real native iso of dragon?

[Mike Quill]

The accurate answers to the questions are:

Dragon is cleanest when rating/exposing for ISO 250.
Dragon has more Dynamic Range at every ISO rating compared to Mysterium-X because there is more total available Dynamic Range. You do "see more of" the Dynamic Range at ISO 2000. However, with Dragon and Mysteroum-X it's all about how that DR gets mapped for your particular ISO and eventual gamma or look.
ISO 800 is a nice middle-ish point where you have approximately equal tonal range above and below middle gray.

Phil,

Been doing some informal tests with my Epic Dragon (w/ STH OLPF), trying to wrap my head around whether I'm sacrificing significant dynamic range when shooting at lower ISOs (e.g. ISO 250). For example, say you point the camera out the window on a bright sunny day. With MX, you would expose at ISO 800, but if you turned the ISO down to 250, chances are your right goalpost would start clipping. With Dragon, this does not seem to happen. Yes the histogram changes and in exposure mode you'll see more red, but the right goalpost does not start clipping. Am I thinking about this correctly?

Thanks,
Mike

 

[Nikhil Kamkolkar]

As some here have said this is a separate issue you won't see this in less you're shooting a very high f-stop

Sorry yes! I was referring to the dot grid pattern. So instead of shooting at a F16 if you use NDs you won't see this? That's a workable solution for me. Apologies. I see now that this was true even on the MX.

 

[David Battistella]

Yup small apertures will cause this red dot grid pattern.

If you nd it down to 5.6 or more open, you will see that problem is greatly reduced.

Battistella

 

[Phil Holland]

Phil,

Been doing some informal tests with my Epic Dragon (w/ STH OLPF), trying to wrap my head around whether I'm sacrificing significant dynamic range when shooting at lower ISOs (e.g. ISO 250). For example, say you point the camera out the window on a bright sunny day. With MX, you would expose at ISO 800, but if you turned the ISO down to 250, chances are your right goalpost would start clipping. With Dragon, this does not seem to happen. Yes the histogram changes and in exposure mode you'll see more red, but the right goalpost does not start clipping. Am I thinking about this correctly?

Thanks,
Mike

Ahoy there Mike. The first thing to know is that Dragon has significantly more Dynamic Range that Mysterium-X across the ISO Range. Red refers to this as "zero penalty" lower ISO shooting. ISO 250 on Mysterium-X was/is risky business due to the sliver of Dynamic Range you'd be working within and it clipped hard. Dragon clips smoother and has that extra DR to assist with those conditions. Which is why you see people successfully shooting Dragon in a variety of conditions at the lower ISO Ratings.

The same general concept stands about Dynamic Range distribution as you increase your ISO Rating as it did before, there's just more of it now. This graphic is the actual read patches from footage showing this:

And these three images show the increased Highlight Retention that can be found with shooting at higher ISO Ratings with Dragon:

I rate Dragon all over the place. Thus far in my nearly year long journey with Dragon I've been shooting at ISO 250, 320, 400, 500, 800, 1000, and 1280 on both OLPFs depending on each shoot's needs. I dig the texture and tonality of ISO 800/1000 on projects that can handle that. I find it rather lovely for narrative work. I'm also working pretty much only at 6K through 4K. I don't work under 4K at all these days.

 

[Mike Quill]

Ahoy there Mike. The first thing to know is that Dragon has significantly more Dynamic Range that Mysterium-X across the ISO Range. Red refers to this as "zero penalty" lower ISO shooting. ISO 250 on Mysterium-X was/is risky business due to the sliver of Dynamic Range you'd be working within and it clipped hard. Dragon clips smoother and has that extra DR to assist with those conditions. Which is why you see people successfully shooting Dragon in a variety of conditions at the lower ISO Ratings.

The same general concept stands about Dynamic Range distribution as you increase your ISO Rating as it did before, there's just more of it now. This graphic is the actual read patches from footage showing this:

And these three images show the increased Highlight Retention that can be found with shooting at higher ISO Ratings with Dragon:

I rate Dragon all over the place. Thus far in my nearly year long journey with Dragon I've been shooting at ISO 250, 320, 400, 500, 800, 1000, and 1280 on both OLPFs depending on each shoot's needs. I dig the texture and tonality of ISO 800/1000 on projects that can handle that. I find it rather lovely for narrative work. I'm also working pretty much only at 6K through 4K. I don't work under 4K at all these days.

