Ok, let me try this again

[Greg Eichman]

I'm very new to the RED Camera. In fact most of my experience is as a gaffer, so I do understand the zone system, film stocks, etc. Obviously with film, it is generally preferable to use a slower speed stock if you have plenty of light(e.g. day exterior). But my understanding is that the sensor/computer in the RED functions best when ASA/ISO is set to 320 for any work other than night at which point an ASA/ISO of 640 is recommended.

Your input is greatly appreciated,

Greg Eichman

[Felix K.]

As I understood:

when you "set ISA/ASA" in the RedCam you do not change the sensor, but only the way the software interprets the data from the sensor. The sensor is still the same. And this sensor reacts like something that could be described as a 320ASA daylight film stock approximation.

If you have lots of light you can change the filmstock to lower ASA and have less grain; but you can't change the chip and it's sensitivity; only the "gain-factor". So if your chips always reacts to light like 320 ASA then you should expose to that and not push the signal with a gain-change. Too much gain means noise.

Am I right?

[Brandon Fraley]

The sensor is natively 320, so you're best off always monitoring that way, however, if you need to, RED allows you to conveniently change the ISO. However, as you increase ISO, you introduce more noise. As you DEcrease the ISO, you loose latitude in the image.

Try to stay as close as possible to 320 as you can, but if you can't add more light to a dark scene, or slap on ND filters in a bright scene, and it looks good to your eye, you're often ok.

[Gavin Greenwalt]

Just think of it like a film stock. There is what there is on the negative. But you can push it and get more noise/grain. However if your neg is black then you can't expose any more and pushing it won't get you any more image.

You can rate a 500 stock as 1000 but you'll just be getting less highlight information. Similarly you can rate RED at 600 but you'll get one less stop of information.

[dave_garcia]

Hey Greg!

Great to see you here. Shout out to the New Mexico crowd.

The camera is rated at 320. I would stay away from shooting 640 ASA. You will wind up with a lot of noise in the shadows. In the year and a half that I've owned and shot with my package I've pushed it to 400 or even 500 when I'm in a pinch, but with you being the owner of such a great lighting and grip house (-Serious Grippage- Call them when in New Mexico!) you really have no excuse. ;)

Conversely, I wouldn't recommend lowering the ISO in daylight as you will reduce your dynamic range and wind up with flatter looking images.

Good luck with the shoot. Feel free to call me if you have any questions. I'll be happy to make time for you.

[Greg Eichman]

Thanks to all. So would most agree with Dave in the you really don't think we should set ASA at 640 for night exterior work?

Greg Eichman

[Nick Gardner]

I've shot a lot of stuff at 640 ASA. It still looks pretty great, as long as you are crushing your blacks you should be fine. It's definitely cleaner at 320, but it's all relative. I'd say the Red is about as noisy as a varicam at 0DB at 640 asa.

Nick

[Brandon Fraley]

I've shot stuff at ISO 1000 that I think looks good. The point it remember to stay as close to 320 as you can. If you simply don't have the light and ISO 1000 looks ok to you, then go for it and crush your blacks a bit.

[Greg Eichman]

Thank you all for your input. Since I own a bunch of big lights, I'm going to go ahead and try to rate at 320.

GJE

[Matthew Rogers]

All the RED is doing when you change ISO is adding curves to the image. The sensor is stuck at a fixed sensitivity so wither you do it on set or in RedCine later, you will get the same exact image. The only thing that would be VERY nice would be able to lower the ISO for when you are shooting outside. That way you don't have to throw on a crap load ND and risk IR pollution. Even if it didn't make the image less noisy, I would still be very happy!

Matthew

[Stefan Christou]

At ASA 250 you have more info in the blacks right. Aren't you just moving the mid point when you change the ASA, rather than changing the sensitivity?