Finally a decent travel zoom from Fuji

On 25 Jul 2019 10:18:08 GMT, Sandman wrote:

In article , Alfred Molon
wrote:

Sandman:
Both physical factors of the lens are affected when comparing crop
to full format. That's why a f4 m43 lens has the equivalent
aperture of a f8 full format lens.

Wrong again. An F4 lens is an F4 lens regardless of
sensor size

No one has said otherwise. A 16-80mm lens is a 16-80mm lens also regardless of
sensor size, but the *equivalent* focal length is 24-120mm, just as the
equivalent aperture is F6 (not F8, my bad)

, because the exposure is the same at F4 and
1/100s both on the small sensor camera and the large
sensor camera. But if you shoot at F8, the exposure time
will be 4x the exposure time at F4.

You're mixing exposure with equivalency. Exposure is light per unit area, a
smaller sensor has fewer of those units, so the amount of total light is
different, meaning that a crop sensor camera need to boost its signal to
create an equal enough image. That's why crop sensors usually are said to have
poorer ISO.

Let's consider two cameras, identical except that one is half the size
of the other. With the smaller camera, the focal length will be
halved, the lens diameter will be halved. i.e. the f value will remain
constant.

With the smaller camera, the sensor area will be one quarter. So too
will be the lens area. i.e. the amount of light entering the lens will
be reduced by a factor of four. But so too is the sensor area to be
covered by the light so that the intensity of the light falling on the
sensor is the same in both cameras.

In other words, when exposed at the same shutter speed and f value the
quantity of light peer unit area falling on the respective sensors
will be the same. There is no need to calculate a different aperture.

BTW, we are talking about a Fuji lens (1.5x crop).

Yeah, my bad. Apologies.

On Thu, 25 Jul 2019 14:34:35 -0400, nospam
wrote:

In article , Alfred
Molon wrote:

There is no such thing as an "equivalent" aperture. F4
is F4 both for a small sensor camera and a large sensor
camera.

for exposure, yes.
for depth of field, no.

Correct.

But its got nothing to do with the size of the sensor. It occurs only
as a result of the use of a shorter focal length lens.

On 25 Jul 2019 10:25:05 GMT, Sandman wrote:

In article , Eric Stevens wrote:

Sandman:
Just as focal length is, by definition, the lens's ability to
converge light. It's a fixed property of the lens. But with lenses
for crop sensors, they often list the equivalent 35mm focal
length, but not the equivalent 35mm aperture.

The 'equivalent 35mm focal length' is intended to guide people who
relate field of view to the focal length of their old 35mm camera
lens.

Not many of those guys left around, are there, though? It is a way to keep a
common format I suppose, and it's somewhat helpful. It's just a remnant of the
industry of old where the issues of today didn't exist. We'd be better using
angle of view instead of focal length.

Sandman:
Both physical factors of the lens are affected when comparing crop
to full format. That's why a f4 m43 lens has the equivalent
aperture of a f8 full format lens. And that's also why you can't
get that short focus distance with (most) m43 lenses.

I don't intend to reopen the argument about equivalent apertures so
all I can say is that I believe to be misguided.

You are free to think so, still

In article , Eric Stevens
wrote:

There is no such thing as an "equivalent" aperture. F4
is F4 both for a small sensor camera and a large sensor
camera.

for exposure, yes.
for depth of field, no.

Correct.

But its got nothing to do with the size of the sensor. It occurs only
as a result of the use of a shorter focal length lens.

nope. it has everything to do with the size of the sensor, and the lens
does not change.

In article , Eric Stevens
wrote:

, because the exposure is the same at F4 and
1/100s both on the small sensor camera and the large
sensor camera. But if you shoot at F8, the exposure time
will be 4x the exposure time at F4.

You're mixing exposure with equivalency. Exposure is light per unit area, a
smaller sensor has fewer of those units, so the amount of total light is
different, meaning that a crop sensor camera need to boost its signal to
create an equal enough image. That's why crop sensors usually are said to
have poorer ISO.

Let's consider two cameras, identical except that one is half the size
of the other. With the smaller camera, the focal length will be
halved, the lens diameter will be halved. i.e. the f value will remain
constant.

With the smaller camera, the sensor area will be one quarter. So too
will be the lens area. i.e. the amount of light entering the lens will
be reduced by a factor of four. But so too is the sensor area to be
covered by the light so that the intensity of the light falling on the
sensor is the same in both cameras.

per unit area, however, the total light is less for the smaller sensor,
which means more noise, producing results that are *not* equivalent.

In other words, when exposed at the same shutter speed and f value the
quantity of light peer unit area falling on the respective sensors
will be the same. There is no need to calculate a different aperture.

there is to obtain *equivalent* results.

On Thu, 25 Jul 2019 18:39:04 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

There is no such thing as an "equivalent" aperture. F4
is F4 both for a small sensor camera and a large sensor
camera.

for exposure, yes.
for depth of field, no.

Correct.

