Wo Gt71 or Gt81 ?

[Neo_uk]

Hi ...

I'm looking at upgrading my imaging system ...currently I'm using a skywatcher ed80 Pro (gold tube) with the skywatcher .8 reducer/flattener with a starlight xpress h694 mono camera and filter wheel .

I'm really torn between the gt 71 and gt 81 from the respect of the fov both with and without the flat 6 reducer and my current ccd camera ...

I know that apature is king but there is about a £500 differance between the two scopes .

What would you do ??? ...

Also if I did push the button on either of these scopes the ed 80 Pro ( gold tube version) and flattener would be surplus to requirements and I'm not sure how much to advertise is for ...it has some marks on the ota from guide rings and the rubbers on the focus knobs are missing...optics are excellent and has the aluminium case finder ..diagonal and eye pieces .

Many thanks for looking and any advice would be much appreciated..

Chris.

[SamAndrew]

Assume they are mechanically the same, it's just a choice on size of the FoV vs size of the objects you're imaging, either is fine. £500 is a big difference for not a lot more apature. Do you find you want more FoV or a longer focal length when using the ed80? or is it just about right. I'd use that to steer your decision.

[Neo_uk]

I guess I'm happy with the ed80 ...I was just thinking of a bit more flexibility with the f.o.v ...but I think its down to the chip size of my ccd camera ...throw in the modded dslr and the field of view of the gt81 widens quite considerably...

[Martthebass]

I briefly had an early version GT81 but, as a newbie, found it a challenge as everything cost and required knowledge/skills I didn't have to fit things to it (and I found the old crayford focusser a bit clunky for AP).  Eventually I sold it on but funds were such that I downsized to the new model GT71.  To be honest, I haven't found a massive difference in performance (focusser aside) between the 2 for AP. So if you are happy with the FOV considerations I wouldn't get too concerned over which model you eventually went for.

[Neo_uk]

Thank you ...for your insight ..as samandrew said £500 is a big difference for not alot more apature..

I did read that some wo scopes suffered from focuser problems ...how do you find the focuser on the new gt71 ? ...

Another side of the coin is if I went for the gt71 for the £500 difference I could get the flattener and matching guide scope and still be in pocket .

[Martthebass]

The focusser on the GT71 (and the GT81) are now R&P.  I've found it rock solid in my GT71 with a ASI533MCP hanging off it.  The Flat6Aiii flattener/reducer screws directly into the current focusser and is a very good fit.

[KP82]

Between 600mm -> 478mm and 600mm -> 420mm, I'd go for the latter due to larger difference in fov (in fact I'd say zs61 with its 360mm focal length would be even better) unless you'd also need the scope for visual. The 10mm difference in aperture is not going to show any difference in imaging since both scopes are f/5.9.

Personally I just got myself an Altair 72EDF to complement my APM 115 and Canon 135mm lens.