Nokton 50mm f/1.1 on R3A

[Sparrow]

If you stay out of the Macro range the DOF is only affected by aperture and magnification, i.e. same aperture and magnification = same DOF.

Yes clearly all 50mm at f8 are the same regardless of maximum aperture, but what about the different magnifications of a 50 and 75 at the same FOV.

 

[ath]

The focal length doesn't matter. Only magnification and aperture.

A 50mm at f/2 taking a tight headshot has the same DOF as a 100mm f/2 taking a tight headshot. The distance is different but the magnification the same.
(the magnification has focal length and distance combined in it)

Type in a few examples in a dof calculater and check yourself.
Alternatively you can do the math.

 

[Toni Nikkanen]

This is the philosophical part I wanted to avoid 😉

The point of the discussion was to get an impression of how hard the 50/1.1 would be to focus. If one has used a 75/2.5 at 1 meter successfully he will know how hard it is to focus the 50/1.1 at 1 meter. Then he will have gotten his answer regardless of the fact that we are talking about an entirely different image; the focusing difficulty was the question.

 

[Sparrow]

This is the philosophical part I wanted to avoid 😉

The point of the discussion was to get an impression of how hard the 50/1.1 would be to focus. If one has used a 75/2.5 at 1 meter successfully he will know how hard it is to focus the 50/1.1 at 1 meter. Then he will have gotten his answer regardless of the fact that we are talking about an entirely different image; the focusing difficulty was the question.

yep that's what I meant originally, then we had a bit of mission creep

 

[Roger Hicks]

Stewart is almost certainly correct -- he is not given to making such categorical statements without checking first -- but I have found the 50/1.5 marginal at less than 2 metres with the smaller magnification finder (R2 series) and I'd suspect that the 50/1.1 would be about equally marginal with the 1.0x. After all,the mechanical accuracy (base length) is not improved: only the effective accuracy (effective base length).

By 'marginal' I mean that while it's possible to focus slowly and carefully, as long as you have excellent eyesight (corrected if necessary), when you're working quickly there may be times when you're pushing your luck.

In other words, it'll almost always work, but not infallibly. Though I suppose that's true of most manual focusing systems. It's even more true of autofocus!

Tashi delek,

R.