Let's Photograph Comet 46P Wirtanen

On Thu, 27 Dec 2018 10:18:00 -0700, Chris L Peterson
wrote:
On Thu, 27 Dec 2018 17:22:59 +0100, Paul Schlyter
wrote:
On Wed, 26 Dec 2018 17:11:40 -0700, Chris L Peterson
wrote:
On Wed, 26 Dec 2018 22:39:47 +0100, Paul Schlyter
wrote:
I havent a clue. All I can say is that maybe your local eye
doctor
might
have an answer.

No he wouldn't. My local eye doctor wouldn't even say 20/30,
she
would say 0.67 perhaps rounding it to 0.7 - as would most
European
eye doctors. The 20/xx stuff is an American idiosyncracy.

No, that's not at all what your local eye doctor would do. If he
were
using a Snellen test to screen your visual acuity (as is common
all
over the world, including Sweden), he would properly express your
results as a Snellen fraction, defined by European ISO 8596,
giving
both the numerator (distance) and the denominator (a normalized
distance). The fraction is never reduced. The only difference
between
the American and the European fractions is that in Europe it's
normally metric. In the U.S. we have 20/20 as normal vision, in
Europe
it's 6/6.

The Snellen fraction is most certainly not an American
idiosyncrasy.

Then how come the last time I had my eyes examined I got a visual
acuity of 1.1 on my left eye and 1.2 on my right eye?

Because you have an incompetent eye doctor who doesn't observe
standards? Maybe a homeopath or some other quack?

Are you claiming that most or all Swedish eye doctor are quacks? All
of the eye doctors I visited, several of whom I did not choose
myself, used decimal fractions to express visual acuity.

You referred to SO 8596 in another post. The Wikipedia article about
ISO 8596 states:

"A simple and efficient way to state acuity is by solving the
fraction to a decimal number. 6/6 then corresponds to an acuity (or a
Visus) of 1.0 (see*Expression*below). 6/3 corresponds to 2.0, which
is often attained by well-corrected healthy young subjects
with*binocular vision. Stating acuity as a decimal number is the
standard in European countries, as required by the*European norm*(EN
ISO 8596, previously*DIN*58220)."


Now, go away in some dark corner for awhile and feel ashamed!
Apologize before you do... Following standards is *not*, repeat,
*not* quackery! And you should of course follow the *whole* standard,
not just parts of it.

Chris L Peterson wrote:
On Thu, 27 Dec 2018 23:30:35 +0100, Thomas 'PointedEars' Lahn
wrote:

Attribution _line_, NOT attribution novel.

Chris L Peterson wrote:
[…] Thomas 'PointedEars' Lahn […] wrote:
Chris L Peterson wrote:
[…] he would properly express your results as a Snellen fraction,
defined by European ISO 8596,
As the name already indicates, standards with prefix “ISO” (International
Organization for Standardization) is NOT a “European” standard, but an
*international* one.
Not all ISO standards are adopted by all ISO body members. ISO 8596 is
adopted by all the European members.
Cite evidence.

No. You're not worth the effort.

Fallacies you just committed:

- explicit: /argumentum ad personam/
- implicit: /argumentum ad ignorantiam/

https://en.wikipedia.org/wiki/Ad_hominem
https://en.wikipedia.org/wiki/Argument_from_ignorance

Your attempt to create a diversion by turning this factual question into
an opinion about me is unsuccessful.

ISO 8596(:2017) is an international standard:

https://www.iso.org/standard/69042.html

You have claimed:

“Not all ISO standards are adopted by all ISO body members. ISO 8596 is
adopted by all the European members.”

Your claim that an international standard would NOT be adopted by all
member states who are participating in creating exactly that standard
is an extraordinary one.

Your second claim which implies that *only* "the European members" would
have adopted it, is also an extraordinary one. To begin with, what are
"the European members" – member states of the EU, EFTA, something else?

“Extraordinary claims require extraordinary evidence.”
–Carl Sagan

You have NOT provided the required evidence, let alone extraordinary
evidence, to support your (extraordinary) claims.

Therefore, your claims stand unfounded.

Therefore, judgment must be reserved on those claims.

--
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

On Friday, December 28, 2018 at 2:17:41 AM UTC-5, Paul Schlyter wrote:

burp

Have you been able to observe Comet 46P during its current apparition?

On Fri, 28 Dec 2018 08:17:37 +0100, Paul Schlyter
wrote:

The Snellen fraction is most certainly not an American
idiosyncrasy.

Then how come the last time I had my eyes examined I got a visual
acuity of 1.1 on my left eye and 1.2 on my right eye?

Because you have an incompetent eye doctor who doesn't observe
standards? Maybe a homeopath or some other quack?

Are you claiming that most or all Swedish eye doctor are quacks? All
of the eye doctors I visited, several of whom I did not choose
myself, used decimal fractions to express visual acuity.

You referred to SO 8596 in another post. The Wikipedia article about
ISO 8596 states:

"A simple and efficient way to state acuity is by solving the
fraction to a decimal number. 6/6 then corresponds to an acuity (or a
Visus) of 1.0 (see*Expression*below). 6/3 corresponds to 2.0, which
is often attained by well-corrected healthy young subjects
with*binocular vision. Stating acuity as a decimal number is the
standard in European countries, as required by the*European norm*(EN
ISO 8596, previously*DIN*58220)."


Now, go away in some dark corner for awhile and feel ashamed!
Apologize before you do... Following standards is *not*, repeat,
*not* quackery! And you should of course follow the *whole* standard,
not just parts of it.

