Noisy blacks

[Mark Toia]

I never see grain unless I have unexposed past the 3 stop barrier.
Shooting at 320 (for everything) does help me alot by not pushing into the noise floor.
The only time I change ISO is when I'm having troubles seeing and image on the client monitors.

Bright glass is The only way to fly. Less chances of under exposure.

However..
Noise looks cool in some shots anyway.

 

[Mark Mannschreck]

Currently I'm exposing to 320 in bright exterior and well lit scenes. 800, otherwise.

Most would argue the opposite... Rating 800 and stopping down, as you said, protects your highlights. In bright exterior and well lit scenes, you are already in a natively low noise situation (especially in daylight) . If you rate bright exterior at 320 you are not only risking clipping, but more importantly giving less DR to the brighter portion of your image... anything above your middle grey

Brook is correct about 800 all the time... but secretly sometimes I'll rate dim interiors at 400 if I am doing my own post. But - If you're not, I cannot stress enough that sliding your ASA rating around is bound to confuse things in post, where camera metadata is frequently discarded... or generally mismanaged (depending of course on where you're finishing)

 

[jake blackstone]

I cannot stress enough that sliding your ASA rating around is bound to confuse things in post, where camera metadata is frequently discarded... or generally mismanaged (depending of course on where you're finishing)

Mark.
Why do you think that? Is it based on a bad experience in the past?

 

[Brad Allen]

If you're needing to salvage this shoot - one trick that's helped me with noise problems is bumping up brightness rather than ISO in your metadata.

I had a quick play with the R3D you shared with us in RedCine-X. The skintones are all over the place in this grade (though I think this could be partly to do with the lighting of the original shoot). I'm sure you could get much better results once in a dedicated grading app. ISO was reduced to 640 and brightness was bumped all the way up. Black were crushed a little to further help reduce the noise + some minor other color tweaks. Hope this helps!

Full Res Jpg > Here
Adjusted R3D > Here

 

[Randall Brown]

@Brook,

Can you explain this to me? With my simple experience, I can get a full range image when shooting at 320 and exposing there. I stay above the floor, and as long as I don't clip i have a full range image and fat negative, and no noise down low. I shoot in exposure view, and I shoot for no red in the scene that I don't want to consider gone forever and I am great. 320 is the lowest ISO that allows you to get full range on the histogram. If you go lower, you can't actually get into the highlights, you will clip 3/4 of the way to the right. I can understand in that situation of clipping highlights and losing range. But at 320 I have full range. Are you saying that at 320iso the stop available above middle grey are lower than at 800 ISO? That rating at 320 I am shifting the range of available stops down toward the shadows?

I would recommend against this STRONGLY. Rate and light to 800 ASA. Just don't rate and light to 2500 ASA, as was the case here.

Rating the camera at 320 ASA will cause you to overexpose by 1 1/3 stops, costing you dynamic range in your highlights.

 

[Randall Brown]

If you rate bright exterior at 320 you are not only risking clipping, but more importantly giving less DR to the brighter portion of your image... anything above your middle grey

@Mark, missed your post. This is the question I have had for the longest. Do you know of anyone who has tested to show the shifting of the range as you rate at different ISO? I have seen one for Alexa, and I know I should do one myself, but... Hate for recreate the wheel. Looking for a test chart shot and results on scopes.

 

[Lliam Worthington]

Most would argue the opposite... Rating 800 and stopping down, as you said, protects your highlights. In bright exterior and well lit scenes, you are already in a natively low noise situation (especially in daylight) . If you rate bright exterior at 320 you are not only risking clipping, but more importantly giving less DR to the brighter portion of your image... anything above your middle grey

Brook is correct about 800 all the time... but secretly sometimes I'll rate dim interiors at 400 if I am doing my own post. But - If you're not, I cannot stress enough that sliding your ASA rating around is bound to confuse things in post, where camera metadata is frequently discarded... or generally mismanaged (depending of course on where you're finishing)

Thanks for the excellent responses. Mark, that makes a lot of sense, thank you.

 

[Lliam Worthington]

@Mark, missed your post. This is the question I have had for the longest. Do you know of anyone who has tested to show the shifting of the range as you rate at different ISO? I have seen one for Alexa, and I know I should do one myself, but... Hate for recreate the wheel. Looking for a test chart shot and results on scopes.

+ 1. Would love to see something like this if it exists.

 

[Martin Stevens]

Here is my quick, simple take on this ISO Exposure issue.

If you have a high Dynamic Range situation that you need to shoot, and you rate your Epic at ISO 320,
and then use an external light meter to find the correct f stop to use....
but then you expose so there is no clipping at all in RAW, as in, you stop the lens down
or add NDs, so that your effective f stop is now different than the one taken from the light meter,
then you are in effect NOT rating your camera at ISO 320 even though it is set to that setting.


