Stepping up to next telescope

[Alexgc]

Hi, 

Since getting into DSO imaging 18mths or so ago, I've been using a WO Zenithstar 61 on an ioptron Skyguider Pro. It's been great but am now stepping up to a beefier mount, namely the skywatcher eq6-r pro. What thoughts do people have regarding a larger scope? I would prefer to stick to a refractor for now and was thinking 90-100mm. I really like the build quality of the WO scopes and was thinking of a Fluorostar 91. I've been saving up but is the price tag justified? What are the options do you think?

Thanks

[Icesheet]

An EQ6-R is sound choice and opens up a lot of possibilities, even beyond an aperture of 90-100mm. Almost too many!
 

I have no experience with the fluorostar but I’m sure it’s a solid choice. It might be worthwhile deciding what focal length the targets you want to image are at. Then you can think about design of scope. Triplet with flattener and/ or reducer option. Maybe you would like a petzval type so you don’t need to mess about with backspacing etc. Focal ratio, weight, mechanics and accessories etc all come into the equation.
 

Then you need make sure that telescope is a good fit for your camera. Do the optics cover the sensor? What image scale does the combo give you?
 

There are just so many options right now it makes sense to have a methodical approach to narrow things down. Finally, buy from a reputable retailer that offers a good returns policy and support!

Good luck with the choice!

Edited June 6, 2022 by Icesheet

[johninderby]

FLOs new SellaMia 90mm is highly rated and getting at reviews by imagers. Compare the StllaMira and Flouostar and they look the same except for the focuser.

https://www.firstlightoptics.com/stellamira-telescopes/stellamira-90mm-ed-triplet-f6-refractor-telescope.html

 

Edited June 6, 2022 by johninderby

[ollypenrice]

I'm not sure about the build quality of WO scopes. I think they concentrate rather too much on making them look pretty, though there are certainly good ones. Anyway...

I think you're starting at the wrong end of the thinking process if you begin with the telescope. To my mind this should be the last item to specify, not the first. My order would be...

1) What do you want to photograph? Small targets requiring high resolution or wider field targets needing more field of view? To answer this you'll need to explore what various chip sizes at various focal lengths cover on your chosen targets. It's possible to fall into a no man's land between long and short FL if you're not careful. You can do this on a software planetarium allowing all the permutations to be modeled. Of all the decisions, this is the most important.

2) Which camera? If you already have it, that's a given. If you don't, or might want to upgrade in the future, you need to think about chip size for field of view and pixel size for resolution. (Note, pixel size and not pixel count.)

3) Which telescope will meet these needs? Is the focal length right for the FOV you'd like? Does the corrected circle cover the size of chip you'll be using? If shooting broadband (OSC or LRGB) you'll want very good colour correction. This will be less important if you're only shooting narrowband.  At a given focal length, more aperture speeds things up, but a faster F ratio is much more expensive to deliver with good quality. (Don't worry about F ratio in isolation, it's F ratio at a given focal length that matters.)

In reality there's a lot of back-and-forth between 2) and 3) above once you've started to close in on your choice.

Olly

Edited June 6, 2022 by ollypenrice
Clarification

[Alexgc]

Thanks for all the above advice. It’s a real help to have an idea about the process of selection with such a bewildering array of permutations as to how the various elements of the setup affect each other. (With an eye on future upgrades as well)
Good job astrophotography takes place at night. I need to sit in a dark room to think it all through!

[johninderby]

The old saying about going down the rabbit hole seems appropriate to AP.

[Alexgc]

14 minutes ago, johninderby said:

The old saying about going down the rabbit hole seems appropriate to AP.

When I do arrive in Wonderland, I hope the weather has consistently clearer skies…

[ollypenrice]

8 hours ago, Alexgc said:

When I do arrive in Wonderland, I hope the weather has consistently clearer skies…

The most important choice of all is which wonderland to go for. In the blue corner we have Las Vegas and, in the red, the Atacama desert...

😁lly