Noise/Pixelation during FPS Timelapse

[Ryan M]

Hi all thank you for this awesome software. I'm running it on my 500D and so far so good. One question though, Watch this video full screen the image starts out great but then degrades as the lapse goes on. I've searched this forum but haven't seen anyone else having this issue. Thoughts on why this is happening, Dirty Sensor? ISO? Warm Sensor? Execution? I have not yet tried the intervalometer to do a traditional lapse as the FPS mod saves so much shutter life, but I might to help rule out the sensor being bad.

Thanks in Advance,
-Ryan

[1%]

Open the file in bit rate viewer and see if bit rate drops when you see the pixelated stuff. Also good to check QP for those frames.

[Ryan M]

 I 'm not seeing a definite drop do you?

[a1ex]

Probably the sensor is getting warm (it's running at 100% duty cycle, while in photo mode it probably runs around 10% or 50%). Add line skipping to this, and also the lack of dark frame subtraction, and you get quite bad low-light performance.

Probably it can be filtered out in post. Idea: try to average all the frames to get a dark frame.

[Ryan M]

Thanks for that suggestion I'll give that post editing a go to try to fix it. Do different models have better sensor performance or is this the Achilles heel of doing a night FPS lapse?

[g3gg0]

i agree, this looks definitely like a warmed up sensor.
one way to work around would be:
- start time lapse with lens cap on
- let it run for 5 min to warm up sensor
- take off cap without stopping recording
- use the last frames (averaged) with cap on as bias frames

then you should have a cleaner video.

[Ryan M]

that's an awesome suggestion thanks I'm going to give it a try tonight Thank you!

[spacef2012]

Hi,
May be some of you could support this particular feature request :
http://www.magiclantern.fm/forum/index.php?topic=3548.0

It is made to  help with the random white pixels caused by liveview.
it should also help getting less noisy frames.

it does not stops you from doing dark frames for "normal" noise but should make noise much less aparent.

Thanks to add "+1" to the feature request. I am sure it will be useful as it adresses a well known problem described in most books, blogs etc.