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12-06-2010, 12:52 AM   #1
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Live View Histogram (on K-5)

Hi,
I have been checking the live view capabilities of my new K-5 (proud owner of a K10D before) and in particular the live histogram and it works fine, or at least as I expected in auto modes, that is when I change exposure compensation the histogram changes, and the histogram I see corresponds to the histogram of the capture I take.
The problem comes when I am in manual mode where no changes in aperture or speed affect the histogram. This is weird. Correct me if I'm wrong but in other brands this is not the case (at least in Canon and Olympus as far as I know). Other thing that puzzles me is the fact that a exposure compensation is available in manual mode (with or without LV) but of course it does not affect the capture (as it should be), however in LV mode it affects the luminosity of the LCD display and the live histogram!! but as I said before not the exposure of the capture. This could be a help when focusing in dim light but what it is not is a histogram of the scene we are about to capture.

Any thoughts on that? Maybe I'm missing something or have miscofigured something. Is this a bug or a feature?

12-06-2010, 01:30 AM   #2
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There is no ev shift in manual mode, so I'm not sure either what the thing in live view is going- sounds like it might just be affecting the screen brightness.

Also, I think the behavior is due to the fact that the camera theoretically doesn't know the aperture setting (i.e. when it's used with M lenses). Try stopping the lens down- maybe it'll help!

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12-06-2010, 01:48 AM   #3
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There is EV compensation in manual mode, and it's pretty convenient. For instance, I dial in +1EV when out shooting (snow everywhere) with an old M-lens and when hitting the green button I will get a compensated exposure right away.
12-06-2010, 01:52 AM   #4
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I'm not using it with a manual lens (35mm 2.8 ltd) but I'm going to change to a manual lens and see what happens if I use the aperture ring.

12-06-2010, 01:53 AM   #5
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QuoteOriginally posted by Gimbal Quote
There is EV compensation in manual mode, and it's pretty convenient. For instance, I dial in +1EV when out shooting (snow everywhere) with an old M-lens and when hitting the green button I will get a compensated exposure right away.
That's true. I didn't think about manual lenses though I own some
12-06-2010, 02:01 AM   #6
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Update: Changing the aperture in manual lenses does not afect the live histogram either. As far as I know the same issue is observed in Pentax K-7
12-06-2010, 04:03 AM   #7
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In M-mode you have to press the green button to get correct exposure, i.e. to make the camera recognize the set aperture on the lens.
12-06-2010, 04:05 AM   #8
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QuoteOriginally posted by mersault Quote
The problem comes when I am in manual mode where no changes in aperture or speed affect the histogram.
This behaviour isn't intuitive.

The LV live histogram reflects the histogram as is currently captured by the sensor. The LV feed uses metering and EV compensation and AE-L.

LV stops the lens down but not necessarily to the exact same f-stop as the exposure when taken. And LV doesn't necessarily use the shutter time of the exposure. Actually, some shutter times like 1/8000s are impossible for the LV feed. So, the entire process is pretty complex. However, via exposure reciprocity, the live histogram normally still reflects the actual exposure.

The important thing to understand is that the LV feed always uses automatic settings. Otherwise, you could open the lens long enough and wide enough to actually damage the sensor (remember the sun/loupe/paper experiment you did as a kid?). Think of a sun image focussed onto the focal plane ... (you could still do that in bulb; but not as easily)


The only "bug" is that the firmware doesn't apply a correction to the live histogram if the manual setting and metered exposure don't match via exposure reciprocity. The "work around" is to use EV compensation in manual to bring the over-/under-exposure scale to zero. This may sound awkward. But you can "dial" EV compensation in manual until you see fit in the live histogram. And then press the green button. And then work from there.


Last edited by falconeye; 12-06-2010 at 04:14 AM.
12-06-2010, 04:57 AM   #9
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Thanks falk,
That's the answer I was looking for. Now I can do What I wanted. See a live histogram of the capture I'm about to take as I aply changes.
11-20-2013, 06:41 AM   #10
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QuoteOriginally posted by falconeye Quote
This behaviour isn't intuitive.

The LV live histogram reflects the histogram as is currently captured by the sensor. The LV feed uses metering and EV compensation and AE-L.

LV stops the lens down but not necessarily to the exact same f-stop as the exposure when taken. And LV doesn't necessarily use the shutter time of the exposure. Actually, some shutter times like 1/8000s are impossible for the LV feed. So, the entire process is pretty complex. However, via exposure reciprocity, the live histogram normally still reflects the actual exposure.

The important thing to understand is that the LV feed always uses automatic settings. Otherwise, you could open the lens long enough and wide enough to actually damage the sensor (remember the sun/loupe/paper experiment you did as a kid?). Think of a sun image focussed onto the focal plane ... (you could still do that in bulb; but not as easily)


The only "bug" is that the firmware doesn't apply a correction to the live histogram if the manual setting and metered exposure don't match via exposure reciprocity. The "work around" is to use EV compensation in manual to bring the over-/under-exposure scale to zero. This may sound awkward. But you can "dial" EV compensation in manual until you see fit in the live histogram. And then press the green button. And then work from there.
Goodday, I'm new on this forum and I'm keen on buying a K-5 II. I'm wondering whether the live view histogram on the K-5 II is implemented in the same way as on the K-5 or even in a more advanced way.
11-20-2013, 08:08 AM   #11
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QuoteOriginally posted by khenna Quote
Goodday, I'm new on this forum and I'm keen on buying a K-5 II. I'm wondering whether the live view histogram on the K-5 II is implemented in the same way as on the K-5 or even in a more advanced way.
It's the exact same thing.

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11-20-2013, 11:12 AM   #12
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QuoteOriginally posted by Adam Quote
It's the exact same thing.
Thanks for your reply. I'm a bit confused here.
From neocamera.com :
QuoteQuote:
Live-View on the Pentax K-5 II is toggled by a dedicated button. During Live-View, the LCD displays a preview of 100% coverage, accurate focus, colors and white-balance. Unfortunately, exposure is not previewed at all, meaning that it falls short of being WYSIWYG. There are optional histograms and blinking areas but both these options are completely useless as they do not represent the exposure, only what is displayed on the LCD. The extremely helpful dual-axis digital level is displayed in live-view. Most controls are usable in live-view, although, strangely, changing exposure-modes and going into playback mode exits live-view.
Dpreview claims about the same about the K-30.

Both review sites don't mention exposure reciprocity, Who is right and can this be substantiated?
11-20-2013, 11:22 AM   #13
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QuoteOriginally posted by khenna Quote
Thanks for your reply. I'm a bit confused here.
From neocamera.com : Dpreview claims about the same about the K-30.

Both review sites don't mention exposure reciprocity, Who is right and can this be substantiated?
The live view display always does its best to "properly" expose the scene. It isn't WYSIWYG on any Pentax camera, including the latest K-3.

I wouldn't call the histogram useless, however, as it gives you a good idea of when you're going to get clipped highlights. But Pentax could do better.

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11-20-2013, 11:39 AM   #14
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QuoteOriginally posted by Adam Quote
The live view display always does its best to "properly" expose the scene. It isn't WYSIWYG on any Pentax camera, including the latest K-3.

I wouldn't call the histogram useless, however, as it gives you a good idea of when you're going to get clipped highlights. But Pentax could do better.
Thanks. I guess I can still use the exposure warning in the viewfinder as a last resort.
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