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Nizo 156 XL Shutter Angle?


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#1 grantsmith

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Posted 16 August 2006 - 01:47 PM

I have an old Weston Master 3 cine lightmeter.

My Nizo has a 225 degree shutter angle as it is the XL version.

I can work this out to yield an effective shutter speed of about 1/30th second

The lightmeter manual says 'type a' setting is angles 90-149 and 'type b' 150-230 so I set it to 'Type 'b'

I'm fine upto this point but what I can't work out is if I will get correct exposure if I set my lightmeter to 18fps with whatever the asa rating is?

Could anyone help me please?

Grant
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#2 Alessandro Machi

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Posted 16 August 2006 - 02:02 PM

I have an old Weston Master 3 cine lightmeter.

My Nizo has a 225 degree shutter angle as it is the XL version.

I can work this out to yield an effective shutter speed of about 1/30th second

The lightmeter manual says 'type a' setting is angles 90-149 and 'type b' 150-230 so I set it to 'Type 'b'

I'm fine upto this point but what I can't work out is if I will get correct exposure if I set my lightmeter to 18fps with whatever the asa rating is?

Could anyone help me please?

Grant


When you switch hte frames per second setting between 18 & 24 while keeping everything else constant, do you see a shift in your f-stop setting of about 1/3 to 1/2 stop? If you do then that means the frames per seconds is not adversely affecting your readings, no?
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#3 grantsmith

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Posted 16 August 2006 - 05:03 PM

It does change Alessandro. I dont think I was making myself clear, I'm sorry. It wasn't the fps I was concerned about It was the shutter angle being 225 degrees as oposed to being 180 or 172 which was concerning me.

Will the larger shutter angle affect my exposure and if so how do I compensate?

thanks,

grant
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#4 Alessandro Machi

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Posted 17 August 2006 - 10:04 PM

It does change Alessandro. I dont think I was making myself clear, I'm sorry. It wasn't the fps I was concerned about It was the shutter angle being 225 degrees as oposed to being 180 or 172 which was concerning me.

Will the larger shutter angle affect my exposure and if so how do I compensate?

thanks,

grant


I think you said the "B" setting handles 150-230 degrees. If it is taking an average of say 190, then by being at 225 you are slightly over. However since the viewfinder takes some light away you are probably actually under by 1/4 to 1/3 to 1/2 of a stop.

One option would be to compare the auto-exposure of the camera to your light meter. Set up a test shot on a tripod, start filming by using the manual setting that you derived with your light meter, than after about five seconds of shooting this way, switch from manual exposure to automatic exposure without stopping the camera, and shoot another five seconds.

Stop the shot and repeat this test using different scenes, always using a tripod, always starting on autoexposure then switching to manual exposure.

When you get your film back you will get to evaluate both the auto-exposure of the camera along with the light meter readings plus you get to cross compare them as well.


When you use your first cartridge for exposure testing in the manner describe above, plus you will also get check the overall functionality of the camera as well.
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#5 grantsmith

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Posted 18 August 2006 - 03:35 PM

Thanks Alessandro, that seems like a very good idea.
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#6 Darren Blin

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Posted 18 August 2006 - 06:14 PM

Grant
I have the same camera (Nizo 156XL) and went through the same dilemma a couple weeks ago.

I shot a roll of 64T. Even though the shutter angle is 225 degrees you don't need to underexpose because you also lose a bit of light through the viewfinder. I used a Minolta IV incident meter and treated the stock as if I was shooting 18fps with a 180 degree shutter. The results were perfect.
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#7 grantsmith

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Posted 18 August 2006 - 06:34 PM

thanks blin
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#8 Alessandro Machi

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Posted 18 August 2006 - 10:47 PM

I made a mistake in my previous post when I was repeating the instructions and the time limit has passed to fix the mistake, so I've copied my previous post and have corrected the mistake..

I think you said the "B" setting handles 150-230 degrees. If it is taking an average of say 190, then by being at 225 you are slightly over. However since the viewfinder takes some light away you are probably actually under by 1/4 to 1/3 to 1/2 of a stop.

One option would be to compare the auto-exposure of the camera to your light meter. Set up a test shot on a tripod, start filming by using the manual setting that you derived with your light meter, than after about five seconds of shooting this way, switch from manual exposure to automatic exposure without stopping the camera, and shoot another five seconds.

(EDIT ALERT, EDIT ALERT)...........

Stop the shot and repeat this test using different scenes, always using a tripod, always starting on MANUAL exposure based on your light meter reading then while the camera is running switch from MANUAL EXPOSURE to AUTOMATIC EXPOSURE. ..........(EDIT ALERT OVER)

When you get your film back you will get to evaluate both the auto-exposure of the camera along with the light meter readings plus you get to cross compare them as well.
When you use your first cartridge for exposure testing in the manner describe above, plus you will also get check the overall functionality of the camera as well.


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