Color gels

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Polaroid22

Well-known member
Hey,

I am looking for some color gels for my ARRI 650W, I found some LEE full CTB and Full CTO gels online that I want to order. As these are the most common color gels out there right? So I can use the "full CTB" for creating moonlight, and the CTO for some warmer looking images right?

Also I found a LEE CTO +6ND gel, this might help me as I do not find any scrims here in belgium or the netherlands. I will just try this ND gel to minimize my light output?

Are these crazy thoughts, or is this just common sense?

Thanks!
 
I rarely find myself using full correction gels. Half and quarter is much more common.
Also, I wouldn't get an 85+ND gel, make your ND gel separate from your color gels or find scrims (they're 6 5/8" diameter).
 
Polaroid22 said:
I am looking for some color gels for my ARRI 650W, I found some LEE full CTB and Full CTO gels online that I want to order. As these are the most common color gels out there right? So I can use the "full CTB" for creating moonlight, and the CTO for some warmer looking images right?
Click to expand...

Not really. The point of a CTB gel is to apply it to a tungsten source and "change to blue", or make it match a daylight source. The point of a CTO gel is to apply to a daylight source and "change to orange", or make it match a tungsten source. That's what these gels are for, and for this duty they are in fact popular and useful.

In the case of your Arri 650, you're starting with a tungsten light. It's already orange. If you put a CTO on a tungsten light, you get something that's extremely orange -- like a candle flame or worse. Not really very useful in "normal" shooting. And if you put CTB on a tungsten light, you get a white like normal daylight (and you loose 2 stops or so output, so your 650w becomes a 163w). For the "moonlight" look you'll have to go considerably bluer than that and when you get there you won't have much light left to film with (if you double CTB gels, and therefore have reduced your light output by 4 stops, that's like using a 40w light to film with).

As to ND gels, don't go there. That's what wire scrims are for, and 300w globes.
 
Oh great, thanks for the info. You should make a tutorial, you would get loads of hits and likes :)

Can you recommend some filters(preferabbly LEE) that will work great for making moonlight. I dont mind the stops as of now, as I find the 650 a lot brighter then I expected indoors in a small room. :)
 
Polaroid22 said:
Can you recommend some filters(preferabbly LEE) that will work great for making moonlight?
Click to expand...

I'm no expert, so take what I say with a (large) grain of salt. There are many ways to get to that "moonlight" look, and it's often a combination of things.

Moonlight it just sunlight reflected off the moon, yes? But because the moon is pretty small in our sky, moonlight is fairly low intensity. To our eyes, there's usually barely enough light to see colors at all. So part of the "moonlight look" is desaturation. It's also crushed shadows, and fairly high contrast (because the moon is a small and therefore very hard light in the sky). These things can be (and probably should be) handled in post. Because if you capture at really low light levels and underexpose to crush the shadows, your camera will give you noisy, ugly video, and you won't be able to recover from that in post.

As to the "blue" look, you can get that with a combination of things. One "easy" way is to white-balance your camera for tungsten light, then use enough CTB on your tungsten lamp to get the shade of blue you want in your video. This will take some experimentation on your part -- try a 1/4 CTB, a 1/2 CTB, and a full CTB for starters. If you can get close enough to the color you want, you can fine tune that color in post.

The important thing to remember about day-for-night shooting, or simulating moonlight, is to not starve your camera of light -- cameras do not reward starvation. At all. Always better to use enough light to get a good exposure in camera, then manipulate brightness, contrast, and color in post. That's not intuitive, but it's what the people who do this sucessfully do. Just sayin'.
 
Polaroid22 said:
So I can use the "full CTB" for creating moonlight, and the CTO for some warmer looking images right?
Click to expand...

I suggest you read this thread in its entirety which has some very good discussion and examples of shooting for a moonlight look.
http://www.dvxuser.com/V6/showthrea...!-What-light-will-you-use&highlight=moonlight

One of my posts there has at least 8-9 links to resources on the web discussing how to get a moonlight look, everything from shooting at night and getting a moonlight look to shooting it during the day and faking it.


Research, test test test....
 
starcentral said:
I suggest you read this thread in its entirety which has some very good discussion and examples of shooting for a moonlight look.
http://www.dvxuser.com/V6/showthrea...!-What-light-will-you-use&highlight=moonlight

One of my posts there has at least 8-9 links to resources on the web discussing how to get a moonlight look, everything from shooting at night and getting a moonlight look to shooting it during the day and faking it.


Research, test test test....
Click to expand...
Thanks That topic looks great. I saw he used HMI's as a back light. And filled in with tungsten. Are HMI's far coolor then tungsten lights? Or did he use a color gel on the HMI to get that blue look? As I want a similar look, and I only own 2 Arri 650W. So one i could use with a Full CTB on it and fill in with the other one right?
Thanks
 
Polaroid22 said:
Thanks That topic looks great. I saw he used HMI's as a back light. And filled in with tungsten. Are HMI's far coolor then tungsten lights? Or did he use a color gel on the HMI to get that blue look? As I want a similar look, and I only own 2 Arri 650W. So one i could use with a Full CTB on it and fill in with the other one right?
Thanks
Click to expand...


HMI's have a daylight temperature of around 5600 kelvin while Tungsten lights are usually around 3200 kelvin. This doesn't actually mean much until you factor in your cameras white balance setting.
Say you white balance for 3200k. This means your camera is set to perceive the light from your 3200k tungsten fixture as White light. As 3200k is warmer in color than 5600k, this means your 5600k HMI will produce what appears to the camera as Blue light. White balance your camera for 5600k and it will be perceiving the HMI light as White instead - Meaning the 3200k tungsten light will appear orange.
Now white balance your camera at somewhere around 4000k and both your tungsten light and HMI light will appear slightly orange and blue respectively.

Gelling a light with a full CT-filter reduces the light output drastically. So making a 3200k 650w tungsten light match a 5600k hmi you're roughly cutting the output down to the equivalent of a 150w light. Most of the time if you need a daylight colored light you're better off renting an HMI.
 
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Ok thanks, I bought a halve CTB. And it does turn the ARRI's light output into somewhat more whiter. I had the camera on auto Wb. I need to practice my WB settings.

Any good tutorials out there on lighting, with some examples, tutorials and exercices?

Thanks
 
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