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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Build 16 ISOs...

the amount of light physically hitting the sensor can't be changed later(exposure). which is controlled by physical entities such as iris, shutter speed, and filtration.


the sensor's interpretation of that amount of light that hit it can change after the fact.(metadata asa).
 
For some reason this whole metadata exposure mishigas is confusing. You need the proper metaphor so people can get their collective heads around the concept.

How's this? It's like...well...film! If you expose, say, 100asa film at, say, 200asa, the only difference is that you're changing the amount of light hitting the film. Since you're planning on pushing it in the lab, you treat it like 200asa in the camera. But 200asa is actually accomplished ex post facto. In post.

I apologize if this has been said before. I'd try to find it, but I can't figure out the the new search tool. I can't get it to work.

A suggestion for Jim. This whole website is loaded with filmmakers. Maybe one of them can come up with a simple tutorial, maybe even animation, that goes through the whole RAW concept and workflow?
 
Dale Launer said:
For some reason this whole metadata exposure mishigas is confusing. You need the proper metaphor so people can get their collective heads around the concept.

How's this? It's like...well...film! If you expose, say, 100asa film at, say, 200asa, the only difference is that you're changing the amount of light hitting the film. Since you're planning on pushing it in the lab, you treat it like 200asa in the camera. But 200asa is actually accomplished ex post facto. In post.

I apologize if this has been said before. I'd try to find it, but I can't figure out the the new search tool. I can't get it to work.

A suggestion for Jim. This whole website is loaded with filmmakers. Maybe one of them can come up with a simple tutorial, maybe even animation, that goes through the whole RAW concept and workflow?
Click to expand...

Dale,

Good suggestion. Any volunteers? :-)

We actually are planning on doing this as soon as we give birth to Build 16. The really good news is that Build 16 makes everything seem very simple.

1. Set your ISO depending on light. 320-500 for normal, higher as the light goes away. Lower if you forgot your NDs.

2. Use your meter, your histogram or your monitor to judge exposure. They will all line up.

3. Open in RED Alert! or REDCINE and the images will look like your monitor did when you pulled the trigger.

4. If you missed exposure (hopefully not by much), change ISO or Exposure in either of those two apps until it looks right.

5. Use Curves to tune up the look of the image. Add or subtract Saturation if needed and you are good to go 90+% of the time. Of course, you can always add looks and other creative magic.

With Build 16 WYSIWYG almost ALL of the time.

Jim
 
Jannard said:
If the proper exposure for a given scene is ISO 125 @ T4, then the proper exposure for that same scene is also ISO 500 @ T8... or ISO 500 @ T4 with a .6 ND. Neither will clip. The ISO 125 image will have less noise (none) but will be a touch softer than ISO 500, which will have extremely low noise. Pick your poison.

Jim
Click to expand...

In this example, the ISO 125 @ T4 and the ISO 500 @ T4 with a .6 ND is exactly the same amount of light hitting the sensor.

Is it most important for people to understand that a RED ISO rating is simple MATH compared to FILM which is a difference in sensitivity?

The RED is never more or less sensitive than it's "sweet spot" between 320-500 ISO. Any other ISO is a mathematical metadata interpolation of the DATA.

The Mysterium SENSOR is never more light sensitive (as a film stock WOULD be) to light, but how you (as a user) choose to expose that sensor still comes down to the MECHANICS of how much you open the iris to let light hit the sensor.

You can't "fake it" with RED and rate it at 800 light it for 800 @ T4 or rate it at 125 and light it all at 125 @ T4 without understanding that this is the point at which you will be compromising the image because it is not in the "sweet spot" of the sensor.

Not saying you can not choose to do this, just do it knowing that you are under or over exposing compared to the BEST image possible as determined by RED.

Is this at all near correct thinking?

David
 
I was having a conversation about this last night and we kind of came to the conclusion that moving the ISO in RED is a bit like GAIN on a video camera, with the important exception that it is in the metadata and not burned in.

You could equally call it REDGAIN and offer it at -9, -6,-3,0,+3,+6,+9,+12,etc

I think you should stick with ISO because it is more in line with cinema.

David
 
Jannard said:
2. Use your meter, your histogram or your monitor to judge exposure. They will all line up.
Click to expand...

