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OT: stops or EVs

 
 
Charles Schuler
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      01-23-2007
I am teaching digital photography in my community and lean toward EVs as
opposed to stops. I know that the two are equivalent, but I also know that
they are not the same thing.

My feeling is that f/stops or f-stops, technically speaking, should only
refer only to the aperture of the lens. I fully understand that an
equivalent exists by changing shutter speed or ISO or both. With all of the
folks now entering digital photography as a hobby, it would be advantageous
to clear this issue a bit.

I also find that camera manuals lean towards EV.

What are your thoughts?


 
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Philip Homburg
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      01-23-2007
In article <(E-Mail Removed)>,
Charles Schuler <(E-Mail Removed)> wrote:
>I am teaching digital photography in my community and lean toward EVs as
>opposed to stops.
>
>What are your thoughts?


It depends on how you intend to use it. An EV is absolute value: it
specifies a certain amount of light reaching the sensor. On the other hand,
'stops' are often used to specify a difference in exposure: "underexpose by
1 or 2 stops".


--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
-- Douglas Adams in Dirk Gently's Holistic Detective Agency
 
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Jim
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      01-23-2007

"Charles Schuler" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed). ..
>I am teaching digital photography in my community and lean toward EVs as
>opposed to stops. I know that the two are equivalent, but I also know that
>they are not the same thing.
>
> My feeling is that f/stops or f-stops, technically speaking, should only
> refer only to the aperture of the lens. I fully understand that an
> equivalent exists by changing shutter speed or ISO or both. With all of
> the folks now entering digital photography as a hobby, it would be
> advantageous to clear this issue a bit.
>
> I also find that camera manuals lean towards EV.
>
> What are your thoughts?
>

Many computer manuals have a chart which shows how the camera selects stops
and shutter speeds as a function of the amount of light.
The charts have vertical lines for shutter speed and horizontal lines for
stop. There are also diagonal lines which are lines of constant EV.

Jim


 
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David Dyer-Bennet
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      01-23-2007
Charles Schuler wrote:
> I am teaching digital photography in my community and lean toward EVs as
> opposed to stops. I know that the two are equivalent, but I also know that
> they are not the same thing.
>
> My feeling is that f/stops or f-stops, technically speaking, should only
> refer only to the aperture of the lens. I fully understand that an
> equivalent exists by changing shutter speed or ISO or both. With all of the
> folks now entering digital photography as a hobby, it would be advantageous
> to clear this issue a bit.
>
> I also find that camera manuals lean towards EV.
>
> What are your thoughts?


EV is dead. Cameras are no longer marked in it, etc. Its use in
manuals is an anachronism. It's just another thing to load into
people's heads (they can't escape the need to know ISO, aperture, and
shutter speed anyway), and it will just cause confusion and waste their
time.
 
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Peter Irwin
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      01-23-2007
Charles Schuler <(E-Mail Removed)> wrote:
> I am teaching digital photography in my community and lean toward EVs as
> opposed to stops. I know that the two are equivalent, but I also know that
> they are not the same thing.


Using "stops" for exposure or even shutter speed is perfectly
good photographic jargon. It is also perfectly reasonable to
use the word "speed" or "fast" for aperture.

So:
1/250s is one stop less than 1/125s.
or
f/8 is twice the speed of f/11.

are perfectly good and have been in regular use by photographers
for most of the history of photography.

You do need to avoid confusion, and there is an oddity in the
vocabulary that a faster shutter speed produces less exposure
while a "faster" aperture produces more exposure.

>
> My feeling is that f/stops or f-stops, technically speaking, should only
> refer only to the aperture of the lens.


I think that while you should make sure that you avoid confusion,
the vocabulary of photography has always had a tradition of using
speed terminology for aperture and aperture terminology for speed.
This was clearly already very common in 1860 when a lens called
the "rapid rectilinear" was introduced. Your students are going
to discover that this is the way photographers have always talked,
and I don't think it would do any good to avoid it.

Peter.
--
http://www.velocityreviews.com/forums/(E-Mail Removed)

 
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Paul Mitchum
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      01-24-2007
Charles Schuler <(E-Mail Removed)> wrote:

> I am teaching digital photography in my community and lean toward EVs as
> opposed to stops. I know that the two are equivalent, but I also know
> that they are not the same thing.
>
> My feeling is that f/stops or f-stops, technically speaking, should only
> refer only to the aperture of the lens. I fully understand that an
> equivalent exists by changing shutter speed or ISO or both. With all of
> the folks now entering digital photography as a hobby, it would be
> advantageous to clear this issue a bit.
>
> I also find that camera manuals lean towards EV.
>
> What are your thoughts?


First of all, the concept is more important than the name.

But secondly: The concept can be illustrated by explaining the
difference between the two names.