Thanks for the response, Phil. This was very helpful. Based on your chart and images, it appears that ISO 800 is still the best DR balance between highlights and shadows; meaning, there are an equal amount of stops above and below middle grey at ISO 800. So, if you are happy with the grain structure at ISO 800, it still makes more sense to shoot day exteriors at ISO 800 (w/ more ND) vs ISO 250 (w/ less ND), keeping in mind that you don't get IR contamination anymore with heavy ND. Does this make sense?

Based on the above, can I apply the same logic to extremely lopsided DR situations? E.g., if I want to protect my shadows in an extremely low light situation, I would shoot at a low ISO and open up my aperture, and conversely, if I want to protect my highlights in an extremely bright situation, I would shoot at a higher ISO than 800 and stop down?

If my thinking is correct, I'm wondering why Nick Morrison is saying that the Dragon w/ STH OLPF has a native ISO of 320?

Thanks,
Mike

 

[Mike P.]

Thanks for the response, Phil. This was very helpful. Based on your chart and images, it appears that ISO 800 is still the best DR balance between highlights and shadows; meaning, there is an equal amount of stops above and below middle grey at ISO 800. So, if you are happy with the grain structure at ISO 800, it still makes more sense to shoot day exteriors at ISO 800 (w/ more ND) vs ISO 250 (w/ less ND), keeping in mind that you don't get IR contamination anymore with heavy NDs. Does this make sense?

Based on the above, can I apply the same logic to extremely lopsided DR situations? E.g., if I want to protect my shadows in extremely low light situations, I would shoot ISO 250 and open up my aperture, and conversely, if I want to protect my highlights in extremely bright situations, I would shoot at a higher ISO than 800 and stop down?

If my thinking is correct, I'm wondering why Nick Morrison is saying that the Dragon now has a "native ISO 320 sensor?"

Thanks,
Mike

That's what it is with MX too. The problem is, with MX, you see a sharp falloff of highlight stops when you go down to ~320 (hell, you even see a sharp falloff of highs at 800ISO too)... That is to say, in high contrast/bright scenes (day exterior) shoot at a higher ISO. In low-light (night) shoot lower ISO. In both cases, how it effects your physical exposure settings (ND, Shutter, aperture) results in better use of the sensor's DR in those scenes. With Dragon it's even more betterness because of how much you actually retain in the highs (presumably).

Off topic, but that's also why I had hoped RED/Graeme could have made a "MEB" (DEB for MX)... If they could've cleaned the lowest stop with a sensor specific raw tweak, we would've been able to get "clean" images at ISO1600, allowing us to expose one stop further down without giving a dirtier image, effectively giving us another stop in the highlights "for free". You can still do it, if you're tolerance for noise is high or if you have decent noise reduction software, but there's a huge performance/rendering hit.

 

[Phil Holland]

Thanks for the response, Phil. This was very helpful. Based on your chart and images, it appears that ISO 800 is still the best DR balance between highlights and shadows; meaning, there is an equal amount of stops above and below middle grey at ISO 800. So, if you are happy with the grain structure at ISO 800, it still makes more sense to shoot day exteriors at ISO 800 (w/ more ND) vs ISO 250 (w/ less ND), keeping in mind that you don't get IR contamination anymore with heavy NDs. Does this make sense?

Based on the above, can I apply the same logic to extremely lopsided DR situations? E.g., if I want to protect my shadows in extremely low light situations, I would shoot ISO 250 and open up my aperture, and conversely, if I want to protect my highlights in extremely bright situations, I would shoot at a higher ISO than 800 and stop down?

If my thinking is correct, I'm wondering why Nick Morrison is saying that the Dragon now has a "native ISO 320 sensor?"

There's many ways to expose with Dragon and all cameras really. All producing various results. Most need to develop and discover "their way". There are plenty of methods for sure. ETTR (exposing to the right), daylight/higher ISO - artificial/lower ISO, locking in at a "believed" native ISO and working from there, etc......

The one thing I've found and how it relates to success and expected imagery is exposing accurately as much as possible. This for me is a combination of the In Camera Exposure Tools and also utilizing a Light Meter. More often than not, I'm working with Dragon like I would with film in terms of the meter. I also rate my ISO per project and/or scene. I don't like changing my ISO values for every setup and I don't want that to happen in post if it can be avoided.

