Help with Motion blur in video.

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bobo31790

New member
Hi guys,
I've been using my canon t2i for lotsa videos me and my friends make and for some odd reason whenever i export videos theres always lots of motion blur. Heres a skate video I just filmed and as you can see theres tons of motion blur.

http://www.youtube.com/watch?v=gGH46-ZFoDY

The day parts were filmed at 200-800 iso, aperture at like 10 and 720p 60fps. I've heard i should have my fps set at like double my recording fps. This one was at 60fps so maybe that is why its so blurry? I convert the files to avi through prism video converter and then i edit in cs4 premiere pro and export it mpeg2 hdtv720p 30fps. I almost every format and i cant get it right. I even set the bitrate up so i have no clue what im doing wrong. I've seen many other t2i videos come out so crisp and clean but mine always seem so downgraded and blurry.
Thanks for your help!
 
Well I'm not a cs4 expert, but I have a question and a couple of comments.

What was your shutter speed? For 720/60p the recommendation is 1/120 sec (but the best you can do is 1/125).

I am not familiar with your transcoder (prism) but it may not handle 60fps properly - are you sure the intermediate file is still 720/60p? If you watch the intermediate AVI how does it look?

The other thing I would look at is your rendering. Make sure you are not frame blending when you drop from 60p to 30p. It would be best to just drop every other frame. Frame blending would definitely cause some motion blur problems.
 
The shutterspeed is too slow.

The normal 'rule' is use a shutterspeed that is double your framerate. So for 60p, 60x2=120 so you want a shutterspeed of 1/120th (or whatever the 550D's closest setting is).

With fast action sports, however, you might want to modify this rule to use a faster shutterspeed. This will prevent motion blur but if you push it too far you'll notice a 'strobe' effect where the motion is not smooth, and the subject appears to jump across the screen from frame to frame.

Something else you might want to try is introducing more camera motion - pans and tracking shots - to keep the rider in the centre of the frame all the time. This way you will notice that the rider will appear sharper in the centre of the frame, but the background will have much more motion blur. This is a good way of seperating your subject from the background particularly in those situations where you have a small aperture and very deep depth of field.
 
Alright yeah i didnt turn up the shutterspeed very much. But the thing is it looks perfect in the preview window during editing. Like peeerrrfect not a tad of blur but right when i export bam its blurry as hell. Soooo annoying
 
bobo31790 said:
Alright yeah i didnt turn up the shutterspeed very much. But the thing is it looks perfect in the preview window during editing. Like peeerrrfect not a tad of blur but right when i export bam its blurry as hell. Soooo annoying
Click to expand...
If that's the case then (as I said above) - take a look at how you are exporting. Make sure you are not blending frames or next time shoot at 1920x1080/30p
 
I wrote a post explaining motion blur vs shutter speed on another thread. I don't want to retype it so here

http://www.dvxuser.com/V6/showthread.php?225204-Guide-Me-Please-!&p=2125098&highlight=#post2125098


J Davis said:
The higher the ISO you select the more digital noise will appear in your image, that is why the others posted advice about low iso's.
Think of it as the same as the GAIN on your old camcorder.

The idea with shooting 180 degree shutter is ...
24 frames per second (usa) you want shutter 1/48 but it isn't an option so select 1/50
25 frames per second (europe) you want shutter 1/50
30 frames per second (tv land) you want shutter 1/60
60 frames per second you want shutter 1/120
in each of these scenarios for each frame there is now an equivalent amount of time for when the sensor is exposed and when it is hidden. ie 180 degree shutter
this gives the most natural looking motion blur.
Similarly a 90 degree shutter angle would be shooting 24 frames per second with a shutter of 1/96 (closest option on a canon is 1/100) and this would be decreased motion blur with
sharp looking images and a staccato feel - good for tense fight scenes

When to be careful of 180 degree shutter is when your shutter speed syncs with any flicker in surrounding lighting. For example the US power supply oscillates at 50 hz so street lights ...
the crappy fluro tube light in the office hallway ... etc, they all flicker at 50hz which is in sync with a shutter of 1/50 so you will get strange moving bands in your image.
Fluro's, HMI's and lighting made for filming are all made with flicker free ballasts so you are ok with them. They are also high CRI lights.
I was just posting about this on Vitaliys thread. When it comes to lighting (and tripods) you get what you pay for, don't got cheap, get the correct ones from the start.
If you absolutely must shoot near a flickering light, eg a night time street scene near street lights move your shutter speed to 1/60 for that scene to prevent the bands screwing up your image.

edit:
sorry, correction, I got it backwards. US power is at 60hz and you want your shutter at 1/60 so that it is in-sync otherwise when it is at 1/50 (slightly out of sync) you get the rolling bands
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