Improving the BASIC Lunt LS50 Tha Solar Scope

[Macavity]

After a bit of experimentation (a lot more pondering!), I have finally arrived at
my personal solution for *consistently* directing the sweet spot of my Lunt 50
onto the "best" part of my mono ASI120MM chip.

The issue SEEMED to be that the "tuning" was not consistent across the wider
chip dimension? That was fairly quickly resolved by rotating the diagonal (and
cam setup) about the optical axis. Another instance of "tricking" (is it called)? 

I could then disassemble / reassemble the setup and retain good Ha images.
But such an arrangement didn't seem completely satisfactory... What I really 
wanted was a T2 "screw on" system of equal path length  to the original...   

The BASIC task in hand is to bridge the gap between the T2 male thread on
the focusser end to the T2 diagonal's male thread! No rocket science but:

The (Teleskop Service) Rotator... (**)

http://www.teleskop-express.de/shop/product_info.php/info/p7356_TS-T2-360--rotator---only-5-5mm-back-focus.html

And T2 female-female Adaptor...

http://www.teleskop-express.de/shop/product_info.php/info/p3728_T2-female-thread-conversion---only-6-5mm-length.html

...does the job to within the nearest millimeter!

OK, I added a couple of THIN (Teflon?) Baader spacers (always a good investment):

http://www.teleskop-express.de/shop/product_info.php/info/p3619_Baader-T2-setting-rings---for-the-right-distance-control---15pc.html 

There are doubtless MANY solution to this issue, but I found that the (TS)
T2 ROTATOR solves many a short-path adapter problem at modest price.
You have the added freedom to rotate, but it also screw clamps rigidly. 

The KEEN eyed may spot a second rotator attached before the camera?
This to recover "orientation gymnastics" the above subjects the image!  

(**) Citation: As ever, also endorsed by SGL's finest: Michael Wilkinson.

[Pete Presland]

Excellent solution to your problem. Do you have any newton rings issues with the new set up?

[Macavity]

23 minutes ago, bunnygod1 said:

Excellent solution to your problem. Do you have any newton rings issues with the new set up?

Hmm... Funny you should mention that one! But yes I (still) do.

At the moment, I "cure" this by adjusting the tracking rate in the
EQMod dialog box to 12.5 from the nominal 15 point something?
Of course, it would be much easier to leave the image put!

For what it's worth, I tried removing the filter from the ASI120MM
The rings (predictably?) persisted. I also showered the CCD with a 
random load of CRUD, but it's now reasonably clean again now.

My thoughts are beginning to turn towards a USB camera that is
not well known for creating Newtons Rings. Ah, but which tho?

I have have a liking for something modestly priced, mono, smaller
pixels (like the ASI120) etc. Suggestions are always welcome...