Jump to content


Photo

Circle of Confusion for a Red and Cooke S4s


  • Please log in to reply
24 replies to this topic

#1 Alex Worster

Alex Worster
  • Basic Members
  • PipPipPip
  • 113 posts
  • Film Loader

Posted 18 January 2008 - 01:59 AM

Quick question which hopefully somebody can help me with. In a couple days I'll be going out with a Red and a couple Cooke S4s, a couple Zeiss Super Speeds, and maybe an Angenieux Optimo 24-290 for a full day of tests for an upcoming feature that I'll be ACing. I was wondering if anybody has worked out an optimum circle of confusion for this set up. It will likely be going to the big screen for at least a couple showings so I need to make sure my focus is not compromised by a circle of confusion that is too lenient. So far I've just used the default CofC that came with pCAM but as my jobs get a little more high profile (not really high profile in the grand scheme of things) I wonder more and more if I should be inputting my own. I've got to admit that I'm a little uneducated as far as CofC goes but any info would help very much especially input from anyone that has worked with a similar type set up.
  • 0

#2 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 18 January 2008 - 02:42 AM

Well, at 2 K or 4-ish K that puts the red in the realm of a transfer from 35mm. Since it has the same frame size as 35mm and you do have to worry about theatrical projection, I would give it the same treatment as 35mm for theatrical projection. It may be a bit on the cautious side but that's good.
  • 0

#3 Alex Worster

Alex Worster
  • Basic Members
  • PipPipPip
  • 113 posts
  • Film Loader

Posted 18 January 2008 - 02:53 AM

That's exactly how I plan to treat it but more what I'm wondering is what exactly people believe would be a good CofC number. My pCAM came default with a 0.001" (25.40 micron) CofC for 35mm. Again because I only understand CofC in theory and am not quite sure what these numbers actually relate to I'm wondering if I should stick with this default number or go with something different? I would want to err on the safe side and input less tolerant CofC, especially because this might be going to a big screen. Any thoughts, numbers, a lesson or two, etc. Thanks in advance.
  • 0

#4 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 18 January 2008 - 03:08 AM

Will you be shooting any tests of a Century focus chart and doing a film out of the footage? It's the best way to really know for sure how sharp your CofC is...in my experience.
  • 0

#5 Alex Worster

Alex Worster
  • Basic Members
  • PipPipPip
  • 113 posts
  • Film Loader

Posted 18 January 2008 - 03:19 AM

First off, thanks Chris for your response. Jonathan, I will probably be able to make a Century chart test happen but I don't believe the final product will be going through a film out, it would be pretty sweet though. I would imagine the final out will be going to some hi def medium. How exactly would you perform such a test if you don't mind explaining or do you know of a link (possibly on this site, I did a brief search I swear but no luck) where I could find info on a good way to find a the CofC that works with what I want to do? Thanks again to those who have the time to help. Also for those ACs that do get to work with 35 or 35 sized sensors and have their work go to the big screen what type of CofC are you generally working with?
  • 0

#6 Alex Worster

Alex Worster
  • Basic Members
  • PipPipPip
  • 113 posts
  • Film Loader

Posted 18 January 2008 - 03:58 AM

The plot thickens... I just received notice that a film out might be in the works for this project so now I really have to be on my game. As always any help is much appreciated.
  • 0

#7 Satsuki Murashige

Satsuki Murashige
  • Sustaining Members
  • 3510 posts
  • Cinematographer
  • San Francisco, CA

Posted 18 January 2008 - 04:20 AM

Hey Alex,

Cooke have their own DoF tables for the S4s: http://www.cookeopti...nsf/product/dfc
They are set for 0.001". You could set your CoC in PCam to 0.0015" if you wanted to err on the safe side.

Awhile back I suggested starting a database here for recommended CoC with specific lens and format setups but no one was interested. One possible reason for this was that determining the correct CoC is very subjective - what may seem like acceptable focus for one person may not be acceptable to someone else. Probably your best bet would be to shoot harp tests for each lens, watch the footage at native res in RedCine or FCP and see how closely the focus matches to your CoC setting. Then adjust your CoC settings as necessary. Chris Keth explains how to perform a harp test here: http://www.cinematog...mp;hl=harp test

I see now that you're possibly doing a filmout. Any idea at what res the filmout will be done at? You can try asking the DP if you can get the test footage filmed out so you can see how that whole process affects the focus. (Good luck with that!). If the DP is also shooting tests that day that are destined for filmout, then maybe you can piggyback your tests onto his.

