Originally Posted by
GrumpyDiver
Remembering of course there are limits of trying to use a frame of a video from a DSLR for a still image. You are not going to get a great still image. Your camera is going to shoot in one of the movie modes (24 frames per second (fps), 25 (PAL) / 30 (NTSC) fps or 60 fps), but only at either 1020 x 720 (1k) or 1920 x 1080 (2k) image size. The camera will be compressing the video using group of fields (GoF) and throwing away most of the data that the sensor is capable of recording. GoFs are generally constant size, regardless of frame rate and image size, so a higher frame rate is going to and higher resolution is going to give more artifacts in the decompressed image. Most DSLRs are going to give you highest quality at 24 fps, but this is not great for smooth, high-speed motion in your pans.
Your shutter speed will generally be slower than what you shoot with in camera mode as a bit of action smearing won’t be noticeable at the frame rate you are viewing a video, but will show up in your still images.
There are all kinds of other techniques used in digital video that reduce the overall quality of an image; colour sampling, compression, interlacing (if you are shooting this mode), etc. that will lower the quality still images. One does not tend to notice this while watching the video, but it will really pop out when studying a still image.
There are some outboard recording devices that at least partially mitigate these issues buy eliminating some of the sampling and compression issues, but these are expensive, but this means the results will be better, but still no where near what a still image will give you.
Bottom line - using video footage to extract a still image is generally going to give you disappointing results...