EVA1: Ideal ISO + Impact on DR - what settings?

F

filmguy123

Veteran
DR is max @ Base ISO 800 + Base ISO 2500, correct?

And moving upward or downward of this, DR decreases, correct?

As such, what makes the optimal image quality @ any given setting? IE let's say I need to shoot at ISO 1250. Is it better to be in base 800 and move up to 1250, or better to be in Base 2500 and move down to 1250?

On one hand, base 2500 and DOWN should net a very clean image @ 1250... would it be cleaner than 800 bumped to 1250? On the other hand, that is further away from BASE - would that net a more limited DR vs bumping up from base 800?

Any chart/graph that shows corresponding DR and noise values at any given ISO in relation to which is base?

Also, why not "auto base" setting which selects optimum at any level like on GH5s? If it's more clear cut, it would make sense to have an "optimum" setting and let the camera just roll onto the optimum setting rather then needing to manually change the BASE ISO and then roll the dial in - extra steps are time killers especially if there's not a strategic user reason to select one over the other (and perhaps there is? hence, my question).
 
Because this is a professional camera that allows the user to make decisions rather than force functions automatically.

It would be up to you which is "better," lower noise with less DR or a greater DR range with a slightly higher noise floor.
 
Thanks Mitch. So there is in fact a difference there as I was guessing?

Any charts or graphs, or even rough indications, of how great or small the affect is per notch up, and where the sweet spots are?
 
It's basic math. Shift one stop, lose one stop of DR. At least for the most part.

Measurement of noise is a harder thing to quantify.
 
And this happens in either upward or downward direction.

Thus, at ISO 1600 it's 1 stop up from 800 - so I lose on stop of DR, and gain noise.

But, ISO 1600 is less than 1 stop down from 2500 - so I lose less dynamic range. And shouldn't I also have a cleaner noise floor?

So why would I ever, ever, ever want to shoot ISO 1600 with a base mode of 800? In fact, it seems I would only ever use Base ISO 800 to shoot ISO 400-1250, and base ISO 2500 for everything else, and that would be optimal in terms of both ISO *and* noise - correct?
 
Dropping the ISO results in a dynamic range loss proportionate to the amount of negative gain you've applied. Take it from 800 down to 200, you lose 2 stops of sensitivity and 2 stops of DR off the top.

Raising the ISO results in added noise, and a loss in DR on the bottom.

So, as Mitch said, determine which you need -- cleaner image or more DR? If you want a cleaner image, then gain down. I generally would choose to use the base ISO that's closest to the target ISO.
 
Thanks Barry. This make sense, and it also seems that there is very little scenario when a form of auto BASE select wouldn't be exactly what you want.

filmguy123 said:
So why would I ever, ever, ever want to shoot ISO 1600 with a base mode of 800?
Click to expand...

Is there ever a scenario in which this would make sense? I mean, I suppose if you really needed to save DR on the highlights and didn't care about a 1-stop loss on the shadows, and were ok with the added noise? (VS dropping from 2500 and losing 1-stop DR in the highlights, but keeping the signal clean).

This seems like a peculiar scenario, and pretty much the only ISO setting on the entire camera where this rare, semi-valid need might present itself and cause a user to want to manually choose their BASE ISO... yeah?

As such, my 2 cents: A pro camera should absolutely offer tools to manually select your settings for whatever quirky reason, I fully think this a must and would be annoyed with the inability to do so. BUT - a pro camera should also make a pro users life as seamless as possible, especially when 90% of the time you're going to be using settings a specific way.

Mitch, may I suggest:

Currently, we have ISO settings of "800", "2500", and "Native Only".

Can we add one called "Optimal" which will allow us seamlessly scroll from ISO 200-5000+ and auto change the BASE ISO setting (like the GH5s does) to the optimal balance for DR/Noise. Alternatively, we could add 2 optimals: "Optimal DR" and "Optimal NF" - but frankly with 800/2500 as close as they, I think one "optimal" would suffice as ISO 1600 (half way between) sounds like it will always be optimal for both noise AND dynamic range, with the possible exception I listed above. Lastly, a 3-tier option could be available: "Optimal DR", "Optimal NF", and "Optimal BAL" (Optimal Balance between DR/NF) - though I think that setting would be redundant unless on a camera with a larger delta between the two BASE settings.

One practical consideration/problem right now for people shooting in fast paced, especially live/docu environments (like myself!): It is currently a Royal PIA to transition between indoor/outdoor, or bright/dim rooms. This is because I cannot free scroll! If outdoors using base 800, I can scroll between 200-2000 but am capped. If we quickly move indoors this means I cannot change the needed settings via physical switch. I must dive into the menu, pull up and change my BASE ISO and now must work between 1000+. So if we move back outdoors, or back out of shade, I'm SOL again without going into the menus which, when seconds count, is very problematic.

Really, there's no reason for this, and the camera really ought to have a free scroll ISO mode that auto-selects the optimal base ISO setting especially when 90% of people 90% of the time will ALWAYS do what Barry suggested and simply be selecting the Base ISO that is closest to the current ISO setting.

Gracias.
 
I can submit a request to the engineers, but I don't know if the menu/command system is structured in a way to alow this to happen.
 
