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Using your light meter..


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#1 Josef Heks

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Posted 25 April 2011 - 11:54 PM

Hi.

So I just got my first meter (Sekonic 758cine)..

my post has to parts. I'd like to hear how you meter (In what order you meter your lights, where you aim it, flat disc vs hemisphere, incident vs spot etc etc)

I also have some questions about how to use it most effectively:

I understand that to take an incident reading, from the subject aimed towards lens, gives a reading to expose an 18% grey card to 50% grey. What I dont get is -
A. The face is not a gray card, nor is it necessarily angled straight to the camera, so does one have to compensate for this and adjust their metered reading accordingly?
B. If a hemisphere incident reading is taken from the face, with more than one light turned on, won't this just average the values, thus causing a flat middleground exposure?
C. Why would one take a flat disc reading aimed at a light, as opposed to a hemisphere reading aimed to the lens?

thx!
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#2 Stephen Williams

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Posted 26 April 2011 - 04:25 AM

Tahing a basic light reading is very easy, don't try to get complicated!

An incident reading will be fine, it's an average reading so will be correct!
A spot reading is 'Advanced' use, most beginners will screw up their exposure because of using one. Google 'zone system' if you want to use a spot meter.

I usually know what I expect the meter to say so will tilt it until is says what I expect!

Hi.

So I just got my first meter (Sekonic 758cine)..

my post has to parts. I'd like to hear how you meter (In what order you meter your lights, where you aim it, flat disc vs hemisphere, incident vs spot etc etc)

I also have some questions about how to use it most effectively:

I understand that to take an incident reading, from the subject aimed towards lens, gives a reading to expose an 18% grey card to 50% grey. What I dont get is -
A. The face is not a gray card, nor is it necessarily angled straight to the camera, so does one have to compensate for this and adjust their metered reading accordingly?
B. If a hemisphere incident reading is taken from the face, with more than one light turned on, won't this just average the values, thus causing a flat middleground exposure?
C. Why would one take a flat disc reading aimed at a light, as opposed to a hemisphere reading aimed to the lens?

thx!


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#3 Markus Rave

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Posted 26 April 2011 - 04:27 AM

Hi.

So I just got my first meter (Sekonic 758cine)..

Very good meter!

my post has to parts. I'd like to hear how you meter (In what order you meter your lights, where you aim it, flat disc vs hemisphere, incident vs spot etc etc)

I also have some questions about how to use it most effectively:

I understand that to take an incident reading, from the subject aimed towards lens, gives a reading to expose an 18% grey card to 50% grey. What I dont get is -

The grey card reflects 18% of the light hitting it.


A. The face is not a gray card, nor is it necessarily angled straight to the camera, so does one have to compensate for this and adjust their metered reading accordingly?

That is correct. Your meter is calibrated to give readings based on an 18% grey card. That said spotting a grey card and reading the incident light on the spot where you had the grey card spotted should give the same readout. A so called caucasian skin should reflect one stop over a grey card. So far the theory. You need to test with chosen filmstock, makeup and the character you wish to shoot. There is a lot of experience involved and lots of testing. Start with measuring your key light, blocking the rest and compare that to exposure when you donĀ“t block the light. Keep in mind that all lights add to the key. So simply turning them off is not the clue.

B. If a hemisphere incident reading is taken from the face, with more than one light turned on, won't this just average the values, thus causing a flat middleground exposure?

That is correct. And that is why you see cinematographers often blocking lights with their hands or use a flat hemisphere to measure just one direction of the light. Again: test, test, test, experience.

C. Why would one take a flat disc reading aimed at a light, as opposed to a hemisphere reading aimed to the lens?

The answer is stated above. It gives a more specific reading of the light you aim to. Whether you block a round hemisphere or use a flat one (your meter offers both) is based on the question you wish to answer and: testing, experience.

thx!


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#4 Ronald Gerald Smith

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Posted 26 April 2011 - 10:17 PM

Hi.

