Welcome to our community

Be a part of something great, join today!

Log in
  • 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 :)

Gio Scope Tool vs The Zone System

David Battistella said:
I actually just did this out of curiosity.

Here is what I found.

On an 18% grey card lit to ISO 800 F8.0

Spot Meter reading, centre of the card

800 ISO, 172.8 shutter, 24FPS F8.0

Camera
800 ISO, 172.8 shutter, 24FPS F8.0

With the above settings the GIOSCOPE lights up at #10


with only GIOSCOPE #11 turned on GIOSCOPE engages GREEN at F5.6 ONE stop over Metered Light on 18% grey.

So, in my fast crude test GIOSCOPE number 10 equals 18% grey at lit to F8.0 ISO 800
Click to expand...

Yep my results are the same. Red has never lined up ISO-wise with meters, I've found it to be about a stop off. Meaning the meter is set for 400 but the cam to 800. What I normally do in practice is set my seikonic meter to have a default EV of -.5 of a stop. This splits the difference between stop 10 and 11 in GIO Scope and allows me to keep the ISO's matching on camera and meter.
 
Thanks Jake, David, and Ryan. That's basically what I wanted reassurance on.

Just to be clear; does chip#11 correspond with "green" when in (raw) Exposure Check mode, or is (raw) Exposure Check mode ISO dependent? I'll be able to test it this afternoon, if no one else has the answer handy.

I'm using Gio on MX, so I think things get even wonkier (because of the lower DR). It also reaffirms my thinking that RED (for the next sensor) should try to maintain equal above/below stops cleanly at their declared "~native (recommended shooting) ISO" as it makes exposure that much easier and that much more intuitive (if you lower or raise ISO a stop, you're also getting one less/more stop of highs vs lows). GioScope really highlights how low-end weighted these sensors are.
 
Gioscope is completely independent of ISO or look applied.

It is consistent. One stop over meter and you are hitting 18%grey.

You can go 1 1/2 stops over meter to dig out the low end. (I'd say more on STH olpf)

But 11 represents 18% grey @meter reading based on 800iso 172.8@24fps at F5.6

battistella
 
I just did a really quick/dirty test, and they seem to be different (Gio-Chip#11 vs. "Green Highlight" of Exposure Check)... Is it possible that Exposure Check *might* take gamma curve into consideration (?), as it's not off by ~1+2/3 stop (800iso vs 250).

EDIT: You know what would be really useful? If you could enable GioScope in RCXp, and enable the chips that way. I mean, I guess it's the same as scopes, but it does seem more black and white (pardon the pun). E.g. "the face is clearly 18%+1stop as seen when we highlight Chip#12.", etc. Obviously doing it on the day with the meter is better, however, if you're not the DoP and you get a ton of oddly exposed footage, it'd help immensely to get it back on track quickly.
 
Last edited:
I think I'd use one or the other and at this moment I trust the Gioscope more. I trust the exposure tool when in raw view mode because that is a predictable reaction, I have noticed the curves do tend to affect the Exposure tool, even though there was a note about it in this later release.

gioscope is nice because no mode you are in or color space you select has any effect on the output, just aperture or lighting or shutter.

Battistella
 
i think gioscope would be the one to trust, since you can literally "see" every stop
 
It would be nice if RED were to explain the GIO Scope so there is basically no uncertainty about it.

It's not very clear in the manual. Just a thought. :)

Perhaps Graeme could chime in here.
 
Well there's reallty not much to say, mid great should "officially" be set at stop 11, and the scope is showing you where every stop lies in the raw, how you use that info is up to you
 
Jake Wilganowski said:
Well there's reallty not much to say, mid great should "officially" be set at stop 11, and the scope is showing you where every stop lies in the raw, how you use that info is up to you
Click to expand...

I see your point, but this "setting middle gray to 11" (at ISO 800) means there are how many stops of highlight latitude above middle gray?
What.... only 5? Shouldn't that be 7 with the High Light OPLF? More info is needed.
 
Martin Stevens said:
I see your point, but this "setting middle gray to 11" (at ISO 800) means there are how many stops of highlight latitude above middle gray?
What.... only 5? Shouldn't that be 7 with the High Light OPLF? More info is needed.
Click to expand...


Yes 5. But you bring up a very interesting thing regarding the 2 OLPF's. If you had 2 dragons set the exact same but with 2 different OLPF's and pointed them at the same scene, what would you see in Gioscope, would they look different? I have a hunch Phill Holland might be able to give us the answer.
 
