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Basic questions in terms of lighting


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#1 Katarzyna Dworak

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Posted 09 February 2014 - 01:11 PM

Hello,

 

I really need some help with these questions. I would appreciate help :)

  1.  What is a reflex viewing system?
  2.  How many pixels are in a full-frame 35mm sensor?
  3. What is the exposure for 24fps/30fps/60fps?
  4. What’s the toe in the linear response curve?
  5. What’s the shoulder in the linear response curve?
  6. Why do we shoot a chip chart? 
  7. Do wide angle lenses have more DOF than telephoto?
  8. WHY DOES A WIDE ANGLE LENS APPEAR TO HAVE MORE Depth Of Field?
  9.  HOW DO YOU USE A Depth Of Field CHART? 
  10. HOW DO YOU SET FOCUS WITH A MEASURING TAPE?
  11.  WHAT IS A CROP FACTOR?
  12. WHAT ARE ND FILTERS?
  13. HOW DO YOU COMPENSATE FOR N3 N6 N9?
  14. what is OPEN FACED LIGHt? 
  15. DOUBLE/SINGLE SCRIM
  16. HOW MANY AMPS DOES A 2K LIGHT PULL?

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#2 Roberto Pirodda

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Posted 09 February 2014 - 01:55 PM

well, these are not so basic questions . You span across many arguments not all  related to lighting. I think that the best option should be to buy a good book about basic photography before.

roberto


Edited by Roberto Pirodda, 09 February 2014 - 01:57 PM.

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#3 Mark Dunn

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Posted 09 February 2014 - 03:15 PM

I would say that some are very basic, some not, but just having them answered in isolation  wouldn't help you much. Roberto's advice is very good. If you are at college, attend the theory classes, if not,  do a lot of reading.

A cinematographer probably doesn't even need to know the answers to all of them anyway. One of the things you need to learn is which questions to ask.


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#4 Katarzyna Dworak

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Posted 09 February 2014 - 03:33 PM

I know that having a book is a really goodd idea. However, I'm attending a cinematography class and we have quiz in two days, so I cannot get the book before that. The teacher gave us only a week to prepare for the quiz with 70 questions like this. These are 16 we cannot find the asnwers for. HELP!!!! :)


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#5 Adrian Sierkowski

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Posted 09 February 2014 - 04:13 PM

Well #2 makes no sense. There are any number of pixels in a sensor, it depends on the sensor's resolution. a 35mm sensor is meaningless. It's like asking How many muffins are in a bakery?

 

Same with #3 and #16. There isn't enough information in the questions to answer them. For example, #16 will depend on the voltage applied to the load (the 2K)-- and whether you want to do paper amps or actually calculate the amps since the formula to figure this out is Watts=Volts*Amps, or in your case Amps=Watts/Volts you simply cannot find the answer without being supplied a voltage.

 

The rest of those answers are readily available in almost any book on cinematography.

 

Though in seriousness, would a Linear Response Curve have a toe or shoulder? I don't think so. A logarithmic one would; but Linear, being a line, doesn't have that type of "compression" on it at the ends


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#6 Freya Black

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Posted 09 February 2014 - 05:09 PM

Wow Adrain is right, a lot of those are really bonkers questions.

 

HOWEVER with a lot of academic stuff there is often a "right" answer they are expecting and you have to know what it is. It's at moments like that when it is handy to have recorded the tutor in the hope they will have mentioned things or given clues as to what their answers are.

 

If I had to guess about the answer to #3 for example well, they mention crop factors later on which is kind of a thing that DSLR people are obsessed with, so it could be 1920x1080, (however many pixels that is). I imagine they must be thinking of a canon 5D as it's the most well known "full frame" camera.

 

You'll be able to work out #16 based on the mains voltage in your country, (because of course you won't ever be shooting in a situation where there is a different voltage).

 

Personally I like #15 best tho! Will that be a double or a single?

 

Was there any context to these questions at all?!

 

Freya


Edited by Freya Black, 09 February 2014 - 05:13 PM.

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#7 Adrian Sierkowski

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Posted 09 February 2014 - 05:15 PM

The answer to #6 is obviously to give us a reason to make sure the film camera isn't making horrible sounds, and spend quality time with the random PA you throw in there for a skin tone reference. Also to keep producer from seeing the monitor while you're lighting looks horrible-- quick, frame up that macbeth before the producers show up and start making choices!


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#8 Freya Black

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Posted 09 February 2014 - 06:00 PM

Wow I always thought the Macbeth was used to try and make your work look more filmic by re-staging classic scenes of the china girls of yore.

 

Seems like it might have all kinds of uses!

 

Freya


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#9 Paul Re Cotsen

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Posted 09 February 2014 - 08:14 PM

 

May I first state that I am not spoiling for a fight with anyone on this site.
 

