How to use DOF calculator with Red ?

[Etienne Caron]

Hi,

I knew that Red sensor have DOF shorter than 35mm, but not as much as ive seen. The DOF drop very drasticly.

I really have to use a good way to know exatly what is in focus and what it is not.

I want to use this DOF calculator:
http://www.dofmaster.com/dofjs.html

and want to know the circle of confusion use for calculate my DOF if:

I shoot 4K 2:1, 1.85 for 2K projection (film print)

and if

I shoot 4K 2:1, 16x9 for 1080 HDTV.


Do i use CoC: 0.010mm for film print and CoC: 0.012mm for HD1080 ? Can i use 35mm setting and open a stop to fit the DOF have with Red at 4K ?

Thanks, it will very help me to know that.

Etienne

 

[David Didato]

I've been using .025mm for 35mm film. I haven't found any definitive answers to this though. Anyone?

 

[Pawel Achtel]

I've been using .025mm for 35mm film. I haven't found any definitive answers to this though. Anyone?

It has been discussed before.

For all intents and purposes the CoC used in calculating DOF would be about 30% larger than the pixel/photosite size. This is a bit smaller CoC than used in film and for Red One Mysterium sensor is somewhere between 8-10 microns.

 

[Etienne Caron]

This is a bit smaller CoC than used in film and for Red One Mysterium sensor is somewhere between 8-10 microns.

Thanks Pawel, so in short i have to use the setting "CoC: 0.010mm" with Depth of Field Calculator ? For exempple, this setting bring a 50mm, f5.6, subject distance at 10 feet with a near limit to 9.36 ft and a far limit to 10.7 ft ? this is really a short DOF that Red sensor have... too much i would say.


Thanks

 

[Hans-Georg Daun]

Etienne,

There is no reason, why the RED sensor should have a narrower depth of field than 35mm film format. The sensor is very nearly the same size as super 35mm and if your final resolution is fixed at 2K or HD (and you do not crop), than both will have the same DOF. Regular 35mm film DOF should be slightly narrower, even.

I have arrived at the same CoC figures as you, by simply dividing sensor size by horizontal resolution. Maybe that is just too aggressive.

Cheers,
Hans