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Nightimte Light Meter usage


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#1 Andy Yeomans

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Posted 03 October 2006 - 08:50 PM

When I use my light meter during nightimte exteriors with natural lighting I find it really hard to judge anything since the meter doesn't pick much if anything up, but I can usually get a several stop increse by removing the diffuser.

So I guess my question is, how affective can I judge the scene with mny light meter with the diffusion removed?

Obviously it's a big change in the reading, and I going for grain. I guess I just don't know how to use my light meter with the diffuser removed.

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#2 Mike Rizos

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Posted 03 October 2006 - 08:54 PM

Which meter are you using?

Edited by Mike Rizos, 03 October 2006 - 08:54 PM.

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#3 Tomas Koolhaas

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Posted 03 October 2006 - 09:00 PM

When I use my light meter during nightimte exteriors with natural lighting I find it really hard to judge anything since the meter doesn't pick much if anything up, but I can usually get a several stop increse by removing the diffuser.

So I guess my question is, how affective can I judge the scene with mny light meter with the diffusion removed?

Obviously it's a big change in the reading, and I going for grain. I guess I just don't know how to use my light meter with the diffuser removed.

Yeomans


usually when you remove the diffuser dome you need to replace it with flat disc (similar to the dome but flat) this varies from meter to meter of course. When using a flat disc instead of a diffuser you usually want to aim it directly at the source you are trying to get a reading of, because it takes a more directional reading (because its flat). This is similar to when you see people using their hand to block certain sources and pointing the dome at one specific source.
I've even seen people with meters that couldnt remove the dome build a small black cone onto it so it could take more directional readings!

Edited by Tomas Koolhaas, 03 October 2006 - 09:05 PM.

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#4 Hal Smith

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Posted 03 October 2006 - 09:21 PM

Spectra IVa's measure reflected light in a 42 degree angle when the diffuser dome is removed. Basically they behave like an old Weston, etc. with the diffuser removed. Metering from a short distance to the principal object to be photographed works much like a spotmeter would - just keep in mind the meter's looking at a 42 degree angle and be careful not to shadow your object. The Combi-II has a similar mode but uses a separate photo sensor on the opposite side from the dome sensor, there's a switch on the back to select which one you use. Both the Combi-II and the IV-a won Technical Oscars, they're good meters.

I don't work for Spectra - I just like their approach to metering.
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#5 Andy Yeomans

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Posted 03 October 2006 - 09:34 PM

I'm using a Sekonic L-358 which has the switchable recessed dome.

Edited by Andy Yeomans, 03 October 2006 - 09:36 PM.

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#6 Hal Smith

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Posted 03 October 2006 - 09:46 PM

I'm using a Sekonic L-358 which has the switchable recessed dome.


Looks like your Sekonic will work the same way - here's the relevant pages from the L-358 manual. Remember keep in mind that the closer you get to your principal subject being photographed the better your reading.

(quote from manual)

When set for reflected light

? This method measures the brightness (luminance) of the light reflected from the subject. It is useful for distant objects such as landscapes, when you cannot go to the position of the subject, or for metering subjects that generate light (neon signs, etc.), highly reflective surfaces or translucent subjects (stained glass, etc.).

< Using the lumigrid > (Receiving Angle 54°)

1. Remove the Lumisphere
The lumisphere unit is removed by holding both the
upper and lower sections of Lumisphere retracting
ring q and turning it counterclockwise while pushing
the Lock lever !4 downward.

2. Mount the lumigrid
To mount Lumigrid @3, align the mount/removal
indicator on the Lumigrid with the mark and, while
pressing it, turn it in the clockwise direction and
secure it in place by raising the Lock lever until it
clicks into place.

3. Take measurements by aiming the lumigrid precisely at the area of the subject to be measured
from the position or direction of the camera.
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#7 timHealy

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Posted 03 October 2006 - 10:04 PM

I love using footcandles instead of f stops with really low lighting levels.

best

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#8 Mike Rizos

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Posted 03 October 2006 - 10:11 PM

You should be able to get very accurate night readings with the Sekonic L-358. With the lumigrid it will meter down to EV -2, at ASA 100. This is about eight stops below of 1/48th at f1.
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#9 Frank Barrera

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Posted 03 October 2006 - 10:31 PM

don't have to remove the dome. what i like to do is just upwardly bias the iso setting on the meter. ie: if the iso of the film stock is 400 then i set the meter up up up (800,1600,3200) until it registers an f stop. then do the math and figure out where medium grey really is. does that make sense?

i'm sleepy.

f

Edited by Frank Barrera, 03 October 2006 - 10:33 PM.

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#10 Mike Williamson

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Posted 04 October 2006 - 12:47 AM

I'm going with Frank on this one, I wouldn't trust a meter that's designed to work with light coming through a translucent material to read without it in any kind of meaningful way. Crank up the ASA and do some math.

The other side of the night exterior situation is knowing how far your particular film stock will read into the shadows. If something is 4 under in an overall dark environment, it may read on film. This is where stock test become very useful.
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