View Full Version : How do you make sure you have enough light in your shot?


MelonDome
11-04-2008, 11:10 AM
My LCD screen on my camera is only so big...(xh-a1). How do I make sure I get the SAME exposure and LIGHTING on my shots... so that my scene looks balanced in lighting. I dont want one shot to have too much light, and one shot not having enough...

calgarydetail
11-04-2008, 11:25 AM
have you thought of buying a monitor for it? might help since the screen will be bigger which should allow you to examine the composition of the lighting alittle bit better

just a thought

MelonDome
11-04-2008, 11:40 AM
sounds expensive :(. I appreciate the feedback though.

Mikey MiGo
11-04-2008, 12:38 PM
I've never tried it myself, but I would think you'd be able to use a small television as long as there's the proper plugs to attatch it to your camera. If you can't film it as you watch it on the TV then shoot a few seconds of test footage, check it out, and go from there.

Anyone use a TV for this? Does it work?

VPTurner
11-04-2008, 09:03 PM
Have you thought about using a light meter?

MelonDome
11-05-2008, 01:25 AM
hmmm. I was hoping someone would mention that. I see alot of people waving a light meter under light and reading something. But I have no idea what, or how they do it. VP, can you educate me a little on the basics? How is it used? how much do they run? I appreciate it.

knightly
11-08-2008, 10:50 AM
Turn on your zebra stripes. I keep mine set to 90 (90% of pure white). You can then dial the exposure to just until the brightest thing in the frame hits zebras and know that you're riding the 100% line without going over.

Light skin should be exposed at 85 and dark skin at 60-65 (which is why there are other settings for the zebras ;) ).

You can then either eyeball the shadows based on your bright exposure or you can change your zebras to the lowest setting and learn to use that to determine if your shadows are underexposed too much. Like a light meter, alot of it is experience.

You'll technically want nothing to hit true white 100%, nor true black 0%. This will allow you the most latitude in post for color correction. Add light to your shadows to bring them within range, you can always crush them back to black in post.

I thought a very telling thing for me was watching a BTS (can't remember what movie) on color grading and seeing how flat and lifeless the images were that were captured in camera. Hollywood DP's light for not only what looks good on set, but they consider the whole post workflow as well and deliver what the coloring folks need for doing their job.

MelonDome
11-08-2008, 08:48 PM
thank you knightly!

MelonDome
11-09-2008, 01:48 AM
so Knightly, I should set my zebra at 90 IRE? And expose at 85 for people with light skin(white people)? And 60-65 for dark skin(black people)? Is this what you were referring to?

knightly
11-09-2008, 02:28 AM
yes... at least that's what I do. I've learned to eyeball when skin tones are correctly exposed based on when highlights in the scene blow out :) Lots of time behind the camera.

MelonDome
11-09-2008, 10:38 PM
Will put the tips to work, thanks again!

VPTurner
11-11-2008, 08:57 PM
Well, I'm learning that the in-camera meter won't help you as much with lighting balance, especially if you're using multiple sources.

The following was written by Randy C. from Houstonfilm.org. I found it very useful:

*************

Any light meter that can read incident and reflective light will work when lighting for video. It can even be a photography meter, but choose a digital meter that displays the f-stops. This will allow you to read the meter quickly. I use a Sekonic 558 meter because it reads incident light and has a spot attachment built-in to read reflective light.

When using a light meter, it doesn't matter what format camera you are shooting with. To calibrate the meter accordingly, you must refer to your owner's manual to get the lux rating of your camera. With most new cameras, the sensitivity will be f-11 @ 2000 lux. If your camera sensitivity is f-11@2000 lux, set your meter at ISO 800 when shooting indoors and at ISO 500 when changing the color wheel filter for shooting outdoors. If you have an older camera that has a lux rating of f-8 @ 2000 lux, then your ISO will be 400 indoors and ISO 250 out doors. You will need to enter the ISO information into the meter along with the shutter speed (or _frame_ rate if the meter is made for cine or Motion picture). The shutter speed is normally 1/60. ISO + Shutter Speed = f-stop

You will get a difference between the incident and reflective because the incident measures the light coming from a source and renders it as 18% gray. So what you are reading, when using an incident meter, is the uninterrupted light output that is reaching your subject at a specific distance (which is also foot-candles). Reflective readings render the amount of light that the camera will be sensitive to AFTER it is altered by the color or density of whatever it reflects off of. Darker tones will render a reading that will indicate that you should use a wider aperture setting while lighter tones will render a reading that will indicate that you use a smaller aperture setting. This is because the meter assumes you want, whatever you point it at to be 18% gray or the same as your key or subject light.

