Outer ISO space...

[Jannard]

There are a lot of people on this board that are (IMHO) worrying about what ISO means as it relates to metadata and RAW capture. My best suggestion is if it doesn't make sense to you, relax on it. It isn't necessary to know Build 16 and forward.

All you really need to know is that the camera's best ISO range is 320-500. And that you should use these (320, 400, or 500) as your setting and exposure reference. Except...

1. If you run out of light. Raise your ISO as little as possible given the T-stop of your lens and the light available.

2. You have too much light (left your NDs at home or they are not strong enough). Lower your ISO as little as possible given the desired T-stop and amount of light.

Easy. If you really need to know the science behind it... have at it.

The camera stores in metadata what you set in-camera as your reference.

If you open your footage and wish you had set a different ISO in-camera (primarily because you missed the exposure), change it in RED Alert! or REDCINE and the RAW file will accommodate you (up to a point). But if you clipped the RAW, it will not give it back to you.

Most problems occur from missed exposure. Build 16 makes it much more difficult to do that. That is one of the main advantages of Build 16. The other is better noise characteristics.

Metadata tells the post app what you did. The RAW file lets you change your mind.

Jim

[Damien Molineaux]

Thank you for the info.

Will you be releasing new versions of RedAlert and RedCine at the same times as the Beta build 16 ?

Cheers,
Damien

[Jannard]

Thank you for the info.

Will you be releasing new versions of RedAlert and RedCine at the same times as the Beta build 16 ?

Cheers,
Damien

We have finished RED Alert! for Build 16 which has gone out with the Alpha build. REDCINE is trying to catch up. Should be ready with the Beta or certainly with the release build.

Jim

[Policar]

Say I shoot something at 100 ISO.
Then I shoot the exact same thing at 800 ISO, but with the same f-stop/shutter/etc. as before--so I expose it three stops over at ISO 800.

I set both clips to 100 ISO when I process them. Are they identical or does the ISO change what is written beyond just the metadata? Is there any analogue gain to the sensor or changes in how redcode handles different ISOs?

I don't understand how you can have roughly the same amount of exposure latitude at all these different ISOs if ISO is just metadata. Wouldn't 100 ISO blow out three stops earlier than 800, but also have three stops more detail in the shadows? Just curious, not trying to be critical at all.

[Damien Molineaux]

Fantastic, looking forward to it.

We have a short I'm DIT on from the 19th to the 24th, if you (Red team) are able to release the beta by the end of next week, I'll play around with it a little and see with the DP if she wants to use. Otherwise it'll be for the next shoot.

Many thanks and cheers,
Damien

PS I keep being amazed to be able to nearly chat one on one with the Red boss, thank you Jim.

[Jannard]

Say I shoot something at 100 ISO.
Then I shoot the exact same thing at 800 ISO, but with the same f-stop/shutter/etc. as before--so I expose it three stops over at ISO 800.

I set both clips to 100 ISO when I process them. Are they identical or does the ISO change what is written beyond just the metadata? Is there any analogue gain to the sensor or changes in how redcode handles different ISOs?

I don't understand how you can have roughly the same amount of exposure latitude at all these different ISOs if ISO is just metadata. Wouldn't 100 ISO blow out three stops earlier than 800, but also have three stops more detail in the shadows? Just curious, not trying to be critical at all.

Here you go... confusing the issue. I'll make another thread for the wonders of ISO/metadata and the meaning of life. Your example starts off exactly opposite to the simple suggestions I just made. If you want to carry this conversation of "what if" further, I would be happy to explain it in another thread. The idea of this one is NOT to confuse people.

Jim

[P Andersson]

seemed like a fair question to me

[Teague Kennedy]

Say I shoot something at 100 ISO.
Then I shoot the exact same thing at 800 ISO, but with the same f-stop/shutter/etc. as before--so I expose it three stops over at ISO 800.

I set both clips to 100 ISO when I process them. Are they identical or does the ISO change what is written beyond just the metadata? Is there any analogue gain to the sensor or changes in how redcode handles different ISOs?

I don't understand how you can have roughly the same amount of exposure latitude at all these different ISOs if ISO is just metadata. Wouldn't 100 ISO blow out three stops earlier than 800, but also have three stops more detail in the shadows? Just curious, not trying to be critical at all.

Not just meta data. My guess is they are using magic pixies to be able to get the most from all ISO's. As a company in tech, they are holding some info close to their hearts. That is apparent from these threads. I would not shoot 800 if you can shoot 350. Your image likely be optimised (sp?) for lower light. Just my guess.

