A proposal: a constant measure for depth of field

[Aryel]

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19 minutes ago, farnz said:

I think it's a picture from a novel Lytro camera, which is a "Light-field" camera that captures all the light rays in the field (not just one plane) at one instant and uses mathematical formulae to subtract light rays afterwards to provide the image at different apertures.  (That's my unclear explanation anyway. )

No idea how the sensor works but I think you are right 😅. Thanks. 

Edited February 16, 2022 by Aryel

[farnz]

6 hours ago, Aryel said:

No idea how the sensor works but I think you are right 😅. Thanks. 

It's also called a Plenoptic camera and it has an array of micro-lenses in front of the sensor that each have a tiny version of the image that arrives from the lens but at a slightly different angle owing to the position of the micro-lens in the array compared to the image directly from the lens.  From this the angle of the light rays can be determined so that the image can be recalculated using the appropriate rays through the particular micro-lenses to show the original images at different planes of focus as desired.  

The web site has a neat little moving diagram that shows how it works and a video clip explaining it.

Pete.

[raizans]

What we're really looking for is the equivalent of Exposure Value.

I.e., Given an arbitrary baseline, assign a Depth-of-Field Value (DV) for combinations of sensor size, lens focal length, and aperture.

For instance, DV 10 can be defined as 135 format, 50mm lens, f/1.4.

That would mean on an APS-C camera, you'd need a 35mm lens at f/1.0 to get DV 10.

You don't need to get into magnification and circle-of-confusion or any of that to make this scale practical.

Edited February 16, 2022 by raizans

[earleygallery]

Just learn photography with an SLR that doesn't have auto aperture, like a Zenit B. You get a good understanding of DOF that you will carry in your brain, without any complicated scales/values to try and compute!

[rcusick]

3 hours ago, raizans said:

What we're really looking for is the equivalent of Exposure Value.

I.e., Given an arbitrary baseline, assign a Depth-of-Field Value (DV) for combinations of sensor size, lens focal length, and aperture.

For instance, DV 10 can be defined as 135 format, 50mm lens, f/1.4.

That would mean on an APS-C camera, you'd need a 35mm lens at f/1.0 to get DV 10.

You don't need to get into magnification and circle-of-confusion or any of that to make this scale practical.

Yes...

[Ouroboros]

 

The whole idea seems like a creative photography killer to me.

 

[laowai_]

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On 2/14/2022 at 10:12 PM, rcusick said:

I was pondering how to capture a constant measure of depth of field.... Why not something akin to a "stop of light?"  I'll call it the "cu stop" after my last name.  

Like a stop of light - where the constant in the equation is the exposure to light - the cu stop constant would be a depth of field.  

Exposure has three variables - shutter speed, aperture and iso.  A cu stop would have thee variables as well - aperture, sensor size and focal length.   

Thoughts?  This would help equalize for different equipment setups - apsc vs full frame vs large format, aperture and type of lens.  

 

Well, there's the Zeiss formula that comes close to your proposal...

https://en.wikipedia.org/wiki/Zeiss_formula