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Walking on the Moon

Sun H-Alpha 14.03.16


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Another early start (gasp)! First, I thought I would revisit this 
brightness asymmetry in my images. Found to my surprise that,
via a further rotation of the diagonal about the axis (clocking), I
I could actually *center* the sweet spot within the solar disk! :)

The immediate effect was that the image was a lot smoother,
but, the previous Newtons Rings seemed more distracting? :o
Anyway, finally worked out a way to combine disks & proms
(Nowhere as good as the experts - Still on learning curve).

This from about 11 a.m. this morning:


I decided I'd have to bite the bullet and TRY the idea of turning off
the tracking during the exposure (Had to go from 1 min to 30sec).
At first I was circumspect - My carefully centered sweet spot clearly
would NOT remain *central* throughout the exposure now ... :icon_rolleyes:

But this from about 2.30 p.m.


HEY, it really worked! Gone are the pesky Newton's Rings! 
Not so easy to remember to DO all these things but...


Edited by Macavity
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I think there is a slight loss of contrast from the (removed) Newtons Rings.
If I can think of a way that doesn't completely STOP the telescope too? :p

I was struggling a bit with colouring the images via HSV, but discovered
the section, from Michael's guide, on using curves in GIMP RGB channels:


As (someone) predicted, this exposes a slight "white lie" about the Sweet Spot being
*absolutely* central, but I sense with a bit more tweaking (in hardware or software) ;)

For this and more, my thanks... and a (manly):



P.S. The purists may note the "offset circles" around the image? I suspect these are
symptomatic of the slightly tilted optical axis? If fairness, I *overcooked* the proms
in my desire to reveal the fainter ones. Or maybe a guide to precise adjustment? ;)

Edited by Macavity
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Wow Chris!  That is very nice work on both the proms and the disk.

Congratulations on getting those NRs under control... excellent detective work.:)

If Gimp will allow you to re-size the image, try shrinking the prom disk 1-2% before fitting the surface to eliminate that small ring.:)

Clear Skies

Edited by Lowjiber
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You use a diagonal ? Why?  Doesn't it add a big chunk of leverage to the focuser ? Maybe that's why your NR went. Just interested. I tried my quark with and without diagonal and it gets you out of staring the sun in the face for visual but I wouldn't hang a camera off the diagonal if I could help it.



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Heheh. No other choice? The essential blocking filters are integral
to the scope diagonal. I sense most imagers wouldn't chose to do
so via a diagonal, but there is no (inexpensive) alternative.  :o


Rather limits the flexibility (in-focus etc.) re. use of Barlow lenses
too. But I'm philosophical? Solar scopes are pretty "leading edge"
for something readily available for the amateur market? ;)

The Newton's Rings are likely generated between the CCD and the
cover plate by cameras which (in all fairness) were never designed
for use with a narrow band monochromatic source... :)

Edited by Macavity
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For interest, I recorded the solar image taken with the diagonal
clamped firmly within the holder at ~90 deg intervals. Recently,
I was at the "Up" position, but improved things to be as "Left".
Of course, randomly, I started out at one of the other two... :p


The results are not "orthogonal". I presume because of the vagaries
of the diagonal, the focuser, integral brass ring clamping system etc. ;)
I do intend to try a direct T2 screw connection sometime...

Edited by Macavity
Changed position of the images!
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The keen eyed may have spotted the image and text didn't correspond? :p

Thanks for the "like", Lowjiber. I think there is still room for your (Earl's)
methodology of "crescent reduction"... PM / Email received - My Thanks! :) 

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