Slow Motion Problems With Twixtor Pro in AE CS5.5

Question

Hello forum! I recorded some footage at 1080p and at 60 fps. My shutter speed was 1/1000 and the ISO was 3200. After importing my footage and applying twixtor pro to a solid and setting the color source to my footage, i get a lot of ghosting effects. Some other things i did with Twixtor: Changed speed % to 20, Cahnged Frame Interp to Motion Weighted Blend, Changed, Input Frame Rate to 29.97, and Finally Changed Warping to Inverse w/ smart blend. Below is my video. If the emedded video below doesn't work (because I'm new to the forums), then heres the link: http://www.youtube.com/watch?v=3qGmW7or3gw

Answer 1

Peregrinecommando99 wrote:
I'm a bit confused... How would a 1/2 shutter speed be better than 1/1000? I thought 1/1000 was faster?
Maybe this will help. If you were going for a target slow mo of 1/2 speed and your playback was going to be at 30 fps then you'd shoot at 60 fps. If you had a film camera with a normal shutter shooting at 60 fps wold give you and exposure of about 1/100 of a second. That means that if you have a video camera that will shoot at 60 P, or even 60I that your shutter speed should not be any faster than 1/100 of a second. Slowing down 60P or 60i footage is easy, It only gets hard when you want to slow something down to 1/4 or even 1/8 normal speed.
Let's take 1/8 speed. IOW one second of real time takes eight seconds of playback time.
If your project was set to 24 fps that means your target filming frame rate would be 8 X 24 or 192 fps. That means your shutter speed would be somewhere close to 1/400 of a second or half the duration of the frame rate. So I guess I should have said frame rate times 2.
Setting the shutter to 1/1000 will give you an unnatural look to the slow mo because the edges will be too sharp. There are some occasions when you want that crystal sharp image in slow mo, but you have to be able to film the original scene at a high frame rate. Images with very sharp fast moving edges give Twixtor a very hard time. The edges end up creating weird ghosting that can’t be interpolated away. It’s just too much information for the motion vectors to successfully recreate. 1/8 speed is about my limit for Twixtor. If the camera was capable of 60i or 60p that that means doesn't mean I could slow down that original footage to 1/16 speed. It means that at 1/8 speed I'd have twice as much original information to work with and would therefore get a better result. It also means that I'd still want a shutter speed that was no faster than 1/400 of a second.
Did you follow that? First rule of slow mo: Film at as high a frame rate as you can with your camera. Second rule: Try and emulate the shutter speed of a film camera that is over-cranked. Third rule of slow mo: Don't try and slow down too much. The amount of slowdown you can successfully achieve depends entirely on the movement in the frame. Unfortunately, the faster the motion, the harder it is to slow it down using software interpolation.
I spent several months working with re:vision fx on deinterlacing and speed changes in interlaced footage. This advice comes from several hundred experiments on several types of footage and from 40+ years behind the viewfinder of film cameras. I hope this helps.