As I wrote in my previous blog posts (post 1, post 2) I am currently testing several methods to see if video material from the 5D Mark II can be converted to 25p. I also uploaded a couple of shots to youtube, links are below.
Being unable to shoot 25 or 24 fps video is, in my opinion, still the biggest shortcoming of the 5D for filmmaking. From my experiments, I would say that retiming using optical flow analysis is a workaround that will work automatically for probably 80-95 % of your short film. It will exhibit some artefacts in the rest. Depending on how sensitive you are about motion artefacts you may or may not notice them when viewing the film the first time. By adding time in the post production workflow to work around the problematic areas by either helping the optical flow analysis with manual foreground extraction or by using frame blending in these cases one should be able to arrive at a decent 25p copy that will feel right to a very large part of your audience.
Stu Maschwitz nailed it when he said: "That's not a workflow. It's finger-crossing" (link to the forum posting). But given enough time and dedication, it IS possible to make almost any material work well enough, so it is a viable alternative to shoot with the 5D and hazard the consequences (long post production, some shots may always feel weird). But, in a way, No Budget filmmaking has always had to make tradeoffs like this.
Now for some of the tests I shot with DoP Philip Leutert, all retimed with Twixtor in After Effects unless otherwise noted:
- A lot of the shots that I thought would be tricky worked surprisingly well. Here is an example of a pond and a duck. Here is another one where you can see some detailed smoke.
- The most problematic type of shots for optical flow analysis is when a foreground object occludes and reveals a background that is clearly visible and has very noticeable detail - human faces are the worst background because we know so well how faces should look like. Here is an example where I walk around a bit. Watch the outlines of the foreground and how it distorts the background. Here is another example where my face is revealed and occluded a couple of times.
- Semitransparent objects in front of a face are also tricky, but in my test twixtor held up rather well. (And yes, I do look silly holding up some semitransparent stuff in front of my face). Here is the same material retimed using frame blending.
The results for me personally are encouraging enough that I would risk shooting a short film with it. It will take a lot of time to get a good 25p copy, but at least I think it is doable. I think the resulting material will never be perfect, but if the story, the sound & the music are good then people shouldn't be thrown out of their experience - and the shallow dof of the 5D can be a very important story telling device, so it may just be the right choice for some projects. Of course, we should all be writing to Canon to stop being stupid and give us 25p (24p would also be nice, but it's not as crucial).
Let me know if you would like to see some more material or if you are interested in alternative techniques (After Effects' Pixel Motion or frame blending) or if you have a copy of Shake and would like to try to retime my test material with it!