:emote_head_explode::emote_head_explode::emote_head_explode:


.....You see, to me setting a camera to a certain ISO means that a certain f stop must be used
to keep middle gray in its place. So setting a camera to an ISO and then changing the f stop
from scene to scene is in effect changing your ISO from scene to scene.

 

[Chris McKechnie]

All this help is amazing!! Reduser = the best community of film makers.

 

[Martin Stevens]

Reduser = the best community of film makers.

I agree.

 

[Gavin Greenwalt]

I disagree on Brook's 800 ISO recommendation I find 800 just a tad too noisy, especially with Scarlet's higher compression which turns Epic's sharp noise into RED One mud. You're lifting your midtones out of a noisy bit of the image for highlight protection. If you're really careful with your exposure 320 ISO will deliver an image more than a stop cleaner. But he is right that you're risking over-exposure. I guess I'm just willing to live on the edge for that much cleaner of an image.

Also beware of the histograms, they're LUT adjusted. They aren't RAW histograms. So I've got a side-handle hotkey now for RAW view (legacy or not) so that I can monitor the actual sensor histograms.

 

[Philipe Ratton]

just a quicky from redcine.

 

[Chris McKechnie]

So are you then exposing for the RAW view or your modified LUT? I think I might get into the habit of trying to attain great RAW view exposure between 320-800 ISO, then switch over to the basic LUT if client needs to see an S-Curve. I too thought 800 was a little noisy in comparison to my 5D, however, dragon has yet to be released and I am banking on that being an incredible low-light sensor.

 

[Evin Grant]

5D is way noisier than Epic, just so low res you can't properly compare it. Seriusly a properly exposed 1600 ISO Epic image is cleaner than just about anything else except maybe the C300, which suffers from the same codec and compression issues as the 5D.

IMHO exposing at 320 is just not necessary or particularly beneficial, even for VFX. Your wasting DR for no preciveable benefit.

 

[Gavin Greenwalt]

IMHO exposing at 320 is just not necessary or particularly beneficial, even for VFX. Your wasting DR for no preciveable benefit.

Except for half the noise... at the exepense of 1/13th of your dynamic range.

 

[Gunleik Groven]

The camera is calibrated at 320/daylight

At those settings there is an actual relation between when the image clips and when you see it and when there is clip in the RAW file

At 800/daylight you have 1,25 headroom in the top, which translates to 1,25 stop lower exposure.

With tungsten settings the calibration translates into approximately 640, because the red channel gets clamped and the blue gained. If you are to develop with tungsten, 320 will still get the max out of the top, but shooting with some extra headroom (640/800+) can be a good idea to avoid clamping in the red channel.

What the sensor actually "is" from a technical perspective?
People measureing it out has found repeatedly that it is around 200-250 measured from where middle grey falls in the linear signal.
Is it thus a good idea to shoot at those settings?
Nope! And be prepared for bad surprises in the highlights if you shoot with lower than 320 settings.
800 is a practical way to expose for te sweetspot of the cam. And is a very good "do this and you won't mess up stuff" advice.

If you know what you do and are in controll of post/know that those doing post actually know what they are doing, there are a few scenarios where shooting 320 has a lot of merit.

Shameless plug:
http://www.gunleik.com/tests/alexmx/RED1_MX_and_Arri_Alexa/ISO_&_Kelvin_-_an_introduction.html

Cheers
Gunleik

(who really had planned to stay out of this discussion...

 

[Matthew Scott]

Finally! Was waiting for you Gunleik, hehe

 

[Martin Stevens]

especially with Scarlet's higher compression which turns Epic's sharp noise into RED One mud.

What???
Scarlet also has low compression,
as in, low as 3:1 just like the EPIC-X.

???

Okay........now I see that it is 6:1 on Scarlet at 24fps.

 

[D Fuller]

The camera is calibrated at 320/daylight

At those settings there is an actual relation between when the image clips and when you see it and when there is clip in the RAW file

At 800/daylight you have 1,25 headroom in the top, which translates to 1,25 stop lower exposure.

With tungsten settings the calibration translates into approximately 640, because the red channel gets clamped and the blue gained. If you are to develop with tungsten, 320 will still get the max out of the top, but shooting with some extra headroom (640/800+) can be a good idea to avoid clamping in the red channel.

What the sensor actually "is" from a technical perspective?
People measureing it out has found repeatedly that it is around 200-250 measured from where middle grey falls in the linear signal.
Is it thus a good idea to shoot at those settings?
Nope! And be prepared for bad surprises in the highlights if you shoot with lower than 320 settings.
800 is a practical way to expose for te sweetspot of the cam. And is a very good "do this and you won't mess up stuff" advice.

If you know what you do and are in controll of post/know that those doing post actually know what they are doing, there are a few scenarios where shooting 320 has a lot of merit.

Shameless plug:
http://www.gunleik.com/tests/alexmx/RED1_MX_and_Arri_Alexa/ISO_&_Kelvin_-_an_introduction.html

Cheers
Gunleik

(who really had planned to stay out of this discussion...

Gunleik,

When are you going to write a book?