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USING A LIGHT METER WITH YOUR SUPER 8 CAMERA


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#1 richard rivera

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Posted 27 October 2007 - 04:41 PM

Hi:

My name's Richard Rivera, Union City, New Jersey, USA.

I just managed to buy 3 identical Super 8 cameras for under a $100. All working and in great shape. They're Sankyo XL-40S.

I have a Sekonic meter from college but I have no idea how to set the light meter in relation to the camera's shutter speed.

How can I determine the correct shutter speed on this camera? Anyone have any idea how I can accurately use a light meter with this unit?

Thanks in advance!
Rich
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#2 Matthew W. Phillips

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Posted 27 October 2007 - 05:01 PM

OK Richard,

According to Super 8 Wiki, your camera has a 220 degree shutter angle.

http://super8wiki.co.../Sankyo_XL_40_S

I'm assuming you will shoot at 24fps, since this is standard for sound cameras (and movie making in general).

1/[(360/220)*24] = 1/39.2727272 or ~1/40 shutter speed.

Formula for shutter speed is: 1/[(360/Shutter Angle)*FPS]

Hope this helps
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#3 jacob thomas

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Posted 27 October 2007 - 07:54 PM

OK Richard,

According to Super 8 Wiki, your camera has a 220 degree shutter angle.

http://super8wiki.com/index.php/Sankyo_XL_40_S

I'm assuming you will shoot at 24fps, since this is standard for sound cameras (and movie making in general).

1/[(360/220)*24] = 1/39.2727272 or ~1/40 shutter speed.

Formula for shutter speed is: 1/[(360/Shutter Angle)*FPS]

Hope this helps


Don't forget to take into account the light lost to the viewfinder prism (1/3 - 1 stop).
(Where's Terry Mester when we need him... :rolleyes: )
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#4 Matthew W. Phillips

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Posted 27 October 2007 - 09:51 PM

Don't forget to take into account the light lost to the viewfinder prism (1/3 - 1 stop).
(Where's Terry Mester when we need him... :rolleyes: )


Jacob, that doesn't have anything to do with shutter speed. Although yes, you should compensate for the light loss. I would be real surprised if you lost a full stop, I usually figure about 1/3 stop is average. If you're unsure, shoot Negative stock, overexpose a 1/2 stop. That way, if you are losing 1/2 stop, you're correctly exposed. If you are losing 1/3 stop, you are overexposed 1/6 of a stop which is only going to add thickness to your negative. You could probably overexpose your negative by up to a stop and, when factoring light loss, you'd have a nice looking neg. I'm trying to decide whether I want to shoot my 500t stock at a full stop over or only 1/2 stop over. I've had good results going 1/2 over, but I've never tried a full stop over.
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#5 jacob thomas

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Posted 28 October 2007 - 04:26 AM

Anyone have any idea how I can accurately use a light meter with this unit?


Don't forget to take into account the light lost to the viewfinder prism (1/3 - 1 stop).


Jacob, that doesn't have anything to do with shutter speed. Although yes, you should compensate for the light loss.


:rolleyes:
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#6 richard rivera

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Posted 07 February 2008 - 11:20 PM

Jacob, that doesn't have anything to do with shutter speed. Although yes, you should compensate for the light loss. I would be real surprised if you lost a full stop, I usually figure about 1/3 stop is average. If you're unsure, shoot Negative stock, overexpose a 1/2 stop. That way, if you are losing 1/2 stop, you're correctly exposed. If you are losing 1/3 stop, you are overexposed 1/6 of a stop which is only going to add thickness to your negative. You could probably overexpose your negative by up to a stop and, when factoring light loss, you'd have a nice looking neg. I'm trying to decide whether I want to shoot my 500t stock at a full stop over or only 1/2 stop over. I've had good results going 1/2 over, but I've never tried a full stop over.


Matt:

Thanks for the repsonse. I'd like to use Kodak BW reversal stock 7266 (plusx). Based on my Sankyo XL-40S and your experience would 1/3 overexposure be correct to get footage as close to a normal shoot?

Thanks in advance
Rich
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#7 Andrew Sobey

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Posted 03 March 2008 - 01:28 PM

Ok, I need someone to check my math here...

I'm using a Canon 814 XL, which has a 150 degree shutter in daylight mode. Also, I'm shooting tungsten balanced film in daylight. I'm not using an 85 filter, I'm planning on overexposing and having the telecine folks do that for me. So here's what I figure:

- Measure exposure using a light meter set to 18fps
- Overexpose by 1/3 of a stop for the shutter angle difference
- Overexpose by 2/3 of a stop for the prism (if that takes from 1/3 - 1 stop off, I'll split the difference)
- Overexpose by 2/3 of a stop for the 85 filter that is going to be added on for the transfer

That makes a grand total of 1 and 2/3 stops over what my light meter tells me to shoot. Does that sound reasonable, or am I just totally missing something?

