Shutter speed for 50/60p

[GuyB]

When shooting 50/60p what are the potential problems shooting with the shutter off. I assume that will set a shutter of one / 50/60 sec compared to a 180degree angle which would set 100/120 sec but this drops sensitivity by about a stop.

When I shoot 1080 50i I believe the shutter is still 1/50sec, so shooting 720 50p with the shutter off (1/50 sec) would be the same wouldn't it?

 

[Iudex]

I don't know if there is any "problem", I think it's just a matter of look. With a slower shutter you will get more light, but movement will become more blurry. To really notice this blur use shutter "off" (360º) in 25p mode. In 50p it should be much less noticable because you are doubling the frames per second, but if you playback that footage at 25p for slowmotion, then the blur should appear, I guess. I haven't done any specific tests.

With interlaced I don't feel like giving a straight answer, but I think that you will get half a stop more vs. progressive (at the same shutter speed/angle) because of how the image is formed.

I don't know why half, but according to some tests I have just done with the camera it seems to be half.

Maybe someone with more experience could shed some light on the theory, but, ultimately, Guy, I think you should simply run some tests from shooting to final product and see if it's not a problem for you to set the shutter to 360º. Maybe then upload something for us to watch . Regarding "... to final product": there should be some difference between telling the editing software to merge 50 frames into 25 and telling it to discard 25, for example.

Cheers!

I.

 

[Cranky]

50p and 50i/25i have the same image rate hence will look exactly the same (aside of different resolution and interlacing artifacts) with the same shutter speed.

 

[GuyB]

Thanks, I"ve started shooting 720 50p for freelance work when the client only wants SD but don't want that stop of light loss if I use 180degree shutter. Most seem to agree that 720 converts bester to SD