andrgl Posted July 5, 2015 Author Share Posted July 5, 2015 It's crude but it works. By alternating the digital gain, we can capture more of the top and bottom of our signal data. It works more effectively than squeezing all signal data into a 12-bit file. Quote Link to comment Share on other sites More sharing options...
Super Members Mattias Burling Posted July 5, 2015 Super Members Share Posted July 5, 2015 "Come on guys, in raw, ISO is just metadata - everybody knows that.Only if you set it to 1600, the curve gets mapped a bit different, to prevent noise in the blacks.But it still is metadata.", Frank Glencairn "When you change the iso value on the bmcc, the clipping point does not change, but the noise floor is pushed down. So lowering the ISO will make the image look cleaner, but you will still be clipping at the same point. So lowering the ISO on this camera in order to help to control the level of light being recorded is not a good idea. Iso 1600 is a slight exception in that although it is still meta data, the way the range is mapped is different, allocating more bits in the shadows.", Tom Majerski "A couple of things worth noting.There's "exposure"....A creative choice.....And then there's the ISO you choose.The sensor is always 800. When you change the ISO in RAW or ProRes, all you're doing is changing a curve that's applied to ISO800. Lower ISO's trade some DR in to get you a nicer looking curve for those lighting conditions. In effect you're "grading" your image down exposure wise, then baking it in if you're shooting ProResI think the reason a lot of people like lower ISO's is that it kind of forces you to to a bit of ETTR, and appears to give less noise. That's because there's less detail in the blacks. The near black information is now crushed along with the noise.The end result of ETTR is that is pushes the noise further down into the blacks....thus reducing apparent noise.When shooting RAW, I often use the ISO 0f 400 or 200 to enable me to overexpose the image a little, and it ALSO gives me a nice looking preview image on the back of the camera.In my thinking, without changing your exposure for a given setting and shot (aperture and shutter angle stay the same) you can always achieve the same result in the grade." , John Brawley mercer and maxotics 2 Quote Link to comment Share on other sites More sharing options...
andrgl Posted July 5, 2015 Author Share Posted July 5, 2015 the curve gets mapped a bit differentThat's the key sentence. 22-bit sensor data has to be mapped into a 12-bit file. You can choose which part of your data is squashed via ISO. Quote Link to comment Share on other sites More sharing options...
TheRenaissanceMan Posted July 5, 2015 Share Posted July 5, 2015 That's the key sentence. 22-bit sensor data has to be mapped into a 12-bit file. You can choose which part of your data is squashed via ISO. ISO values on the Pocket have no bearing on its RAW files besides giving you a different preview. Of I'm incorrect, please provide a source that clarifies how and why. andrgl 1 Quote Link to comment Share on other sites More sharing options...
Guest Ebrahim Saadawi Posted July 5, 2015 Share Posted July 5, 2015 How about raw stills. Is it all just metadata too and ISO doesn't change the data? That's not what I am seeing. I see amplification of the sensitivity that hugely affects the final image. I just never bought that idea that raw you adjust ISO in post the same as you would in-camera, and I always though it was just a clever implementation of Redcinex software giving you an ISO slider that blew people's mind (which is basically an exposure slider as in windows paint), but hey I don't need to worry about ISO whilst shooting, and I believed this though was reinforced by their cameras' bad low-light performance and extremely limited ISO range, so we all leave it at the optimum and work around it. Yet changing the ISO on a red to 320 ISO or to 1600 did make significant changes in the image DR, noise, exposure, just like all the cameras I've ever used, ISO it inherent to the data not just a flag changeable in post even if there's an exposure slider named ISO that darkens/brightens the final image.I have no clue whether this is true or not, but from my experience with all raw cameras, that's what I see. ISO/Gain affects the image irreversibly, just how reversible it is varies upon cameras. Again no clue what I am talking about just throwing what on my mind... Quote Link to comment Share on other sites More sharing options...
