Jump to content




Photo

Red Iso

Noise

  • Please log in to reply
14 replies to this topic

#1 Paul Tackett

Paul Tackett
  • Basic Members
  • PipPip
  • 72 posts
  • Cinematographer
  • Los Angeles

Posted 11 January 2015 - 07:12 PM

There have been several posts about ISO but I have not found this specific question.

 

On Red's website they state: "For most scenes and uses, exposing with an ISO of 640-2000 strikes the best balance between highlight protection and low image noise."

 

I have found that shooting at 800 on the Red Epic MX with the Redcode at 8:1, the image has a significant amount of noise in a dark scene.

 

So, I'm wondering, does changing the ISO to 640 or 500 really make much of difference in the noise level of darker scenes? I'm talking about an image where there is no need to lift the blacks.

 

 


  • 0




#2 Stuart Brereton

Stuart Brereton
  • Basic Members
  • PipPipPipPip
  • 2575 posts
  • Cinematographer
  • Los Angeles

Posted 11 January 2015 - 07:19 PM

800 ISO has the best dynamic range, but 400 will give you cleaner blacks.


  • 0

#3 Paul Tackett

Paul Tackett
  • Basic Members
  • PipPip
  • 72 posts
  • Cinematographer
  • Los Angeles

Posted 11 January 2015 - 07:28 PM

Yeah I've heard the rumor that 800 has the best dynamic range, but I've also heard that all iso settings have the same amount of dynamic range, just a different priority over blacks or highlights. 


  • 0

#4 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 18789 posts
  • Cinematographer
  • Los Angeles

Posted 11 January 2015 - 07:42 PM

It's not so much that you get the best dynamic range at 800 ISO, but that your information is split evenly between highlights and shadows, at an overall noise level that most people find acceptable.  But at 400 ISO, you'd have less noise and you'd lose one-stop of overexposure information at the gain of one-stop of underexposure information.

 

With most of these digital cameras, there is an ISO range where the total dynamic range captured is the same and you are just playing noise against overexposure latitude when choosing different ISO settings.  But then you reach a point at lower ISO levels where you are just overloading the sensor and not getting the widest range possible.  I think with the MX sensor, that is around 320 ISO.


  • 0

#5 Albion Hockney

Albion Hockney
  • Basic Members
  • PipPipPipPip
  • 414 posts
  • Cinematographer
  • LA

Posted 11 January 2015 - 07:59 PM

For me the general rule is shoot 800 ISO if you want to have the most highlight latitude ( I find highlight clipping to be the RED's biggest weakness as the roll of isnt as nice as Alexa). That said if I'm shooting something without a lot of highlights and I want a cleaner image (especially in terms of noise in the shadows) I will shoot 320iso. For example a commerical with a night interior.


  • 0

#6 Daniel Reed

Daniel Reed
  • Basic Members
  • PipPip
  • 28 posts
  • Other
  • San Francisco

Posted 02 May 2015 - 12:07 AM

For MX, 320 w/ controlled lighting when shot, then push to 800 in Redcine-X gets good results.  In terms of highlight roll-off for MX, a low strength LowCon works well, like a 1/4 or 1/8

 

Dragon is is a different animal and new territory; recently I've been shooting it at 500, then raise it somewhere between 640 to 2000 in Redcine-X.  

Make sure to use DEB and keep compression ratios as low as possible.

When I stick to that, and keep compression at or below 8:1, I find there Is never a need for Noise Reduction.


  • 0

#7 Satsuki Murashige

Satsuki Murashige
  • Sustaining Members
  • 3081 posts
  • Cinematographer
  • San Francisco, CA

Posted 02 May 2015 - 10:06 PM

I keep Epic and Scarlet at 500. Have only tested Dragon with Skin Tone OLPF, it seems to have 2-3 stops of overexposure latitude and falls apart when underexposed by more than 1 stop, so I'd feel comfortable shooting at 400 or 200. Have not tested Low Light OLPF.
  • 0

#8 Leigh Miller

Leigh Miller

    New

  • Basic Members
  • Pip
  • 7 posts
  • Director
  • Melbourne

Posted 22 June 2015 - 08:59 AM

I also have a question regarding noise, specifically on the Dragon. We have shot with this camera before and had no problems, it then got the upgrade to the Dragon and we took it out for a run, and found the RAW footage had tons of noise, especially in the darker scenes. Though, some of the shots didn't have noise at all, mainly the daylight scenes, but some of the daylight scenes did have noise as well. My assistant and I can't think of anything we did differently from previous shoots, apart from use the Dragon, so we're wondering what could cause this amount of noise to be in the image. 

