Thread: I want to love the Raven but.....

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  1. #21  
    Quote Originally Posted by Steven Abrams View Post
    Red lists the Helium and Dragon sensors in their tech specs as having 80db signal to noise ratio, which is around 13.2 stops.
    http://www.red.com/products/weapon-8k#tech-specs

    16+ is what they rate HDRx being. If the ursa 4.6K is 14-15 stops it makes sense the OP sees more useable dynamic range on the ursa if not using HDRx.
    Im not sure I follow.

    Signal to noise ratio does not really dictates how many usable stops the camera has.

    And if you use HDRx then even with a half miss you can get out far more than 16+ stops out of any red camera that has hdrx. Lets say for simple calculation that a red camera has 10 stops. Then you turn on HDRx and set it to... for example 2 stops. Then you got one exposure with 10stops then you got another exposure that covers highlights 4 times as good as the A exposure.... now if you combined those two expos in post you for sure can drive out far more than those 10 stops. Now the debate is possibly not if dragon has 10 stops is more about where it is bettween 14 and 16+ stops all depending on how much noise or low level of detail you consider a usable image. But people have mesured 16+ stops with dragon without Hdrx on. Which I think is not done with the ursas. But I might mix it up the mini with the orginial ursa but again I think if the mini would trump the dragon in that regard then there would be quite a few test charts to prove it.


    And red always, as long as i can remember, listed their cameras with 80Db signal to noise ratio. Now its quite clear that epic scarlet has more noise and less DR than helium still both got 80Db noise ratio listed so would be great if you explain how the 80Db number in the listings correlate to anything. exept per pixel noise levels.
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  2. #22  
    Senior Member AndreeMarkefors's Avatar
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    Quote Originally Posted by Björn Benckert View Post
    Signal to noise ratio does not really dictates how many usable stops the camera has.
    Well, I honestly can't see how it won't.

    If we simplify the discussion as much as possible: a sensor at full well capacity will reach a certain charge level. If you then compare that to the sensor's noise floor, that will have to be defined, you get a de facto signal to noise ratio. According to the principles of each stop of light doubling the intensity of the previous stop, we get the well known exponential curve. But this also dictates you can only double the signal strength so many times within a certain range (like 80dB) before there are no 'stops' left. Each stop correlates to a 6dB increase and if you take 80 dB divided by 6 dB you get 13.3. And oh, for the record, Canon rates their cinema sensors at around 64-68 dB or something...

    So let's say you can double the signal strength 13.3 times in linear light before running out of dBs.... Where do the other stops come from? No amount of spreading the 'linear light' out over a logarithmic cure will change the underlying DR potential. Making an image flat doesn't increase true DR per se.

    Many cameras today stipulate they are set at ISO 800 or so.... that would give you (?) 3 additional stops compared to an assumed base ISO/gain of 100/0.

    I'm not at all interested in a "brand A" vs "brand B" discussion, but I would like to learn more about how a manufacturer's claimed native sensor SNR compares to captured DR. Right now, it doesn't quite make sense to me.
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  3. #23  
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    Just some info from Alen Roberts:
    Red Epic Dragon https://tech.ebu.ch/docs/tech/tech3335_s16.pdf
    Arri Amira https://tech.ebu.ch/docs/tech/tech3335_s15.pdf
    Arri Alexa https://tech.ebu.ch/docs/tech/tech3335_s11.pdf
    Ursa Mini 4,6k http://www.newsshooter.com/2017/01/0...t-used-in-raw/
    Ursa min pro 4,6k not measured yet, but better then Ursa Mini 4,6k according to slashcam.de https://www.slashcam.de/4K-Kamera-Vergleich.html (it has better de-bayer).

    Do with it what you want, I'm happy with my BMD ursa mini pro and for higher res. I rent.
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  4. #24  
    I couldn't see what settings were used in REDcine for the test you highlighted...

    And to the original poster - you're really going to want to learn more about post.

