Finally got to the point where no new camera holds my interest(waiting for specific offering)

On Fri, 11 Jan 2019 12:50:41 -0500, Alan Browne
wrote:

On 2019-01-11 03:46, Eric Stevens wrote:
On Fri, 11 Jan 2019 00:18:28 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


EV's are equivalent to stops for any purpose related to exposure.

I can change exposure value without changing the stop setting.

No ****. That's sort of the point.

It's my point. Stops aren't exposure values. Exposure values are not
stops.

they are.

Lets leave it at that.

ok, but you saying so doesn't make it correct.

Allright then. Please explain to your readers how you set a lens to an
EV of 20.

For what ISO and speed?

No, no. No ISO or speed. The lens calibration is equivalent to stop
settings according to nospam so it must be possible to set a lens to a
particular EV. I picked 20 as an example.

That's the whole nutshell. Done. Period.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 10:28:25 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


This illustrates the disadvantage of not using the language with
precision. As I said, all my lenses make use of f/numbers which are a
measure of stops. Your thoughts have jumped the rails and are now
talking about the intervals of Exposure Value of which the camera is
capable. The exposure value may be used to set lens aperture, shutter
speed or ISO. They are not identical to stops.

EV's are equivalent to stops for any purpose related to exposure.

I can change exposure value without changing the stop setting.

you are confusing f/stop with stop.

'stop' is an abreviated way of referring to an obsolete way of
changing lens aperture. It's use as a reference to lens aperture is
now normal.

doing so is what you call 'sloppy'.

you're confusing stop, f/stop and aperture and also ev.

You are crackers. I'm trying quite hard to get you to make a
distinction.

i have been all along.

Haw.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 10:28:26 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


You are still missing the point: lens aperture, shutter speeds or ISOs
are not identical to stops.

At this point my old physics professor would ask for dimensional analysis.
What's the dimensional analysis of "EV" vs "stop" ?

Aah! Some common sense.

Lets have some definitions.

good idea, assuming they're correct.

Stop is an abreviation of a name for the
aperture of the lens opening. It may be the f-stop or a T-stop (or an
H-Stop.)

bad idea, when they're wrong.

f/stop, stop and aperture are different.

Now YOU are lecturing me on usage!

The fstop is [Image distance]/lens aperture.

also wrong. f/stop = focal length/aperture.

Aha! Your correction of me is an approximation. See
https://en.wikipedia.org/wiki/F-number

"... as one focuses closer, the lens' effective aperture becomes
smaller, making the exposure darker. The working f-number is often
described in photography as the f-number corrected for lens
extensions by a bellows factor. This is of particular importance in
macro photography".
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 12:45:53 -0500, Alan Browne
wrote:

--- snip ---

If you want to continue arguing to the contrary I will be happy to
leave you to it.

Reciprocity games. "Introduction to photography 101."

You are still missing the point: lens aperture, shutter speeds or ISOs
are not identical to stops.

I have not missed any points at all. To a PHOTOGRAPHER your PEDANTRY is
MEANINGLESS and in fact MISLEADING.

To some photographers ... it is annoying. But it is amazing what I
have learned out of this thread.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 12:47:20 -0500, Alan Browne
wrote:

On 2019-01-10 23:38, Eric Stevens wrote:
On Thu, 10 Jan 2019 07:43:24 -0500, Alan Browne
wrote:

On 2019-01-10 04:12, Eric Stevens wrote:
On Wed, 9 Jan 2019 08:36:24 -0500, Alan Browne
wrote:

Its amazing what Google can produce. This is DxO's own account of the
situation at:
https://www.dxomark.com/dxomark-came...ol-and-scores/

"Dynamic range corresponds to the ratio between the highest
brightness a camera can capture (saturation) and the lowest
brightness it can capture (which is typically when noise becomes
more important than the signal — that is, a signal-to-noise ratio
below 0 dB). A value of 12 EV is excellent, with differences below
0.5 EV usually not noticeable. Dynamic range is an open scale."

