Future Thinking

[simmo39]

Hi all, for the past few years I have been using a SW 130 pds and have found it a V good scope and have been pleased with most of the images it has produced. But, and its becoming a big but!, collimation and diffraction spikes are becoming a bit of a bug bear. I recently bought a SW 72 ED pro for wide field stuff and although I havent really had chance to use it properly it has convinced me fracs is the way to go. I should say at this point that this is a future wish list at the moment and I may have to struggle on for one more season with my 130..

Anyway to the the crux of the matter, I have a SW HEQ 5 mount and have no wish at the moment of changing it and as far as I can find out is good for upto 11KG imaging rig. I have been looking at the Esprit 100 as a possible way to go but the price is high ( for me ) and it weight with all the little extras may be v close to the 11KG limit. Do any of you out there use this scope with a HEQ 5 and if so do you have any problems?

The second question is there any other good alternatives ( preferably cheaper ) that would be a good replacement for my 130 pds.

Oh the camera I use is a Zwo 1600mm with filter wheel.

Thanks in advance.

Edited May 15, 2019 by simmo39

[vlaiv]

I think that price of Esprit 100 is ball park of what you are looking at if you want to replace 130PDS.

If we assume let's say 94% per mirror reflectivity and 26% central obstruction (these are of the top of my head, but I'm certainly that they are fairly close), then to replace it, you need ~118mm clear aperture scope with 650mm FL - or ~F/5.5.

Most 4" - 4.5"  APO scopes suitable for imaging with FF/FR are going to cost about the same as Esprit 100 (give or take).

Possible alternatives to Esprit, that I would look at:

115mm F/6.96 Triplet with FPL51 / lanthanum element - available at TS, but AA as well (at least I think so), yes here it is:

https://www.altairastro.com/altair-wave-series-115-f7-ed-triplet-apo.html

Pair that with Riccardi FF/FR - https://www.teleskop-express.de/shop/product_info.php/info/p11122_Riccardi-0-75x-APO-Reducer-and-Flattener-with-M63x1-Thread.html

and you get 600mm F/5.2 system.

There are two cheaper options, but these are doublets and you might need special Lum filter that is a bit narrower with these:

ED120 with matching reducer

Or

https://www.altairastro.com/Starwave-102ED-FPL53-Refractor.html

(StellarVue and TS variants are also available)

Again with suitable FF/FR (but I would recommend above mentioned Riccardi FF/FR).

[simmo39]

Hi Vlaiv. Thanks for the reply and the pointers. I will have to have a good read and digest what you have said. The SW 100 ED seems to be good value ( relatively ) the only real concern is the weight on my HEQ5. I will have a good look at your recemondations. Thanks once again.