Frankencope Tests! (Apologies for absence)

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
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Oh, I get it now!
Oh, I get it now!
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Joined: Tue Mar 15, 2016 11:45 am

Frankencope Tests! (Apologies for absence)

Post by Macavity » Fri Aug 18, 2017 10:44 am

Hi (again) Folks! (Throws HAT in) :)

Apologies for absence! As often with Astronomy Forum activities,
one cannot be "everywhere at once" (I notice welcome overlap!).
But also perhaps one should have *something to say* as well? :P

In the *interim* I have been producing "composite" disks like:

Combined.jpg (671.95 KiB) Viewed 593 times

I also produce the occasional (2x2!) Matrix. Disk / Prominence
animations. White Light (Solar Cont, DS CaK filtered etc. etc.)

But my scopes remain a *modest* Lunt50 & Altair ED66 Frac!
The former (at least) may not change much in the future? lol
So I find my enthusiasm FIRED by ideas of a Frankenscope! :D
Yet it is only recently that I had "the courage" to have a go...

!Franken102.JPG (239.02 KiB) Viewed 593 times

And (amazingly!) it does show signs of actually working... :mrgreen:

The objective is a (much disguised) Skywatcher ST102. I am
making heavy use of "wood technology" for the OTA "bung"!
I HAVE bought myself a nice Baader 90mm ERF and I'm now
working on making a "proper" (tilted) mounting cell for it...

It is thus far a modest increase in aperture / focal length
50mm f/7 to... 70mm f/7 but I have managed to convince
myself it is "better"... or at least progress is being made! ;)

Lunt 50 owners will know that there is "very little space
to operate" with the original Helical Focusser. But I use
the nose-piece of an Antares 3x Barlow for a 2x increase.

Firstly the Lunt50 Barlowed 2x:
02.LuntBar.thumb.jpg.0c3d577fb031315f15cfae65a48702a3.jpg (355.22 KiB) Viewed 588 times

Now my "Lunt 70" (Frankenscope!) Barlowed 2x:
03.FrankBar.thumb.jpg.6513d15a061dfd6d68f5ced5134f73bd.jpg (359.73 KiB) Viewed 588 times

Yesterday, I threw caution to the wind (Yay Sunspots!)
As a "control" re. seeing etc. I took an image with my
ED66 (F=400mm) Barlowed approx 3x for White Light:

01.WLX3.jpg (234.96 KiB) Viewed 593 times

And now my MIGHTY 70mm f/500mm Frankenscope
Barlowed by 4x (I quickly "scaled" the image a bit!):

02.HAX3.jpg (226.32 KiB) Viewed 593 times

NO "Lunt 80" or "ED120 Quark"? But I'm still Excited!
If I can extend the focal length to 600mm... Just a
BIT more aperture... f/7 would give me 86.7mm! :cool:

At the moment I am pondering other and better(?)
Donor Scopes! I can extend my ersatz construction
method (and can afford) an ST120 OTA... Would it
be "good enough" re. Spherical Aberrations? What
if I stop it down to 90mm to match the ERF? etc.

I will also be limited to a Lunt BF600... I cannot
"Change the Laws of Physics", but maybe *bend*
them just a little? It's all "Light cones and Solar
Image diameters", right? [teasing] & <thinking> :lol:

Donor Scope suggestions are now very welcome!
Apologies for the extended <wibble>! Maybe this
might provide a similar *incentive* to others... :D

Oh, I get it now!
Oh, I get it now!
Posts: 29
Joined: Tue Mar 15, 2016 11:45 am

Re: Frankencope Tests! (Apologies for absence)

Post by Macavity » Sat Oct 14, 2017 2:01 am

To complete this quickly and to answer a question from another thread!
(Adapted from other notes, so continuity / intelligibility not guaranteed!) :P

Since the above I bought an ST120 (to reclaim my ST102 grab & go OTA!)
The ST120 also maximizes the focal length for the Lunt BF600 and gives a
bit more "elbow room" for making "wood-technology" components! I have
also now finished an ERF cell and improved the "quick-release" clamping.

Without access to a lathe and requiring a quick & easy way of prototyping
I opted for the Hole Saw + "Redneck Lathe" (**) using MDF Lite (fibreboard).
To add a bit of accuracy I used the structurally firmer hardboard to make
the outer layer of what is (effectively) DIY plywood! :mrgreen:

** {Basically you make up a set of disks of appropriate outer diameter and
SPIN them using a power drill (in drill press) to fine tune outer diameters
using a file / sandpaper etc. N.B. Be careful applying lateral pressure to a
drill bit as this is not their intended purpose!! On the other hand MDF is
very soft? Do remember to wear a MASK to avoid breathing any MDF dust!} :shock:

It is usually necessary to make fairly exact diameter for the inner holes.
But, using the general method + a little imagination(?), you can make:

The Bung:
Bung.JPG (233.14 KiB) Viewed 414 times

90mm Baader ERF Cell:
ERF_Cell.JPG (291.83 KiB) Viewed 414 times

I found some PVC duct of larger diameter than the Refractor Dew Shield
and made the outer wall of the ERF cell by cutting /gluing TWO lengths
pipe around one another... You can also add ERF filter tilting etc. etc.
Pipes.JPG (250.25 KiB) Viewed 414 times

THE END result:
!Franken2.JPG (201.23 KiB) Viewed 414 times

Collimation proved reassuring trivial! I just tried to square / shim the
OTA's as best as possible, using a engineer's square / digital level etc.
Focus is "restored" by sliding the Lunt OTA back and forth in the Frac!
I have included some *safety features*... A locking clamp and a BOLT.
I certainly don't want my Lunt 50 sliding onto the observatory floor!

Basically I am now operating the f/5 120mm ST120 at a stopped-down
86mm... To give the optimal f/7 light cone for the Lunt50 Etalon etc.
I suspect it may reduce e.g. spherical aberrations of an f/5 achromat?

I am not a particular master of Solar Processing, but I feel there is a
a significant increase of resolution in the approx 4x Barlowed images!

Native Lunt 50 (f=350mm):
01.Full.jpg (295.65 KiB) Viewed 414 times

Barlowed 86mm "Frankenscope" (f=1200mm):
06.Best.jpg (677.47 KiB) Viewed 414 times

For the moment I am happy enough with this. Clearly you can
"upgrade" it in a number of ways... Use a "better" objective...
Get a skilled machinist to make the components for you etc.

I part justify the cost of the ST120 by claiming I *needed* a
NEW and bigger ST120 Richest field (nighttime!) scope. But
that will be its main / alternative use in the quick release
scheme. The cost of a 90mm ERF was thus the "only" thing? :lol:

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Re: Frankencope Tests! (Apologies for absence)

Post by marktownley » Mon Oct 16, 2017 8:10 pm

Looks really good!
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

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