Thread: What is a native ISO for RED Gemini Low Light mode?

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  1. #11  
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    Quote Originally Posted by Iaroslav Kerget View Post
    Hello, i am a newbie 1AC and i am a little bit confused about Gemini Dual Sensitivity mode, what is the second native ISO of the camera first is ISO 800 in standard mode, and what is a native ISO in Low Light mode, some videos on youtube and articles says its 1600, some its 3200.
    Please can you answer my question what is a Native ISO for RED Gemini Low Light Mode?
    Thank you
    Beyond “noise”, there is also highlight detail.

    When you are in standard mode, iso 800 has a nice highlight roll off and plenty of detail in both the shadows and the highlights. But when you push to iso 1600, all of a sudden there is some noise in the shadows, BUT the highlight retention is amazing. If you don’t mind a little noise, iso 1600 in standard mode can be gorgeous and organic looking. Just have to be careful with under exposure.

    In LL mode, iso 1600 clips the highlights a little earlier, but is pretty clean in the shadows. Makes me wonder if the native LL is closer to 2500-3200. By the time you get to iso 6400LL the highlight roll off is pretty good again, and retains a lot more highlight detail, but at the expense of a lot of noise. Just because it’s dual native, doesn’t mean LL is going to be as clean as standard mode. Iso 4000LL-5000LL may be the better compromises.

    The Gemini gives two flavours of iso 1600 that are both very usable. Maybe you want the windows to blow out white, then shoot in LL mode and run the iso down to iso 1600LL or even iso 800LL, and the highlights go a bit faster, allowing the outside to go completely white. But if you are going for a gritty organic look, try iso1250 or 1600 in standard mode, and you can retain all or most of the detail outside the windows, with a lovely highlight roll off. Makes shooting with hard light a little funner.

    Dual native iso gives a lot of stylistic options. It isn’t just about low light. After the A7s hit, everyone thinks a low light king is iso 40million clean, and shoot night for day. But honestly, being able to choose how the camera reacts to different scenes, and being able to adapt to any location’s ambient light levels, and still get that image quality is HUGE!
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  2. #12  
    Quote Originally Posted by James Sielaff View Post
    Beyond “noise”, there is also highlight detail.

    When you are in standard mode, iso 800 has a nice highlight roll off and plenty of detail in both the shadows and the highlights. But when you push to iso 1600, all of a sudden there is some noise in the shadows, BUT the highlight retention is amazing.
    There is no highlight retention difference in capture on a same analog gain, camera records the same data as set to 800.

    You simply underexpose by a stop and use a different image representation with a stop push, where the upper part has a stop more of headroom for more gradual falloff to clip. The difference in the camera is just image representation. What saves the highlights is your exposure choice.
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  3. #13  
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    Quote Originally Posted by Hrvoje Simic View Post
    There is no highlight retention difference in capture on a same analog gain, camera shot the same thing as set to 800.

    You simply underexposed by a stop and used a different image representation with a stop push, where the upper part had a stop more for more gradual falloff to clip. The difference in the camera is just image representation. It was you who closed down the iris and saved the highlights.
    Ha! Tell that to the person looking at the proxies.
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  4. #14  
    Quote Originally Posted by James Sielaff View Post
    Ha! Tell that to the person looking at the proxies.
    I don't follow.

    : )
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  5. #15  
    I think the principal confusion that many people have about RED cameras is that they treat the sensor has if it offers a wide range (ISO 50-128000) of film stocks, when in fact most offer effectively a single stock that can tolerate (with noted degradation) a wide range of processing options--JUST LIKE A SINGLE FILM STOCK DOES. Gemini changes the game a little bit, offering effectively two stocks, normal and LL. And those two modes have their own wide range of processing that can be applied, with unique degradation applying to each.

    I think that the misconception that the RED sensor behaves like a wide range of film stocks is responsible for a huge percentage of the noise on this forum, due in part to the huge amount of imagining noise that such a misconception creates for each new RED user. This video doesn't help: https://www.red.com/red-tech/red-tech-iso-settings because it oversimplifies the role of the ISO setting to that of overall light sensitivity. It does make many statements that are truthful in isolation, but taken together, it encourages precisely the wrong approach to using ISO, which is a ham-fisted reaction to available light rather than as the all-important basis of a look that depends on equally important decisions about lighting, frame rate, shutter angle, and aperture.

    Just as Ansel Adams counseled so many years ago, the person responsible for imaging must understand what they want as their black point, their white point, their mid-tone gray, and then everything derives from that. Total scene contrast? Ratio of white point to black point. Compressed highlights or shadows? Pick the right middle-tone value. Clean blacks? Set black point to at least 5 using GIO scope. Clean highlights? Make sure white point is at most 13 using GIO scope. Etc. Etc.

