I too am quite interest in time-lapse photography. The ability to shoot RAW and additionally have a final image in excess of 4K is quite appealing. So I'll share with you what I've learned over the past few months regarding flicker reduction. I'm going to approach this from two distinct spectrums of time: past and future. What I mean by that is: I don't know precisely how to eliminate flicker in any time lapses that you've already generated. On the up side: I do have some techniques for (mostly) eliminating flicker from sequences you shoot from here on out.
"Fixing the past"...
I've also heard about GeDeflicker. Sounds promising, when gauged by the results I've heard from others, on various forums, around the web. For a second or so I even considered, installing Windows (Boot Camp or virtually), getting a Win. version of AE, getting GeDeflicker and...then I came to my senses! That's a bunch of loot to pay to fix something that I really wanted to nail in the field. So I abandoned that concept about 4 seconds after realizing it.
Down the same path though is a free piece of software called "Virtual Dub". (
LINK). It's an open source image processing app. that can modify image sequences. Problem is that it also is Windows only. On the upside there's a free filter called "Deflicker" for Virtual Dub. And in the same arenas where I've heard compliments about GBDeflicker, I've heard equal if not better praise for this latter combination of free tools. VirtualDub + Deflicker. (
LINK) Windows XP Pro is pretty cheap on eBay now. So this is one path to consider.
Finally, regarding fixing your current sequences in FCP: I don't know. It's going to be tough and, frankly, probably never perfect. In theory you could keyframe the settings in the 3-way Color Corrector. But I wouldn't hope for miracles. Whatever success you can achieve depends on what's changing in the scene. Did you manually white-balance these shots? If so, there might be some hope. If not, that's one more thing - other than a pure "luma" shift that you're fighting. Trying to equalize chroma and luma across shots is going to be quite difficult in my opinion. Hopefully someone else can contribute more.
Don't know if you have AE for Mac. But there's an "effect" called Color Stabilizer. It actually does a nice job of fixing flicker. With one serious caveat! You can tell it whether you want to stabilize "levels", "brightness", or "curves". In our case we'd want brighness. The trick is that it's going to want you to pinpoint a black point and/or white point in the scene. That's fine if you planned for it and actually have these points to select. ie: something that is to be construed as CONSTANTLY black or white in the scene. If for instance you're shooting nothing but a moving sky then there is no constant white or black area. Now you're relegated to a frame-by-frame keyframing of one of these points throughout time. Ouch!
Now for the good news: I've discovered some truly helpful shooting techniques for reducing this flicker in the field. So hopefully these tips will help you in future as well.
1.) As you likely already know: manual shutter & aperture.
2.) Manual white balance. (Otherwise you'll likely have different color temps. across shots)
3.) Other people have suggested trying to use as slow a shutter as possible. So this might require stacking up some neutral density filters to get a slower shutter in bright light. But the theory is that this reduces any shutter speed inconsistencies. For example, if you're exposing (theoretically) for .1 seconds but theres a .01 fluctuation across shots that's a 10% change in shutter speed. If you, however, are exposing for 8 seconds with the same .01 second fluctuation, then that's only .125% change. Much less percentage change! Either way. I don't worry about this so much. I've had success with reducing flicker with shots that were all well exposed for fractions of a second. And that's because of the final tip, I think...
4.) Lock the aperture! You made mention of setting a precise aperture. So you probably already realize what I'm about to say, but I'm going to throw it out there regardless, for others that might stumble upon this. On old-school lenses when you dialed in the aperture, there were physical moving parts that slid into place and REMAINED there. With modern DSLRs this is not the case. The bodies control the aperture and they literally force the aperture into position
ever single time you fire a shot. So there's room for error. The aperture does NOT land in the absolute precise spot every time. This variance, be it ever so subtle, is still enough to cause a visible flicker when the images are played back consecutively.
However, with Canon cameras there is a workaround. Set your aperture, shutter speed and white balance. Before you start shooting, push the little "Depth of Field Preview button" beside the lens. This flys the aperture into it's soon-to-be shooting position. While holding this button, push the button to release the lens as though you were going to remove it. Twist the lens the slightest amount possible to release the contacts between the lens and body. The result: the aperture remains locked in space and time. It won't be constantly moving into position, relaxing, into position, relaxing. There are (at least) two issues I know of: this lens-twist requires the smallest movement!! If it's too large you're going to get camera errors and zero shots fired. Secondly, the lens-twist is going to break the communication of aperture reporting into the EXIF info. ie: each shot is going to appear to have it's aperture be 00. You can fix this with other tools. (
LINK) (Beware, it's not necessarily elegant: You'll be diving into OS X's Terminal.) But for me, it's somewhat irrelevant and certainly not a deal-breaker!
So that's the key piece to this puzzle in my mind: truly maintaining as many constants as possible. And this lens-twist trick seems to be the capstone for me. Here are some links:
My 1st ever time lapse. Flicker is prominent. And it's because I had Auto White Balance set. And I did knot yet know of about the lens trick.
2nd time lapse. Even with blue skies and clouds, aperture drifts can bring on obvious variations. I really just don't see it here. Here I've employed manual everything + lens twist.
3rd time lapse. Same parameters as second example. No flicker.
Finally, I'd hang out over here:
Timescapes.org. There's a great forum. In fact,
that's where I learned most of the info I'm passing on here. Great group of people. Highly skilled, knowledgable & open to sharing. Huge resource for the time lapse community.
Hope this helps some! Again, I know I didn't really talk much about fixing these sequences in FCP (or other components of the suite.) But if you've got AE for your Mac then I'd start there with the Color Stabilizer. Behind the scenes, it's operations are very similar to what GeDeflicker does.
Best regards,
Kevin