Read the standard. There is a reason it requires using a pair of
numbers, because that is more diagnostically useful than a single
fraction. It properly represents the way the test was performed.

If your doctor uses a decimal number, it means they aren't interested
in following standards. If you're comfortable with a doctor who
operates that way, fine.

On Saturday, December 29, 2018 at 3:51:01 AM UTC-5, Paul Schlyter wrote:

many
optalmophologists may operate with too limited resources so they may
not be able to afford an eye test room which is large enough. If so,
they should report normal visual acuity as not 20/20 but instead as
15/15 or perhaps even 10/10 depending on how large a test room they
had access too.

Mirrors.

On Sat, 29 Dec 2018 09:50:55 +0100, Paul Schlyter
wrote:

I don't have one single eye doctor. For my visual acuity test it's
been different opthalmogists almost every time, and they all gave my
visual acuity as a decimal number.

Well, thanks for the heads-up. If I ever have an eye problem in
Sweden, I'll cross the border into Denmark to get it addressed, since
I know that Danish ophthalmologists follow international standards.

On Sat, 29 Dec 2018 08:26:41 -0700, Chris L Peterson
wrote:
On Sat, 29 Dec 2018 09:50:55 +0100, Paul Schlyter
wrote:

I don't have one single eye doctor. For my visual acuity test it's
been different opthalmogists almost every time, and they all gave
my
visual acuity as a decimal number.

Well, thanks for the heads-up. If I ever have an eye problem in
Sweden, I'll cross the border into Denmark to get it addressed,
since
I know that Danish ophthalmologists follow international standards.

Boy are you paranoid....

So if you, while visiting Sweden, would catch a sudden eye infection
which required immediate treatment, would you then delay such a
treatment until you made it to Denmark just to avoid having to
perform a division?

You know something? In Denmark they do the same, I.e. express visual
acuity as a decimal number, and keeping the Snellen chart at standard
distance during the examination. Yes, over most of Europe they would
do the same. You'd have to catch a plane home to the USA to be
certain to find an eye doctor who gives your visual acuity in the
20/xx format you cling to so desperately. Meanwhile your eye
infection might get worse, perhaps blinding you in the end. And all
this just to avoid having to perform a division...

On Sun, 30 Dec 2018 08:54:35 +0100, Paul Schlyter
wrote:

You know something? In Denmark they do the same, I.e. express visual
acuity as a decimal number, and keeping the Snellen chart at standard
distance during the examination.

Actually, they don't. I had a lens replaced a few years ago in Aarhus,
and they did a new refraction as well as a corrected one. I noticed
immediately the use of the metric fraction, which I was not familiar
with.

On Sun, 30 Dec 2018 07:12:45 -0700, Chris L Peterson
wrote:
On Sun, 30 Dec 2018 08:54:35 +0100, Paul Schlyter
wrote:

You know something? In Denmark they do the same, I.e. express
visual
acuity as a decimal number, and keeping the Snellen chart at
standard
distance during the examination.

Actually, they don't. I had a lens replaced a few years ago in
Aarhus,
and they did a new refraction as well as a corrected one. I noticed
immediately the use of the metric fraction, which I was not familiar
with.

When did this happen?

Was the numerator different from 6?

And if that eye doctor had performed the division, giving you 1,0
instead of 6/6 (assuming you had normal visual acuity), would you
then have considered him a homeopath?

Perhaps that eye doctor was nice to you, giving your visual acuity in
fractional instead of decimal notation because he knew that you, as
an American, was used to that and he wanted to avoid confusing you.
Americans all over the world experience just that, other people
adjusting to their way of thinking, so often that they take it for
granted.

Don't you see the beauty in performing that division? You said you
were not used to the "metric fraction". If the visual acuity had been
given as a decimal number it would have been the same no matter if
metric, English, old French, old Danish or some other kinds of units
were used. 1.0 is normal visual acuity, period, there's no need to
convert it between metric and non-metric units. OK those 6m or 20ft
gets lost of course, but it is the standard distance to the Snellen
chart which always is used anyway, so it can be considered to be
implied.

On Mon, 31 Dec 2018 08:55:22 +0100, Paul Schlyter
wrote:

On Sun, 30 Dec 2018 07:12:45 -0700, Chris L Peterson
wrote:
On Sun, 30 Dec 2018 08:54:35 +0100, Paul Schlyter
wrote:

You know something? In Denmark they do the same, I.e. express
visual
acuity as a decimal number, and keeping the Snellen chart at
standard
distance during the examination.

Actually, they don't. I had a lens replaced a few years ago in
Aarhus,
and they did a new refraction as well as a corrected one. I noticed
immediately the use of the metric fraction, which I was not familiar
with.

When did this happen?

2016

Was the numerator different from 6?

3

And if that eye doctor had performed the division, giving you 1,0
instead of 6/6 (assuming you had normal visual acuity), would you
then have considered him a homeopath?

I would look back after this discussion and wonder what other medical
standards he might not have been observing.

BTW, I spent years working with ophthalmologists around the world, and
looking back at the research reports we generated regarding cataract
surgery outcomes, I note that pre- and post surgical acuity was always
expressed as a fraction, never a decimal. France, Germany, Spain, and
Turkey.

Don't you see the beauty in performing that division?

Nope. It discards useful information. It's like characterizing a
telescope by focal ratio, and not providing the focal length and
aperture. A patient with 6/6 vision and one with 3/3 vision may have
significantly different visual acuity; if you normalize them to 1.0,
you lose that distinction.