Or zebra for quick shots. Though I've been using FC & histogram for exposing shots in slower shooting scenarios, I've also been using zebra heavily since August for "run & gun" situations - using Zebra 1 and racking iris until just a tiny bit of zebra pattern shows in the brightest part of the framed image, then closing the iris down slightly until the zebra pattern just disappears. Exposure has been very accurate using this procedure in previous builds and I assume it will be in Build 16. Again, when I have time, I go through the whole FC & histogram route, but in my experience, in some types of fast-paced, mobile shooting environments zebra is the best choice for exposing RED ONE.
 
battistella said:
I was having a conversation about this last night and we kind of came to the conclusion that moving the ISO in RED is a bit like GAIN on a video camera, with the important exception that it is in the metadata and not burned in.

You could equally call it REDGAIN and offer it at -9, -6,-3,0,+3,+6,+9,+12,etc

I think you should stick with ISO because it is more in line with cinema.

David
Click to expand...


No gain, please.

It's a preview.
 
battistella said:
I was having a conversation about this last night and we kind of came to the conclusion that moving the ISO in RED is a bit like GAIN on a video camera, with the important exception that it is in the metadata and not burned in.

You could equally call it REDGAIN and offer it at -9, -6,-3,0,+3,+6,+9,+12,etc

I think you should stick with ISO because it is more in line with cinema.

David
Click to expand...


No, it is. And that's why it is SO confusing to people. It is nothing like gain, which happens in camera. Maybe you want to call it POST GAIN. Or EX POST FACTO GAIN.

Now, after you expose, the metaphor breaks down a bit. You can considered it like exposed film but not processed film. And if you exposed, at say, 640, the metadata acts like an automatic check in the notes that go to the lab "Please push 1 Stop" (or whatever've you selected as ISO/ASA).
 
Dale Launer said:
No, it is. And that's why it is SO confusing to people. It is nothing like gain, which happens in camera. Maybe you want to call it POST GAIN. Or EX POST FACTO GAIN.

Now, after you expose, the metaphor breaks down a bit. You can considered it like exposed film but not processed film. And if you exposed, at say, 640, the metadata acts like an automatic check in the notes that go to the lab "Please push 1 Stop" (or whatever've you selected as ISO/ASA).
Click to expand...

Yeah, I know. It's only a post thing and never on the file. But just do this.

Put up a chart:
set the F stop to F4 1/48th shutter.
expose 10 sec at 320
expose 10 sec at 500
expose 10 sec at 640
expose 10 sec at 1000
expose 10 sec at 1250

Open them in Redcine and set them all to back to 320. You have exactly the same image. So the gain analogy just kind of echoes this idea. You push the r3d file to expose brighter or darker than what how you exposed it. You can not change the r3d file JUST THE DISPLY PARAMETERS.

That is why hitting expose in the RED is more like shooting SLIDE film than NEGATIVE film. (WAIT!!! That is a big exageration, I did not mean it quite that way)

David
 
And -- Wouldn't it make more sense to set it at 320ASA and NEVER change it -- ever -- on the camera? Adjust iris, shutter, light and NDs, but leave the control set to what the sensor ACTUALLY sees?

(This relates to my other question about if changing ISO on the camera affects any signal processing of the RAW data, or not?)
 
"Put up a chart:
set the F stop to F4 1/48th shutter.
expose 10 sec at 320
expose 10 sec at 500
expose 10 sec at 640
expose 10 sec at 1000
expose 10 sec at 1250

Open them in Redcine and set them all to back to 320. You have exactly the same image."

Well that would settle it. Is this true, and verified with Build 16?
 
mail4joeg said:
Is this true, and verified with Build 16?
Click to expand...

Only a handful of alpha testers are using build 16 right now so you you would have to ask them.

I am sure that build 16 Beta is around the corner and then the party can begin!

David
 
mail4joeg said:
And -- Wouldn't it make more sense to set it at 320ASA and NEVER change it -- ever -- on the camera? Adjust iris, shutter, light and NDs, but leave the control set to what the sensor ACTUALLY sees?

(This relates to my other question about if changing ISO on the camera affects any signal processing of the RAW data, or not?)
Click to expand...


OK.

Just for you. I did the test. Here are the parameters.

