fast shutter speeds and visible spinning ground glass problem

Nightwalker

Nightwalker

Active member
I have M2 and when i higher shutter speeds from 1/50, it starts to get visible.
Is this a general problem with spinning glass system? Or with M2? Or me?

Can't i shoot at faster shutter speeds?

Should i spin the ground glass faster? etc.. etc.. etc...

http://hayalet.net/ext/m2/problem1dv.avi (3 seconds dv avi)

problem1.jpg
 
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I just filmed a test with the SGpro (also a spinning GG disk) to test how it holds up to higher shutter speeds (as requested by Chris Barry above).

The limit depends on a combination of shutter speed and the 35mm lens's aperture setting. The further you close the 35mm lens's aperture, the more chance there is of seeing grain and the same holds true the more you raise the shutter speed.

I have got the shutter on the my FX1 @ 1/600th with no grain, but if you stop the 35mm lens down as far as F8, then grain is visable.

I will capture the footage and upload for you guy to see tonight.
 
i'll record it again tomorrow with exact information related to shutter speeds. I don't want to guess about shutter speeds. I'll give you the exact numbers tomorrow.

I kept my nikon 135mm f2.8 at 2.8.
Changing shutter speed of dvx102b results in this situation. It's perfect in 1/50. It has this situation at 1/500 and 1/1000. ( It may also have it between 1/50 and 1/500, but let me to track it again tomorrow for better information. )

By the way, i fixed the video file link.

Be sure to watch it with clean codec. Media player may show it with more gamma or brightness.. If so, try vlc player or any other players or just drop to your NLE software.
 
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Yeah it's my understanding that this is an issue across the board with any moving GG adapter

You just have to balance lens aperture camera aperture and shutter speed.

On a static light alone helps hides the grain.

On a moving GG light and motion blur help hide the grain.

At a high shutter speed you have crispser and more discrete motion samples so you are working against the motion blur that hides the grain - just like you can see the individual beads of water in a fountain stream at high shutter but at a lower shutter, you can see the individual beads of grain.

It's been my experience that you can offset it some by experimenting with both the lens and camera aperture settings but only to a degree. The grain will also be more visible against a light or white background due to the contrast.
 
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I am using the battery came with M2 for the first time.
I am not satisfied with examples, i couldn't have time to make a good test again! Some of these tests are with auto iris (which wasn't a mistake before i see that i have no time left for further test shots :S ), so problem does not show it self in 1/250 shutter. But in fact it starts at 1/250. visible spinning GG.
f2.8_shutter500.jpg
f2.8 1/500
f2.8_shutter1000.jpg
f2.8 1/1000
f9.6_shutter500.jpg
f9.6 1/500
f9.6_shutter1000.jpg
f9.6 1/1000
f16_shutter250.jpg
f16 1/250
interlacedf2.8shutter2000.jpg
interlaced f2.8 1/2000

Ok f 1/1000 or f 1/2000 may be extreme!.. But even 1/500 has very visible effect..
To summarize, i start to see spinning GG starting from 1/250.
I want to be able to use higher shutter speeds for effects and not for limiting the light. I was not especially hard testing M2, i was just trying to shot a test scene which i had wanted to be very sharp and with most strobing, with less motion blur. This thing is really limiting me.. I read somewhere that unscrewing motor a little bit makes it turn faster? I think that there is no solution than using a faster motor, or making it turn faster.... Or just don't shoot at 1/250 or faster.. :/
 
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