This appears to confirm that the situation is as I deduced: they are
not testing the dynamic range as recorded in a raw file. They are
testing the range that a camera can capture. i.e. it is the dynmaic
range of the sensor. It is not the dynamic range of the raw file.

It doesn't actually say that, however.

How, specifically, are they bypassing the raw file to get the data?


By measuring not the data in the file but the range of brightness that
the camera can capture from their test set up.

And where _specifically_ are they getting that data? What is the probe
point? What is the probe?

Read the URL. The use multiple light sources, each of different
calibrated illuminance. It's rather like photographing an gray-scale
wedge.

Oh. Thanks. Now it's CLEAR TO ME YOU HAVE NO CLUE.

My question related to how they measure the brightness at the camera.

And you're not replying with an answer to that. At all.

The object is the measurement of the ability of the camera to detect
both low light and bright light. To do this they get the camera to
photograph a target containg multiple light sources covering a range
of luminances. Some are too bright and the other too dark for the
camera to properly capture. It is the difference between these which
determines the dynamic range of the sensor. note that they evaluate
the DR in terms of a RGB composite analysis, the details of which I am
not aware. With this technique there is no need to measure the
brightness at the camera.
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:

If you want to continue arguing to the contrary I will be happy to
leave you to it.

Reciprocity games. "Introduction to photography 101."

You are still missing the point: lens aperture, shutter speeds or ISOs
are not identical to stops.

I have not missed any points at all. To a PHOTOGRAPHER your PEDANTRY is
MEANINGLESS and in fact MISLEADING.

To some photographers ... it is annoying. But it is amazing what I
have learned out of this thread.

what's amazing is that it doesn't appear that you've learned a thing,
despite repeated explanations from several people.

In article , Eric Stevens
wrote:

You are still missing the point: lens aperture, shutter speeds or ISOs
are not identical to stops.

At this point my old physics professor would ask for dimensional analysis.
What's the dimensional analysis of "EV" vs "stop" ?

Aah! Some common sense.

Lets have some definitions.

good idea, assuming they're correct.

Stop is an abreviation of a name for the
aperture of the lens opening. It may be the f-stop or a T-stop (or an
H-Stop.)

bad idea, when they're wrong.

f/stop, stop and aperture are different.

Now YOU are lecturing me on usage!

yep, and not just usage either, but basic concepts.

The fstop is [Image distance]/lens aperture.

also wrong. f/stop = focal length/aperture.

Aha! Your correction of me is an approximation.

it's not in any way an approximation.

See
https://en.wikipedia.org/wiki/F-number

from that link,
The f-number of an optical system (such as a camera lens) is the
ratio of the system's focal length to the diameter of the entrance
pupil.

exactly what i said it is.

"... as one focuses closer, the lens' effective aperture becomes
smaller, making the exposure darker. The working f-number is often
described in photography as the f-number corrected for lens
extensions by a bellows factor. This is of particular importance in
macro photography".

selective snipping. that's *not* cool.

that quote is from the working f-number section,
https://en.wikipedia.org/wiki/F-number#Working_f-number

which begins:
The f-number accurately describes the light-gathering ability of a
lens only for objects an infinite distance away. This limitation is
typically ignored in photography, where f-number is often used
regardless of the distance to the object.

note this part: 'this limitation is typically ignored in photography'.

did you somehow miss that part?

it's ignored for a very good reason: the difference is insignificant,
except in certain situations, namely macro. see below.

moving on,
In optical design, an
alternative is often needed for systems where the object is not far
from the lens. In these cases the working f-number is used.

which is not relevant here.

