Folk - you know your optics and are off on that path.
Advice solicited.
For nautical / yachting and coastal hiking - a monocular.
The Monocular you have is better than the better binoculars /
telescope in the drawer at home...
There's often binoculars in the cockpit of a yacht anyway and you can
adjust them for your eyes while you are at the helm / using them.
What the monocular needs:
* good magnification - >= 12X otherwise it's barely worth using them
* gathers light to still see in low light beneficial
* clarity / sharp image
* no (minimal) chromatic and other aberrations
What it does not need:
* wide field of vision - you are looking at a small object in a big seascape
* close focus - you are always looking minimum hundred metres away
More explanation:
With a monocular, given you are in a seascape with its single defined
horizon, there's a trick where the horizon through the monocular
lines-up with the horizon the unaided eye sees. Then what you see
through the monocular is a magnified duplication of what your unaided
eye sees straight-ahead. eg. if it's a yacht, your mind knows the
close large yacht full of detail is a repeat of the little spec just
to its Left Hand Side in the overall seascape - but your eyes are
accepting one continuous scene.
(benefit of firearms training in the US - had a firm taskmaster who
had me from the start both acquiring the sights and keeping scanning
all around)

Need opposite of wide field of vision - want a small inset in your
unaided eye's overall - even "close" would be less than 3deg of
angle (say 10m vessel at 200m)

Ideas?
I have a 10X monocular which fits in a pocket but although there are
worse it isn't notably sharp as you'd be singing praises about and
there's lurid chromatic aberrations messing up what you see.

On Sat, 18 Mar 2023 13:48:29 +0000
Richard Smith <null@void.com> wrote:

<snip>
>Ideas?
>I have a 10X monocular which fits in a pocket but although there are
>worse it isn't notably sharp as you'd be singing praises about and
>there's lurid chromatic aberrations messing up what you see.

A young healthy human eye has around 4.5mm opening available through the
wide open iris. As we age this value decreases. So 10x50mm binocs will
pass 5mm to your eye. Anything more than this is of no use and this is
even 1mm than you can probably make use of...

My favorite binoculars are 8x42, have roll down eyecups (I wear
glasses) and will focus to ~5ft. I need that close focus for
butterflies, birds, frogs... stuff that isn't so big to begin with and
you want to observe in more detail...

So for you I would recommend 10x40 minimum (40/10=4mm exit pupil) if you
wish full light gathering potential. Problem with 10x is that it is
hard to hold steady in the hand. For that 8x is about the max. You're a
smart guy though and could probably still get higher powers to work by
cheating in some way to steady the image ;-)

There are a LOT of airgun stores/shops in the UK. Most sell monoculars
and such of varying quality. Stop in and see what they have of interest
knowing you want something with around a 4mm exit pupil.

Hawke makes some decent stuff and have a few to consider:

https://uk.hawkeoptics.com/

--
Leon Fisk
Grand Rapids MI

"Richard Smith" wrote in message news:ly5yay187m.fsf@void.com...

Folk - you know your optics and are off on that path.
Advice solicited.
For nautical / yachting and coastal hiking - a monocular.

------------------------

I fully agree and keep a monocular in the car to identify aircraft
(warbirds) and ships from my sister's favorite beach near the commercial and
military harbor of Portsmouth NH USA. A few times I've recognized the sound
of a Merlin engine overhead but it was gone before I could get outside.

Seeing the magnified and normal sized images simultaneously took me some
effort, I practiced on the Rockettes in NYC. It also helps with a narrow
field of view night vision scope if there's enough light to see faintly with
the other eye, as our peripheral vision is more sensitive than our central
(foveal) vision to low light levels and motion.

The thermal imager I bought sees very clearly outdoors in darkness since
things cool at different rates at night.
https://www.amazon.com/VEVOR-Thermal-Imaging-Camera-Rechargeable/dp/B0BGRSF97F/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1

When I cut up a roast chicken in night school cooking class I could see and
separate the areas that hadn't reached the safe temperature.

On Sat, 18 Mar 2023 11:48:37 -0400
"Jim Wilkins" <muratlanne@gmail.com> wrote:

<snip>
>I fully agree and keep a monocular in the car...

I've just a really cheap 8x25mm in the car. Works good enough to read
the Business Hours on the store door and I don't have to look the fool
walking up and tugging on the locked door ;-)

--
Leon Fisk
Grand Rapids MI

"Jim Wilkins" <muratlanne@gmail.com> writes:

> "Richard Smith" wrote in message news:ly5yay187m.fsf@void.com...
>
> Folk - you know your optics and are off on that path.
> Advice solicited.
> For nautical / yachting and coastal hiking - a monocular.
>
> ------------------------
>
> I fully agree and keep a monocular in the car to identify aircraft
> (warbirds) and ships from my sister's favorite beach near the
> commercial and military harbor of Portsmouth NH USA. A few times I've
> recognized the sound of a Merlin engine overhead but it was gone
> before I could get outside.
>
> Seeing the magnified and normal sized images simultaneously took me
> some effort, I practiced on the Rockettes in NYC. It also helps with a
> narrow field of view night vision scope if there's enough light to see
> faintly with the other eye, as our peripheral vision is more sensitive
> than our central (foveal) vision to low light levels and motion.
>
> The thermal imager I bought sees very clearly outdoors in darkness
> since things cool at different rates at night.
> https://www.amazon.com/VEVOR-Thermal-Imaging-Camera-Rechargeable/dp/B0BGRSF97F/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1
>
> When I cut up a roast chicken in night school cooking class I could
> see and separate the areas that hadn't reached the safe temperature.

I had no idea I was talking any sense with any of this.
Well I am getting over a big surprise!
With no sidearms here (UK) no-one has been confronted with training the eye.
I was once saved by an optical surgeon who told my yachtmaster friend
that on the contrary this is the technique used, because my
yachtmaster friend thought I had "lost it this time".