So you talk about stops and relative aperture size, and how opening and
closing the aperture by stops changes the exposure. In the infancy of
photography, changing the aperture was the primary way of altering
exposure, which is why the term 'stop' came to refer to the amount of
light exposed.

And then you move on to the EV chart, showing how changing different
settings can compensate for each other, yielding the same exposure (same
exposure, but perhaps different picture). The wikipedia article on EV is
pretty good. <http://en.wikipedia.org/wiki/Exposure_value>

One of the other commenters was correct, though, in that EV itself isn't
widely used beyond the exposure compensation setting. Used that way,
'EV' and 'stop' are pretty well synonymous.

You can also go on a tangent from there into the Zone System. Wooooo!
 
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MarkČ
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      01-24-2007
Charles Schuler wrote:
> I am teaching digital photography in my community and lean toward EVs
> as opposed to stops. I know that the two are equivalent, but I also
> know that they are not the same thing.
>
> My feeling is that f/stops or f-stops, technically speaking, should
> only refer only to the aperture of the lens. I fully understand that
> an equivalent exists by changing shutter speed or ISO or both. With
> all of the folks now entering digital photography as a hobby, it
> would be advantageous to clear this issue a bit.
>
> I also find that camera manuals lean towards EV.
>
> What are your thoughts?


Exposure value and stops are not synonyms.

If you are teaching students, you really should teach them the standard
language they'll face in the industry...so in my opinion, they should become
aquainted with the term "stops."

--
Images (Plus Snaps & Grabs) by MarkČ at:
www.pbase.com/markuson


 
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Bill Funk
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      01-24-2007
On Tue, 23 Jan 2007 17:45:48 -0500, "Charles Schuler"
<(E-Mail Removed)> wrote:

>I am teaching digital photography in my community and lean toward EVs as
>opposed to stops. I know that the two are equivalent, but I also know that
>they are not the same thing.
>
>My feeling is that f/stops or f-stops, technically speaking, should only
>refer only to the aperture of the lens. I fully understand that an
>equivalent exists by changing shutter speed or ISO or both. With all of the
>folks now entering digital photography as a hobby, it would be advantageous
>to clear this issue a bit.
>
>I also find that camera manuals lean towards EV.
>
>What are your thoughts?
>

When I teach digital photography basics, I teach what aperture,
shutter speed and ISO speed are.
Then I teach that one EV is equal to one f-stop, or one doubleimng or
halving of a shutter speed, or one doubling or halving of an ISO
number.
I think it's important to understand the basics first, then teach the
way they interact, then teach how to understand the interaction with
respect to getting he results you want.
Because EV is used in many magazines and on-line articles, I think
it's important to expose the photographers to it, so they can
understand what's being said. Ignoring the term "EV" because you don't
agree with it doesn't help.

--
Washington Post humorist
Art Buchwald was eulogized
by friends Friday after a
long and hilarious career.
Reports of his death may be
exaggerated. Every comedian
thought he had died and gone
to heaven when Hillary Clinton
announced she is running for
president.
 
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Neil Ellwood
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      01-24-2007
On Tue, 23 Jan 2007 17:45:48 -0500, Charles Schuler wrote:

> I am teaching digital photography in my community and lean toward EVs as
> opposed to stops. I know that the two are equivalent, but I also know that
> they are not the same thing.
>
> My feeling is that f/stops or f-stops, technically speaking, should only
> refer only to the aperture of the lens. I fully understand that an
> equivalent exists by changing shutter speed or ISO or both. With all of the
> folks now entering digital photography as a hobby, it would be advantageous
> to clear this issue a bit.
>
> I also find that camera manuals lean towards EV.
>
> What are your thoughts?


If you are teaching photography - God help your students.

--
Neil
Reverse 'r' and 'a', delete 'l' for email.
 
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Cgiorgio
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Posts: n/a
 
      01-24-2007

"Charles Schuler" <(E-Mail Removed)> schrieb im Newsbeitrag
news:(E-Mail Removed). ..
>I am teaching digital photography in my community and lean toward EVs as
>opposed to stops. I know that the two are equivalent, but I also know that
>they are not the same thing.
>
> My feeling is that f/stops or f-stops, technically speaking, should only
> refer only to the aperture of the lens. I fully understand that an
> equivalent exists by changing shutter speed or ISO or both. With all of
> the folks now entering digital photography as a hobby, it would be
> advantageous to clear this issue a bit.
>
> I also find that camera manuals lean towards EV.
>
> What are your thoughts?

I think the easiest way to explain about EV's, f-stops and shutter speeds is
to explain how an old fashioned analogue exposure meter is used if you have
one. Then discuss how aperture values and focal lengths affect depth of
field and what the minimum shutter speeds for a given focal length should
be.

EV is probably useful to describe the dynamic range of the sensor and for
estimating the effect an exposure compensation setting will give on a
camera.


 
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