 

Should also note that we had a split on the day which is pretty nice and we, nor the director or anyone notice noise levels like this, it looks nice on all the monitors. 

 

exposed for 800iso

Noise (dark) - http://postimg.org/image/5d6c03of3/(obviously far more noticeable when played)

Clean (day) - http://postimg.org/image/g4svcdc69/

Would love to hear any possible ideas. Is it simply just too dark? Though I've shot things this dark before pre Dragon and not had an issue. 

 

It's been suggested that perhaps we didn't wait for the Dragon to get to temperature before shooting, though I don't think this likely as we'd frame up and light, rehearse, do multiple takes etc. 


  • 0

#9 Miguel Angel

Miguel Angel
  • Sustaining Members
  • 563 posts
  • Cinematographer
  • Spain / Ireland / South Africa

Posted 22 June 2015 - 09:57 AM

Then there are people like me who like pushing the Mx sensor to the limits and shoot at 1280ASA 

 

A030_C014_0610FB.0003568F%202.jpg

 

Anyway, I would have preferred to shoot that with a T2.8 lens but the only lens I have at the moment is T4 1/2. 

 

Thanks to that I have discovered that I like the texture when shooting at 1280ASA with the Redone MX and seeing it on a 2K projector in a lab is quite interesting as the amount of noise you might see on your laptop it is not that much when seeing it in proper conditions. 

 

Some day I will shoot something else rather than a test! 

 

Regarding the RED ISO, it works like the one on the Alexa as some other people pointed out. 

http://www.arri.com/...exa_family_faq/

 

While ALEXA's 14+ stops of exposure latitude (as measured with the ARRI Dynamic Range Test Chart (DRTC)) and unique highlight handling approaches that of film, there is one major difference between the way film and digital cameras behave: with digital cameras, a change in EI will shift how many stops are available above and below 18% grey - each EI step shifts the location of 18% grey. 
 

greyscale_mapping_01.jpg
 

As a shortcut, we have come up with the following method of writing ALEXA’s exposure index:

 

sensitivity_trans.png
 

Values behind the exposure index are the number of stops above and below 18% grey. These values are for Log C. Rec 709 and DCI P3 have 0.5 stops fewer in the low end at EI 160, 0.4 stops fewer in the low end at EI 200 and 0.2 stops fewer in the low end at EI 400. Otherwise they are the same.

 

 

 

Leigh, I would suggest keep in touch with the community on reduser if you have not done it yet, they might help you understand why you are getting a lot of noise. 

 

It could be just a matter of your camera not having the right OLPF for dark scenes which is the following one: http://www.red.com/s...-optimized-olpf

 

Or it could be just blackshading.  

 

Have a good day. 


  • 0

#10 Miguel Angel

Miguel Angel
  • Sustaining Members
  • 563 posts
  • Cinematographer
  • Spain / Ireland / South Africa

Posted 22 June 2015 - 09:57 AM

Edited because I posted it twice. 

 

If somebody could delete this last post it would be great!

 

Thanks.


Edited by Miguel Angel, 22 June 2015 - 10:07 AM.

  • 0

#11 Satsuki Murashige

Satsuki Murashige
  • Sustaining Members
  • 3081 posts
  • Cinematographer
  • San Francisco, CA

Posted 22 June 2015 - 03:58 PM

Dragon is also super sensitive to black shading, much moreso than MX. Changing shutter speed, especially toward slower speeds can throw off your black shading. You can see this by checking the temperature readout - you want to see sensor/core temp (green/green). Yellow is ok, but red means you should change your black shade settings. A quick way to check black shading visually is to put the port cap on and set the ISO to max 12,800. If frame is evenly black with a consistent noise pattern across the frame, then you're good. If not, then change the fan settings to run the camera hotter/cooler or black shade.