    Prior to REDs ipp2 pipeline I'd say REDs on set look (their various 709 presets) have been more contrasty, saturated, and abrupt in the highlight roll off than some people prefer. But in post you could use Redlog Film with a LUT and find gentle, low contrast, soft roll off to suit ones taste. We didn't typically just grade in Redlog film without some form of a LUT because it takes a lot of wrestling to really bring out the balance and saturation (which is what the LUT would do).

    But now with ipp2 you can use specific settings in the release build of your camera and specific LUTs from RED that work in Resolve (on top of Redlog film) and you should be able to dial in your base settings quite quickly. REDs done a really good job here. Or use a beta build and you can handle this in camera without the LUTs

    Hope that helps...
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  5. #25  
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    Can you post comparative .dng and .r3d frames?

    I agree with Paul above; I'm seeing easily distinguishable improvements with IPP2 even on MX footage! It's not a miracle worker or anything, but definitely a good 5% better colour/highlight retention (and better roll-off too).

    That said, the 4.6k is definitely a much larger sensor to Raven, especially in 16:9 frame sizes... Actually it has over 60% larger surface area than dragon at 4k 16:9 (~25.34x14.25mm compared to ~20.5x10.8mm); as in, there's a 63% more surface area an 1.32x crop factor between the two. The 4.6k is a smidgeon smaller than 5k MX and 5.5k dragon. It also does 16:9 in full 4k DCI (4096x2304) like the R1 did... And while it "only does" 60p at 4.6k, it can do so uncompressed, 3:1, or 4:1 (whereas Raven goes down into 8:1 at 4k HD 60p, which isn't too bad... But 13:1 at 120p is taxing, even for REDcode).

    OH, and you may wanna refrain from saying RED has "a look"; it's raw and can do whatever you want (and, as crazy as it sounds, people have gotten banned for saying such things.)
    Last edited by Mike P.; 09-10-2017 at 07:49 PM.
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  6. #26  
    Quote Originally Posted by Misha Engel View Post
    It has the same excellent OLPF as the ARRI ALEXA 65, but it is a bit noisier due to, among others, the smaller pixels.
    Do you have any source for that, Misha ? I didn't know the UMP had an OLPF...
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  7. #27  
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    Quote Originally Posted by Stefan Antonescu View Post
    Do you have any source for that, Misha ? I didn't know the UMP had an OLPF...
    Yes Arri Alexa 65 and BMD UMP don't have an OLPF (so the have the same, just air and it's excellent you can even breath it).
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  8. #28  
    Quote Originally Posted by Misha Engel View Post
    Yes Arri Alexa 65 and BMD UMP don't have an OLPF (so the have the same, just air and it's excellent you can even breath it).
    The Alexa 65 doesn't have an OLPF ? Do you have a source ?
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  9. #29  
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    Quote Originally Posted by Stefan Antonescu View Post
    The Alexa 65 doesn't have an OLPF ? Do you have a source ?
    Most of the time you state what you have, not what you don't have.
    I can't find a source that the ARRI Alexa65 doesn't have a spare tire or a boat, Arri however doesn't state that it has.
    The last time I was in Germany they didn't have it and I can't find it on their website so I think they still don't have it.
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  10. #30  
    Moderator Phil Holland's Avatar
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    Quote Originally Posted by Steven Abrams View Post
    Red lists the Helium and Dragon sensors in their tech specs as having 80db signal to noise ratio, which is around 13.2 stops.
    http://www.red.com/products/weapon-8k#tech-specs

    16+ is what they rate HDRx being.
    Really just need to step in here and say this is incorrect. 16+ stops is the rating without HDRx...... And it's been measured by many.

    I've found 16+ securely and publicly. Most who have a conflicting opinion state 15 stops.

    You can't always use the "good old standard" SNR for straight DR measurements these days for a variety of reasons. i.e. How REDCODE RAW is encoded.

    Continue on.
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