A good night for a 90mm

[Tonys]

I put my 90mm Skywatcher Mak ( on AZ3) out last evening around 18:30 to have a look at the moon and by the time I started an hour or so later the transparency had dropped dramatically. The sky was very steady though and after a while I pointed to barely visible Castor to see how high I could push the magnification. I ended up with my Tal 7.5mm ep and 2x barlow for some of the best central disks and first diffraction rings I've seen. The disks were rock steady and the first bright rings were almost perfect circles with barely a tremor. Very impressive I thought, given that the magnification was 37x per cm of aperture ( if I've summed it right). The sky cleared a bit shortly afterwards and I thought it was a good chance to do a star test on Polaris, but the increased clarity was accompanied by a less stable sky and Polaris was dancing around a bit too much. I find that this moving around of the whole image owing to unstable seeing is typical for my small scopes, whereas the bigger ones tend to break up the image.

[russ]

They are a very impressive and inexpensive little scope. One of the gems in the Skywatcher range. After an impromptu star party in my garden on Saturday when a few work mates brought round their scopes that i had recommended they bought (a 114P and 130P), i came to the clear conclusion the Skymax 90 was a far nicer scope than either of the Newts. Embarrasingly they also commented to the same effect and wanted to know why i had steered them to something that was much larger, more expensive, needing constant tuning and inferior image. Tried to explain about aperture and how their scopes would come into their later. They were having none of it. Don't blame them, the Skymax 90 spanked their two scopes on the moon and Jupiter. While a few doubles looked better still.

[Tonys]

Mine certainly seems to "punch above it's weight", which I think is down to the Mak design (eg all spherical surfaces) and the small aperture (not so affected by seeing). I think the famous Questar Mak also happens to be 3.5 inch. The low price of the Skywatcher does show up in the mechanicals though eg the mirror carrier, which seems to rely on a thick grease to maintain smooth focusing action.

[russ]

I suppose they have to make some cuts here and there to meet the price point. And the thick greasy mirror carrier is one. That said it still works better than your average (or even above average) SCT focsuer. But way off the buttery smoothness of a decent Crayford.