Edited by Andrew Sobey, 03 March 2008 - 01:31 PM.

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#8 ioannis belimpasakis

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Posted 05 March 2008 - 06:11 PM

That makes a grand total of 1 and 2/3 stops over what my light meter tells me to shoot. Does that sound reasonable, or am I just totally missing something?
[/quote]


That is a very very good point, indeed :unsure: i also have a feeling that according to the reflectance of the source the light loss varies. is that possible? i have tried my canon 814 xls and my sekonic lightmeter on a grey card and can not make a point about the amount of lightloss (as it varies between 2/3 - 1+1/3 f-stop).
Does anybody have an answer guys?
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#9 Jim Carlile

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Posted 08 March 2008 - 04:00 AM

Ok, I need someone to check my math here...
I'm using a Canon 814 XL, which has a 150 degree shutter in daylight mode. Also, I'm shooting tungsten balanced film in daylight. I'm not using an 85 filter, I'm planning on overexposing and having the telecine folks do that for me. So here's what I figure:

- Measure exposure using a light meter set to 18fps
- Overexpose by 1/3 of a stop for the shutter angle difference
- Overexpose by 2/3 of a stop for the prism (if that takes from 1/3 - 1 stop off, I'll split the difference)
- Overexpose by 2/3 of a stop for the 85 filter that is going to be added on for the transfer

That makes a grand total of 1 and 2/3 stops over what my light meter tells me to shoot. Does that sound reasonable, or am I just totally missing something?


Well, kind of, but you're making it too hard to visualize what you're doing.

At 18fps and a 150 degree shutter angle, your shutter speed is about 1/40th of second-- it's not that crucial (it's 150/360th of 1/18th of a second, or about 1/42 -- a little less than half of how long each frame sits at the gate at your chosen film speed.)

So you meter for that shutter speed, and then add about 2/3 of a stop for all the light path internals, and that's it. If you want to-- recommended-- then open up the lens aperture even more to overexpose the film for transfer and color correction-- Kodak say one whole stop is good.

So-- whatever your reading is at 1/40th of a second, open up from 2/3 to 1 2/3 stops (or more) from the reading. A stop-and-a-half would be a good place to start out from. But external metering can be dicey so you should really test and bracket to see how your camera handles it. Testing is cheap. Film isn't.
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#10 Michael Nash

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Posted 08 March 2008 - 09:43 AM

Ok, I need someone to check my math here...

I'm using a Canon 814 XL, which has a 150 degree shutter in daylight mode. Also, I'm shooting tungsten balanced film in daylight. I'm not using an 85 filter, I'm planning on overexposing and having the telecine folks do that for me. So here's what I figure:

- Measure exposure using a light meter set to 18fps
- Overexpose by 1/3 of a stop for the shutter angle difference
- Overexpose by 2/3 of a stop for the prism (if that takes from 1/3 - 1 stop off, I'll split the difference)
- Overexpose by 2/3 of a stop for the 85 filter that is going to be added on for the transfer

That makes a grand total of 1 and 2/3 stops over what my light meter tells me to shoot. Does that sound reasonable, or am I just totally missing something?


Missing a couple things...

A 150 degree shutter is less than 1/4 stop loss from 180.

Color correction does not "add on" a filter -- it adjusts RGB levels. They'll drop the blue channel and boost the red to achieve color balance. No stop loss for basic correction.
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#11 Michael Nash

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Posted 08 March 2008 - 09:49 AM

That is a very very good point, indeed :unsure: i also have a feeling that according to the reflectance of the source the light loss varies. is that possible? i have tried my canon 814 xls and my sekonic lightmeter on a grey card and can not make a point about the amount of lightloss (as it varies between 2/3 - 1+1/3 f-stop).
Does anybody have an answer guys?


I don't mess with Super 8 much, but that sounds like you might have a dirty prism "fogging" the light path on the way to the TTL meter.

Edit: *Doh* :blink: Okay, now that I've had my morning coffee I can see the obvious:

Of course your camera's meter is measuring the content of the entire frame and trying to average that to medium gray. If there's a lot of white in frame it'll tell you to close down; a lot of black it'll tell you to open up. You have to fill the entire frame with the gray card if you want to find what level your camera wants to be "medium gray."
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