WilliamPaolini wrote: ↑Sat Nov 27, 2021 3:40 am
I will second John's recommendation for a nice compact 5" Mak (or 6" SCT) with goto. While 8" Dobs are quite capable, they are also large, heavy, and a difficult carry to take in and out, plus the larger mirror may need a lot of acclimation time before cooled enough for planetary. For a beginner kid I feel if a Dob is gotten, then a 6" one is plenty capable for a wide variety of targets including deep space. And it is much much easier being small and light in comparison to an 8".
On the 6" Dob I prefer the Sky-Watcher over the Orion as it has a 2" focuser so you can use 2" eyepieces for those wider views.
https://www.adorama.com/skws11600n.html ... dl-gbase-p
Actually, on thinking more, I would remove the 6"
SCT from consideration. I've had all the scopes mentioned and the
SCT is a bit more complicated to operate effectively than a 5" Mak. It has a longer thermal acclimation time so that means more prep time before observing, the thin glass on the corrector plate tends to dew up much faster than the thick glass on the Mak's front meniscus lens, collimation is a bit more difficult with the adjustment screws being on the front of the unit as opposed to on the back for the Mak, and finally the conventional
SCT (i.e., non-Edge or ACF - FYI only Meade makes a corrected 6"
SCT their ACF models, there is no Celestron 6" Edge
SCT) will show lots of
coma and field curvature in the off axis whereas the Mak design has a lot less of that so the off-axis star points look much better through a Mak.
Now some will rightly point out that the Mak has a longer focal ratio so the true field of view (TFOV) will be rather small with something like a 24mm 68 degree wide field or 32 Plossl both of which give the maximum TFOV for a 1.25" eyepiece. On the Celestron 5" Mak that John linked to, it is
f/12, meaning the max TFOV with 1.25" eyepiece will be 1 degree (about 2 full Moon widths). However, the standard Celestron or Meade
SCT .63x reducer works perfectly on these little Maks so using one of those inexpensive accessories on the 127 Mak will allow that 24mm 68 degree wide field or 32 Plossl get you a nice 1.6 degree TFOV. I believe the Sky-Watcher Maks need no adapters to use the .63x reducers, others like the Synta Orion branded Maks need adapters which can be gotten at
http://www.scopestuff.com/ss_smsa.htm. When I had the 127 Mak it was a joy to use as 5"
aperture was plenty nice for the prominent
DSO and it was such a small form factor that it was a pleasure to travel with. So a nicely capable small instrument that cut no corners IMO when mated with a reducer for those wider views.
Below is a view comparison using the 127 Orion Mak I had. I used a 2" diagonal on it which increases the focal ratio of the instrument due to the light path it adds. But if you look at the yellow and green circles you can see how dramatic of a difference the reducer made with the a 1.25" eyepiece that has a 27mm field stop like a 24 Pan or 32 Plossl/Konig. Made it so a 2" diagonal not really needed.
The 8" will show a huge amount more, but it's bulkier and can be hard to find things with if you're new to this.
