color flicker? in 24pa

J

jaredalv

Well-known member
While shooting some outdoor footage of my baby niece, I noticed in post that there is a frame by frame 'hue shift' back and forth. Has anyone experienced this before?

i.e. She's wearing an electric pink outfit and is against a trees and sky background. As the hue shift occurs, the color on the whole clip goes from normal to slightly pinkish and then back again and again.

I'll try and post an example soon, but 'til then, if anyone can 1)understand what I'm trying to say and/or 2) relate any similar experiences and fixes, I'd appreciate it.

Thanks,
Chico
 
Re: color flicker? in 24pa

my only guess is that its cuase by excessive refraction from the pink dress shes wearing. the pink light can flare or somewhat seem to coat the lense. youll get the same effect if you shoot in an all white room, with one green bulb or bright or shiney thing in the center of the room, the light can be refracted making certain other things look greenish. of course im just taking a first guess , but what on earth else would cause the frame to specifically go pink?.. perhaps the sunlight refraction across the lense from a very specific angle on one layer of the lense coating? ? ?
 
Re: color flicker? in 24pa

Sounds like you might have had auto-tracking white balance on, and it might have been hunting for the right white balance.

Try locking the white balance into one of the presets and see if the phenomenon goes away.
 
Re: color flicker? in 24pa

I uploaded a small clip with the problem.  It's not on all the footage I shot during this shoot (that sounds confusing).  Only on this and one other shot I used.

I ended up throwing this clip out because of the composition.  Just couldn't get a better angle because of a 30 foot drop off next to me :-).  But still, I'd like to know what is causing the strobing so I can avoid it in the future if possible.  It would suck to have this happen while capturing 'the kiss' at a wedding.

It's kind of hard to see in this small window, and it actually comes out more white in color than pink, so maybe it's not related to her dress. The strobing is much more pronounced in a larger sized clip.

http://f2.pg.briefcase.yahoo.com/bc/jared.a@sbcglobal.net/lst?.dir=/dv+stuff&.view=l
Go to the above link and choose the color_strobing file.  It's easier to see if you just use the right arrow to slowly advance the clip rather than play it.

Thanks for the help,
Chico
 
Re: color flicker? in 24pa

I bought my DVX this past weekend. The first footage I shot with it was outdoors of my children and their cousins. One of them had a red jacket on and upon viewing the footage there was a red halo that spread 5-7 feet into the yard around the subject. (kinda like Pig Pens dust cloud) I thought it was odd.
 
Re: color flicker? in 24pa

I read Adam's thing a while ago, but this is different. In Adam's sample, only the red book is experiencing the strobing. In this little clip, the whole frame is strobing. Also, why did it only happen in this clip. I shot other clips with them in the same spot and myself on only a slightly different angle without this effect. hhmmmm.

Like I said, I'm mainly trying to see if anyone knows what it could be so I can avoid it in the future.

Thanks for your help,
Chico
 
Re: color flicker? in 24pa

ah...that's a different story.  strobing is a problem when shooting in progressive modes, and unfortunately there's only so much you can do to fix it.

first, and most importantly, if you are panning use a tripod & keep your pans slow.  the ASC has a chart used for pan speeds while shooting film that is applicable to the DVX.

secondly, be sure your vertical detail settings are set for "THICK" mode and not "THIN" if your playback method is a video monitor.  Thin mode will provide more vertical resolution than the monitor can handle, thus producing strobing artifacts.

thirdly, make sure the OIS (Optical Image Stabilizer) is set to OFF.  If it is on, strobing will occur on juddery camera movements.

lastly, try a slower shutter speed.  1/36th seems to be the magic number for most DVX users, giving you a happy (or lesser of the evils) medium between shutter blur (slow shutter) and strobing (fast shutter).

hope this helps.
 
Re: color flicker? in 24pa

..hes tlaking about shifts in the coloration of the image in certain frames on and off, in a strobe light sort of fasion . not the "stobing" or judder from camera movement. :)
 
Re: color flicker? in 24pa

The cam was on a tripod and it was a static shot. There was no camera movement at all. Oh well. Doesn't seem like anyone really knows. Could have just been a one-time phenomenon(spell?).

Anyway, hope it doesn't happen in the future.

Thanks guys,
Chico
 
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