The problem is our starting point wich is RAW. Don't you have to translate that RAW data into some kind of luminance visualisation/stop ? What luminance has red VS grenn VS blue and how will I map it to a gray value? I've not played with it yet. But It seems promising. But I wonder if there can be some "definive" answer for the stop values as long as color science is still improoving? To make a definitive answer, the sensor should have a linear response to colors wich I doubt it has.

Pat
 
Sidney L. Plaut said:
i also see a difference between "exposure" and "gio"
in regards to 'green' (18%). and all tools including stop lights
show different 'red' burn out which is what
worries me most.
Click to expand...
I just checked and Gio Scope at stop 11 is giving me a very similar green false color to the Exposure and Video check modes in both REDgamma3 and REDgamma4. Gio Scope is covering a slightly larger range, but pretty consistent for the most part.

BTW, if anybody hasn't seen my Gio Scope Test video, it's here:
http://www.reduser.net/forum/showthread.php?127855-Scarlet-Dragon-Gio-Scope-Exposure-Test-(LLO-OLPF)
 
Thanks Akin.

I was on MX when I compared. There could be differences in how the two sensors (MX and Dragon) read stops... Certainly there's more differentiation/gradation (since Dragon has like 25% more) and, as such, it'd make sense that Dragon was more accurate... Plus I feel like it's a ground-up-Dragon tool that's been retrofitted to MX.
 
Jake Wilganowski said:
Red has never lined up ISO-wise with meters, I've found it to be about a stop off.
Click to expand...

Yes.

Hans.

PS: This ist the reason why I find the Dragon's "real" sensitivity set at ISO 400. The recommended ISO 800 is one stop underexposed. In many situations this may work well.
 
Have any more definitive conclusions been made regarding the following:

1. Should Caucasian skin be mapped to chip 12 (one stop above chip 11 which is 18% grey)?

2. Is chip 11 in GIO Scope mode equivalent to green in the 'exposure' tool?

3. Is chip 12 in GIO Scope mode equivalent to pink in 'false color' mode?

Thanks,
Mike
 
MichaelJQuill said:
Have any more definitive conclusions been made regarding the following:

1. Should Caucasian skin be mapped to chip 12 (one stop above chip 11 which is 18% grey)?

2. Is chip 11 in GIO Scope mode equivalent to green in the 'exposure' tool?

3. Is chip 12 in GIO Scope mode equivalent to pink in 'false color' mode?

Thanks,
Mike
Click to expand...

I my testing I felt middle grey was on on chip 10. Then 11 is one stop over middle grey. In my testing with STH OLPF, this is where I felt the sweet spot is. So I would map Caucasian skin to chip 11 for one stop over.

the rest of your logic follows (point 2 and 3), but I would pick one of these two tools, rather than compare them directly. Once you get into gioscope your in more of a classic zone system rather that a thermal color zone system with the exposure tool. I'm sure some correlations can be made but it's probably best to do a bit of testing to find your comfort zone.
 
Thanks David. The more I experiment and think about this topic, the more it seems that the practice of 'mapping caucasion skin to chip 11 or 12 aka one stop above middle grey' to be misleading/simplistic.

Doesn't the above totally depend on your environment and the look you're going for? For example, if you are exposing a Caucasian person's face under direct sunlight (i.e., you are using the sun as a 'key light' as opposed to a 'backlight'), shouldn't that be like 2 to 3 stops above middle grey, which would place the key side of the subject's face on chip 13 or 14? If, on the other hand, you are using the sun as a 'backlight,' and 'keying' the subject's face with the ambient skylight, then here you might place the subject's face on chip 12 (one stop above middle grey).

Following the same logic, imagine a Caucasian subject in a dark club environment, where the 'key light' is a candle on the table. Mapping your subject's face to chip 12 would feel too bright for that kind of low light environment. It would seem more natural to map the person's face to one or two stops under middle grey, which would be chip 9 or 10 if using GIO Scope.

So, whether we are applying The Zone System (w/ a spot meter) or Red's GIO Scope, I'm wondering what 'map Caucasion skin to one stop above middle gray to produce proper exposure' really means?

I'm hoping to get a more detailed explanation than, 'It's just a healthy place to set exposure, and you can push or pull the image in post' or 'It's always better to expose to the right and crush your image in post to minimize grain.' Or if these are simply the 'correct' answers, please go into a little more detail :)

Thanks much,
Mike
 
Last edited:
You must log in or register to reply here.
Back
Top