I used a NIKON 17-35 zoom at 35mm F2.8
the chart is lit with a single light panel LED at 5600Kelvin
The meter reading is set to 320, incident light reading of 40 f2.8
The control frame is the 320 ISO .tiff

Here is what I did.
Exposed clips at
320
400
500
640
800
1000
1280
1600
2000

Then I opened in RED alert and exported at each clip at the ISO it was shot at.

Then I reset the ISO to 320 for each clip and exported that.

No sharpening, no curves. straight out.

Latest release build of build 15.

No rocket science here.

you can download the tiffs here in about 15 minutes.

Enjoy.

http://www.f8films.com/client/redtest/

Username: red
Password: red


David
 
Hi

Hi

Thanks, David.

I'm going to assume that build 16 doesn't change this. Because it's a fundamental feature of the camera.

So, technically, you could say there IS no "ASA" or "ISO" control. The control is REALLY a monitor brightness control (with transferability to the software). Isn't it?

If so, then calling it "ASA/ISO" is misleading and confusing at the outset. The red sensor apparently does not change sensitivity. "ISO/ASA" is a measurement of film sensitivity to light, and it changes when a film that is more or less sensitive is loaded. There is no direct correlation between the Red "ASA" and a film "ASA." The camera (apparently) has a fixed sensitivity, and all this talk about changing it is essentially meaningless.

Would you disagree?
 
mail4joeg said:
If so, then calling it "ASA/ISO" is misleading and confusing at the outset. The red sensor apparently does not change sensitivity. "ISO/ASA" is a measurement of film sensitivity to light, and it changes when a film that is more or less sensitive is loaded. There is no direct correlation between the Red "ASA" and a film "ASA." The camera (apparently) has a fixed sensitivity, and all this talk about changing it is essentially meaningless.
Click to expand...

Yes, but you also might rate a film stock differently based on your scene. A film stock's manufacturer's rating is also just a "suggestion". I like to think of rating RED ISO as an EXPOSURE LUT that impacts the image similar to rating film, but not EXACTLY. You WILL get less noise rating it lower... and more higher. You can save shots that might have been unusable on other camera systems... Since the Red apps (red alert, red cine) and even the quicktime proxies read camera ISO metadata until you change it, it is more imortant than you might think... but with the added benefit that it CAN be changed. Once you rate something differently, however, you will have a tendency to change aperture, shutter, ND's, whatever... I think that is where some of the confusion lies.
 
Manny said:
Yes, but you also might rate a film stock differently based on your scene. A film stock's manufacturer's rating is also just a "suggestion". I like to think of rating RED ISO as an EXPOSURE LUT that impacts the image similar to rating film, but not EXACTLY. You WILL get less noise rating it lower... and more higher. You can save shots that might have been unusable on other camera systems... Since the Red apps (red alert, red cine) and even the quicktime proxies read camera ISO metadata until you change it, it is more imortant than you might think... but with the added benefit that it CAN be changed. Once you rate something differently, however, you will have a tendency to change aperture, shutter, ND's, whatever... I think that is where some of the confusion lies.
Click to expand...


Manny,

You're right. I tend to rate the RED at 500 because I think I get a bit more out of the sensor that way.

As far as having ISO in camera I think it is important and DSLR's still have ISO ratings because it is a different way of measuring or rating sensitivity.

I did this test to show people that the ISO rating is a non destructive thing as long as you never change the amount of light hitting the sensor it has no effect on your image.

Many people who think in terms of ISO think about it exactly as MAIL4JOEG think about it, as a measurement related to films sensitivity. And you can actually choose to rate it that way, you still have to know what you are doing to the image and how much light you are letting on to the sensor.

Doing tests like this help you find that "sweet spot" that everyone is talking about, but this thread will be mute after build 16 is released.


David
 
Manny said:
Yes, but you also might rate a film stock differently based on your scene. A film stock's manufacturer's rating is also just a "suggestion".
Click to expand...

That's exactly correct, not only that, but most manufacturers no longer supply their film with an ASA/ISO rating, which is based on a scientific testing procedure. Now days most films come with an EI, or exposure index, rating. The EI rating is not determined by any definitive scientific tests, but is rather the rating at which the manufacturer feels you will get the most balanced performance from the film, its "sweet spot."

In that context I think it's appropriate to say that the RED has an EI of 320 with favorable push and pull characteristics, as a film manufacture might put it.
 
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