[kmlo1984]

After whole week test
i finally found some setting might cause flickering and colour shift,
it;s when i use exposure compensation

when i out normal, or minus - no problem.
but when i increase the exposure,
the flickering comes

ironically, if i get the same exposure by the camera itself without using the E.C.
no problem.

still running some test on this n that

but in short

avoid dialling to plus zone in E.C.
also don't under expose too much, i see lots of banding in shadow area.

may be avoid high speed shutter - i have yet to run a test on it.

but when i test the camera at Phnom penh, at new yr party all great
but when i shoot at out door, i first think it's the overheat.

anyway, it;s not trouble free with this 700$ K-x

though in general i can live this camera.

K.M.Lo

[kmlo1984]

[falconeye]

The first video is private, we cannot see it.

The second video doesn't flicker. However, it seems to be taken in very low light and white balance seems to fluctuate which is understandable. Probably, shadow enhancement is on too which pronounces the visible effect.

Try to fix your WB setting prior to recording (don't use automatic). The K-x allows to do so


Flickering when using -EV: Every camera flickers in tungsten light if exposure time is shorter than the flicker (typically 50Hz/2 or 60Hz/2). The EV-setting as such has nothing to do with it. Try the longest possible exposure time (1/24s or 1/30s) which should mimimize the effect. You can use a small fixed aperture setting to force a slow shutter time. But don't use a too small aperture as it would make the video noisy (high ISO) without reducing shutter time any more.

#FYI. Your English is extremely hard to understand. Don't expect too many answers

[kmlo1984]

dear Falk
thanks
I just fixed it, u can downlaod from vimeo

i think it might be the ISO.
as i did a new test last nite at 2am ( or morning)
yes, under tungsten light it flickers
and i suspect its when the ISO becomes very high.
the shadow/highlight adjust - well if i turn it off
it's a yellowish halo banding around the burn highlight.

and in general, i see it's darker and more contrast
( i compare the histogram of all settings)

WB shift - i also notice this even i double check the WB is at daylight.

so is that what u mean - under low light/high ISO, colour change WB shift is unavoidable?

I only use daylight so far. i m not an automatic person.
all in manual mode if i can.

the lens is old FD lens. mount without touching any eletronic contacts.
my custom image setting,
saturation -3
HUE +-0
SHA/HIGH +3
Contrast -4
Sharpness -4

D range - only highlight is ticked
Colour space - sRGB

i think will run an all EV test to map out all combination
What software u use to read the data like shutter speed/ISO from video
Exiftool - i m not sure it correctly tell.

pardon my english ( my 2nd language)

K.M.Lo

[falconeye]

the shadow/highlight adjust - well if i turn it off
it's a yellowish halo banding around the burn highlight.

and in general, i see it's darker and more contrast
( i compare the histogram of all settings)

That's what it is supposed to do.

WB shift - i also notice this even i double check the WB is at daylight.

so is that what u mean - under low light/high ISO, colour change WB shift is unavoidable?

No, I meant that WB set to AUTO can lead to a fluctuating WB.

But in your video, if I now look again, it isn't the WB. It actually seems like the lighting isn't constant. The flickering ONLY appears to the deep shadows which flicker between black and deep brown.

It looks like there is a DISTANT (out of frame) light source illuminating both your balcony and the tree.

Such flicker of (possibly fluorescent) tungsten light sources are unavoidable with a camera which cannot be set to 1/25s in 50Hz land or 1/30s in 60Hz land.

It can only be made weaker with a slow exposure like 1/24s which you can enforce by closing the aperture or adding +EV compensation (ISO is automatic always).

What software u use to read the data like shutter speed/ISO from video
Exiftool - i m not sure it correctly tell.

pardon my english ( my 2nd language)

K.M.Lo

Exiftool GUI. But if I download your video from vimeo, the EXIF data are all missing. Don't know for the K-x but with K-7, EXIF data are filled in.

Even with EXIF data filled in, you still need to reinterpret them. The AExxx values are only hints to the video controller. It will pick appropriate ISO/shutter/aperture combinations based on the hints. In general, it will try to stay as close to ISO100 (or 200) and 1/24s (or maybe 1/25s or 1/30s) as possible.

pardon my english ( my 2nd language)

As for many of us. It's not a question of pardon. If people don't understand what you post then your post and effort was useless in the first place. And this would be a pitty.



By the way ...

What interesting night scene do we observe in your video? Looks like paid work in a public street

[netrex]

Exiftool GUI. But if I download your video from vimeo, the EXIF data are all missing. Don't know for the K-x but with K-7, EXIF data are filled in.

It is with the K-x also. I use ExifToolGUI as well.

[falconeye]

It is with the K-x also. I use ExifToolGUI as well.

This is interesting. So vimeo touches the original file before offering it for download "original" file... It may or may not alter the content. But it does recreate the AVI container for sure.

[kmlo1984]

Hi falk

shadow/highlight adjust - may be this is the problem
I think i set max may trigger some dark area flickers.
i now try different settings.
but sure cant be min. the highlight banding with halo is very bad
also in general it flattens the contrast a bit.

That's what it is supposed to do.


No, I meant that WB set to AUTO can lead to a fluctuating WB.
I always set at Daylight not even change to tungsten in shooting 3200K, i prefer do it in post.


But in your video, if I now look again, it isn't the WB. It actually seems like the lighting isn't constant. The flickering ONLY appears to the deep shadows which flicker between black and deep brown.

I see it too.

It looks like there is a DISTANT (out of frame) light source illuminating both your balcony and the tree.

Under day light only , i check and find same issue.

