[stevebrot]

I was asked to shoot a little video with my K-3 at a July 4 celebration (not my usual thing) and was dismayed when I got home to find that several clips were unusable do to artifact that I can only describe as looking like "focus peaking" in live view. Here is a screen capture with examples circled:



The circled writing on the balloon is simply black marking pen.

Symptoms:

• White outlines at hard contrast transitions
• Poor color saturation
• Bizarre contrast

Settings:
Exif attached to this post as text file

• 1080p 24fps
• P mode
• Matrix meter

Conditions:

• Bright day, late afternoon
• Open shade
• ~ 93° F

Full Clip (DropBox):

https://www.dropbox.com/s/dv3bquy2y4jzr6q/IMGP0716.MOV?dl=0 (Flash Player)

https://www.dropbox.com/s/dv3bquy2y4jzr6q/IMGP0716.MOV?dl=1 (download .mov)

I had been doing a fair number of clips and the camera body was growing warm to the touch. Could this have been caused by overheating? There were no warnings or blinky-flashy that I remember. Any suggestions to avoid future occurrences would be appreciated.


Steve

P.S. Forgive me if this behavior has been discussed before. I tried a forum search and got little in the way of helpful results.

Attached Files

bad_mov.txt (6.4 KB, 155 views)

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Last edited by stevebrot; 07-20-2015 at 12:01 PM.

[stevebrot]

OK...I did find a previous thread where this was discussed, but with no resolution.

https://www.pentaxforums.com/forums/172-pentax-k-3/250619-focus-peaking-during-video.html


Steve

[JinDesu]

Looks almost like a filter applied to the video lol

[stevebrot]

Looks almost like a filter applied to the video lol

I was thinking more along the lines of some sort of rave drug...


Steve

[Na Horuk]

Does the jpeg mode have an effect? Looks like oversharpening or something

[Tanzer]

Looks like the problem is evident in the grass too ...

[Giklab]

This looks very similar to the Bleach Bypass preset...

[stevebrot]

This looks very similar to the Bleach Bypass preset...

Exif says it is turned off.


Steve

[stevebrot]

Does the jpeg mode have an effect? Looks like oversharpening or something

JPEG mode? The above image is a screen capture of a video clip.


Steve

[Na Horuk]

JPEG mode? The above image is a screen capture of a video clip.

I know. But still. You know how you can choose Jpeg mode for stills, to make it vibrant, or black and white, or sepia, or muted, or film reversal,..? I think these filters get applied to video, as well. And some of these filters include things like sharpening, contrast, saturation, hues.. So I would look there first. Jpeg mode and digital filters (digital filters are the things that mimic toy camera, or defocus and others), I think both are in the Info menu when taking stills.

[stevebrot]

I think these filters get applied to video, as well. And some of these filters include things like sharpening, contrast, saturation, hues.. So I would look there first. Jpeg mode and digital filters (digital filters are the things that mimic toy camera, or defocus and others), I think both are in the Info menu when taking stills.

Got it! Yes, they will be applied if set, but the active filter was "natural" for this clip. I did a test clip with bleach bypass turned on, but the results were dissimilar.


Steve

[K David]

Were you using the Rokinon 8,mm f/3.4 fisheye lens? I've had TERRIBLE luck using my fisheye with video on My K-3. Check out the intro six seconds to this video:

Youtu.be

Youtu.be

Set it to HD in the settings and you'll see it's REALLY soft for an HD video. That level of quality, or lack thereof, continues for each shot using the Takumar 17mm f/4. However, here's another video with the same lens:

Youtu.be

Youtu.be

The second is significantly sharper and it's the same lens. So here's my theory on Pentax DSLRs and fisheyes and video: I think that the lenses capture all the extraneous overhead light (you can see in your video how blown out the sky is) and that light just bounces around in the lens like a pinball in a rubber band factory. I think that the cameras are recording excess light and contrast loss as artifact noise and softness. In both cases DSLR was in shade. In the first, the sun was overhead and in front(ish) of the lens. In the latter, it was setting and off to the side or slightly behind the lens.

Nothing in your settings appears bad and your bitrate is really high, so there's no reason from a video quality perspective for there to be any issue. I think it's just a limitation of Pentax DSLRs with fisheye lenses in the sun when shooting video.

[LaurenOE]

Was the camera in manual mode?
Were you shooting hand held?
Was there a lot of motion?

I went and looked at the video.

Judging by the fact that you were semi-shooting into the sun, with dark ground and bright sky, and appear to be moving around a bit, it's no wonder that you might have some artifacts in the shot based on your technique.

For that shot, I would have used an ND grad to compensate with the camera in manual mode.
And of course, on a tripod.

The K3 - and for the most part - any dSLR requires a cinema technique more than a "family-cam-corder" technique.

[stevebrot]

Were you using the Rokinon 8,mm f/3.4 fisheye lens?

Yes, the Rokinon 8mm. The sky in the background was bright, but the subject and camera were in open shade with the sun position being out of scope for the frame to the right (18:13 PDT, camera pointed SSW and sun low in the sky to the WNW). I can provide a similar clip taken 1 minute later with similar camera orientation, but no white fringing. Exposure was poor, however. I have a third clip taken immediately before also showing severe fringing where the sky is not in the frame.

Was the camera in manual mode?
Were you shooting hand held?
Was there a lot of motion?

P mode, hand-held, very little motion (See link to actual clip above). It is not a matter of some artifacts. The full frame is full of fringing from start to end of clip. The severity is most obvious when viewed at full resolution.

I attempted to reproduce this evening with Rokinon 8mm, but was unable to do so despite similar lighting conditions. Both color and contrast was much better than even best clip taken during the period before and after the clip I linked above.


Steve

[Aaron28]

I think that the cameras are recording excess light and contrast loss as artifact noise and softness

view finder light pollution?