I basically could focus more heavily on aperture, composition and focus, rather than dwell on whether I had decent enough shutter speeds, or was taking shots with unecessary high ISO etc.
Our use of KP characteristics is quite different. I use TAv mode in precisely this circumstance for precisely this reason. I am quite confident in the image the KP will deliver to me in the ISO range I have set. TAv mode enables me to pick both the shutter speed and the aperture - thereby concentrating on focusing and composition rather than dwelling on whether shutter speed or aperture choice is wrong - because I have capped ISO at a value below 'unnecessarily high ISO' for the KP.
06-24-2019, 03:56 PM   #13
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Just tested ks2. Blinks and turns red when parameters force shutter below 1/4.
06-24-2019, 04:39 PM   #14
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Just did more tests. Lens mm didn't matter but f stop changes when shutter speed blinks. F/5.6=1/4 minimum but at f/4=1/6 and f11=1"
06-24-2019, 04:46 PM - 2 Likes   #15
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Your KP is fine. It's the K-1 that has the bug. In LV mode, the K-1 does not warn the user that the light level is too low to be metered.

In LV mode with an f/2.8 lens, TAv set to 1sec f/2.8 putting the lens cap on pushes the ISO to 25600 but no higher. But there's no blinking and the histogram shows gross under-exposure. Changing the shutter speed or aperture causes the usual counter-adjustments of ISO with no blinking/red text, but the scene is still grossly under-exposed

In ordinary OVF metering with the K-1, TAv set to 1sec f/2.8 shows ISO climbing as the lens cap slowly goes on, seems to show valid exposures up to ISO 1600, starts blinking at ISO 2200, and gets no higher than ISO 4500 (and blinking) with the lens and OVF totally in the dark.

(NOTE: this behavior does depend on the max aperture of the lens -- whatever algorithms are used for AE in both LV and OVF know this aperture and use it to adjust the results)

P.S. The K-5 acts more like the KP for AE in LV mode -- if the scene gets too dark, the K-5 shows blinking red exposure values.
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