I'm trying to figure out the focal length of my camera. I'm trying to figure out the distance from my camera to an object using the equation listed here (How do I calculate the distance of an object in a photo?) and I had this camera taking a video recording (http://www.bhphotovideo.com/c/product/1022655-REG/sony_hdrcx240_b_hdr_cx240_full_hd_handycam.html) which says the following under Focal Length:
35mm Equivalent Focal Length 29.8 - 804 @ Aspect Ratio: 16:9 Video mode 29.8 - 804 @ Aspect Ratio: 16:9 Photo Mode 36.4 - 984 @ Aspect Ratio: 4:3 Photo mode
I'm simplifying my assumptions as much as possible and am trying to assume the video was not zoomed in at all. At this point I do not have any stills, which I understand contain more information than a video. Does that mean I should be using the "29.8" value for the Focal Length in the equation? (which seemed appropriate based on this post, How to get focal length from a camera specification which gives a value like "4.5-22.5"?)
When I do that my distance is outrageously small, and the Focal Length is the only thing that I don't have a good estimate for. Thanks!