[Jannard]

seemed like a fair question to me

In the context of this thread?

I think it is a very fair question. On some other thread. The purpose of this one is to ease the minds of confused customers. This is the type of question that confounds everyone... seemingly including policar.

There is another ISO thread. If the question is asked there, I'll be happy to answer it. These "what if" questions are theoretical and have little to do with the practical application of shooting. You don't need the answer to this question to make good ISO and exposure decisions. The reason I posted this thread was to relieve the anxiety of those that think they have to understand it.

Jim

[Steve Gal]

seemed like a fair question to me

I feel for ya Jim.....

[Matthew Rogers]

Say I shoot something at 100 ISO.
Then I shoot the exact same thing at 800 ISO, but with the same f-stop/shutter/etc. as before--so I expose it three stops over at ISO 800.

I set both clips to 100 ISO when I process them. Are they identical or does the ISO change what is written beyond just the metadata? Is there any analogue gain to the sensor or changes in how redcode handles different ISOs?

I don't understand how you can have roughly the same amount of exposure latitude at all these different ISOs if ISO is just metadata. Wouldn't 100 ISO blow out three stops earlier than 800, but also have three stops more detail in the shadows? Just curious, not trying to be critical at all.

I don't know why Jim thinks this is so confusing. It's pretty simple! If your f stop, shutter, etc. doesn't change then shooting one at 800 and one at 100 with setting both at 100 in post will give you the EXACT same look. It doesn't matter if you shoot at 2000 or 100, the sensor native is still 320 ISO. When you change the ISO in camera all you basically are doing is playing with curves. Of course, you want to be careful that you don't set the camera at ISO 1000 and then set your f-stop at 11f because you've got more light that you could work with at a lower ISO which equals less noise.

Jim, I think if people actually DID understand the whole ISO/metadata thing better, they would be able to push the camera to better results.

Matthew

[Alexander Nikishin]

In other words, shoot at ISO 320-500 WHENEVER POSSIBLE! If you're lacking light, raise your ISO as little as possible in order to attain the best results (which can be had at 320).

If you're outside and have the sunny 16 going on but have no ND's, pull your ISO down from 320 as slowly as possible while first stopping down your lens' T-stop keeping in mind your lens' ideal performing T-stop. Also, you can adjust your camera's shutter at your own risk keeping in mind the motion changes that occur with a shutter change.

[Policar]

Here you go... confusing the issue. I'll make another thread for the wonders of ISO/metadata and the meaning of life. Your example starts off exactly opposite to the simple suggestions I just made. If you want to carry this conversation of "what if" further, I would be happy to explain it in another thread. The idea of this one is NOT to confuse people.

Jim

Ultimately, "simplifying" things so far that you make something as quantitative as ISO measurement into "try and shoot at 320 ISO unless you can't" confuses the issue by reducing it to something that it's not. Certainly it's a good guideline you've provided, but on set, under time pressure, you're constantly pushed beyond guidelines. And maybe someone simply wants an extremely "clean" look (thus a lower ISO) or to retain extra highlight detail in a very high contrast scene (thus a higher one). Depending on how the camera works, different approaches might be best, but if we don't know, it's hard to choose.

You claim that there's "no penalty" for shooting at a lower ISO, and that the viewfinder will now match what we see in post. I'm just wondering if this is because the ISO is now more than metadata.

If you want to delete my posts from this thread, that's fine. But I am curious (in another thread or via PM) how the new build's ISO actually works. Because this would change how I shoot things, and I'm sure it would change how many other people approach the camera, too.

If I am confused, and maybe I am, I'd appreciate it if you clarified. But people will continued to be confused by ISO if they don't know what it really is--and not providing an answer to my question isn't going to help anyone find out.

[Jannard]

Jim, I think if people actually DID understand the whole ISO/metadata thing better, they would be able to push the camera to better results.

Matthew

We have done all the "pushing and pulling" for you in Build 16. There are too many people lost in this and it has been properly explained a dozen times on reduser... people still can't wrap their heads around it. Good news, and message of this thread, is they don't have to. Anyone who wants to can read the explanations already given or re-ask the questions on another thread.

