Shutter problem

[melquiades]

Days ago I shot a shortfilm and, by mistake, some shots were shotShutter problen with SHUTTER OFF, the good way was SHUTTER ON, 25 Pfs. Is there any problem when transfer this video material to film? Do I need to do something in post?

 

Thanks

[David Mullen ASC]

No, it won't affect the transfer to film, only the how much motion blur you got in the image. No matter what shutter speed you use, the camera generally only records in one format (let's say, 50i if it's a PAL camera). Certain extreme shutter speeds will create odd-looking motion artifacts, of course, because it may involve frame buffering, etc. when the shutter speed is longer than the recording speed.

 

For example, if you are capturing in 25P and recording to 50i (meaning each frame is stored as two fields), the longest exposure time for something shooting 25 times a second is 1/25th of a second with no shutter used. So if your camera allows something even slower, like 1/12th of a second at 25P, then it's no longer capturing an image 25 times per second --- but no matter what, it's doing whatever is necessary to still record 50 fields per second, by repeating fields, whatever.

 

And then for the film-out, you are still working with a 50i recording and combining every two fields back into one frame, etc.

 

So playing with the shutter mainly affects motion blur. However, when selecting exposure times longer than the capture rate, you may be losing some vertical resolution if field-doubling is required by the camera to keep recording in its normal format. But post can't fix that anyway. But in your case, "shutter off" means either exactly that, at 25P you are shooting at 1/25th of a second OR it really means "shutter default" which is probably 1/50th of a second. Or if you are shooting in 50i, it means 1/50th of a second either way, and that's pretty much the standard shutter speed you would be using. But no matter what, you weren't accidentally shooting at exposure times longer than the capture rate.

[melquiades]

Thank you for your answer...

 

I've used Sony F-900 capturing in 25 Pfs. Most of the time, the shutter settings were Shutter ON: 1/50. But later on I realized that everytime we changed the bat, the settings changed automatically to Shutter OFF, so the cam had to be recording with a 1/25 instead of 1/50 shutter. There will be a visible difference between what was shot in 1/50 and the 1/25 recording? :huh:

[David Mullen ASC]

That's odd because the F900 normally doesn't make changes to shutter settings after a battery change or any power loss -- they should have remained where they were last set. And you can get the shutter speed to be displayed in the viewfinder. I switch between 1/32 and 1/48 all the time so I have it displayed in the viewfinder.

 

Shooting at 1/25th, besides the one-stop gain in exposure (you didn't notice that you were getting twice as bright an image after you re-powered the camera?) gives you more motion blur, a sort of ghosty, smeary motion. So how much you notice that depends on how much movement there is in the frame. In a typical talking head close-up, you might not notice it much.

 

You normally have to manually select 1/25th, so are you sure the camera switched itself to it?

[melquiades]

Hi again!

 

In the last three weeks I've shot a shortfilm and a commercial with Sony F-900, 2 different machines. During the shortfilm sometimes it suddenly happened that the scene was like one-stop overexposed. At that time I didn't know the reason (the viewfinder display was off -mistake!!!) so I closed the iris to compensate. Last week, during the shooting of the commercial, It happened the same after changing the battery. Then I realised, as this time the viewfinder display was on.

 

As far as I know, after changing the battery the settings should have remained, but I guess they didn't... So I really don't understand.

[David Mullen ASC]

Looking at the F900's Owner's Manual, it says:

 

"Once the shutter speed is selected, it is retained even when the camcorder power is turned off."

 

Maybe someone was accidentally toggling the shutter select switch under the lens? It's right next to the trigger button and the white balance switch and I've seen some cameras where the plastic cover to the shutter toggle has fallen off. Or the camera has a serious problem with powering up...

 

Anyway, know you know why I like to have all the info displayed in the viewfinder (shutter speed, gain setting, filter wheel selection, etc.), including zebras. I'd rather be annoyed by it than not see it at all. Too many little switches that can get bumped.

[Elhanan Matos]

I've never had that kind of problem before. But I do know that if you turn the shutter off, either in the menus or with the switch, and you perform and auto level it will automatically switch the shutter back on to its preset.

 

Now i'm not sure about this, but if you had your shutter preset to OFF and you performed an auto level, it could have switched it back.

 

I'll research this a bit more and get back to you when I get the time.

[Mike Brennan]

Hi again!

 

In the last three weeks I've shot a shortfilm and a commercial with Sony F-900, 2 different machines. During the shortfilm sometimes it suddenly happened that the scene was like one-stop overexposed. At that time I didn't know the reason (the viewfinder display was off -mistake!!!) so I closed the iris to compensate. Last week, during the shooting of the commercial, It happened the same after changing the battery. Then I realised, as this time the viewfinder display was on.

 

As far as I know, after changing the battery the settings should have remained, but I guess they didn't... So I really don't understand.

<{POST_SNAPBACK}>

 

Did you have a rmb 750 or RMB 150 plugged into the camera?

 

Mike Brennan