Sparrow
Veteran
ath
Well-known
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.
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
Well-known
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.
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
Veteran
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
Veteran
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.
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.