S-log, cheap 'n easy?

Alister Chapman · January 23rd, 2011, 03:05 AM

With a noisy camera there is no advantage to 10 bit over 8 bit for acquisition as all the extra bits don't contain any useful extra data. The posterisation is caused by the sensor noise itself or by quantisation artefacts. Increasing the bit-rate to reduce quantisation is certainly beneficial and often the advantage seen from a 10 bit over 8 bit codec may be due to a significant bit rate increase (provide you factor in the extra data required to record 10 bits and any codec efficiency factors), thus a reduction in quantisation. You need to ensure you have a noise figure for the sensor that is better than 58db for a traditional gamma curve, with log it is a bit different because of the way the samples are spread further apart as you go higher up the curve.

Editing is different as when you change or manipulate the image you will then be creating new samples and it is beneficial to be able to record those new samples with as little truncation as possible.

AFAIK the F3 will only have Cinegammas unless you get the Dual Link upgrade.

James Houk · January 23rd, 2011, 09:11 AM

According to Peter Crithary from the Rule Boston Camera presentation a couple of the Cinegamma settings (that ship standard) are hypergammas:

Cine 1 (Hypergamma 4)
460%, 109% output

Cine 2 (Hypergamma 2)
460%, 100% output

Cine 3 & 4
(Same as EX1 & EX3

(Watch 12 minutes, 53 seconds in)

Alister Chapman · January 23rd, 2011, 12:03 PM

This is nothing new. All PDW-F3** and EX's have the 4 Cinegammas and CG 1 has always been the same as HG4 and CG 2 has always been the same as HG 2. I've written about this many many times. It is not unique or new to the F3 as claimed by Peter, they have been around for at least 5 years. A bit like his statement that S-Log is like Raw, it is not anything like Raw, S-log is a processed signal and is not straight from the sensor.

AFAIK the standard F3 will have the same 4 CG's as an EX1/3, it just so happens that 2 of these are the same as hypergammas.

Bruce Schultz · January 24th, 2011, 08:29 PM

"Originally Posted by Jim Tittle
I understand--with S-log, there's so much data that it takes dual SDI and a special recorder to handle it."

I am currently shooting 4:4:4 RGB C-Log (same as S-Log) on an Arri Alexa for film-out on a Dreamworks Animation project. We are recording onto 32Gb SxS cards.

James Houk · January 24th, 2011, 08:37 PM

Glad to know SxS cards are fast enough for 4:4:4 footage, but you still need a recording device with the right hardware.

The PMW-F3 may have SxS card slots, but that doesn't mean it has the hardware to actually feed a 4:4:4 signal to those slots.

Even if it costs 20k to activate S-Log output on the camera and buy a field recorder (likely less using CineDeck) that's going to clock in at half the price of an Alexa.

Dave Sperling · January 24th, 2011, 09:15 PM

The SxS cards should be fast enough for the compressed pro-res that the Alexa records on them. The new SxS cards have a data rate around 1200 Mbps as I recall, while the prores is compressing the 444 at about 330 Mbps. Of course with the Alexa as well, to record at a higher data rate you'll need to do that to an outboard record system.
I'd be interested to learn more about the specifics of the Dreamworks project - is this live action footage that's being used as an element in animation? / what kind of downstream manipulation is the footage getting between the camera record and the eventual filmout?

January 23rd, 2011, 03:05 AM	#16
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	With a noisy camera there is no advantage to 10 bit over 8 bit for acquisition as all the extra bits don't contain any useful extra data. The posterisation is caused by the sensor noise itself or by quantisation artefacts. Increasing the bit-rate to reduce quantisation is certainly beneficial and often the advantage seen from a 10 bit over 8 bit codec may be due to a significant bit rate increase (provide you factor in the extra data required to record 10 bits and any codec efficiency factors), thus a reduction in quantisation. You need to ensure you have a noise figure for the sensor that is better than 58db for a traditional gamma curve, with log it is a bit different because of the way the samples are spread further apart as you go higher up the curve. Editing is different as when you change or manipulate the image you will then be creating new samples and it is beneficial to be able to record those new samples with as little truncation as possible. AFAIK the F3 will only have Cinegammas unless you get the Dual Link upgrade. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

January 23rd, 2011, 09:11 AM	#17
James Houk Regular Crew Join Date: Jan 2011 Location: Nashville, TN Posts: 78	According to Peter Crithary from the Rule Boston Camera presentation a couple of the Cinegamma settings (that ship standard) are hypergammas: Cine 1 (Hypergamma 4) 460%, 109% output Cine 2 (Hypergamma 2) 460%, 100% output Cine 3 & 4 (Same as EX1 & EX3 Learning Lab: Sony?s PMW-F3 Super 35 Digital Camera on 1.19.11 on Vimeo (Watch 12 minutes, 53 seconds in) __________________ www.viddovation.com

January 23rd, 2011, 12:03 PM	#18
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	This is nothing new. All PDW-F3** and EX's have the 4 Cinegammas and CG 1 has always been the same as HG4 and CG 2 has always been the same as HG 2. I've written about this many many times. It is not unique or new to the F3 as claimed by Peter, they have been around for at least 5 years. A bit like his statement that S-Log is like Raw, it is not anything like Raw, S-log is a processed signal and is not straight from the sensor. AFAIK the standard F3 will have the same 4 CG's as an EX1/3, it just so happens that 2 of these are the same as hypergammas. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

January 24th, 2011, 08:37 PM	#20
James Houk Regular Crew Join Date: Jan 2011 Location: Nashville, TN Posts: 78	Glad to know SxS cards are fast enough for 4:4:4 footage, but you still need a recording device with the right hardware. The PMW-F3 may have SxS card slots, but that doesn't mean it has the hardware to actually feed a 4:4:4 signal to those slots. Even if it costs 20k to activate S-Log output on the camera and buy a field recorder (likely less using CineDeck) that's going to clock in at half the price of an Alexa. __________________ www.viddovation.com

January 24th, 2011, 08:29 PM	#19
Bruce Schultz Major Player Join Date: Apr 2008 Location: Malibu, CA Posts: 480	"Originally Posted by Jim Tittle I understand--with S-log, there's so much data that it takes dual SDI and a special recorder to handle it." I am currently shooting 4:4:4 RGB C-Log (same as S-Log) on an Arri Alexa for film-out on a Dreamworks Animation project. We are recording onto 32Gb SxS cards.

January 24th, 2011, 09:15 PM	#21
Dave Sperling Major Player Join Date: Jan 2010 Location: Tinton Falls, NJ Posts: 780	The SxS cards should be fast enough for the compressed pro-res that the Alexa records on them. The new SxS cards have a data rate around 1200 Mbps as I recall, while the prores is compressing the 444 at about 330 Mbps. Of course with the Alexa as well, to record at a higher data rate you'll need to do that to an outboard record system. I'd be interested to learn more about the specifics of the Dreamworks project - is this live action footage that's being used as an element in animation? / what kind of downstream manipulation is the footage getting between the camera record and the eventual filmout?