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On 10/24/2015 7:02 PM, Sean C wrote:
> All,
>
> Attached are the teaching aid graphics I made for Rommel. I'm posting
> them here in case anyone else might be able to get some use out of them.
> Enjoy!

Sean

Nicely done. A step 2 instead of step 1, step 3 then step 3. Much
clearer than the original. ;-)

Under the category of "Everyone is a critic," there are some issues with
the original blog graphic that remain unresolved for me in your artful
renditions.

1. The position of the sun in the scope. You corrected the original
debatable decision to align the center of the sun with the (not visible)
horizon. The horizon is centered vertically in the scope's FOV--great.
But...the sun far to the right of the scope's center may reduce accuracy.

2. Which brings me to my pet peeve. It is clearly a traditional mirror
with a lower-power scope as opposed to higher magnification scopes or a
whole horizon mirror. Unless the scope has been poorly adjusted
laterally, the viewer will not see squat if the sun is off the "magic
spot" we take for granted.

Borrowing from Ken G describing what a sextant does, "It measures
angles." Anything past that for a booth visitor looking through a
sextant while holding it upside down was superfluous. The next important
step after turning the sextant right side up in introducing a newbie to
sextant use is IMHO--and borrowing from firearm jargon--the sight picture.

With iron sights you align the front sight to the rear sight and the
target until it looks like the provided diagram of a sight picture. That
is similar to to the approach I use with someone who has never looked
through a sextant scope before. I've done it in the rain with a broad
building, a lighthouse then a natural water horizon. Set the sextant a
few degrees or so off alignment for the target and ask them to locate
the spot where they see ghost images on two sides. Now turn the
micrometer drum until the ghost images overlap exactly.

Which may be the long road to my point, but I feel without illustrating
the overlapping diminishing-transparency horizon and index images it
leaves the reader or student like a male dog with a full bladder between
four trees--not a leg to stand on. Or illustrate whole horizon mirror.

I understand I'm being picky, but when introducing a concept to someone
who is tabula rasa, I put myself in their place, remembering when I
first learned. What I take for granted now may well be uncharted
territory for the student.

Keep up the good work.

   

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