Difference between 25pf and 50i(1/25 shutter speed)

[Vladimir]

I just made an experiment - with 2 footages:

1) in 25pf mode, F1.8, 1/25
2) in 50i mode, F1.8 1/25

IMHO this 2 modes looks exactly the same for me. Low light sensitivity absolutely the same. Both modes has progressive video frames(no interlace at both). Vertical resolution for me - looks the same. Can someone please explain me, why Canon made 25pf mode, if we can see the same results with 50i at 1/25 shutter speed?

[Worley]

Did you record movement?

If you record a static - or near-static - scene, you probably won't notice much.
Also, try 1/50 shutter speed. 1/25 is quite slow and you may notice streaking where bright object move .

[Vladimir]

Did you record movement?

If you record a static - or near-static - scene, you probably won't notice much.


Yes, i try it with static. But i was found elsewhere boards, that the best HV20 low-light sensitive in 25pf mode. So after my tests(static) i can say that 25pf low light sensitive = low light sensitive in 50i (1/25 shutter speed), are you agree with that?



Also, try 1/50 shutter speed. 1/25 is quite slow and you may notice streaking where bright object move .

I try 1/25 shutter speed in 50i in order to get progressive looking video = the same looking video as 25pf. If you shoot 50i with 1/25 shutter speed, HV20 able to capture both fields together between shutter closed, so you'l see absolutely the same progressive results as 25pf mode.
I'm not sure about absolutely the same vertical resolution, but i can shoot 2 test footages and upload them here.

[lordtangent]

I've done a similar test on the 60i version of the camera. Basically, 1/30th sec shutter on 60i, and what comes out looks like a progressive frame. The cam has no choice but to save what looks like a progressive frame since the shutter is open the entire duration of the two fields. You can take things even further and go with a 1/15th of a sec shutter as well. The HV20 holds a single frame for two frames on tape in that case.

I also tested the trick in "24p" mode with a 1/24th of a second.

The results are nice. If you have a very low light scene and don't want to have the gain kick in, it's a great way to get another stop of exposure out of the camera. But it arguably isn't "filmic" since a 360 degree shutter is technically impossible with a film cam. I personally will take the "non-filmic" shutter speed any day over gain noise though.

(of course, most of my stuff is shot in very controlled situations. what I would really NORMALLY do is just get more light into the scene!) :hv20-smilie03: