Thanks for the replies.
The photos are taken from a Samsung Android phone, believe it or not. What I do is merely take a camera video of the flight, then download it into my PC. I run the video and pause it right after countdown. Sometimes it takes many tries to time hitting the pause button so that it stops on a frame showing liftoff. Once I have that, I take a screen shot, which gets exported into Paint for photo editing and conversion to a jpeg. I typically find I can glean three shots of a model during take-off on every video. The first shows engine ignition, the next shows the model anywhere from mid launch rod to just clearing it, and I usually get another frame where the model is several feet off the rod.
The pictures are, by no means, the clearest that can be done, but they're good enough for my documentation purposes.