Re: [Phys-L] astronomy binocular buying advice

[John Denker <jsd@av8n.com>]

On 05/02/2017 04:53 PM, Larry Smith wrote:

> classroom set

> Sometimes the vendors aren’t much help: too many models to choose
> from, and why are the “better” models cheaper?

Hmmmm, this may be an opportunity to make lemonade.  One
could perhaps make a list of plausible contenders, and then
buy some of each.

Rationale:
 *) There is no law that says a class set has to be homogeneous.
 *) Different models have different strengths and weaknesses.
  -- For example, some students might appreciate some extra
   eye relief, while others don't care.
 *) Different models might work better or worse depending on
  the target, so there is no absolute notion of "better".
  -- For example, some targets reward an extra-wide field,
   but others don't.
 *) You could collect information about ruggedness etc.
 *) You could have students trade off during an observing
  session, and then report on the perceived differences.
  This is reasonably representative of what real astronomers
  do for a living.  They spend a fair amount of time evaluating
  and optimizing the optics, not just observing using instruments
  that somebody handed them on a silver platter.


The usual "science fair" dogma says that you should be able to
figure out what's going to happen before doing the experiment
... but in the real world sometimes it's easier and better to
just do the experiment.  AFTER doing the experiment, then you
can write a report, from a position of strength.


On 05/02/2017 07:42 PM, Anthony Lapinski wrote:

> Binoculars are hard to hold and keep images stable without a tripod.

That depends on the magnification.  If you stick to 7x, hand-held
should be fine.  People can perceive images that aren't 1000% stable.
(If you want to study something that requires higher magnification,
e.g. the rings of Saturn, get a proper telescope with a proper mount.)

>  I don't recommend a class set.

That kinda depends your goals and the students' goals.  Most
folks in the real world will get far more use out of a pair
of binoculars than they will out of a telescope.  On a hike,
the binoculars you have with you are more helpful than the
telescope you left at home.  Showing students what they can
(and can't) do with binoculars has some value.  Besides, the
things don't wear out, so the amortized cost per lesson is
pretty small.

==========

As for telescopes:

Nowadays you're more likely to see a buggy whip or a medicinal
leech than you are to see an astronomer looking through the
eyepiece of a telescope.  For professionals, and even for serious
amateurs, it's all CCDs.

As a side benefit, a whole class can look at the CCD image
at once (rather than taking turns at the eyepiece).