I think there is a danger that the responses however well intentioned are missing the point.  Without being patronising to Katarzyna, she is obviously just starting out in her chosen field.  She has been presented with a number of questions using terminology that means very little to anyone outside of the film and television industry.  Her tutor is probably hoping the class will utilise the internet to find answers, and that some of it might be absorbed; but it's really more a test of their initiative which is to be encouraged as an important part of the learning process.  The answers to these questions or the theory behind the answers are not the most important part of the test they have been set.
 

Miss Dworak deserves a little more understanding.  Her first language is possibly not English.  I haven't tried it myself, but I would imagine internet translations of technical explanations of some of these questions would be largely unintelligible.  

 

Freya's comments are neither helpful nor funny.

Paul Cotsen


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#10 Mark Kenfield

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Posted 09 February 2014 - 08:26 PM

A good point Paul, I think a bit has been lost in translation, because if not - I'd be more worried about the quality of education provided by a school that poses so many nonsensical questions to it's students.
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#11 Adrian Sierkowski

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Posted 09 February 2014 - 08:35 PM

I don't know. It seems reasonable to me that if you are in a class,being taught, you are given the resources for the tests. This isn't asking for further explanation on a topic; but just for answers. It's not "i don't understand how to figure out amps" it's "I want the answer to this question."


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#12 David Mullen ASC

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Posted 09 February 2014 - 08:36 PM

What is a reflex viewing system?
 
It's a system that allows you to look through the actual lens while shooting, usually involving a mirror to flips down in front of the sensor/film to reflect the light from the lens to an optical viewfinder with a ground glass when you want to see the image and then flips out of the way to let the light pass through the lens onto the sensor/film.
 
How many pixels are in a full-frame 35mm sensor?
 
Depends on how many the manufacturer put in there.
 
What is the exposure for 24fps/30fps/60fps?
 
The only way this would make sense is if the question was -- for example -- what was the exposure time when using a 180 degree shutter at 24 fps (the answer would be 1/48th of a second).  Otherwise, how could it make any sense?  If you are shooting a movie at 24 fps, do you expect the exposure to be the same whether you are shooting in sunlight or by candlelight?
 
What’s the toe in the linear response curve?
What’s the shoulder in the linear response curve?
 
How can there be a curve with a shoulder or a toe if the response is linear, i.e. not curved???
 
Why do we shoot a chip chart? 
 
As a frame of reference with measurable values usually.
 
Do wide angle lenses have more DOF than telephoto?
 
No, they just appear to.  Keep in mind you said "wide angle" lenses, not shorter focal lengths.  Whether a focal length gives you a wide-angle view or not depends on the size of the sensor/film format.
 
WHY DOES A WIDE ANGLE LENS APPEAR TO HAVE MORE Depth Of Field?
 
Because the distorted perspective makes distant objects recede in size faster and when a background detail is smaller, it is harder to tell if it is in focus or not.
 
HOW DO YOU USE A Depth Of Field CHART?
 
They are self-explanatory when you look at one -- you input f-stop and focus distance, plus factors like focal length, format, etc. and it tells you the depth of field -- the range from near to far in which objects will look acceptably sharp.
 
HOW DO YOU SET FOCUS WITH A MEASURING TAPE?
 
You're seriously asking how to use a measuring tape to measure distance?
 
WHAT IS A CROP FACTOR?
 
The image projected by a lens (which is a circle) is cropped by the shape and size of the sensor/film and smaller sensors/film formats will crop that lens image more.  So if you decide that your base reference is the image projected by a 50mm lens onto a Full-Frame 35mm sensor (8-perf 35mm horizontal still film), which is 36mm wide, then when you put that lens onto a smaller format (let's say Super-35 cine / APS-C, roughly 24mm wide) you can calculate the crop factor between the two formats (in this case 1.5X is the crop factor between 36mm and 24mm wide formats, if you are just measuring the horizontal.)  This figure can be used to calculate the focal lengths for smaller formats that you need to use to get the equivalent view of certain focal lengths on larger formats.
 
WHAT ARE ND FILTERS?
 
Neutral Density filters.
 
HOW DO YOU COMPENSATE FOR N3 N6 N9?
 
ND.30 is a 1-stop loss, ND.60 is a 2-stop loss, ND.90 is a 3-stop loss.
 
what is OPEN FACED LIGHt?
 
Usually a tungsten light with just a bare globe in a reflector dish, no lens of any sort in front like a fresnel.
 
DOUBLE/SINGLE SCRIM
 
A net material that cuts output in front of a light by a 1/2-stop (single) or full stop (double).  Scrims are usually made of metal wire when dropped right in front of a light, or fabric when used on frames farther from a light.
 
HOW MANY AMPS DOES A 2K LIGHT PULL?
 