{formula snipped}

In photography this means that as one focuses closer, the lens'
effective aperture becomes smaller, making the exposure darker.
The working f-number is often described in photography as the
f-number corrected for lens extensions by a bellows factor. This is
of particular importance in macro photography.

not exactly.

as one focuses closer, the effective *focal* *length* becomes *longer*,
however, it's not enough to matter in typical situations.

for macro, where the working distance is very short, the effective
focal length can become quite long, requiring lens extensions (tubes,
bellows, etc.).

http://www.nicovandijk.net/pb6E.jpg

focusing closer can also be done via a close-up lens, which will have
no effect on the f/stop. however, it's an additional optical element in
the path and most of them aren't all that good.

tl;dr you're *really* grasping at straws.

In article , Eric Stevens
wrote:


EV's are equivalent to stops for any purpose related to exposure.

I can change exposure value without changing the stop setting.

No ****. That's sort of the point.

It's my point. Stops aren't exposure values. Exposure values are not
stops.

they are.

Lets leave it at that.

ok, but you saying so doesn't make it correct.

Allright then. Please explain to your readers how you set a lens to an
EV of 20.

For what ISO and speed?

No, no. No ISO or speed. The lens calibration is equivalent to stop
settings according to nospam so it must be possible to set a lens to a
particular EV. I picked 20 as an example.

by picking 20 (or any number), you demonstrate you don't understand it.

In article , Eric Stevens
wrote:

It might be commonly referred to as a stop but that is just plain
sloppy usage.

it's not sloppy at all. in fact, it's exactly correct.

On that basis you might as well call the shutter speed a
stop or even the ISO a stop.

the *difference* is called a stop, aka 'interval on the photographic
exposure scale':
Exposure value is also used to indicate an interval on the
photographic exposure scale, with a difference of 1 EV corresponding
to a standard power-of-2 exposure step, commonly referred to as a
stop.

iso 800 is one stop more sensitive than iso 400.
1/250th is one stop less light than 1/125th.
f/4 is one stop more light than f/5.6.

Assuming noting else changes.

it doesn't matter what else changes. they're independent statements.

iso 800 is one stop more sensitive than iso 400.

Providing no one fiddles with the shutter speed.

false.

1/250th is one stop less light than 1/125th.

Providing no one fiddles with aperture setting.

false.

f/4 is one stop more light than f/5.6.

That's about the only thing which is correct.

why is that one exempt from fiddling, while the other two are not??

not that it matters, since what i wrote is correct and you are wrong.

I initially mentioned this topic in passing when I referred to sloppy
writing. I didn't call for examples.

unfortunately for you, examples were provided and they show that you
don't understand it.

That's the problem with sloppy writing: people frequently don't
understand it.

your lack of understanding is not due to sloppy writing.

But you would say that, wouldn't you?

yes i would, given that it's clear you don't understand what you're
talking about and continue to say things that range from simply wrong
to completely nonsensical.

In article , Eric Stevens
wrote:

Do your lenses have stops?

Yes.

Exactly. So they are indeed calibrated in EV. ([1] above).

No. EVs can be deduced. See
https://en.wikipedia.org/wiki/Exposure_value

"In photography, exposure value (EV) is a number that represents a
combination of a camera's shutter speed and f-number, such that all
combinations that yield the same exposure have the same EV (for any
fixed scene luminance)."

Finding some convenient words doesn't obviate the facts. Your camera
and lenses are calibrated in EV. What words are used (stops for
example) do not matter at all.

Dear me! I can change the EV to which my camera is set without
changing the lens aperture. My lenses are not calibrated in EVs.

Further, lenses do not determine EVs on their own. It is also
necessary to set a shutter speed.

Wow! You could pass Photography 101, chapter 3 (Basics of exposure).

CONGRATS!

Now you have followed me that far, you may be interested to see

https://upload.wikimedia.org/wikiped..._Ib_with_EV.jp
g

Notice how the bottom of the shutter speed ring has a pointer with
which you can set the EV. That enables the aperture ring (dimly seen
behind the pointer) to be moved in synchronism with the shutter speed
ring so as to maintain constant the preset EV. This is an early
pre-prescient camera. According to nospam modern cameras don't need
the EV to be set. The aperture ring knows the EV all on it's own.

i never said any such thing.

stop lying.