You can save up to 4 black shades in the camera now and they take about 5min/each to do which is a huge improvement. What I like to do is set a range that covers most of my shooting situations. So if you're staying in roughly the same temperature environment but shooting 6-60fps with 180 shutter, I go with: 1/12, 1/30, 1/48, 1/120, all at 65C. With this, I find the temp readout occasionally goes yellow, but never into red, so I never have to re-shade on set. In addition, you need to give the sensor about 15 minutes to warm up at the start of the day, and keep the camera on as much as possible once up to temperature. I always use Adaptive Quiet fan mode now.
  • 0

#12 Satsuki Murashige

Satsuki Murashige
  • Sustaining Members
  • 3081 posts
  • Cinematographer
  • San Francisco, CA

Posted 22 June 2015 - 04:17 PM

Also, I think your first shot is just underexposed. When shooting very low-key scenes in digital, I find what happens is that everyone forgets to recalibrate their monitors and consequently, because you are using the monitor for lighting reference you end up grossly underexposing, thinking that there is more shadow detail than there actually is.

Since you can easily expose brighter and bring down the exposure in color grading, I find it to be safer practice to use a lower ISO (for cameras shooting raw) in these situations. I'd also keep checking your histogram, waveform, and false color tools as a guide. If you know how many footcandles you need for your base ISO setting, than an incident meter can be quite helpful as well.
  • 0

#13 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 18789 posts
  • Cinematographer
  • Los Angeles

Posted 22 June 2015 - 06:07 PM

What happens is that when viewing the monitor in a darkly-lit set, the monitor becomes the brightest light in the room and you tend to underexpose the images to make them feel dark enough.  Same thing happens the other direction when viewing a monitor outside in daylight, even under a flag or heavy shade, the monitor isn't as bright as the surrounding scene so you tend to overexpose the images to make them feel normal in brightness.

 

Generally when I get back 2nd Unit footage that is too hot or too dim, this is the cause 90% of the time even when they swear they were exposing with a waveform or light meter.


  • 0

#14 Leigh Miller

Leigh Miller

    New

  • Basic Members
  • Pip
  • 7 posts
  • Director
  • Melbourne

Posted 24 June 2015 - 07:08 PM

Thanks for all the info again guys, I'll check out redusers and certainly check black shading more.

 

 

Also, I think your first shot is just underexposed. When shooting very low-key scenes in digital, I find what happens is that everyone forgets to recalibrate their monitors and consequently, because you are using the monitor for lighting reference you end up grossly underexposing, thinking that there is more shadow detail than there actually is.

Since you can easily expose brighter and bring down the exposure in color grading, I find it to be safer practice to use a lower ISO (for cameras shooting raw) in these situations. I'd also keep checking your histogram, waveform, and false color tools as a guide. If you know how many footcandles you need for your base ISO setting, than an incident meter can be quite helpful as well.

 

Am I right to assume though, even if the shot is underexposed the blacks should not be that noisy? I have shot dark scenes before and never had that much noise, and of that 'kind' so to speak, it looks very 'digitaly' compared to regular RED noise. 


  • 0

#15 Satsuki Murashige

Satsuki Murashige
  • Sustaining Members
  • 3081 posts
  • Cinematographer
  • San Francisco, CA

Posted 25 June 2015 - 12:00 AM

To be honest, I'm really not seeing much noise in the frame you posted. But noise is difficult to judge in a compressed low-res still image. If you want, you can post an .R3D still frame which would allow us to check a full-res raw frame in RedcineX or Resolve. This would also allow us to see a histogram and check your develop settings. If you're shooting above 500 ISO and/or boosting ISO in post, you will certainly have noise in the shadows. Also, if you shot with a limited color spectrum and boost the underexposed color channels at all, you will have noise.
  • 0



Broadcast Solutions Inc

Glidecam

Abel Cine

Aerial Filmworks

rebotnix Technologies

Rig Wheels Passport

Tai Audio

CineTape

CineLab

Ritter Battery

Visual Products

The Slider

Technodolly

Pro 8mm

Willys Widgets

Paralinx LLC

Zylight

Rig Wheels Passport

Paralinx LLC

Abel Cine

Broadcast Solutions Inc

Visual Products

CineLab

The Slider

rebotnix Technologies

Aerial Filmworks

CineTape

Tai Audio

Glidecam

Technodolly

Zylight

Pro 8mm

Ritter Battery

Willys Widgets