William optics GT71+ Flattener or Altair 70 EDQ-R F5?

[IDM]

I have got myself in a knot trying to decide which way to go for a shorter focal length astrophotography scope and cannot decide between the Williams and the Altair. I like the idea that the Altair doesn’t require fiddling around with back space for the reducer, but the Williams reducer is also adjustable which I think/hope might make getting the back-space right easier.

I currently have a SW Esprit 100 and would like a scope of similar mage quality but more wide-field and fast. I am also thinking something portable so I can take it on holidays without filling half the boot of the car with astronomy equipment!

Does anybody have any thoughts on these two scopes or indeed better alternatives?

[Elp]

I wouldn't worry about setting backspacing. I've got different setups so have to account for different spacing all the time, it becomes second nature as long as you write it down.

As for scope, don't have them but have a z61 and it's an excellent scope, does everything I've put it through well (DSO, planetary (small planets), lunar, solar (with filters), visual and photographic).

[david_taurus83]

I've had both! Both lovely scopes but if I had to choose again I would get the Altair petzval again. Very good correction to edges with a full frame Canon 6D. Better than the Redcat I currently have. Prob one of my regrets of kit I have sold.

Edit: You can't use the petsval for visual observing so if that's an issue go with the WO.

Edited February 2 by david_taurus83

[IDM]

1 hour ago, david_taurus83 said:

I've had both! Both lovely scopes but if I had to choose again I would get the Altair petzval again

That does really help. I have seen a positive review on The Sky at Night website but not much more for the Altair. I do like its simplicity. 

[Adam J]

On 02/02/2023 at 10:43, IDM said:

I have got myself in a knot trying to decide which way to go for a shorter focal length astrophotography scope and cannot decide between the Williams and the Altair. I like the idea that the Altair doesn’t require fiddling around with back space for the reducer, but the Williams reducer is also adjustable which I think/hope might make getting the back-space right easier.

I currently have a SW Esprit 100 and would like a scope of similar mage quality but more wide-field and fast. I am also thinking something portable so I can take it on holidays without filling half the boot of the car with astronomy equipment!

Does anybody have any thoughts on these two scopes or indeed better alternatives?

I would drop down to 50-60mm for a scope to take on holiday as opposed to the 70mm range. 

https://www.firstlightoptics.com/askar-telescopes/askar-fra300-60mm-f5-petzval-astrograph.html

Adam

[IDM]

1 hour ago, Adam J said:

I would drop down to 50-60mm for a scope to take on holiday as opposed to the 70mm range. 

https://www.firstlightoptics.com/askar-telescopes/askar-fra300-60mm-f5-petzval-astrograph.html

Thanks Adam. I probably should have been clearer in that my intention was to drive through Europe with our caravan and therefore flight size was less important to me. Indeed on Monday I received the Altair scope. Which I managed to get out briefly last night (clouds were not good) but based on the limited time to play with the scope it seems optically excellent. I agree with your comments on size, in that the 70mm scope is probably a little large to take on a plane (not impossible). But I was keen to get fast optics, so the Altair at 70mm F5 is pretty good. Last night I managed to frame the California nebula and could clearly see a lot of the detail in a single 2 min sub. 

Size wise it’s so much smaller and lighter than my esprit 100 it will be easier to setup and take down making it more likely that I will use when conditions are less perfect (most of the time in UK).

The other thing I really like about the design is that when you put a filter in it’s easy to sharpen the focus without having to do  all the back focus compensation with spacers that are required for normal flattener.

 

will report on more as I get more used to it

Edited February 8 by IDM
Typos due to using my phone!

[UKAstroBill]

This is helpful. Any photos from the Altair with a full frame camera would be very useful to me. I’m pondering a new short refractor and the Altair is on my shortlist. I’m used to sorting out Backfocus but for a more portable rig where I might use no filter or filters of different thickness it looks very good. I had a look at it at PAS - slightly bigger and heavier than expected but immaculately made. Photos please!