You are also able to use a spot meter to read luminance on a set. Once you establish, with your incident meter, what f-stop your key light will be set at, in order to render our subject at 18% gray or let's say 80% on a waveform monitor, all we need to do to be able to control other reflective light in a scene is to measure it with a spot meter and adjust it's output until it matches that of the key light or slightly over or under as desired.

By understanding the contrast range and capabilities of the format camera that you are using, and then using a light meter to measure the ratios of a scene, you will be able to control the high lights and shadows scene to scene so that little adjustment will be needed to be done in post.


• CONVERTING "MINIMUM LUX" TO ISO.
Trying to fiqure the ISO for a mini DV camera when all the manual gives as a reference is a minimum lux can be a bit confusing, so here is some math to help fiqure out what the ISO may be.
.
Using my camera's sensitivity of f-11@ 2000 lux and it's established ISO of 800 as a reference, we can illustrate how to find the ISO from a minimum lux rated camera.

If we already know that f-11@ 2000 lux is the maximum illumination for an 800 ISO camera, and we want to find out at what f-stop and lux rating my minimum illumination is for that same camera, all we need to do is run down the math as follows:

2000 lux = f-11
1000 lux = f-8
500 lux = f-5.6
250 lux = f-4
125 lux = f-2.8
60 lux = f-2
30 lux = 1.6
15 lux = 1.6 with 6db of gain (every 6 db of gain = 1 stop)
8 lux = 1.6 with 12 db of gain
4 lux = 1.6 with 18 db of gain

It seems to me that If I were to include my maximum gain setting of 18db as part of my minimum illumination, my 800 ISO speed camera would have a minimum illumination of approximately 4 lux which would put a minimum illumination of 3 -5 lux. Our example is pretty darn close, if not exact.

*************

knightly
11-11-2008, 09:34 PM
That article doesn't actually give any math for converting minimum lux to ISO :P

I've priced out light meters and determined that they're more expensive than I'm willing to spend. So I've learned to eyeball the image (an external monitor - like my laptop) is a better way to look at the image than the tiny eye piece in the camera for me though.

VPTurner
11-11-2008, 10:43 PM
That article doesn't actually give any math for converting minimum lux to ISO :P

...

Yes, I noticed that. But that's why I cited where it came from so I wouldn't get slammed. :)

Remember this discussion? http://www.indietalk.com/showthread.php?t=12517

I never finished my ISO experiments to confirm the alleged ISO 160 rating of the XL1s. So my lighting method is starting to become a 2 step process. I don't use the meter to set the camera exposure (for that, I'm learning the zebra pattern method you mentioned). I use the meter to measure the individual lights and their ratios to one another.

Reading back through that older discussion made me realize that I haven't seen Doug around in awhile. I hope he's still coming here. I was learning a lot from him.

WideShot
11-11-2008, 11:08 PM
The question in the original post is like asking how long is a short wave?

How much light you need depends on the shot you are trying to achieve.

Is it day? night? dusk? dawn?

Are there multiple light sources, or just one?

Do we want moody cinematic drama lighting (high contrast), or flat office building light?

I suppose the question more relates to lighting ratio, which is the ratio between the shadow stop and the highlight stop. Usually 4:1 produces a nice effect, as in a difference of 4 stops.

How can you tell? A Light meter of course. You can eyeball it too but use a meter to get it as close as possible. As knightly mentioned, the "video" way to do this is with a zebra which is quick and easy. It will show you the areas that will blow out but not necessarily alert you to the lost shadow detail.

This is why generally, despite the fact that it goes against our purist tendencies, its much better to achieve a more neutral look in production ( a flatter lighting ratio), and then crush it in post. But you can't go the other way ... I mean you can but video is so limited in its latitude that you're just going to be fighting an uphill battle if you've blown out or lost too much detail.

The absolute answer to "what is enough light", its when you have an image that is acceptable and still above the widest aperture (lowest fstop) you can get to without using gain. Gain = evil.

Ideally, the traditional goal to aim for is f4 where it is believed most film stocks and lenses achieve their sharpest level of detail.

MelonDome
11-11-2008, 11:35 PM
How does one know if they have reached f4? great info guys

VPTurner
11-12-2008, 10:06 AM
How does one know if they have reached f4? great info guys

They way I interpret this is you'd set your aperature to f4 (assuming 1/60) on the camera and check the zebras. If it's too dark, add more light. If it's too bright, take away light. You can do this by moving the lights closer to or farther away from the subject or by using scrims and/or higher wattages. Dimmers are evil. Every one I've tried has an annoying buzz associated with it. It's fine if you're planning to replace the sound in post, but not good if your doing critical sound recording on set.

