Working with native ISO

[Michael Frymus]

I was wondering..
If the native ISO is 800 like on the scarlet, and I can still switch it through the lcd monitor, do I have to shoot 800 or not?

Since its all metadata, what difference does it make if I switch it to a lower iso than 800?

When I did a shoot one, on 800 it looked really gainy so I switched it to a lower ISO and just shot it wide open instead.

Did I do it right or wrong?

 

[Andy White]

Have you looked through the materials here? - http://www.red.com/learn/red-101/exposure-with-red-cameras

There isn't a perfect recipe, it depends on the variables of your specific shoot (and lights/resources available etc)... think about your mid-grey and the level of highlight protection.

 

[Mike P.]

When you shot wide open you may have clipped the highlights a stop or two more than necessary. Now, generally speaking, if you're shooting in low-light clipping the highlights probably isn't an issue (as it tends to only be light sources and reflections, which should clip anyway.)

OH, and dynamic range goes down on lower ISOs... Or at least the captured dynamic range does (since you'd be blowing the highs earlier.) This is actually news to me; I seem to recall Arri claiming Alexa maintains its DR across ISO ratings and I just assumed RED/MX was the same way.

EDIT:
http://www.reduser.net/forum/showthread.php?94476-Double-Dragon&p=1150101&viewfull=1#post1150101

 

[Michael Frymus]

I see. So, higher iso, like the native 800 iso is best to preserve the highlights.
So, if I changed the metadata on set to 320 iso, it shoudlnt make a difference if I changed it back to 800 iso in post... Should it not? Or does that not apply?

When I shot a film once, it was a dark room but had two large hot spots. They were supposed to be at the edge, but not necessairly clipped. It was shot with 320iso. So, if I used 800iso and used NDs to drop it down about 2 stops it would have been better results?

With 800 iso I was seeing a lot of ugly noise in the blacks. So, that is why I switched to 320 and just increased the light and shot it slightly more open.

 

[Mike P.]

Shooting 320 and raising to 800 is definitely not the same as shooting 800. As you said, when you shoot 800, you'll use real-life/physical (non-metadata) controls to lower exposure (shutter, aperture, NDs) and this will ensure you're capturing as much of the highlights as possible. Conversely, shooting at 800 and then lowering to 320 in post will arguably give you the "best" image possible (cleaner lows and retain as much of the highs as possible). When it doubt, light for ISO320-640, but shoot at ISO800. That will ensure your shadows are not underexposed beyond (cleanable) recovery... You're using the raw exposure goalposts right? They tell you if the shadows are into noise and/or if the highlights are blown.

If the darks are seriously noisy at 800, try blackshading... If they're still really noisy, then they're just too underexposed and will need to be crushed down a little in post (or add fill to the shadows... it doesn't even need to be much light).

 

[Philipe Ratton]

It may seem counter intuitive but I always shoot 800 in bright light and 320 in low light.
It helps not to clip the highlights and not to raise the noise levels.

 

[Michael Frymus]

Okay, thanks

 

[Alex Frausto]

I look at it like this, ISO has no direct effect on your recorded image. It does have a psychological effect on how you perceive the camera to be capturing an image. You then adjust the camera based on said psychological response.

 

[Michael Frymus]

Hold on, so I should generall shoot ISO 800 all the time.

Light it to say 320 ISO but shoot it at 800 ISO.
So, I'd need an ND.6 to match it.

So, if I'm shooting at f/4.0 in 800 ISO, but I want the least amount of noise... If I'm correct, I need to reduce the ISO metadate in post down to 320 ISO? - then I'd need to reduce the overall image as it would be overexposed?? - or do I keep it at 800 ISO the whole time?
If that's the case, how would that give me less noise and be cleaner?
Then again, if I have to reduce it in post to 320 ISO, won't the exposure be effected badly being overexposed?

 

[Daniel Carruthers]

If you light for 320 iso and set the camera to 800iso It wont make a difference, it will still be like your shooting at 320iso, and risking the chance of clipping the highlights.
You need to set your lights and exposure on set for 800 iso, so you underexpose the 320iso sensor preserving more highlight detail.
if your getting noise at 800 iso, then you must be underexposing your image a lot more than just 1 1/2 stops
its possible you might need to do a blackshading calibration on your Red cam

 

[Michael Frymus]

Sorry, I said it backwards.

So, I want the aperture to be T/4.0
I have the ISO set to 800 and light for that. Use ND's as necessary to achieve T/4.0 - If it was ISO 320, it would be like a T/2.0 7/10

So, if it was 320 ISO it would be underexposed by just over a stop.

So, after it has been shot, what needs to be done? Im hearing I need to reduce the 800 ISO metadata to 320 ISO in post.
Thus resulting in a drop of approx 1.5 stops. Is this correct? Althought your saving your highlights, wont you be dropping the overall exposure down?
Or are you supposed to do it differently?