    If you start from what you want from the image, you can get what you want from the image. If you start with "I need ISO 3200 so I don't have to use a larger lighting package" you will get the noise that comes from that compromise. If you start with "I need ISO 100 so I don't need to put an ND filter in a matte box I don't have" you will get the clipped highlights that comes from that decision.
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  6. #16  
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    Quote Originally Posted by Hrvoje Simic View Post
    There is no highlight retention difference in capture on a same analog gain, camera records the same data as set to 800.

    You simply underexpose by a stop and use a different image representation with a stop push, where the upper part has a stop more of headroom for more gradual falloff to clip. The difference in the camera is just image representation. What saves the highlights is your exposure choice.
    Just about every post, including the OP references native or base iso. Even Patrick’s post references the behavior of pulling from a base iso.


    I mentioned native iso, but my post was rather wordy. I wanted to describe the look and feel, since everyone already seemed to understand the idea behind native iso and a raw workflow.
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  7. #17  
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    Quote Originally Posted by Michael Tiemann View Post
    I think the principal confusion that many people have about RED cameras is...
    Not much we can do about all that. ;)
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  8. #18  
    Quote Originally Posted by Michael Tiemann View Post
    I think the principal confusion that many people have about RED cameras is that they treat the sensor has if it offers a wide range (ISO 50-128000) of film stocks, when in fact most offer effectively a single stock that can tolerate (with noted degradation) a wide range of processing options--JUST LIKE A SINGLE FILM STOCK DOES.

    Pretty much sums it up.

    : )

    This misconception is wider than Reduser community and this started with stills cameras.

    In general, there is the idea that the DoP is "rating" the camera as if affecting its sensitivity and that exposure choice boils down to image signal-to-noise.

    In reality:

    - "Rating the camera" is imagining "as if its sensitivity is equivalent to that rating" and exposing on that premise.

    - Camera has the SAME sensitivity regardless of the rating and will capture the same raw negative.
    (higher analog gain changes the negative, improving S/N in shadow range, digital ISO value does nothing to negative, only adds higher gain-mimicing push on captured signal & image viewing)

    - Exposure choice does not affect ONLY S/N and the range between extremes but also image "density" (available data per luminance range) determining the quality of what is between the extremes, and a stop lower exposure gives a half thinner negative.

    - "Rating the camera" = image properties you are willing to accept by choosing the ISO equivalent gain
    > For greater awareness it helps to sit in post with a colourist checking the differences between shaping of exposure (rating) test shots and half or 3/4 thinner negatives. Not charts but real life scenes which include faces, textures and organic colour mixtures.

    - Higher "rating" = push
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  9. #19  
    Quote Originally Posted by James Sielaff View Post
    Just about every post, including the OP references native or base iso. Even Patrick’s post references the behavior of pulling from a base iso.

    I mentioned native iso, but my post was rather wordy. I wanted to describe the look and feel, since everyone already seemed to understand the idea behind native iso and a raw workflow.
    I understood what you meant and many do.
    But many do not also.

    My comment is there for those who still have the impression that within a switch from 800 to 1600 rating camera is doing something special in capture and somehow improving highlight performance. It is not.

    The improvement in highlight capture is due to half the exposure, chosen based on a stop pushed image preview, which gives a a stop more in upper range and headroom for more gradual transition to clip.
    It is the same result as if using ISO 800 underexposed one stop just viewed through a push.

    That has a price, which is not just noise, noise is less of a problem in normal circumstances. The price is tonal depth, shadow depth and overall image quality affecting the aesthetic, consistency and post image manipulation results. Proper "rating" in that context has both subjective and objective factors to be aware of.

    I realise bringing this up every now and then may be annoying, but it is sadly needed due to the rapid expansion of the production market and tools and online epidemic of wishful thinking.


    To conclude, by getting back on thread focus : most of today's cameras offer the best ratio of DR handling and density and overall image quality between ISO640 and 800 and departure from those figures is a matter best left to informed creative decisons.

    Gemini offers outstanding results in luminance range which generally matters the most, rated at 800. Texture is fantastic (tested at 2:1), shadow rendition rich and cinematic, tonal depth is great and things drift off to black beautifully (superiror to Alexa) and highlights are generally not a problem and end where they end, as with every camera. Falloff to clip is shapeable. Underexposed negative - not so much.

    Regarding LL mode, I've had great results with Gemini exposed to 3200, but I lowered the digital gain in post and shaped it manually.

    Also, be aware of light type and quality, imaging performance varies depending on what is being captured, especially with pushed material.
    Test, test, test.
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  10. #20  
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    Quote Originally Posted by Hrvoje Simic View Post
    I realise bringing this up every now and then may be annoying, but it is sadly needed due to the rapid expansion of the production market and tools and online epidemic of wishful thinking.
    Not annoying at all. This is a forum, sharing experiences and insights is always good. You just keep quoting me, and i couldn’t tell if you were talking to me or the hypothetical general readership. Thank you for clarifying. Wishing you a happy new year!
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