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Pulling wild focus


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13 hours ago, David Mullen ASC said:

Greg, what do you think of the 1/1000th of an inch CoC figure used for 35mm cine format? Seems a bit random in today’s world of different sensors, different presentation systems, different viewing sizes, etc.

I hear what you’re saying David. I’m comparing the Kelly Wheel to the Samcine which offers the user 3 different CoCs to choose from. The Kelly does not. 
 

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On 8/28/2020 at 11:22 AM, David Mullen ASC said:

Greg, what do you think of the 1/1000th of an inch CoC figure used for 35mm cine format? Seems a bit random in today’s world of different sensors, different presentation systems, different viewing sizes, etc.

Good question!

I'm actually curious to know how often cinematographers and ACs actually use depth of field tables (or apps) with set COC figures these days? 

Is it something you use to plan the lighting needs for an upcoming scene, or to help work out blocking/actors marks for a particular aperture/focal length, or to just get a general sense of what your workable depth of field is during a scene?

With modern monitors can't you gauge what your acceptable depth of field is just off the monitor, or is that not always a reliable indication? How does the calculated depth of field from an app compare to the perceived depth of field from a monitor?

Does anyone select COC figures depending on the camera or the delivery resolution rather than the sensor size/format?

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17 minutes ago, Dom Jaeger said:

Good question!

I'm actually curious to know how often cinematographers and ACs actually use depth of field tables (or apps) with set COC figures these days? 

Is it something you use to plan the lighting needs for an upcoming scene, or to help work out blocking/actors marks for a particular aperture/focal length, or to just get a general sense of what your workable depth of field is during a scene?

With modern monitors can't you gauge what your acceptable depth of field is just off the monitor, or is that not always a reliable indication? How does the calculated depth of field from an app compare to the perceived depth of field from a monitor?

Does anyone select COC figures depending on the camera or the delivery resolution rather than the sensor size/format?

That’s another good question Dom. The CoC really doesn’t come into consideration on a daily basis. These days with 8K resolution and the want of shooting wide open, all you need to know is that there isn’t any dof. Stay vigilant. If any dof charts are used these days, I would say the P-cam app is it. But you’re right in observing that we can see the depth on HD monitors. The random times that I will still look up a dof calculation would be for wide shots when I have to hold a specific range in focus. I can pretty much calculate it in my head faster than I can look it up but I still sometimes need to confirm my expectations. Otherwise, what’s the point? Just do your job and keep the shot in focus!

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The app I use (Pocket AC on android) has several CoC options which are pretty useful based on the camera format selected. Either 'traditional' based on sensor size, 'resolution' based on photosite size, and 'hybrid/dynamic' which combines the two.

I switch depending on output the format that is likely as music videos are usually only seen on phone screens and commercials could be seen on 55" TVs.

Most of the time there's not much need to check these days. Mostly looking through the app before working with a new format to see how it compares to formats I'm familiar with.

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Where I think a DOF calculator is more useful is planning deeper focus shots and wondering what range will hold, how deep do you have to stop down (like for shooting miniatures) though the truth is that the first thing you do when you want deep focus is to light to the deepest stop that is possible! But I guess if you know that you won't be able to get beyond f/8, for example, on a particular set-up, then the calculation would tell you what will fall into acceptable focus.

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