More clearly:

1. If you don't want to know, can't understand it or don't care... read my 1st post.

2. If you do want to know (knowledge is power), read the other threads or ask on another thread.

Jim

[Jannard]

You claim that there's "no penalty" for shooting at a lower ISO

I amended that comment... there is a very slight penalty for going up from ISO 500 and down from ISO 320. It gets worse the further you go away from these "standard" ISOs.

Jim

[bobbystone]

The "Film" is rated at 320. If you need to you can pull or push it, but you'll suffer consequences whose severity will be relative to how far you move away from the base ISO rating. Pretty much exactly how it happens in film. You have to push it it gets more grain (noise) . Can't wait to try it out.

[Bob Torrance]

The "Film" is rated at 320. If you need to you can pull or push it, but you'll suffer consequences whose severity will be relative to how far you move away from the base ISO rating. Pretty much exactly how it happens in film. You have to push it it gets more grain (noise) . Can't wait to try it out.

Didn't Kodak once release a variable ISO film stock (may have been still film).
I believe the ISO rating was related to light source. This reminds me. Jim, didn't you say you were going to do a tungsten ISO test? No - Yes?

Bob

[Fredrik Callinggard]

ISO is like gain in video world, that swings both ways :wink:. It will "force" the camera to go where it's actually not set for (it's set for 320ASA/ISO - FINAL, but can be tampered to be 400, 500ASA without noticing). The only difference is that in reality your not doing anything because it's all just a "preview" in your monitor, showing what the footage will look like when "forced" to the same settings in post (for example REDAlert or REDCine).

So just like with gain you'll get a noisier image by higher ISO/ASA - just like gaining.

and of course you'll get a "darker" image by lowering - therefor need more light and you will eliminate noise in shadows (because your lighting them, don't forget the camera is NOT set to that it's still in reality 320ASA/ISO - therefor it's essentially like lighting shadow areas, eliminating shadow noise on 320ASA).

Now, since all the camera is ALWAYS on a 320ASA setting, you fool the preview to believe it's not, so when you set it differently there will be consequences to that action (just like with gain on video) and that's what Jim is trying to explain.

It's important to know that RED WILL NOT REACT AS VIOLENTLY as video, on the contrary a lot of you guys will maybe not even notice, unless you're going for the extremes.

(I hope I wasn't wrong here - I'm not a video guy :whistling: )


Fredrik Callinggard

[Radoslav Karapetkov]

Say I shoot something at 100 ISO.
Then I shoot the exact same thing at 800 ISO, but with the same f-stop/shutter/etc. as before--so I expose it three stops over at ISO 800.

I set both clips to 100 ISO when I process them. Are they identical or does the ISO change what is written beyond just the metadata? Is there any analogue gain to the sensor or changes in how redcode handles different ISOs?

I don't understand how you can have roughly the same amount of exposure latitude at all these different ISOs if ISO is just metadata. Wouldn't 100 ISO blow out three stops earlier than 800, but also have three stops more detail in the shadows? Just curious, not trying to be critical at all.


Yeah, maybe not for this particular thread, but this is a good question.

I was about to ask something similar.

We had this discussion at ScarletUser.com, and from what I wrote\understood there, the situation is this:

If everything else is untouched [lens settings\exposure, lighting, etc.] and we shoot the same scene twice: first with 100 ISO and then with 800 ISO, then the originally-800-ISO shot brought down to 100 ISO in RedCine, should look identical to the originally-100-ISO shot.

Please correct this if necessary?

BTW, here's the thread:

http://scarletuser.com/showthread.php?t=213

[Fredrik Callinggard]

If everything else is untouched [lens settings\exposure, lighting, etc.] and we shoot the same scene twice: first with 100 ISO and then with 800 ISO, then the originally-800-ISO shot brought down to 100 ISO in RedCine, should look identical to the originally-100-ISO shot.


YES it will look the same because the sensor is and will always be 320ASA, but only in it's RAW form not what you see in your preview of your monitor. So any changes in ISO are just made in monitor preview (and the zebra indicators etc) on set - for you to see how and what it will react to in the scene when ISO/ASA is played around with in REDCine/REDAlert.

Fredrik

[jacknusa]

I've been following this ISO thing for a while, and it seems to me that the questions (and to some extent the answers) are only confusing me further.

Jim says:

Quote//
1. If you run out of light. Raise your ISO as little as possible given the T-stop of your lens and the light available.
//end quote

Here's what I think it boils down to:

Is there a difference - in the CAPTURED/STORED Image - between A) Doing what Jim says above, or B) simply choosing to underexpose?

Is there?