I think the one thing I've learned over time is shooting is more about making deliberate and thoughtful decisions which should result in a given method for working. In this world where some expect the camera to do a lot of the lifting, it's important that the person behind it guides it as closely to the target as possible.

I won't go down the "native ISO" path too much as it's a woefully wrong term in regards to how people commonly use it. It's second nature now and people make that definition and I'm certainly fine with people running with something that works for them. The same holds true for "base ISO" for that matter, which is the approximate range where there are equal stops above and below 18% Gray from a "readable" highlight and shadow, particularly in the log representation (REDlogFilm). Dragon in that way has it's "base sensitivity" at ISO 800 and for me after measuring a lot of patches it could also be more in the realm of ISO "800-1280".

It's all good. There's many paths. It's all a crazy dance really. And much of it comes down to people's wants, desires, and expectations in regards to image noise and dynamic range. The thing is that there isn't one answer to that particular thing "for everybody" and even for a given shoot. For instance I'm on location at the moment and the focus is more in producing clean images and that's influencing my ISO choices, where on my last shoot which was narrative I enjoyed the texture and wanted a more "film-like" look.

 

[Nick Morrison]

where on my last shoot which was narrative I enjoyed the texture and wanted a more "film-like" look.

I've been listening to Patrick's "Wandering DP Podcast" (which you are on!), and Max Goldman said much the same about shooting Alexa - how he likes to shoot 1280 RAW and get some "texture" into the image.

Love how many ways there are to skin to a cat - shoot clean, textured, new glass, old glass, filtration, no filtration, underexpose, overexpose...it's like cooking...choose your recipe and ingredients...and try something new every time!

 

[Brian Merlen]

i think the amira night exterior shots are revealing of the low light performance of Alexa... good example of it on vimeo/youtube somewhere...i think people who wanna shoot low light need the low light OLPF if they go for Dragon, it'll help... as would lights, opening the iris, other things too

 

[Mike Quill]

There's many ways to expose with Dragon and all cameras really. All producing various results. Most need to develop and discover "their way". There are plenty of methods for sure. ETTR (exposing to the right), daylight/higher ISO - artificial/lower ISO, locking in at a "believed" native ISO and working from there, etc......

The one thing I've found and how it relates to success and expected imagery is exposing accurately as much as possible. This for me is a combination of the In Camera Exposure Tools and also utilizing a Light Meter. More often than not, I'm working with Dragon like I would with film in terms of the meter. I also rate my ISO per project and/or scene. I don't like changing my ISO values for every setup and I don't want that to happen in post if it can be avoided.

I think the one thing I've learned over time is shooting is more about making deliberate and thoughtful decisions which should result in a given method for working. In this world where some expect the camera to do a lot of the lifting, it's important that the person behind it guides it as closely to the target as possible.

I won't go down the "native ISO" path too much as it's a woefully wrong term in regards to how people commonly use it. It's second nature now and people make that definition and I'm certainly fine with people running with something that works for them. The same holds true for "base ISO" for that matter, which is the approximate range where there are equal stops above and below 18% Gray from a "readable" highlight and shadow, particularly in the log representation (REDlogFilm). Dragon in that way has it's "base sensitivity" at ISO 800 and for me after measuring a lot of patches it could also be more in the realm of ISO "800-1280".

It's all good. There's many paths. It's all a crazy dance really. And much of it comes down to people's wants, desires, and expectations in regards to image noise and dynamic range. The thing is that there isn't one answer to that particular thing "for everybody" and even for a given shoot. For instance I'm on location at the moment and the focus is more in producing clean images and that's influencing my ISO choices, where on my last shoot which was narrative I enjoyed the texture and wanted a more "film-like" look.

Thanks for the great info, Phil.

 

[Marc Rochon]

I'd like to know if ISO makes a difference in exposure or not. I've been reading a lot about it in the forums. Here is my understanding and correct me if I"m wrong. The Red Dragon is like getting a camera that has only one ASA film loaded into it. That ASA is 320. The only way to control proper exposure is to open or shut my aperture or change my shutter speed/angle. If my aperture is wide open and my shutter angle is at 360 my only other option to get "correct" exposure is to add more light to get my exposure correct. If that is not an option I can change the ISO on the Dragon but really all that is doing is "push processing" my film. With that will come grain. I can do that on the camera and see the result on screen or I can shoot it at 320 and push it to 800 in post and get the same result. If I change the camera to 800 ISO and get a good looking histogram I may be actually underexposing the image because the film in my camera is really 320.

