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06-07-2015, 08:31 AM   #1
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Annoying Liveview Behavior: Fixable? Bug?

Hi all,

So has anyone witnessed the following behavior?

- Use an A-series or more recent lens;
- set the camera to M-mode and turn on Liveview;
- dial in a proper exposure using a fairly open aperture;
- now start closing the aperture using the in-body aperture control (not the aperture ring on the lens - if your lens has one it should be set to "A");
- you should see that as the aperture setting increases, the LCD gets progressively dimmer and dimmer, to about -2 eV, from which point onwards the brightness remains steady.

I just tested this also on my K-01 and it does not behave the same way as my K-3. Instead, on the K-01 the LCD's brightness stays the same regardless of how underexposed the camera thinks the shot will be once the shot is taken.

This behavior of the K-3 is very annoying! I shoot a lot of macro with manual flash in M-mode and with Liveview. Since the camera has no way of knowing the flash power, it thinks the shot will be quite underexposed, and dims the LCD, as described above. So, I'm shooting with an artificially, and quite unnecessarily dimmed LCD! Under some circumstances, that's the difference between getting and not getting the shot.

If I'm using a lens with an aperture ring, a workaround is to use the aperture ring to set the shot's aperture rather than use in-body aperture control. This is much less convenient, but at least when I do that, the LCD display remains at normal brightness even if the camera foolishly thinks the shot will be underexposed. But if I'm using a lens without an aperture ring, then I think I'm up the proverbial creek.

So, what do you think? Is there a setting that will turn this off? Is it a bug? I don't think it's a feature, but you might?

I'm running FW1.11.

06-07-2015, 08:53 AM   #2
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Why would the LCD be dimmed if you are using the k-mount lens with aperture lever control? It should stay wide-open until the shutter is released (tripped the aperture lever).
06-07-2015, 08:56 AM   #3
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I think I've always heard the opposite complaint around here -- that when in M mode they want the screen to show how the shot is actually going to turn out instead of artificially brightening it. So this will be a fix to those people. Flash changes the equation, of course...
06-07-2015, 08:58 AM   #4
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QuoteOriginally posted by aleonx3 Quote
Why would the LCD be dimmed if you are using the k-mount lens with aperture lever control? It should stay wide-open until the shutter is released (tripped the aperture lever).
I have noticed LCD dimming in live view due to lens stop-down, but not quite as described by the OP and not just with vintage glass*. This is problematic when using live view for critical manual focus or when doing AF/focus screen calibration confirmation. I believe there is a work-around, but I will have to spend some time with the camera to refresh my memory as to how I dealt with it in the past.


Steve

* I have seen it happen in response to bright ambient light.

06-07-2015, 09:02 AM   #5
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QuoteOriginally posted by aleonx3 Quote
Why would the LCD be dimmed if you are using the k-mount lens with aperture lever control? It should stay wide-open until the shutter is released (tripped the aperture lever).
Note: the aperture itself stays open until the shot is taken, of course. In a way, what I'm seeing could be described as a kind of "badly-placed exposure preview" (especially badly-placed when using manual flash, IMHO).
06-07-2015, 09:06 AM   #6
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QuoteOriginally posted by Doundounba Quote
Note: the aperture itself stays open until the shot is taken, of course. In a way, what I'm seeing could be described as a kind of "badly-placed exposure preview" (especially badly-placed when using manual flash, IMHO).
I see what you are driving at... got to try it myself as I have both k-3 and k-01 although I seldom use LV on my k-3.

I just tested mine A-28/f2.8 on k-3 using Live view, the LCD screen staying the same 1) aperture ring in A position, turning rear dial to change aperture and 2) aperture ring off A position, and turning aperture ring to different setting.
In both cases, the screen remain unchanged. I am not sure if your k-3 is off or something with the setting.

Last edited by aleonx3; 06-07-2015 at 09:14 AM. Reason: updated after testing..
06-07-2015, 09:11 AM   #7
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QuoteOriginally posted by stevebrot Quote
I have noticed LCD dimming in live view due to lens stop-down, but not quite as described by the OP and not just with vintage glass*. This is problematic when using live view for critical manual focus or when doing AF/focus screen calibration confirmation. I believe there is a work-around, but I will have to spend some time with the camera to refresh my memory as to how I dealt with it in the past.


