film vs CMOS
 

On 2018-08-14 09:08, nospam wrote:
In article , NY
wrote:

One other factor to bear in mind: the depth of field varies with lens focal
length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

film vs CMOS
 

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with lens
focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes, and
in some cases (usually movies), t/stops are used, which is actual light
transmission through the lens, not a simple ratio.

film vs CMOS
 

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with lens
focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes, and
in some cases (usually movies), t/stops are used, which is actual light
transmission through the lens, not a simple ratio.

film vs CMOS
 

On 2018-08-25 15:06, nospam wrote:
In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with lens
focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes, and
in some cases (usually movies), t/stops are used, which is actual light
transmission through the lens, not a simple ratio.


Are you claiming that focal length has no bearing on depth of field?
That's an interesting viewpoint.

film vs CMOS
 

On 2018-08-25 15:06, nospam wrote:
In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with lens
focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes, and
in some cases (usually movies), t/stops are used, which is actual light
transmission through the lens, not a simple ratio.


Are you claiming that focal length has no bearing on depth of field?
That's an interesting viewpoint.

film vs CMOS
 

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with lens
focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes, and
in some cases (usually movies), t/stops are used, which is actual light
transmission through the lens, not a simple ratio.

Are you claiming that focal length has no bearing on depth of field?

for the same subject size and same image quality (coc), no.

That's an interesting viewpoint.

not really. it's just math.

film vs CMOS
 

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with lens
focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes, and
in some cases (usually movies), t/stops are used, which is actual light
transmission through the lens, not a simple ratio.

Are you claiming that focal length has no bearing on depth of field?

for the same subject size and same image quality (coc), no.

That's an interesting viewpoint.

not really. it's just math.

film vs CMOS
 

+++ATH0 wrote in
:

On 2018-08-14 09:08, nospam wrote:
In article , NY
wrote:

One other factor to bear in mind: the depth of field varies with
lens focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

That is correct. For any given focal length, the smaller the aperature, the
greater the depth of field. That is why pinhole cameras focus from closeup
to infinity without a lens.

film vs CMOS
 

+++ATH0 wrote in
:

On 2018-08-14 09:08, nospam wrote:
In article , NY
wrote:

One other factor to bear in mind: the depth of field varies with
lens focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

That is correct. For any given focal length, the smaller the aperature, the
greater the depth of field. That is why pinhole cameras focus from closeup
to infinity without a lens.

film vs CMOS
 

nospam wrote in
:

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with
lens focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes,
and in some cases (usually movies), t/stops are used, which is
actual light transmission through the lens, not a simple ratio.

Are you claiming that focal length has no bearing on depth of field?

for the same subject size and same image quality (coc), no.

That's an interesting viewpoint.

not really. it's just math.

No matter what the focal length of the lense is, the further away the
focal plane is, the greater the depth of field will be for any aperature.

As an example, if one is taking a head and shoulders portrait with a
large aperature, it is quite likely that part of the subject will be out
of focus slighty. Moving back a few feet with the same lense and
aperature will result in a deeper depth of field, so that all of the
subject should be in focus. The drawback is that the image size will be
smaller, and thus require more enlargement to obtain the same size image,
with the resulting loss of resolution with the enlarged image.

film vs CMOS
 

nospam wrote in
:

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with
lens focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes,
and in some cases (usually movies), t/stops are used, which is
actual light transmission through the lens, not a simple ratio.

Are you claiming that focal length has no bearing on depth of field?

for the same subject size and same image quality (coc), no.

That's an interesting viewpoint.

not really. it's just math.

No matter what the focal length of the lense is, the further away the
focal plane is, the greater the depth of field will be for any aperature.

As an example, if one is taking a head and shoulders portrait with a
large aperature, it is quite likely that part of the subject will be out
of focus slighty. Moving back a few feet with the same lense and
aperature will result in a deeper depth of field, so that all of the
subject should be in focus. The drawback is that the image size will be
smaller, and thus require more enlargement to obtain the same size image,
with the resulting loss of resolution with the enlarged image.

film vs CMOS
 

In article , Tim
wrote:

One other factor to bear in mind: the depth of field varies with
lens focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

That is correct.

nope.

For any given focal length, the smaller the aperature, the
greater the depth of field.

in other words, physical aperture.

physical aperture is often confused with f/stop. the former is the
diameter of the entrance pupil and the latter is the ratio of focal
length to that diameter.

That is why pinhole cameras focus from closeup
to infinity without a lens.

pinhole cameras have no refractive elements, so everything is 'in
focus' (ignoring diffraction effects and optimal pinhole diameter).

film vs CMOS
 

In article , Tim
wrote:


No matter what the focal length of the lense is, the further away the
focal plane is, the greater the depth of field will be for any aperature.

from your description below, you mean subject distance, not focal plane.

As an example, if one is taking a head and shoulders portrait with a
large aperature, it is quite likely that part of the subject will be out
of focus slighty. Moving back a few feet with the same lense and
aperature will result in a deeper depth of field, so that all of the
subject should be in focus. The drawback is that the image size will be
smaller, and thus require more enlargement to obtain the same size image,
with the resulting loss of resolution with the enlarged image.

you're changing the distance, resulting in photos with different size
subjects, so not a valid comparison. maintain the same subject size at
different distances (via different lenses) and the dof will be the
same, although the perspective won't be.

film vs CMOS
 

On 8/25/2018 9:13 PM, Tim wrote:
:
d thus require more enlargement to obtain the same size image,
with the resulting loss of resolution with the enlarged image.


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

https://en.wikipedia.org/wiki/Cardin...)#Nodal_points

The relationship between the censor size (film Size) the focal length of
the lens and the aperture, (whether fixed or variable) works the same
whether it is digital or a chemical film.

One of the laws of nature that can not be altered, which some people
thing are no longer in effect.


--
2018: The year we learn to play the great game of Euchre

film vs CMOS
 

On Sun, 26 Aug 2018 01:13:11 GMT, Tim wrote:

nospam wrote in
:

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with
lens focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes,
and in some cases (usually movies), t/stops are used, which is
actual light transmission through the lens, not a simple ratio.

Are you claiming that focal length has no bearing on depth of field?

for the same subject size and same image quality (coc), no.

That's an interesting viewpoint.

not really. it's just math.

No matter what the focal length of the lense is, the further away the
focal plane is, the greater the depth of field will be for any aperature.

As an example, if one is taking a head and shoulders portrait with a
large aperature, it is quite likely that part of the subject will be out
of focus slighty. Moving back a few feet with the same lense and
aperature will result in a deeper depth of field, so that all of the
subject should be in focus. The drawback is that the image size will be
smaller, and thus require more enlargement to obtain the same size image,
with the resulting loss of resolution with the enlarged image.

Thee are several ways of thinking about depth of focus and several
independent variable to consider. That's why people get so het up when
arguing about this: it's too complicated to discuss rationally without
mathematics. There is also the complication of whether you mean depth
of focus or depth of field. I suggest
https://en.wikipedia.org/wiki/Depth_of_focus as a good place to start
sorting all this out.
--

Regards,

Eric Stevens