Sigma lens OR small refractor

[Chris33benoit]

Hi y'all, I was wondering if I would make a wise decision by buying a small refractor for my SkyWatcher Star Adventurer.  My budget is 100-200$ (new not used).  And I already know that WO Zenith and SW Evostar 72 is one of the best scopes (budget) there is but don't have the cash flow.  I do astrophotography as a hobby like 3-4 times a year.  My next pictures are from a Nikon DSLR camera with the Sigma 70-300mm F/4-5.6 lens.  I did use a barn style tracker (NYX) for these pictures (no SW adventurer).  So again I am asking for your opinions.  My future scopes are (OTA usage only):

- Celestron Powerseeker 80AZS 400mm focal length

- Svbony 80mm 400mm fl

- Visionking 80mm 400mm fl

 

I know that the factor "tracker" is not fair in a way, I mean I will have better tracking with the SW Adventurer so unfair to say that it will beat the barn door tracker by a landslide.  

So will it make a big or light difference quality wise (pictures) ?  And should I buy?  Sigma VS Powerseeker.

Any feedback would be appreciated, thanks.