Using a DOF simulator for ULF 14X16" Film 800 mm Lens

[Tin Can]

I use this online DOF and a bit lost in how to best use the title combo

https://dofsimulator.net/en/?x=F9ADcArKgAAAJMwkAAADgAA

It only goes to 11X14

I want to use my 14X16" film and holders

THIS Summer!

[MAubrey]

I use this online DOF and a bit lost in how to best use the title combo

https://dofsimulator.net/en/?x=F9ADcArKgAAAJMwkAAADgAA

It only goes to 11X14

I want to use my 14X16" film and holders

THIS Summer!

An 800mm lens at f/22 on 14x16 would be equivalent to ~672mm f/18 on 11x14. The crop factor for DoF between the two formats is .84x.

[Tin Can]

Thank you!

[rawitz]

DOF is physically relative to focal lenth and the f-stop of the lens, not to the film format. A 150mm lens at f11 always gives the same DOF no matter the film format (a 150mm lens as a telelens for 35film, a normallens for 4x5, or uwidelens for 8x10).
The DOF calculations relative to the film format are defined to a final printsize. For a target printsize of 20x28´ you have to enlarge 35mm film 20x, a 4x5 film 6x and 8x10 film 3x, so for the same printsize DOF sharpness a 8x10 filmshot can be about 7x less sharp than a 35mm. DOF unsharp-circle tolerance for 35mm film is 0,03mm, for 8x10 is 0,2mm. These values are defined by convention, not physic.

[Tin Can]

Thank you

DOF is physically relative to focal lenth and the aperture of the lens, not to the film format. A 150mm lens at f11 always gives the same DOF no matter the film format (a telelens for 35film, a normallens for 4x5, or uwidelens for 8x10).
The DOF calculations relative to the film format are defined to a final printsize. For a target printsize of 20x28´ you have to enlarge 35mm film 20x, a 4x5 film 6x and 8x10 film 3x, so for the same printsize DOF sharpness a 8x10 filmshot can be about 7x less sharp than a 35mm. DOF unsharp-circle tolerance for 35mm film is 0,03mm, for 8x10 is 0,2mm. These values are convention, not physic.

[rawitz]

If the DOF calculator gives 0,3mm tolerable unsharp-circle for 11x14, this calculation gives about 0,4mm for your 14x16. That expands the 11x14 values to about x1,2 or x0,8f-stop number (as said obove).
But its your decision, whether you are satisfied with equal DOF sharpness compared to much smaller filmsizes or you want to profit from the superior sharpness of ultralarge format. The general recommendation here is to stop down at least one, better two f-stops more as the DOF calculation.

[Tin Can]

I shoot soft focus people

The eye matters

I sometimes close down my NIKON 610 f9

If the DOF calculator gives 0,3mm tolerable unsharp-circle for 11x14, this calculation gives about 0,4mm for your 14x16. That expands the 11x14 values to about x1,2 or x0,8f-stop number (as said obove).
But its your decision, whether you are satisfied with equal DOF sharpness compared to much smaller filmsizes or you want to profit from the superior sharpness of ultralarge format. The general recommendation here is to stop down at least one, better two f-stops more as the DOF calculation.

[rawitz]

I shoot soft focus people
The eye matters
I sometimes close down my NIKON 610 f9

That changes the task. Not the most obtainable DOF, but the most pictorially DOF is what you want. For that task trust your eyes on the screen of your camera.

[Tin Can]

I do my best

I am going blind and no longer drive

I am setting up the string method

and 30' RO hose for a big Packard

That changes the task. Not the most obtainable DOF, but the most pictorially DOF is what you want. For that task trust your eyes on the screen of your camera.

[Drew Bedo]

Not sure I understand the problem.

I have never used anything larger than 8x10.

I am visually impaired (lets leave it at that for this thread) and this is what I have found to be helpful: I set up a table-top or still life and put one or more focusing aids in the composition, usually these are a bar code from a package. I can see the bars snap in and out of focus wide open and use that to set up the front tilt/swing. Then stop down to see if it holds. I have used a strong tactical flashlight as a spot, moving it from bar code to bar code while checking stopped down.

I have read (here) of photographers using a laser pointer in a similar way when shooting outdoors.