Anyway, good luck - it sounds like an awesome gig! Let me know if you need any help, I'll be around.
  • 0

#8 Satsuki Murashige

Satsuki Murashige
  • Sustaining Members
  • 3510 posts
  • Cinematographer
  • San Francisco, CA

Posted 18 January 2008 - 06:11 AM

P.S. If you're renting any of that gear at Lee's, I would give Charlie a call. He's going to be the RED rental expert there, or so he tells me. Just don't call him on your cell phone, or he'll eat up all your minutes. :)
  • 0

#9 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 18 January 2008 - 07:36 PM

How exactly would you perform such a test if you don't mind explaining or do you know of a link (possibly on this site, I did a brief search I swear but no luck) where I could find info on a good way to find a the CofC that works with what I want to do?


You basically want to shoot a test of this chart: Posted Image

CoC wise, you only care about the horizontal and vertical lines marked with letters. But this chart is great for getting as much lens information as you can to make sure focus is good all across the frame.

You'll want to shoot the chart at full frame, accurately measured for distance and in focus for each prime lens and at various f/stops. S4's are quite sharp when they're wide open, but all lenses are at their best when they're closed down a little. And if there's any difference, you'll definitely see it in a projected 35mm print. If you plan to have a zoom lens for the shoot too, be sure to test it using the same method but at varying focal lengths of course.

So, once you have the print up and projected, you'll have to watch those lines marked with letters and make a subjective decision as to at which point, or what "letter", is the image out of focus. It's been a while, but I believe there's a cross reference to the letters on the chart that gives you your CoC.

Lee Utterbach has a test chart in their prep area/lobby, so you could probably set up there and shoot your tests.

IMO, CoC reallly isn't really the most important aspect from an AC's point of view. But in learning about the Red camera and it's film out capabilities, it'll be really interesting to see those tests from a DP's point of view. Your main concern on the shoot as focus puller should be DoF and staying as dead on as possible. Since it's a 35mm sensor, your DoF is the same as if you're shooting 35mm film...or at least it should be.

But, try and hold onto that print afterwards, I'd love to have a chance to see it if you're willing to share it!.
  • 0

#10 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 18 January 2008 - 07:39 PM

P.S. If you're renting any of that gear at Lee's, I would give Charlie a call. He's going to be the RED rental expert there, or so he tells me. Just don't call him on your cell phone, or he'll eat up all your minutes. :)


That's pretty cool. Charlie's just a good guy in general.
  • 0

#11 Simon Miya

Simon Miya
  • Sustaining Members
  • 82 posts
  • Other
  • Portland, OR

Posted 21 January 2008 - 12:26 PM

They are set for 0.001". You could set your CoC in PCam to 0.0015" if you wanted to err on the safe side.


You should set the circle of confusion to a smaller number for that purpose. You specified a larger value.

0.001" is the number recommended for 35mm cameras and projected output. You should not need to change it for full-frame Red use.

Edited by Simon Miya, 21 January 2008 - 12:28 PM.

  • 0

#12 Satsuki Murashige

Satsuki Murashige
  • Sustaining Members
  • 3510 posts
  • Cinematographer
  • San Francisco, CA

Posted 21 January 2008 - 01:51 PM

You should set the circle of confusion to a smaller number for that purpose. You specified a larger value.

0.001" is the number recommended for 35mm cameras and projected output. You should not need to change it for full-frame Red use.

Oops, you're totally right Simon! So sorry about that - I meant to say 1/1500" is tighter tolerance than 1/1000" but that would be about 0.0006" and not 0.0015".

BTW, do you always use 0.001" for all 35mm print work, or do you change it if you're shooting scope, or shooting spherical with softer lenses like the old Cooke Speed Panchros?
  • 0

#13 David Negrin

David Negrin
  • Basic Members
  • PipPip
  • 15 posts
  • Cinematographer
  • L.A.