But its got nothing to do with the size of the sensor. It occurs only
as a result of the use of a shorter focal length lens.

nope. it has everything to do with the size of the sensor, and the lens
does not change.

Are you discussing the use of the same lens on two different cameras?

I thought that other people were discussing the effect of using a
proportionally smaller (focal length and aperture dimensions) on two
proprtionally different cameras.

On Thu, 25 Jul 2019 18:39:05 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

, because the exposure is the same at F4 and
1/100s both on the small sensor camera and the large
sensor camera. But if you shoot at F8, the exposure time
will be 4x the exposure time at F4.

You're mixing exposure with equivalency. Exposure is light per unit area, a
smaller sensor has fewer of those units, so the amount of total light is
different, meaning that a crop sensor camera need to boost its signal to
create an equal enough image. That's why crop sensors usually are said to
have poorer ISO.

Let's consider two cameras, identical except that one is half the size
of the other. With the smaller camera, the focal length will be
halved, the lens diameter will be halved. i.e. the f value will remain
constant.

With the smaller camera, the sensor area will be one quarter. So too
will be the lens area. i.e. the amount of light entering the lens will
be reduced by a factor of four. But so too is the sensor area to be
covered by the light so that the intensity of the light falling on the
sensor is the same in both cameras.

per unit area, however, the total light is less for the smaller sensor,
which means more noise, producing results that are *not* equivalent.

That's not what is being discussed.

In other words, when exposed at the same shutter speed and f value the
quantity of light peer unit area falling on the respective sensors
will be the same. There is no need to calculate a different aperture.

there is to obtain *equivalent* results.

What is the nature of the different results for which you have to
change the aperture?

In article , Eric Stevens
wrote:

, because the exposure is the same at F4 and
1/100s both on the small sensor camera and the large
sensor camera. But if you shoot at F8, the exposure time
will be 4x the exposure time at F4.

You're mixing exposure with equivalency. Exposure is light per unit area,
a smaller sensor has fewer of those units, so the amount of total light is
different, meaning that a crop sensor camera need to boost its signal to
create an equal enough image. That's why crop sensors usually are said to
have poorer ISO.

Let's consider two cameras, identical except that one is half the size
of the other. With the smaller camera, the focal length will be
halved, the lens diameter will be halved. i.e. the f value will remain
constant.

With the smaller camera, the sensor area will be one quarter. So too
will be the lens area. i.e. the amount of light entering the lens will
be reduced by a factor of four. But so too is the sensor area to be
covered by the light so that the intensity of the light falling on the
sensor is the same in both cameras.

per unit area, however, the total light is less for the smaller sensor,
which means more noise, producing results that are *not* equivalent.

That's not what is being discussed.

yes it is.

In other words, when exposed at the same shutter speed and f value the
quantity of light peer unit area falling on the respective sensors
will be the same. There is no need to calculate a different aperture.

there is to obtain *equivalent* results.

What is the nature of the different results for which you have to
change the aperture?

depth of field.

In article , Eric Stevens
wrote:

There is no such thing as an "equivalent" aperture. F4
is F4 both for a small sensor camera and a large sensor
camera.

for exposure, yes.
for depth of field, no.

Correct.

But its got nothing to do with the size of the sensor. It occurs only
as a result of the use of a shorter focal length lens.

nope. it has everything to do with the size of the sensor, and the lens
does not change.

Are you discussing the use of the same lens on two different cameras?

that doesn't matter.

I thought that other people were discussing the effect of using a
proportionally smaller (focal length and aperture dimensions) on two
proprtionally different cameras.

they might be, but again, that doesn't matter.

On Jul 25, 2019, Eric Stevens wrote
(in ):

On Thu, 25 Jul 2019 18:39:04 -0400,
wrote:

In , Eric Stevens
wrote:

There is no such thing as an "equivalent" aperture. F4
is F4 both for a small sensor camera and a large sensor
camera.

for exposure, yes.
for depth of field, no.

Correct.

But its got nothing to do with the size of the sensor. It occurs only
as a result of the use of a shorter focal length lens.

nope. it has everything to do with the size of the sensor, and the lens
does not change.

Are you discussing the use of the same lens on two different cameras?

I thought that other people were discussing the effect of using a
proportionally smaller (focal length and aperture dimensions) on two
proprtionally different cameras.

The bottom line for me as an individual who actually uses an APS-C camera
with matching lenses designed for use on said APS-C cameras, is to ignore the
35mm equivalency arguments. I am not using FX glass on an DX/APS-C body so
whatever my subject might be I am exposing, and composing based on what I am
working with, not what I should be getting with some 35mm/FF equivalency.

I have a very strong feeling that the great majority of M4/3, and APS-C
shooters using native glass, regardless of brand happily go about shooting
within the limitations of their camera systems without giving a thought to
35mm/FF equivalency.

I also have a feeling that the new Fujifilm, XF16-80mm f/4 will prove to be a
best seller for Fujifilm without any of those buyers considering 35mm/FF
equivalency.