Depends on the country and line-loss, but the math is W = V x A.  So W ÷ V = A.  In the U.S. a household outlet is usually 120V so 2000 ÷ 120 = 16.67A.
 
Now that I've answered all that, my question to you is why didn't you just Google this information???

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#13 Katarzyna Dworak

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Posted 09 February 2014 - 10:21 PM

Thank you for your help. I did Google the information, but I could not find anything clear enough. 


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#14 David Mullen ASC

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Posted 10 February 2014 - 12:05 AM

Google gets you links like this:

 

http://en.wikipedia...._density_filter

 

http://en.wikipedia....s_reflex_camera

 

http://en.wikipedia....ry_disc_shutter

 

http://en.wikipedia....iki/Crop_factor

 

http://www.rapidtabl...Watt_to_Amp.htm

 

http://en.wikipedia....ki/Sensitometry


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#15 Freya Black

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Posted 10 February 2014 - 03:34 AM

Freya's comments are neither helpful nor funny.

Paul Cotsen

 

On the one hand I would agree that my sense of humour might at best be an acquired taste but it happens to be the one I am stuck with, so it is what it is I'm afraid.

 

As to being helpful, there were already postings that fell into that category and I think that explaining that the world of academia can often be more about having the right answers rather than the correct ones is an important thing to note. In fact it's not just limited to academia. Microsoft is also well known for this kind of thing in their certification tests.

 

The truth is that there is only so far you can get with research as this student has discovered. This is why it is really important to pay attention in class. It is only in class where you can learn the right answers.

 

 

Miss Dworak deserves a little more understanding.  Her first language is possibly not English.  I haven't tried it myself, but I would imagine internet translations of technical explanations of some of these questions would be largely unintelligible. 

 

 

Whether her first language is English or not, Katazyna would appear to have fantastic English skills!

 

I think it is out of order to attempt to push the blame onto the student for the quality of the questions, as you are suggesting by implying they are poorly translated. This assumption on your part is basically grounded in the fact that she has what to you is a foreign sounding name but we have no information to suggest her classes are not in English and if they were not in English the terms are English terms. It is very clear that it is not the students fault for the quality of the questions. In fact I was somewhat disturbed to find we have already reached the point that stuff like "crop factors" is now being taught in a cinematography class!

I guess it was always just a matter of time.

 

Freya


Edited by Freya Black, 10 February 2014 - 03:34 AM.

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#16 Freya Black

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Posted 10 February 2014 - 03:53 AM

 

I think there is a danger that the responses however well intentioned are missing the point.  Without being patronising to Katarzyna, she is obviously just starting out in her chosen field.  She has been presented with a number of questions using terminology that means very little to anyone outside of the film and television industry.  Her tutor is probably hoping the class will utilise the internet to find answers, and that some of it might be absorbed; but it's really more a test of their initiative which is to be encouraged as an important part of the learning process.  The answers to these questions or the theory behind the answers are not the most important part of the test they have been set.

 

I would also add that we are not here in order to do peoples homework or research for them.

If you just give people the answers it takes away the ability of people to learn as well as they could exploring the questions themselves.

 

This is why people have pointed out that some of the questions cannot be answered because there is no point in the student banging their head against the wall. It is also why myself and others have made comments that point people in the direction of more research rather than handing over the answers.

 

Freya


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#17 Chris Millar

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Posted 10 February 2014 - 03:59 AM

Having been in and out of the education system for years now indeterminate questions like the ones pointed out are hardly note worthy... As Freya points out you just gotta figure out which is the 'right' answer, and if you're 'wrong', decide if you want to push it or not, for some reason there is usually some bright spark teachers pet who'll attempt some not so private tuition on you.

Good times ;)
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#18 Freya Black

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Posted 10 February 2014 - 04:59 AM

Freya's comments are neither helpful nor funny.
 

 

Nearly forgot to ask but what was it exactly that you bought to this thread that was either helpful to the original poster or for that matter funny?!!

 

(especially the latter!) :)

 

Freya


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#19 Katarzyna Dworak

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Posted 10 February 2014 - 03:01 PM

My first language is not English. However, I'm taking cinematography class in United States as an exchange student, so the questions were given to me in english. Thank you all for help and interesting discussion :) 


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#20 Adrian Sierkowski

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Posted 10 February 2014 - 03:14 PM

That's awesome Katarzyna. I would recommend, though, in future to ask with help with the concepts, if you don't understand them, as opposed to the stock blanket answers, ya know. We'll all go crazy if we get to explain a concept.


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rebotnix Technologies

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Willys Widgets

Tai Audio

Gamma Ray Digital Inc

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Wooden Camera

Broadcast Solutions Inc

Abel Cine

Glidecam

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Ritter Battery

Media Blackout - Custom Cables and AKS

Visual Products

Technodolly

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