So I just got my first meter (Sekonic 758cine)..

my post has to parts. I'd like to hear how you meter (In what order you meter your lights, where you aim it, flat disc vs hemisphere, incident vs spot etc etc)

I also have some questions about how to use it most effectively:

I understand that to take an incident reading, from the subject aimed towards lens, gives a reading to expose an 18% grey card to 50% grey. What I dont get is -
A. The face is not a gray card, nor is it necessarily angled straight to the camera, so does one have to compensate for this and adjust their metered reading accordingly?
B. If a hemisphere incident reading is taken from the face, with more than one light turned on, won't this just average the values, thus causing a flat middleground exposure?
C. Why would one take a flat disc reading aimed at a light, as opposed to a hemisphere reading aimed to the lens?

thx!


Just FYI, I think the correct term for the 'sphere' is lumisphere and not hemisphere. What I like to do is I like to observe the light hitting the lumisphere. You should have an evenly lit lumisphere instead of a lumisphere that is lit partly with hard bright light, and one in the shadow. To find a reading for the main (key) light, I like to point the lumisphere at the light source and let the light source evenly cover the whole lumisphere, then take a reading. When I want to read the shadows, I like to take a reading with the lumisphere in shadow (block any stray bright lights with your hand) - and keep your eye on the lumisphere and make sure that it is completely in shadow and there are no stray lights hitting it. Make sure that your lumisphere field is even. Pretend that the surface of your lumisphere is a person's face, and you want to measure the light hitting it and the shadows as well.
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#5 Stuart Brereton

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Posted 27 April 2011 - 03:46 AM

J. You should have an evenly lit lumisphere instead of a lumisphere that is lit partly with hard bright light, and one in the shadow.


As long as you understand how to interpret the readings from your meter, it makes no difference how the sphere is illuminated. If you need to meter an individual source, use the flat receptor. For most other situations you should find that the spherical receptor provides you with a averaged reading which will generally match the balance that you can see by eye. I'd advise some experimentation using your meter in conjunction with a DSLR to learn how to interpret your readings in a consistent way.
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#6 Ronald Gerald Smith

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Posted 30 April 2011 - 09:35 PM

As long as you understand how to interpret the readings from your meter, it makes no difference how the sphere is illuminated. If you need to meter an individual source, use the flat receptor. For most other situations you should find that the spherical receptor provides you with a averaged reading which will generally match the balance that you can see by eye. I'd advise some experimentation using your meter in conjunction with a DSLR to learn how to interpret your readings in a consistent way.


Isn't there a possibility that it will create inaccuracies? I like to measure the lit side and shadow side separately. I like to be absolutely sure.
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#7 Markus Rave

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Posted 01 May 2011 - 05:41 AM

If you want to be sure, put a grey card where you want the reading and spot measure it. From your testing you will then know if the reading is over or under and if an object will render. Still you need experience to judge. Remember we are not scientists but hopefully artists with some knowledge. I read even guys like Roger Deakins have bad dreams when shooting film sometimes.
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#8 Stuart Brereton

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Posted 02 May 2011 - 12:41 PM

I I like to measure the lit side and shadow side separately. I like to be absolutely sure.


There's nothing wrong in that, but once you've metered both sides, you still have to decide where to put your exposure. It's often simpler to use the hemisphere to give yourself an averaged reading and work from that.
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#9 Ronald Gerald Smith

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Posted 05 May 2011 - 02:42 AM

There's nothing wrong in that, but once you've metered both sides, you still have to decide where to put your exposure. It's often simpler to use the hemisphere to give yourself an averaged reading and work from that.


Yeah, it's definitely the way that the majority of people use light meters and it works for a lot of professionals. However, I like taking it a step further because I don't like averages. I like to know exactly if the lit part of the face will be exactly 1 stop above, 1/2 stop above, at key, and the shadows 1/2 stop under, etc. And I spot meter surfaces in the background to know exactly how it will be exposed on my camera. I also like to do tests with the camera to make sure exactly what 1/2 under on my camera looks like and 1/2 brighter, 1 stop brighter, etc.
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#10 Stephen Williams

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Posted 05 May 2011 - 03:02 AM

Fairly quickly you will just be able to use your eyes for that!

Yeah, it's definitely the way that the majority of people use light meters and it works for a lot of professionals. However, I like taking it a step further because I don't like averages. I like to know exactly if the lit part of the face will be exactly 1 stop above, 1/2 stop above, at key, and the shadows 1/2 stop under, etc. And I spot meter surfaces in the background to know exactly how it will be exposed on my camera. I also like to do tests with the camera to make sure exactly what 1/2 under on my camera looks like and 1/2 brighter, 1 stop brighter, etc.


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