Such flicker of (possibly fluorescent) tungsten light sources are unavoidable with a camera which cannot be set to 1/25s in 50Hz land or 1/30s in 60Hz land.

It can only be made weaker with a slow exposure like 1/24s which you can enforce by closing the aperture or adding +EV compensation (ISO is automatic always).

I use Av to find out the shutter speed reading, i use only spot metering
then dial to Video mode and lock AE. i find video mode is slightly over about 1/3 stop when compare to AV still mode. by this I can always use the range of1/50 to1/20sec.


Exiftool GUI. But if I download your video from vimeo, the EXIF data are all missing. Don't know for the K-x but with K-7, EXIF data are filled in.

Even with EXIF data filled in, you still need to reinterpret them. The AExxx values are only hints to the video controller. It will pick appropriate ISO/shutter/aperture combinations based on the hints. In general, it will try to stay as close to ISO100 (or 200) and 1/24s (or maybe 1/25s or 1/30s) as possible.

It may be i use virtauldun to trim it and lose the metadata.

As for many of us. It's not a question of pardon. If people don't understand what you post then your post and effort was useless in the first place. And this would be a pitty.

I try to write clearer.



By the way ...

What interesting night scene do we observe in your video? Looks like paid work in a public street

Thanks, u know how many sleepless nights in Phnom penh, i woke up 2am to test the camera. it;'s a night food stall. for coconut juice and fried noddles with lots of MSG.

thanks for ur effort to answer me
K.M.Lo

[kmlo1984]

hi all,
here is the link:


i think i work in a way to avoid the flickering
dont set the shadow and highlight adjust to max, i m using middle at 0.

dont let the video underexposed.
and instead, over exposed a bit , and then darken it to it should be,
well be aware of burning in highlight,
i set up the alert.
this might help to crash to black and trigger the flickering.

KM

[Radix]

My K-x seems to produce this colour flicker. It is quite annoing in videos and also strange, because it doesn't appear always and I haven't found any consistency when it happens.

I did a test. SR off, camera on a table, white balance set to daylight, exposure locked in AV to ISO 100 and 1/50 s and then switched to video mode (shadow and highlight corretion off). The only source of light was the sun, so the flicker can't be due to 50 Hz electricity. The result was that there's random red flicker in the whole video clip and each flicker appears only in one consecutive frame. And when there's a flicker, it is evenly distributed on the whole frame.

There's an example image in the attachments. I took three 100% crops of concecutive frames from the same area.

Right after taking that video I did a new one locking exposure to ISO 1600 and 1/25 s and filming the same scene. I can't see any flicker in that video. That's why I think that the heating of the sensor isn't causing this, because it should be warmer in the latter video.

Edit: There seems to be two different kinds of flicker in the flickering videos: red and green. And the normal, non-flickering parts of flickering videos are neither red nor green.

[falconeye]

There's an example image in the attachments. I took three 100% crops of concecutive frames from the same area.

(side note: the above is in "ACER X243W kalibroitu3" color space which is a VERY BAD idea to post on the web...)

I boosted exposure by +6EV to make the effect easily seen. Because when viewed normnally, all three frames are just black which is means w/o flicker... The boost is like boosting ISO100 to ISO 6400.

The red/green/blue channels in normal frames are like 0.45% luminosity.
The green/blue channels in flicker frame are the same.
The red channel in flicker frame is like 1.06% luminosity or ~2.4x more.


It looks like there is some form of preprocessing going on on data that low in the blacks. Part of the image pipeline which is partly responsible too for K-x's high dynamic range (disclaimer: speculation on my part!).

All in all, this looks like a firmware bug in some of the more subtle areas of the image processing pipeline.

[Radix]

I uploaded that video to Vimeo (you can download the original):

[Radix]

I did some further testing trying to find out when the flickering occurs and when not. It seems to be much more probable that there is flickering in a video than no flickring.

I found out that there seems to be a certain level of exposure, bellow which the flickering stops suddenly and completely. For example when exposure is locked at a certain level, there's no flickering at -2/3 ev compensation, but at -1/3 ev compensation the flickering starts. I also found out that changing the aperture from a manual lens doesn't affect flickering at all although the light coming to the sensor changes. I did these tests with locked white balance, sr on, custom image settings all to normal except minimun contrast and in artificial lightning (50 Hz). The 50 Hz lightning didn't cause the flickering, because the same flickering occured also when I filmed outside of my window and electricity causes different kind of flickering (I saw that when I used certain shutter speeds). The camera got hot during these tests but it didn't affect the flickering at all and I got videos with no flickering at the end of the testing.

[davidvandoren]

@Radix

I noticed color-shifting too before. Your video has a lot of noise even though it's very much out of focus.

[Radix]

I did a new test. Now it seems that there is also a point of exposure bellow which the flickering starts again. I locked the exposure and used exposure compensation to see when the flickering occurs. Now it didn't occur when the exposure was from 1/40 s to 1/25 s at ISO 100 (I checked it in av mode while the exposure was locked) but it occured with 1/50 s and 1/20 s. Yesterday I remember that the exposure in av mode was 1/13 at ISO 100 when there was no flickering (that's about 1/25 s at ISO 200 in video mode). Therefore it seems that the non-flickering exposure value changes from time to time. I can see the flickering also in live view mode when taking still photos.

Edit: I noticed that there can be still some flickering in the videos taken in the non-flickering exposure values, but it is very rare. There was only 1 red flicker in a 11 second non-flickering video but many flickers per second in flickering videos.

Edit 2: It seems that a quite reliable way to prevent flickering is locking exposure to 1/40 s ISO 100 in av mode and switching then to video mode (with manual lens).