Posted 31 January 2008 - 10:31 AM

Hey Alex and Others

I recently been dealing with red directly, and their ( Randy or Travis ) support team said they were going to be sending me conversions
via Email. I was told ... the 24.4mm sensor is the same as 35mm film, thats why the red can use regular spherical cine. lenses .
When We shoot 35mm film if you've ever actually measured the film, you'd see that the film we shoot is only 32mm, 35mm is print film
with room for optical sound. Out of that 32mm we use and image area of 25mm (1"). thats why the 1" sensor is such a big deal ... the capture
area of the chip matches the size of film, So, there is no conversion on depth. However, we all know that HD see more detail than the human eye
( just look at any "beautiful" woman in a ecu ) so Always give a glance to the onboard you can pull off the HD monitor. It defintely is an acquired
taste especially if your use to doing traditional focus. I remember a D.P. named Hugh Garnier, he was 800 years old and I was 23 when we
worked together, I pulled out the samcine to see what I had as far as depth, he Looked at me and said " Kid your either in or out, put that thing
away until I ask for a focus split ... I've never used it since, I've loaned it to the other guys, but not myself.
So, breathe, relax,and have a good shoot
  • 0

#14 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 31 January 2008 - 10:22 PM

" Kid your either in or out, put that thing away until I ask for a focus split ... "


I like that. It's generally my philosophy. Except for the few times when I or a DP wants EVERYTHING in focus or something.
  • 0

#15 Alex Worster

Alex Worster
  • Basic Members
  • PipPipPip
  • 113 posts
  • Film Loader

Posted 31 January 2008 - 11:11 PM

It sounds good but, no disrespect intended, that i disagree. It does sound funny but really those calculators (pCam, samcine or whatever) are invaluable. What happens if it's dark so you're shooting wide open and the actor walks into close up and misses their mark. The director calls cut and you ask the actor and camera to hold for focus. The op looks at you and says it looked okay but you break out the tape and the calculator and it turns out you missed it by a couple inches. It may look okay in the finder but on the big screen you've got a shot that's just enough out of focus to be annoying or even worse, unusable. Why wast everyone's time and the production's money if you think you missed it and request another take but a simple dof calculation says you're fine or move on when you have missed it but the op doesn't report a problem. It seems like your job is to make sure what should be in focus is in focus and any tools that help why not use? Especially if they do save time and therefore money. On the flip side I have seen 1sts get lost in their dof calculators and cost time therefore money. It's a fine line I guess.

I guess what really prompted this question was that with the Red's (really this goes for any 4k camera) 35 sensor, the sharpness 4k can capture, and the "cleanness" of 4k HD/ lack of film grain to give the image some texture, I would be afraid that any slightly buzzed shots would be more apparent. Maybe I'm obsessing about it too much or maybe it's because I'm still fairly new to the game but I just want to be able to do my job with confidence and not ever get a call a week down the road about a shot I blew.

I'll feel much better when the HD/SDI outs on the Red start working and 4k capable monitors come around. Until then I don't truly trust monitors with the Red, same for any 4k camera I guess. I still think of Red monitors like onboards I guess.

The more I think about it and type out what I think it seems like these neurosis might fade the more confident I get but until then I like the numbers to make me feel better.

On another subject I didn't know camera original was 32mm. I thought it was 35mm and shooting regular 35 you just weren't shooting in the soundtrack area but it was still there. And then with super 35 you were shooting that extra soundtrack area. If that's true I've learn a little something new here today.

Thanks as always for everyones input.
  • 0

#16 David Negrin

David Negrin
  • Basic Members
  • PipPip
  • 15 posts
  • Cinematographer
  • L.A.

Posted 19 February 2008 - 10:52 PM

It sounds good but, no disrespect intended, that i disagree. It does sound funny but really those calculators (pCam, samcine or whatever) are invaluable. What happens if it's dark so you're shooting wide open and the actor walks into close up and misses their mark. The director calls cut and you ask the actor and camera to hold for focus. The op looks at you and says it looked okay but you break out the tape and the calculator and it turns out you missed it by a couple inches. It may look okay in the finder but on the big screen you've got a shot that's just enough out of focus to be annoying or even worse, unusable. Why wast everyone's time and the production's money if you think you missed it and request another take but a simple dof calculation says you're fine or move on when you have missed it but the op doesn't report a problem. It seems like your job is to make sure what should be in focus is in focus and any tools that help why not use? Especially if they do save time and therefore money. On the flip side I have seen 1sts get lost in their dof calculators and cost time therefore money. It's a fine line I guess.

