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



 
 
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  #201  
Old January 11th 19, 10:00 AM posted to rec.photo.digital
Eric Stevens
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Posts: 12,655
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

On Thu, 10 Jan 2019 23:47:23 -0500, Ron C wrote:

--- snip ---

Reciprocity games. "Introduction to photography 101."


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. 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.) The fstop is [Image distance]/lens aperture.

I can't properly translate the algebra but you will find it in
https://en.wikipedia.org/wiki/Exposu...xposure_values

It goes something like EV = Log(sub2)*LS/K whe

"N is the relative aperture (f-number)
t is the exposure time ("shutter speed") in seconds[2]
L is the average scene luminance
S is the ISO arithmetic speed
K is the reflected-light meter calibration constant"

It gets more complicated if you want to use T-stops instesad of
f-stops.
--

Regards,

Eric Stevens
  #202  
Old January 11th 19, 04:28 PM posted to rec.photo.digital
nospam
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Posts: 22,342
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

In article , Eric Stevens
wrote:

dxo is reporting the dynamic range of various *cameras*.

and even if you ignore the 14 bit issue, their numbers are highly
suspect.

the nikon d800 and d800 are identical cameras, the only difference
being the lack of an anti-alias filter on the d800e, something which
does not affect dynamic range (only aliasing). thus, the results should
be *the* *same* (other than alias artifacts on high frequency content).


Light passes through the filter which affects the spectrum detected by
the sensor. Of course this will affect the dynamic range.


nonsense. an aa filter has *zero* effect on dynamic range.

dxo claims that the d800 has 14.4 stops dynamic range and the d800e has
14.3 stops.


Even ignoring error bars, this is not at all surprising.


it's very surprising that two identical sensors (other than an aa
filter, which has no effect except for aliasing) in identical cameras
with identical electronics have different results, without any
explanation as to why.
  #203  
Old January 11th 19, 04:28 PM posted to rec.photo.digital
nospam
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Posts: 22,342
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

In article , Eric Stevens
wrote:


The problem is clearly DXO's testing methods. No matter how you look
at this, you have to be able to imagine all kinds of sources of
inaccurate measurements, especially if they are slight. I have to
agree with nospam and Alan. You can't get DR outside of the limits of
the ADC because that is the output you see, but you can certainly get
test results outside of that limit.


But the digital DR of the output of the ADC is not the same as the
analog DR of the sensor. Nor is there any reason why it should be.


nobody said it was, however, it's always going to be limited by the adc.

and if it really *is* the sensor they're measuring, then it should be
the *same* for the *same* sensor, and it is not.

if they're supposedly measuring the sensor's dynamic range, explain why
the nikon d50 & d70 differ by a half-stop, both of which used the same
popular 6mp sony sensor (as did pentax). other results also differ.

https://www.dxomark.com/Cameras/Nikon/D50
https://www.dxomark.com/Cameras/Nikon/D70
  #204  
Old January 11th 19, 04:28 PM posted to rec.photo.digital
nospam
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Posts: 22,342
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

In article , Eric Stevens
wrote:


My lenses are not calibrated in EVs.


actually, they're calibrated in 1/3 evs, unless they're old, when it
wasn't possible to be that accurate.

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


and iso.


You say that my lenses are calibrated in EVs and then agree there are
factors additional to the lens which determine EV. Is my lens somehow
prescient or are you an idiot?


ad hominem.
  #205  
Old January 11th 19, 04:28 PM posted to rec.photo.digital
nospam
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Posts: 22,342
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

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.

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.
  #206  
Old January 11th 19, 04:28 PM posted to rec.photo.digital
nospam
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Posts: 22,342
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

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.


asking such a question shows you do not understand the topic.
  #207  
Old January 11th 19, 04:28 PM posted to rec.photo.digital
nospam
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Posts: 22,342
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

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.
  #208  
Old January 11th 19, 04:28 PM posted to rec.photo.digital
nospam
external usenet poster
 
Posts: 22,342
Default Finally got to the point where no new camera holds my interest (waiting for specific offering)

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.

The fstop is [Image distance]/lens aperture.


also wrong. f/stop = focal length/aperture.
  #209  
Old January 11th 19, 04:53 PM posted to rec.photo.digital
Ken Hart[_4_]
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Posts: 449
Default Finally got to the point where no new camera holds my interest(waiting for specific offering)

On 1/10/19 11:14 PM, Eric Stevens wrote:
On Thu, 10 Jan 2019 10:32:22 -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.


The British astronomer, John Waterhouse (1806-1879), invented Waterhouse
Stops, metal plates with a hole that could be inserted into a slot in
the lens. Prior to this, lenses were 'stopped down' by unscrewing them
and inserting a metal disc with a hole inside the lens.

I couldn't find why the word "stop" is used, but, based on the fact that
Waterhouse's home (Well Head House in Halifax, Yorkshire) had extensive
gardens and greenhouses with exotic plants, I suspect that the term
might have come from plumbing. The irrigation systems may have had
"stops" to control the water flow to the different plants. This is
entirely a guess- don't bother arguing!


--
Ken Hart

  #210  
Old January 11th 19, 05:00 PM posted to rec.photo.digital
Ken Hart[_4_]
external usenet poster
 
Posts: 449
Default Finally got to the point where no new camera holds my interest(waiting for specific offering)

On 1/11/19 4:00 AM, Eric Stevens wrote:
On Thu, 10 Jan 2019 23:47:23 -0500, Ron C wrote:

--- snip ---

Reciprocity games. "Introduction to photography 101."

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. 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.) The fstop is [Image distance]/lens aperture.

I can't properly translate the algebra but you will find it in
https://en.wikipedia.org/wiki/Exposu...xposure_values

It goes something like EV = Log(sub2)*LS/K whe

"N is the relative aperture (f-number)
t is the exposure time ("shutter speed") in seconds[2]
L is the average scene luminance
S is the ISO arithmetic speed
K is the reflected-light meter calibration constant"

It gets more complicated if you want to use T-stops instesad of
f-stops.


And now the "Sunny-16" rule makes perfect sense!

--
Ken Hart

 




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