TheRenaissanceMan Posted July 5, 2015 Share Posted July 5, 2015 Some cinema cameras, like the Bolex, Blackmagic, and Alexa, have only one native ISO. They use digital gain to "push" that data and produce brighter results for higher ISO values, but the RAW data never changes. It always captures at its native ISO on the sensor level. Some cameras, like all DSLRs/DSLMs, Canon's Cinema line, and the Panasonic Varicam 35, have more than one native ISO. They use analog gain on the sensor level to change the way the sensor actually "sees" photons, resulting in better dynamic range and noise characteristics at higher sensitivities. Hope that clarifies things. Here's the difference, Ebrahim. Some cameras apply that gain digitally, in software, and some apply it analog, on the sensor itself. Cinema cameras like RED and Blackmagic use digital gain for higher ISO's; stills cameras use analog. Quote Link to comment Share on other sites More sharing options...
andrgl Posted July 5, 2015 Author Share Posted July 5, 2015 ISO values on the Pocket have no bearing on its RAW files besides giving you a different preview. Of I'm incorrect, please provide a source that clarifies how and why. Thank you. You're absolutely correct. Shot a high DR scene at 200, 800 and 1600. All files identical. TheRenaissanceMan 1 Quote Link to comment Share on other sites More sharing options...
TheRenaissanceMan Posted July 5, 2015 Share Posted July 5, 2015 Thank you. You're absolutely correct. Shot a high DR scene at 200, 800 and 1600. All files identical.Haha, great to hear we're getting the same results! :)Can you elaborate more on what you're trying to accomplish in your landscape work, what tools you're using to expose, and how you're processing your files? Perhaps we can fine tune your method to help get you the results you want. andrgl 1 Quote Link to comment Share on other sites More sharing options...
andrgl Posted July 5, 2015 Author Share Posted July 5, 2015 Haha, great to hear we're getting the same results! Can you elaborate more on what you're trying to accomplish in your landscape work, what tools you're using to expose, and how you're processing your files? Perhaps we can fine tune your method to help get you the results you want. You and Max got me pointed in the right direction. I want something highly portable that can capture ridiculous DR. I had it in my head that signal gain was what I wanted, but it's obvious I want to alternate shutter angle values with a high frame rate camera.I'll have to take a look at what the max FPS is with ML/Canon cameras. But I think my options at this point are, Blackmagic Micro (can we cycle shutter angle during recording and quick enough?) or just buy a USB3 camera sensor. Quote Link to comment Share on other sites More sharing options...
Super Members Mattias Burling Posted July 6, 2015 Super Members Share Posted July 6, 2015 You and Max got me pointed in the right direction. I want something highly portable that can capture ridiculous DR. I had it in my head that signal gain was what I wanted, but it's obvious I want to alternate shutter angle values with a high frame rate camera.I'll have to take a look at what the max FPS is with ML/Canon cameras. But I think my options at this point are, Blackmagic Micro (can we cycle shutter angle during recording and quick enough?) or just buy a USB3 camera sensor.The Micro Cinema which will indeed give you 60fps but at an even lower DR than the current Pocket Camera. Quote Link to comment Share on other sites More sharing options...
Nikkor Posted July 8, 2015 Share Posted July 8, 2015 Dual iso on the new a7000. 15.5 stops.http://www.sonyalpharumors.com/sr3-sony-a7000-is-the-first-e-mount-camera-with-15-5-stops-on-sensor-hdr/Hmmm, I'm tempted, let's hope it works in 4k and in slog2 dahlfors and andrgl 2 Quote Link to comment Share on other sites More sharing options...
dahlfors Posted July 8, 2015 Share Posted July 8, 2015 Dual iso on the new a7000. 15.5 stops.http://www.sonyalpharumors.com/sr3-sony-a7000-is-the-first-e-mount-camera-with-15-5-stops-on-sensor-hdr/Hmmm, I'm tempted, let's hope it works in 4k and in slog2Nice find. I've been waiting for that camera. Suddenly it seems even more interesting Nikkor and andrgl 2 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.