Steve

* I have seen it happen in response to bright ambient light.
That is a HUGE problem and I don't know why it doesn't get more complaints. Not the dimming (it usually compensates with increased gain instantly), but the stopping down in bright light. Using a fast AF lens on the K-01 (where LV is the only option) in the daylight, for instance, is basically impossible -- you can't take an in-focus shot at f/2.8 or faster EVER (because it focuses with the lens at stopped down to f/5.6). You can workaround it with manual focus by using the zoom-in function which opens the aperture, but with AF there is nothing you can do that I know of. Anyway, that's getting off-topic. It sounds like the K-3 has some differences with LV, but I guess I can still look forward to still NOT being able to using LV AF focusing in the future?
06-07-2015, 09:31 AM   #8
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QuoteOriginally posted by Doundounba Quote
I'm running FW1.11.
QuoteOriginally posted by aleonx3 Quote
I see what you are driving at... got to try it myself as I have both k-3 and k-01 although I seldom use LV on my k-3. I just tested mine A-28/f2.8 on k-3 using Live view, the LCD screen staying the same 1) aperture ring in A position, turning rear dial to change aperture and 2) aperture ring off A position, and turning aperture ring to different setting. In both cases, the screen remain unchanged. I am not sure if your k-3 is off or something with the setting.
Firmware version?
Or perhaps an option that is set differently?

06-07-2015, 12:14 PM - 1 Like   #9
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QuoteOriginally posted by vonBaloney Quote
That is a HUGE problem and I don't know why it doesn't get more complaints. Not the dimming (it usually compensates with increased gain instantly), but the stopping down in bright light. Using a fast AF lens on the K-01 (where LV is the only option) in the daylight, for instance, is basically impossible -- you can't take an in-focus shot at f/2.8 or faster EVER (because it focuses with the lens at stopped down to f/5.6). You can workaround it with manual focus by using the zoom-in function which opens the aperture, but with AF there is nothing you can do that I know of. Anyway, that's getting off-topic. It sounds like the K-3 has some differences with LV, but I guess I can still look forward to still NOT being able to using LV AF focusing in the future?
I just pulled out my K3 to see what the OP was describing because I've never had any issues. It does act as the OP describes, though, I don't find it problematic. I did notice that it stops down to 5.6. during AF. I tested this with my 50/1.8. So I don't see this as a huge issue for AF either.
Sorry, I just re-read your post. I get your point.

Last edited by sundr; 06-07-2015 at 12:20 PM.
06-07-2015, 12:19 PM   #10
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my k-s2 also dims the screen in lv. I shoot at night so lv is useless for me since I have flash not continual light. Then again in sun I can't see the screen so it's useless. I can only use it on a tripod so I can change the shutter to frame and focus then change back to shoot. Rare when I can't use the view finder.
06-07-2015, 12:35 PM   #11
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QuoteOriginally posted by sundr Quote
I just pulled out my K3 to see what the OP was describing because I've never had any issues. It does act as the OP describes, though, I don't find it problematic. I did notice that it stops down to 5.6. during AF. I tested this with my 50/1.8. So I don't see this as a huge issue for AF either.
Sorry, I just re-read your post. I get your point.
Yeah, if you're shooting at f/5.6 or smaller, it is ok, but if you are shooting at f/1.8 and it focuses at f/5.6, more than likely what you focused on will be badly out of focus for the actual shot. How dumb is that?
06-07-2015, 01:05 PM   #12
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QuoteOriginally posted by vonBaloney Quote
Yeah, if you're shooting at f/5.6 or smaller, it is ok, but if you are shooting at f/1.8 and it focuses at f/5.6, more than likely what you focused on will be badly out of focus for the actual shot. How dumb is that?
Yep, that is the larger issue, though it might be argued that even at smaller apertures, there is only one true point of focus. The question is whether the CDAF system is able to detect that point when the light to the sensor is low.