Jack

[Fredrik Callinggard]

I've been following this ISO thing for a while, and it seems to me that the questions (and to some extent the answers) are only confusing me further.

Jim says:

Quote//
1. If you run out of light. Raise your ISO as little as possible given the T-stop of your lens and the light available.
//end quote

Here's what I think it boils down to:

Is there a difference - in the CAPTURED/STORED Image - between A) Doing what Jim says above, or B) simply choosing to underexpose?

Is there?

Jack

NO it's essentially the same and then you push your footage to preferred ISO/ASA in REDCine. The only "thing" is that you can "monitor" on set.

Fredrik

[Alberto Caprioglio]

will the new version of RedCine be able to open and deal with footage shot with pre-build16 AND the one shot with build16, in the same project?
Thanks

[Mark Toia]

JIM,

Don't worry about the lost, I'm sure the day Build 16 hits the streets and everyone has had a play, this conversation will die.

Some DOP's for years and years have shot one stock for all conditions. Mainly 500T or 200T, Myself I was a 50D and 250D man.

For me with RED I just pretend I have put a roll of 320D in the mag and shoot accordingly using ND's for the day, Super speeds for the night.
Adjusting ISO's in camera we felt was fruitless. Going to 500 worked fine, but... at the end of the day, no great advantage.

Having good ND's and Good bright glass (super speeds) is what makes this camera rock!

We haven't had any noisy images yet that we didn't like and any blown out high lights that were any worse than any film high lights we have ever had.

People will adapt to the tool as they have with film for the last 40 years or more.
The range isn't as good as a good roll of 500T vision3, yet at the same breath, RED is sharper, cleaner, richer than it.

Keep it coming big fella.
I'm lovin the ride.

[lumiere]

Changing your ISO is like changing your monitor (headphone) volume when you record audio. It does nothing to what is recorded, it's just monitoring.

BUT... if it's set improperly (too loud or too low) it could lead you to making mistakes when setting your recording volumes.

---

The difference here is that it replays your headphones volume using metadata but you can adjust it afterwards.

[Radoslav Karapetkov]

Changing your ISO is like changing your monitor (headphone) volume when you record audio. It does nothing to what is recorded, it's just monitoring.

BUT... if it's set improperly (too loud or too low) it could lead you to making mistakes when setting your recording volumes.

---

The difference here is that it replays your headphones volume using metadata but you can adjust it afterwards.


That's a good description, IMHO.

[Jason Wingrove]

Think of it like you only have ONE FILM STOCK in the mag, Mysterium stock...regardless of ISO settings on the camera.

Flipping the ISO doesn't magically change the mysterium chip over for a NASA probe infrared chip or a night vision camera. The iso setting is simply an 'on set' guide of what can be achieved later in post. Like having an instant rushes print on set thats been 'pull' or 'push' processed.

AND just like in the film world there's no substitute for correct exposure.

Jas

[Policar]

Thanks for the analogies; they're all good, but I think I got it since it became clear that it's just metadata.

[Joe G.]

Again the confusion. I'd like to hear the answer to this question:

Is camera "ISO" JUST Metadata, or is it now affecting the Raw image as with the allusions to "curves" and "algorithms?"

The answer to that question could clear up a lot.

[Joshua Provost]

Again the confusion. I'd like to hear the answer to this question:

Is camera "ISO" JUST Metadata, or is it now affecting the Raw image as with the allusions to "curves" and "algorithms?"

The answer to that question could clear up a lot.

It is a false question that cannot be fairly answered.

Yes, ISO setting is metadata, but you use the ISO setting in conjunction with your lightmeter to determine and set the F-stop of the lens.

ISO setting + lightmeter + F-stop change on lens = your images is changed.

It all goes hand in hand.

[Steve White]

As I understand it, the lighting, filters, lens, aperture and shutter speed define the exposure. These are the physical parameters that define how much light is entering the camera. If I set these things, regardless of what I set my camera ISO too, I will have the identical RedCODE RAW file.

While shooting, the ISO setting defines the conversion curve from the linear RAW data to the log/gamma of the on-set monitors. When using a light meter, I dial the ISO setting into it in order to determine the correct exposure. Adjusting the ISO doesn't change the exposure though.

In post, the ISO is just a way to modify the intensity conversion curves of the image - and possibly the debayer process, if there's some additional magic to be had there.

[jbeale]

I think Spiff's explanation is very clear... should probably go into a FAQ.