EDIT: a side note about dimmers, I used a dimmer on that lamp in the background in this shot, and it worked okay because it was outside the cone of the mic. Note that this is from my very first DV project almost two years ago, so don't be too critical. :)

http://i5.photobucket.com/albums/y152/CySevans/Paul1.jpg

MelonDome
11-17-2008, 01:41 AM
Good stuff! I will try this out, thank you

ad2478
12-02-2008, 07:33 AM
well nice topic. Though im readin it a little late. I have aquestion. Suppose i am willing to make a suspnse thriller with 98 % indoor shoot. And i am very much willing to play the best with lighting to create atmosphere what should i do keeping mind that my budget is estreamly low and i dont have a light meter of a TV ( or Monitor ) to see the results.

Arrangement of TV might be or Monitor ossible .................might be.....................but still just suppose it s GUerella type film then what will be your sugestion.


Will we have to rely only on LCD of CAM.

By the way i hope many cams ( specially HV 20) has the slot for getting connected with monitor or TV...


By the way i once contacted DV site. I forgot the exact name but they do transfer from Digital to FIlm. They recommneded me to go with a Monitor. I will post the details for convinence.


regards


Regards

knightly
12-02-2008, 05:45 PM
Many cameras have a feature called "Zebras". which place stripes on parts of the image that are over exposed. Most of them are also adjustable for the percentage of exposure (0%=black, 100%=pure white). The canons allow you to adjust the amount of zebras from about 65% (proper exposure for dark skin) to 85% (light skin) to 90, 95, 100 (for determining the points of your picture that will blow out).

These work as a visual light meter... letting you know if your scene is lit correctly, but has the advantage of giving the immediate feedback of if it's exposed correctly in the camera. That way, you can frame with the view finder ( an external monitor would be better, but not necessary ) and know you're getting proper exposure.

I have one of these ( http://www.bhphotovideo.com/c/product/504148-REG/Delvcam_DELV_FP2_DELV_FP2_System_5_6_LCD.html )... and use iMovie on my Macintosh to monitor as well... I tend to use iMovie more than the field monitor though.

ad2478
12-03-2008, 02:16 AM
thanks for guidense Knightly.

MelonDome
12-03-2008, 02:34 AM
agreed!love the zebras

VPTurner
12-04-2008, 09:15 PM
I picked up one of these: LCD4Video Bundle (http://lcd4video.com/products.php?product=7%E2%80%9D-LCD-Monitor-Studio-Bundle-w%7B47%7D-12v-Battery-Kit). And now I see they have a Canon battery adapter. Works pretty good so far.

MelonDome
12-06-2008, 12:16 AM
I picked up one of these: LCD4Video Bundle (http://lcd4video.com/products.php?product=7%E2%80%9D-LCD-Monitor-Studio-Bundle-w%7B47%7D-12v-Battery-Kit). And now I see they have a Canon battery adapter. Works pretty good so far.

good price! My brother has one of those mini-portable dvd players, with a 8 inch screen on it. I wonder if I can connect that to my camera with the proper cables?

VPTurner
12-06-2008, 10:08 AM
good price! My brother has one of those mini-portable dvd players, with a 8 inch screen on it. I wonder if I can connect that to my camera with the proper cables?

You should be able to. That's what I started out with. I like having it mounted on the camera, though, and I said the same thing when I first saw the one I bought. My only complaint about it was the adhesive on the sun shade's velcro was gummy (never set up), so I had to clean it all off with alcohol and hot glue the velcro back on. Everything else is working okay so far.

knightly
12-06-2008, 01:11 PM
it has to have A/V in plugs (usually RCA Plugs).

Dave Pastecchi
01-01-2009, 10:54 PM
a light meter is everything...you should have one...every DP should have one and know how to use it...i really cant see lighting things without one....

using a monitor to light is really not the answer...you need to know what stops your lights are at and to keep the same ratio and stops within a scene...

how would one set a stop without a meter? how would you know your DOF for the puller without one?? how would you know if you had even light for a walk without one??? and on and on...

everyone thinking of doing camera work should learn how to use a meter...its a simple tool that means so much...and you can learn to use one in no time at all....

and as a side note...all this F4 talk...means nothing...f4 is great for a focus puller, but more lens used in film should be 1.4...so many things a shot around 3 or a third under...but again...that would be up to the look you are going for and the camera you use...what is the best stop for the framerate and lens you have...this is what will determine the stop you will be lighting for...hell if its outside in sunlight it may be an 11 and if it were inside at night it could be wide open at 1.4...even though the lights are at a 2.6...there is now ideal...its all a look