Steve

Last edited by stevebrot; 06-07-2015 at 04:25 PM.
06-07-2015, 01:19 PM   #13
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QuoteOriginally posted by stevebrot Quote
Yep, that is the larger issue, though it might be argued that even at smaller apertures, there is only one true focal point. The question is whether the CDAF system is able to detect that point when the light to the sensor is low.
I found out when testing that it actually is more generous on locking focus (even in PDAF) if you have it set to a smaller aperture. So if it confirming focus but not dead-on what you want, setting the aperture to wide-open first can help, i.e. you should set your aperture (if you are setting it yourself) before you focus...
06-07-2015, 01:34 PM - 1 Like   #14
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Ok, I was able to reproduce the behavior the OP described. For convenience, here is the setup:
  • M mode
  • Lens with "A" contacts. If there is an aperture ring, it must be in the "A" position.
  • Live view
  • Easier to detect if the camera is pointed at a blank wall. I would also suggest moderate to fair dim light to make sure the lens stays full open the entire time (see below). Also easier to see if the lens is f/2 or faster.
  • Using e-dial set the the lens wide open and adjust shutter speed to match for a correct exposure
  • Observe screen brightness while using the e-dial to choose progressively narrower aperture settings. Confirm that the actual aperture has remained full open at all times and that the display has grown progressively dimmer.
That being done, how about shutter speed?
  • M mode
  • Lens with "A" contacts. If there is an aperture ring, it must be in the "A" position.
  • Live view
  • Easier to detect if the camera is pointed at a blank wall. I would also suggest moderate to fair dim light to make sure the lens stays full open the entire time (see below). Also easier to see if the lens is f/2 or faster.
  • Using e-dial set the the lens at f/5.6 and adjust shutter speed to match for a correct exposure. Confirm that actual aperture is wide open.
  • Observe screen brightness while using the e-dial to choose progressively faster shutter speeds. Confirm that the actual aperture remains wide open while the screen grows progressively dimmer.
  • Repeat using progressively slower shutter speeds and confirm that the display grows progressively brighter while the actual aperture remains wide open.
Well, isn't that interesting?!

Back in the dim recesses of my mind, I seem to remember that this matter came up for discussion some time back. The conclusion at that time was that it was a feature intended to show the user screen brightness representative what will be present in the actual capture. This would be potentially useful when doing intentional over/underexposure in M mode. Yes...a feature, not a bug.

Addendum: It occurred to me that modes other than M might have the "dimmer" too. As it turns out, X mode acts pretty much the same as M mode. For P, Sv, Tv, Av, and TAv the dimmer makes an appearance when exposure compensation is used. So, the rule of thumb would be that the live view display will dim/brighten to reflect an intentional over/under exposure case.

As for the second issue noted by both vonBaloney and myself, here are steps to reproduce:
  • Any mode
  • Lens with "A" contacts. If aperture ring is present, the ring must be in the "A" position.
  • Live view
  • Choose a quiet location having both bright and dim areas as potential subject targets
  • Point the camera at the dim area first and visually confirm that the aperture is wide open. An assistant is helpful here.
  • Shift the view to point to the bright area and notice that you can hear the aperture actuator working. Notice too that the display darkens in response. Confirm that the aperture is now stopped down to some arbitrary diameter.
  • Shift the view back to the dim area and listen for the aperture actuator opening the lens back up. Confirm that the lens is once again full open.
Hmmmmmm...this is not good since the DOF displayed is not always the actual DOF for the exposure-time aperture. This is also not good when doing manual focus or when attempting fine focus for other reasons. I was told that the reason might be to avoid damaging the sensor with too bright a light. Longer sensor life sounds like a good thing. Memo to self...do not use live view in bright light with non-A lenses.

The workaround is to move the aperture ring off the "A" setting. The camera only does this monkey business when the "A" contact is detected. For lenses lacking the aperture ring, another workaround would be to do focus testing, calibration, and such in relatively dim light or with an ND filter attached. Addendum: vonBaloney was good enough to find another workaround, that being use of magnified live view. When full magnification (OK button) is on, the lens will be full open. FWIW, I seem to remember comments that this type of live view behavior was present in non-Pentax cameras as well.


Steve

Last edited by stevebrot; 06-07-2015 at 04:04 PM.
06-07-2015, 01:56 PM   #15
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QuoteOriginally posted by sundr Quote
... It does act as the OP describes, though, I don't find it problematic. ...
QuoteOriginally posted by stevebrot Quote
Ok, I was able to reproduce the behavior the OP described.
Thanks to all responders, but to you both particularly! I was wondering if my camera was maybe misconfigured. While I agree this might possibly be considered a "feature" when shooting natural light, I think we can agree it's a bug when shooting manual flash, and under all circumstances I feel we should be able to turn it off. When I'm shooting in dim light to begin with, sometimes the display goes so dim that I can barely see a thing, and it becomes more or less impossible to focus (by moving the camera and using magnified liveview to achieve focus). And sometimes even if there's enough light, if I'm looking at the camera from an odd angle (remember, I shoot macro), or the sun is shining into the LCD, then the dimming is also very aggravating.

As I wrote before, using the aperture ring is a viable, if inconvenient, workaround. But I guess I won't be buying that D-FA 100mm WR macro I've been thinking about to get a WR macro body & lens combo...
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