Mitch Gross said:
I can submit a request to the engineers, but I don't know if the menu/command system is structured in a way to alow this to happen.
Click to expand...

Mitch, would love to see some kind of scene file switch or HFR switch so that when you want to go from UHD 24p 10bit internal to UHD 60p overcrank 8bit internal the EVA1 would switch recording codecs automatically. Sucks to have to change the recording codec every time I want to go over 30p. Not sure this is possible
 
Thanks Mitch! I know exactly where it could be quickly implemented on the menu screen to an existing menu.

100% agree with soar - a form of presets would be invaluable for switching multiple parameters st once (frame size, codec, frame rate). It’s a bear right now.
 
filmguy123 said:
Thanks Barry. This make sense, and it also seems that there is very little scenario when a form of auto BASE select wouldn't be exactly what you want.



Is there ever a scenario in which this would make sense? I mean, I suppose if you really needed to save DR on the highlights and didn't care about a 1-stop loss on the shadows, and were ok with the added noise? (VS dropping from 2500 and losing 1-stop DR in the highlights, but keeping the signal clean).

This seems like a peculiar scenario, and pretty much the only ISO setting on the entire camera where this rare, semi-valid need might present itself and cause a user to want to manually choose their BASE ISO... yeah?

As such, my 2 cents: A pro camera should absolutely offer tools to manually select your settings for whatever quirky reason, I fully think this a must and would be annoyed with the inability to do so. BUT - a pro camera should also make a pro users life as seamless as possible, especially when 90% of the time you're going to be using settings a specific way.

Mitch, may I suggest:

Currently, we have ISO settings of "800", "2500", and "Native Only".

Can we add one called "Optimal" which will allow us seamlessly scroll from ISO 200-5000+ and auto change the BASE ISO setting (like the GH5s does) to the optimal balance for DR/Noise. Alternatively, we could add 2 optimals: "Optimal DR" and "Optimal NF" - but frankly with 800/2500 as close as they, I think one "optimal" would suffice as ISO 1600 (half way between) sounds like it will always be optimal for both noise AND dynamic range, with the possible exception I listed above. Lastly, a 3-tier option could be available: "Optimal DR", "Optimal NF", and "Optimal BAL" (Optimal Balance between DR/NF) - though I think that setting would be redundant unless on a camera with a larger delta between the two BASE settings.

One practical consideration/problem right now for people shooting in fast paced, especially live/docu environments (like myself!): It is currently a Royal PIA to transition between indoor/outdoor, or bright/dim rooms. This is because I cannot free scroll! If outdoors using base 800, I can scroll between 200-2000 but am capped. If we quickly move indoors this means I cannot change the needed settings via physical switch. I must dive into the menu, pull up and change my BASE ISO and now must work between 1000+. So if we move back outdoors, or back out of shade, I'm SOL again without going into the menus which, when seconds count, is very problematic.

Really, there's no reason for this, and the camera really ought to have a free scroll ISO mode that auto-selects the optimal base ISO setting especially when 90% of people 90% of the time will ALWAYS do what Barry suggested and simply be selecting the Base ISO that is closest to the current ISO setting.

Gracias.
Click to expand...

Sounds all a little bit complicated to me. We have the setting „optimal DR“ - that would be to shoot with the two native ISOs only. With a difference of two stops between the two native ISO settings, what is better then nothing.

You can also enable noise reduction to each of the two native settings individually, but I know that a lot of people do not like that.

True, if you want to apply additional noise reduction by choosing another lower ISO you have to reduce the ISO below the native ISO and loose DR. And true, maybe a faster switch between the two native ISOs could be assigned to a user button. But the question what will be optimal should not be resolved by an automatic. It is a cinema camera and not a run&yuck camera, to my opinion. But on the other side, as long as such an automatic can disabled why not?
 
We don’t have an optimal setting, this is the suggestion, and yes, it would be optional to user.

The “complicated” part of the post is assessing why it is extremely rare that you would ever not opt for the “optimal” (automatic) setting.
 
Simply because I will not need that. The SNR may be different between the two native ISOs, but not too different. I can go down with the ISO in 1/3 stop changes if necessary. For me that is enough.

But if they can build in that you can assign a different user button with the change between the two native ISOs and use the assignable wheel to fine tune the ISO - that would help.
 
I just want to point out that the S1H does exactly this...

There are options for AUTO, LOW, HIGH.

This makes filmguy happy.

Mitch - any chance we can get this feature on the EVA1? Auto, Low, High? It would sure make changing ISO a lot quicker, I still frequently need to jump between 800 and 2500 and everything in between (and a little above and below). Not having to dig in to the menu so much would be extremely welcome. I think the S1H implementation is perfect.
 
if a gain profile is fixed at the optimum ISO/DR , then shifting your exposure index should not change DR, but shift middle gray one way or the other within the total DR range. Under exposure protects highlights, over exposure gets a cleaner image.
Instead of changing ISO, try some tests bracketing exposures in 1/3rd stop increments around the base ISO to find out what the usable latitude is.
No one seems to know how gain is structured for ISO’s other than the two base references. Changing ISO could just be changing the gain on the monitor output so it looks normal, but not changing sensor response.
 
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