I guess what really prompted this question was that with the Red's (really this goes for any 4k camera) 35 sensor, the sharpness 4k can capture, and the "cleanness" of 4k HD/ lack of film grain to give the image some texture, I would be afraid that any slightly buzzed shots would be more apparent. Maybe I'm obsessing about it too much or maybe it's because I'm still fairly new to the game but I just want to be able to do my job with confidence and not ever get a call a week down the road about a shot I blew.

I'll feel much better when the HD/SDI outs on the Red start working and 4k capable monitors come around. Until then I don't truly trust monitors with the Red, same for any 4k camera I guess. I still think of Red monitors like onboards I guess.

The more I think about it and type out what I think it seems like these neurosis might fade the more confident I get but until then I like the numbers to make me feel better.

On another subject I didn't know camera original was 32mm. I thought it was 35mm and shooting regular 35 you just weren't shooting in the soundtrack area but it was still there. And then with super 35 you were shooting that extra soundtrack area. If that's true I've learn a little something new here today.

Thanks as always for everyones input.


Alex -
If you've got the director calling for focus before the D.P. ; Camera Operator ; or yourself ... then there's a larger camera dept. problem
that needs to be rectified. Being sort of new ? maybe you haven't done a long lens type of show. I work in episodic Predominantly where there is no other stop than WFO and the MM would be from 180 mm - 275 mm all day. No forgiveness, no missing, or you'll end up missing. After a while of pulling, the DoF charts will be memorized just by checking them out so often , As for Obsessing , that's good in moderation. Remember your target format ( t.v. : theater ) . the parameters for television is much more forgiving than theater, Much in the way that as overwhelming as a 4k signal is, the only 4k theater I know of is at Dalsa , the makers of the origin camera in woodland hills , So even a 4k signal is going to have to down res. before anyone can use it for public presentation, And as much as it lacks professionalism that means that small buzzes will be lost in down res. .
The difference between someone who's good and someone who's great is know what rules can bend.

Dave
  • 0

#17 Alex Worster

Alex Worster
  • Basic Members
  • PipPipPip
  • 113 posts
  • Film Loader

Posted 20 February 2008 - 12:58 AM

Just to be clear I wasn't trying to attack you personally. Hope it didn't come across that way.

I think you're right. Just to clear up the director has never asked me to check focus, it's always me, I agree that would be a little weird. I think there is a lot the idea of an AC sixth sense being learned over time. Kind of like on the few features I've done the dof calc comes out less and less as the days go by.

TV sounds scary man. Hopefully if the strike put you out of a job things get rolling soon.

Good point about the down res before distribution. I hadn't thought of that.

Edited by Alex Worster, 20 February 2008 - 12:59 AM.

  • 0

#18 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 20 February 2008 - 01:28 AM

How'd the tests go? Has production begun yet, or come & gone yet?
  • 0

#19 Alex Worster

Alex Worster
  • Basic Members
  • PipPipPip
  • 113 posts
  • Film Loader

Posted 20 February 2008 - 01:41 AM

Tests went well. Haven't seen the picture yet but the camera is not a disaster as I thought it might be, granted there are still some serious issues that need to be taken care of. I planned for the worst so I guess that way I'm always pleasantly surprised. Doing another test next week to see how it handles green screen and plate work. Should be fun, the package will be nicer than last time with ultra primes thrown in the mix to see how those stack up. should be a fun couple days. As of now production is slated to begin in early Juneish I think.
  • 0

#20 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 20 February 2008 - 01:47 AM

Nice, keep us posted!

I have the opportunity to work with the SI-2K camera next month, I'm really looking forward to it :)
  • 0


Rig Wheels Passport

Willys Widgets

Gamma Ray Digital Inc

Visual Products

Metropolis Post

Paralinx LLC

Broadcast Solutions Inc

Technodolly

Opal

Glidecam

The Slider

Tai Audio

rebotnix Technologies

Aerial Filmworks

Media Blackout - Custom Cables and AKS

Abel Cine

Ritter Battery

CineTape

Wooden Camera

CineLab

FJS International, LLC

Ritter Battery

Abel Cine

Opal

The Slider

Technodolly

Willys Widgets

Paralinx LLC

Tai Audio

CineTape

Glidecam

FJS International, LLC

Visual Products

rebotnix Technologies

Broadcast Solutions Inc

Wooden Camera

Aerial Filmworks

Media Blackout - Custom Cables and AKS

Rig Wheels Passport

CineLab

Gamma Ray Digital Inc

Metropolis Post