I get that some people may want to shoot at different ISO's to get texture or grain but is the true ISO of the film/sensor 320?

Exposure stategy: Skintone OLPF start ISO at 320 and using aperture and shutter angle to get exposure. Finally add more light if possible.
LowLight OLPF start ISO at 800 and using aperture and shutter angle to get exposure. Finally add more light if possible.


-Marc

 

[Mark L. Pederson]

I get that some people may want to shoot at different ISO's to get texture or grain but is the true ISO of the film/sensor 320?
-Marc

Not true.

ISO on RED cameras is a PROCESSING parameter. It does not effect how much light hits the sensor.

Rate a DRAGON at ISO 320 and set the lens T5.6 and rate a DRAGON at ISO 1280 and set the lens to T5.6 and you will be recording the EXACT same image - because the same amount of light is hitting the sensor. The images will be, by default of the camera generated meta data, processed differently - but the RAW file is the same.

BUT choosing an ISO does effect your EXPOSURE METHOD - which is whatever method you decide to use to choose your exposure. Lightmeter, histogram or just looking at the monitor.

Shooting lower ISO will drive you to open up more - to bang more light into the sensor - which results in a cleaner image. It also helps you if you want to shoot with a very shallow depth of field by working wide open apertures. Shooting a higher ISO will drive you to expose with LESS light making it's way to the sensor - which can create more noise - but can be leveraged as "texture" as a creative choice.

Whatever ISO you choose - that is how the RAW image will be processed. Rating at 320 gives a great result. So does 250, 500, 640, etc.

For what it's worth - I recommend rating BOTH OLPFs the SAME. I prefer the skintone OLPF by a mile - and I personally think that "low light optimized" is a bit misleading name for that OLPF - because folks think they are gonna get an extra 2 stops by switching the OLPF. Not true. You get slightly cleaner blacks - and you can also get magenta OLPF flare - which you might like.

You can do GREAT night exteriors at ISO 800 with either OLPF. You get a LITTLE more love in the shadows with the low light - but honestly - the color fidelity of the skintone OLPF and lack on the magenta flare FAR outweigh the minor difference you can get in the shadows IMO. But, awesome to have the choice.

I wish people would focus more on refining what EXPOSURE METHOD they were using - as opposed to beating the "what's the best ISO" to death.

 

[David Mullen ASC]

The correct ISO is whatever gives you the results you like, anything else is just academic. There is a point where you can oversimplify things when explaining how things work.

 

[Nick Morrison]

Exposure stategy: Skintone OLPF start ISO at 320 and using aperture and shutter angle to get exposure. Finally add more light if possible.
LowLight OLPF start ISO at 800 and using aperture and shutter angle to get exposure. Finally add more light if possible.
-Marc

I personally would not use shutter angle as an exposure tool unless you really need to. I generally leave it at 180 degrees and call it a day, or unless we need to correct some flicker. But otherwise I'm loathe to change it as I'm very partial to the traditional motion blur of 180.

Otherwise yes...it's certainly a good place to start...by rating Skintone at 320 and lowlight at 800...but under certain circumstances it's also possible to push them both w/out too much of a penalty (ie shoot Skintone at 1280 and Lowlight at 4000-6000). Additional variables like resolution and compression are also major factors on your "noise".

Shooting 6K would be less noisy than 5K, as you're not as "cropped in" on the noise. There's also a larger canvass to denoise from.

Shooting at 5:1 would give you a much cleaner image than 15:1.

For my crew and I, the more we "push" our image, the more we try to keep everything else "in balance". It's like an equation:

EXPOSURE + RESOLUTION + COMPRESSION = IMAGE QUALITY

If we take from exposure (ie we underxpose), we try and compensate by shooting at Max resolution and as uncompressed as possible. That way we give ourselves the best chance at success.

Hope this helps!

 

[Abe Espinoza]

The only way to control proper exposure is to open or shut my aperture or change my shutter speed/angle.

If that is not an option I can change the ISO on the Dragon but really all that is doing is "push processing" my film. With that will come grain. I can do that on the camera and see the result on screen or I can shoot it at 320 and push it to 800 in post and get the same result. If I change the camera to 800 ISO and get a good looking histogram I may be actually underexposing the image because the film in my camera is really 320.

