LS35/ST80 Frankenscope taking shape

[michael.h.f.wilkinson]

I have been tinkering again, this time by replacing the stock focuser of an ST80 I picked up quite a while ago with a 2" helical focuser from TS, and inserting a 63mm ERF in the tube, just behind the anti-reflection baffle. This assembly is then put into home-brew tube rings on a 34cm vixeb dovetail bar (also TS). I am still missing the F=-174mm negative meniscus lens that will be mounted in the 2" helical focuser, converting the ST80 into a 2.3x Galilean scope. The LS35 can be mounted on the same dovetail bar, and aligned using its standard guide-scope rings , or perhaps mounted with purpose made rings (I have made a set, but do not know what will be best). It should be possible to remove the ERF of the LS35. I will also put a little shroud between the 2" helical focuser and the etalon. The total focal length of this beast will be 920mm, but as I have a B1200 blocking filter already fitted that should not be a problem. No doubt the 2.3x magnification of the front scope will increase sweet-spot issues, but I have seen some results with a 6" LS35 Frankenscope, so I am not too worried.

The meniscus lens should arrive later this week, and then all I need is some sunshine to align everything.

[Mick J]

Well Professor I am liking that,  always worth looking at your posts but the “home-brew tube rings” are an inspiration, thank you for that    

[RichM63]

Cool ! Great job on the tube rings.

Quick question, I am about to order a dovetail from TS, would you please confirm that the bar is perforated in such a manner that it is possible to mount the ST80 around the center position.

On the TS site they only mention a 32cm bar (too short) and from what I can see it is only perforated and tapped at the very ends which wont work for me, piggy backing onto a 200P with 33.5cm ring spacing.

Thanks in advance,

Richard

[michael.h.f.wilkinson]

The dovetail I got is 34 cm long and the longest distance between holes is 31.5 cm, and several holes and slots along its length. I got this one:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p4647_Starway-universelle-Vixen-GP-Level-Prismenschiene---Laenge-34cm.html