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What's the deal with high fps and low resolution?

posted 12 years ago by FinnurE
1 reply | jump to latest

When I was younger my dad had an 8mm film camera that I used to experiment with. This camera wasn't all that great - had no sound and the images turned out pretty dark - but it had a feature that I liked: You could play around with the number of frames it captured per second. The lowest speed was 18 fps, which would give you fast motion at 24 fps, and the fastest was either 36 or 48 which would give you slow motion at 24 fps.

Today it's a different world. There's an abundance of different digital formats, cameras, lenses, microphones and other features available to the layman but what about the custom frame rate of my dad's old 8mm? Not one single digital camera I've come across has this feature! Well, some do but there are two catches to this: 1) You can only select from a handful of "available" frame rates. Usually the frame rates are limited to 24, 25, 30, 50, 60, etc. and more importantly: 2) As the frame rates go higher the resolution gets lower and at the highest frame rates the video is barely viewable!

I have surfed the web relentlessly looking for some sort of technical explanation for this but my efforts have so far been fruitless. Either there are major technical difficulties in producing custom or high frame rate digital cameras in full resolution or camera manufacturers are just being dicks. I was wondering if any of you were tech-savvy enough to be able to give me an explanation for this or at least point me to an article or website that explains this predicament. Any help appreciated!

[–] dangus 12 years ago

Maybe the compression speed (of the camera) and write speed (of the media) are the problem. Presumably those bottlenecks will improve in time, and eventually even consumer camcorders will be able to shoot at 48 or 60 fps.

Perhaps some cameras will have larger RAM buffers so they can shoot bursts at high frame rates, then compress and write them to flash (or hard drive). Or use parallel SD cards, with the video striped across them like RAID 0 on a hard disk array.

Higher frame rates mean higher shutter speeds, so you'll need the equivalent of higher speed film. I'm not sure how that works with digital sensors; a brief search suggests that the main tradeoff is more noise.