Auto ISO in Creative Motion Picture Mode

O

Ozpeter

Well-known member
It seems that the only way to get control of shutter speed and / or aperture is in Creative Motion Picture Mode - the manual says enigmatically in the shutter and aperture priority and manual control sections "It will be a normal motion picture recording when recording a motion picture. Use the Creative Motion Picture Mode when you would like to record by setting the aperture or shutter speed".

I wonder what "normal motion picture recording" means? I guess some lengthy experimentation might give a feel for what happens as there's no displayed information on shutter speed or aperture during motion picture recording. So one has no clue of what it's up to unless using Creative Motion Picture Mode, and even then you only know what you've set, not what the camera is choosing.

When it's doing whatever it does in those non-Creative Motion Picture Mode [CMPM] modes, reaction to changing light conditions is smooth. When you use CMPM, aperture is stepped, which is a pity - you can see the changes. Trying to compensate manually in-shot for changing light leads to noise if using the built in mic, it's probably hard to achieve without moving the camera very slightly even on a tripod, and the change would probably be visible in the shot.

It would be handy if...

1. CMPM could allow smooth reaction to lighting changes, not stepped.

2. Current aperture and shutter speed and actual ISO (even when auto) were continuously displayed in all modes.

3. Program shift were available in CMPM "P" setting - only compensation works.

4. Auto ISO were available in CMPM "M" setting.

That last one might sound a bit illogical - why have something set automatic in manual mode? - but if you want to set shutter speed and aperture to settings you want, and the light levels are variable, then if the ISO could optionally vary itself to cope at least partly with the variation, that would seem to be a handy facility (and for those not wanting auto ISO in manual mode, don't set it).

I suspect that some if not all of those might be possible via a firmware update. Or am I alone in these concerns?
 
Ozpeter said:
When it's doing whatever it does in those non-Creative Motion Picture Mode [CMPM] modes, reaction to changing light conditions is smooth. When you use CMPM, aperture is stepped, which is a pity - you can see the changes.
Click to expand...

I've noticed the same thing. At first I thought it was only with low light recording, but I see this same 'dramatic' light level change when zooming with a fixed shutter speed in bright light.

I really don't know why this happens, but it does detract from using manual controls for video recording.
 
I recorded some random street scenes yesterday, doing slow pans, tracking passing vehicles at some speed, closeups of flags blowing in quite strong wind in front of coniferous trees blowing about - and the one issue which for me stands out as significantly more serious than mud, stutters, focus issues, banding, or whatever, is aperture jumping (unless on full manual mode). Sometimes the aperture even jumps on a static wide angle shot with no obvious change of light happening. I really do hope that can be fixed in due course - it's very obvious and becomes somewhat annoying.

Or maybe someone's got a usage suggestion to avoid it? Apart from full manual which means possible under/over exposure if the light levels change whether in moving or static shot.
 
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Did you try sp or ap and then hit ae lock on cmm, on this setting you have auto iso and have now locked in exposure/a and s? and the iso may vary with light unless it locks that to! will try it again myslef, but had come to this conclusion that full manual outside in the day causes all sorts of issues, some flickering as well. AE lock is a great tool and can be used to lock exposure if you can use iso to tweak the exposure may be a good solution.
 
Following some off-topic debate in another thread on whether the aperture is stepless or not, here's a short sample showing, to my satisfaction, that it's certainly not stepless. Five distinct and abrupt changes in exposure can be seen, and at some points that clearly upsets the codec too (1080 AVCHD).

http://www.fileden.com/files/2007/9/22/1451533/00016.MTS

The file was recorded in Creative Motion Picture mode, shutter priority at 50th second, ISO fixed at 400. 27MB, 14" long. Sorry about my weedy garden.
 
is this only with the kit lens? maybe it's just something electronically. has nobody played with the gh1 using a zoom lens from nikon?
unless you're using it other than narrative film making, why wouldn't you want it on full manual mode?
 
Yes, with the kit lens. Sure, full manual mode gives you total exposure control (apart from the changes in exposure when you zoom, but probably you shouldn't be zooming anyway) so long as you have total control of the lighting of the scene. If your shot will encompass a variation in lighting which the dynamic range of the GH1 cannot capture, then you'll probably want to use shutter priority mode, but IMHO you'll then be stuffed by the sudden changes of exposure caused by the iris not being as stepless as some claim it to be.
 
I don't have a GH1 yet, but in theory, if aperture is set to f5.8 or more there should not be any iris changes forced by zooming.
If you manually set shutter and ISO and manually set aperture to 5.8 or more you should be able to zoom in and out without any exposure changes. This happens because the kit lens is a 14-140mm / F4.0-5.8 which means it can open to f4.0 when fully wide, but will close to f5.8 when fully zoomed in.
 
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