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Super 8 Light Metering


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#1 Pat Daniels

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Posted 28 January 2006 - 08:48 PM

I read that trying to use light metering (other than the camera's) when filming with super 8 can yield results that you may not want. Is this true? And if so, are there still some options to use some kinda spot meter method so I could still have more control over filming than the camera reading over/under exposed.

Thanks
Pat Daniels
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#2 Joe Gioielli

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Posted 30 January 2006 - 03:25 PM

Pat, I think (and others who know more will help out if I get this wrong) you might be referring to 'F" stops and "T" stops. Personally, I've never used a camera that used "T" stops so I won't pretend to konw about them. This is what I found on www.usecoles.com by Matthew Cole:

"There is a concept called t/stop, for transmission stop, which is a measure of the actual light transmission of the lens rather than the simple ratio of the aperture to the focal length. The t/stop can vary from the f/stop because you have a lot of lens elements (big zoom lenses might have these) or you have one lens coated and another not coated. About the only people who need this level of precision are professional cinemaphotographers who use the t/stop to set exposure. Their lenses sometimes have both f/stop and t/stop scales marked. Even when they know the t/stops of the lens, the f/stops remain important because depth of field is driven by the f/stop regardless of the light-passing ability of the glass. I have never seen a still photography lens marked in t/stops, but the concept is out there so I thought I'd mention it. "

As long as you are using the same terms "T or F stop" on your meter and your lens, you should be fine. More than likely you will be dealing with F stops. F stops refer to how much light will strike your film. It is related to film speeds, lighting conditions, and detph of field. The above wesite covers about what you need to know.

Now, there are also different kinds of metering: reflective(center weighted, matrix, and spot", and incident. Reflective metering measures light reflecting off things, incident measures light falling on things. You will get different results depending on which you choose. There are a million variables. Believe me, it sounds a lot harder than it really is.

The last issue you may be looking at is the fact that many Super8 camera are auto-matic exposure and set for 40 asa film speed, which is no longer avaliable. Other stock are available but if you have an auto only camera, well, you're out of luck. If you camera is manual, you should be fine.

So, you should have no problem using a seperate light meter with you movie camera. Just make sure you know how to use the meter for cine film (you have to account for sutter angle and frame rate) Again, it sounds harder than it is. It should all be in the instruction book or you can search the web.

Sorry for the long confusing post
Joe
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#3 Mark Dunn

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Posted 31 January 2006 - 04:09 PM

Most super-8 cameras have beam-splitter viewfinders which absorb some light so you need to allow for that. T-stops refer to the effective f-stop taking into account any light loss in the lens- maybe a third of a stop for a zoom. (T2.5, f/2.2 for the Angenieux 12-120mm, for example). When you change lenses you need that number for consistent exposure from shot to shot. Typically an SLR with TTL metering makes that correction for you.
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#4 Rick Palidwor

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Posted 02 February 2006 - 11:22 PM

Use the in-camera meter for your final decision because it gives you T-stops - the meter is typically "behind" all the other variables and knows how much light actually made it to the film.

Use an external meter to supplement, if you want, by simply calibrating that meter to what the camera's meter is telling you. Then you have the luxury of walking around your set, taking readings, adjusting light and so on without disrupting your camera set-up.

Rick
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