-Marc

As Nick noted, you should stick to a 180 shutter unless there is a specific reason to change it as it will effect your motion blur. But if you do, you have to take into account the fact that you are changing the amount of time each frame is being exposed and will therefore either increase or decrease your exposure depending as to whether you are slowing it down or speeding it up.

Frames per second also effects exposure. For example, you would lose a stop of light if you were to shoot at 48fps as opposed to 24fps.

Rating your camera at ISO 1280 while shooting will not physically make the sensor more sensitive to light compared to 320 ISO but it will change where middle grey sits.

 

[David Kuhn]

So (going to gripe a bit)... I've got some Tex-mex in me and a couple Margarita's (down near the boarder this week... Austin) so I'm feeling feisty (there's no telling what I might do!). I see a lot of questions about how best to expose the Dragon (or the Epic for that matter). Many of us guess at the 'Native ISO' and try to figure out the sweet spot that will give us the best DR. In my mildly inebriated state at the moment... I'm thinking "why don't digital camera makers just TELL US". If the Dragon is a 16bit sensor then the "Native ISO" should be around 100 (maybe less) based on my preliminary exploration (I just ordered a couple grand in calibrated standards to let me pin it down... I'm sure some of you have already done this). Now I know they're doing some nonlinear games with the data... and that makes sorting out the fundamental performance of the sensor a bit tricky. But while I THINK native ISO is around 100... my camera doesn't seem to want me to set ISO to less than 250 or something like that... so there're definitely some things I'm not really understanding yet about the Dragon. I'm not complaining overall... I know it makes fantastic images, and I know it has pretty damn great dynamic range, but I'm a scientist... I want the math... and it seems like there're some things being done with the raw data that I've just not gotten a handle on yet.

Marc... the reality is that (to my knowledge) ALL digital sensors are really just like having a film stock with a fixed sensitivity (you mention ASA 320... I think my monochrome dragon is closer to ASA 80-100 if it's 16bit as advertised... but I'll be damned if I know for sure). Fundamentally... photons hit sensors (pixels) and are converted to electrons and counted. I don't think anyone is playing games to change the sensitivity of their sensors... so ALL the ISO games are essentially math... lossy calculations against the raw image data.

SO... a sensor pixel will accumulate charge at a fixed rate over time depending on the number of photons hitting it... sounds simple eh? The part I'm struggling with is the processing going on in the camera to make it work more like a film camera... and that stuff makes it harder to sort out. It KINDOF works (high 'ISO' equals more noise or grain), but it's not really the same thing. To get the 'mathematical' most data out of single image... you'd want to have the camera set to report it's 'RAW' data... and you'd want your image to use the full dynamic range of the sensor (some pixels reporting "just barely zero" charge... and some pixels reporting "just barely saturatated"). BUT there's no RAW setting on the Dragon (well there is but it does't seem to actually be the raw sensor data)... so I think it'll be hard for anyone to tell you what the real 'Native ISO' of the Dragon is.

Then there's the whole question about relevance... because a true 16 bit signal has WAYYYYY more dynamic range than a human eye is capable of discriminating... but that's a different discussion.

 

[Akin A]

I'd like to know if ISO makes a difference in exposure or not.

This more recent and more comprehensive thread is better IMO:
http://www.reduser.net/forum/showthread.php?126194-Native-Dragon-ISO%85once-and-for-all!

 

[Marc Rochon]

your right. I read through that one and I'm going back to shooting the way I always have and call it a day.

Come in and set up. Set my RED to the lowest ISO I think I can for the situation. Keep my shutter angle at 180 and set the aperture to what I want. If my histogram or image is dark I'll open up the aperture if I can, and if I don't want to change that I'll bump up ISO until I get there. I'll get worried if I start to have to head over 1280 ISO.

That's it. Back to shooting.

-Marc

 

[Nick Morrison]

your right. I read through that one and I'm going back to shooting the way I always have and call it a day.

Come in and set up. Set my RED to the lowest ISO I think I can for the situation. Keep my shutter angle at 180 and set the aperture to what I want. If my histogram or image is dark I'll open up the aperture if I can, and if I don't want to change that I'll bump up ISO until I get there. I'll get worried if I start to have to head over 1280 ISO.

That's it. Back to shooting.

-Marc

And maybe just check your goalposts/stoplights to see what's actually clipping or not.

 

[Marc Rochon]

of course.