# Minolta Spot Meter F

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### #1 Steven Carubia

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Posted 21 October 2010 - 12:23 PM

Just got one and I'm wondering how to set it properly for cinematographic use. ISO is pretty straightforward, but I'm unclear on what shutter to use. 1/50 seems closest, am I right? Is the difference between 1/48 and 1/50 negligible or is there some kind of compensation required? Or am I completely wrong? I appreciate your contributions.
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Posted 21 October 2010 - 12:35 PM

Negligible, 1/50 can be used if there is not a 1/48th setting, so long as you're shooting 24FPS with a 180 degree shutter.
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### #3 Mitch Gross

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Posted 21 October 2010 - 12:38 PM

1/50th. I've had a Minolta F for a couple decades and love it still.
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### #4 Brian Rose

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Posted 21 October 2010 - 12:43 PM

I swear by this meter in my work, and it's quite simple to use. You just need to know your shutter angle and frame rate, and you can calculate the shutter speed for the meter, via this formula:

(FPS X 360)/Shutter Angle

So with a shutter angle of 180 degrees and a frame rate of 24:

(24 x 360)/180 = 8640/180 = 48

Your shutter speed is the inverse (1/48).

My spot meter goes in multiples: 1/15, 1/30, 1/60, which is a little off for 1/48. HOWEVER, on the inside of the cover for the battery compartment, there is a handy chart that offers conversion numbers that advise you how to compensate in your f-stops.

BR
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### #5 K Borowski

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Posted 21 October 2010 - 01:22 PM

The difference between 1/48 sec. and 1/50 sec. is a difference due to rounding. They're the same thing for all practical intents and purposes. It's the same thing with 1/125 of a second. It's the same thing as 1/120 sec. They use 125 because it rounds into pretty 1000s if you keep halving it. Same with film speeds. If you have a 125-speed (ASA) film, it's twice as fast as 64 film, not 62.5 speed film. (This is why I laugh at people who shoot their digital cameras at "1280 ASA" or "2560")

Where you have to be careful, is if you do not have a 180° shutter on the camera.
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### #6 Brian Rose

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Posted 21 October 2010 - 02:45 PM

Where you have to be careful, is if you do not have a 180° shutter on the camera.

Exactly. Bolexes are the worst...you gotta practically check the serial number to verify your model type, because it could be 133 or 145. And of course, this is important if you're using any camera with a variable shutter.

BR
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### #7 K Borowski

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Posted 21 October 2010 - 02:49 PM

Exactly. Bolexes are the worst...you gotta practically check the serial number to verify your model type, because it could be 133 or 145. And of course, this is important if you're using any camera with a variable shutter.

Thanks for the tip, Brian. I didn't know that about the old Bolexes!

As for 1/48 sec., it also rounds to 1/45 sec instead of 1/50. I've always just treated this as halfway between 1/30 and 1/60. In fact, I remember using a spot meter and a Bolex C8 to do just that to shoot some home movies once. I remember the thing has a little metal placard on the side that listed, I want to say 1/48 sec. as the shutter speed. I wonder if sometimes they got the placards wrong then with differing models of camera released. . .
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### #8 christopher valkenburg

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Posted 20 November 2012 - 09:07 AM

Where you have to be careful, is if you do not have a 180Â° shutter on the camera.

Can you explain this please? What is the problem with a 180 degree shutter?
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Posted 20 November 2012 - 09:18 AM

There is no problem with a 180 degree shutter; it's what light meters assume you have anyway (and most cameras are set for). However, as the shutter angle effects the shutter speed, when you change your angle, you need to make sure your meter knows you are now at a different shutter speed is all. Something like shooting with a 172.8 shutter (is it 172.8 or 178.2? I forget) it's close enough to not be an issue. However, let's say you're @ a 90 degree shutter well now you're a stop off from where you'd be with a 180 degree shutter (assuming you didn't tell your meter hey, look, i'm shooting @ 90 degrees and not 180)
Hope that makes some semblance of sense. I'm only on my first cup of coffee after a long night.
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### #10 christopher valkenburg

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Posted 21 November 2012 - 08:20 AM

Yes, it makes sense! Thanks for clarifying it for me!
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### #11 Matthew Parnell

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Posted 22 November 2012 - 03:37 PM

Brian,
If you dont know this already, You should be able to get to 1/50. Just keep pressing the down button after 30mins. Took me ages to discover this on my meter.
Cheers.
Matt
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### #12 Tom Jensen

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Posted 03 December 2012 - 11:19 AM

best meter ever. i had the model that took AA batteries which was the most convenient. i lent it to a dp friend and he liked it so much, he never gave it back. read the manual that came with it.
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