Celestron Nexstar SLT 127

This is a five-inch Maksutov-Cassegrain. The optics are superb, no chromatic aberration and pin-sharp. Thanks to the long focal length (1500mm), focussing is easy, despite a basic focussing knob. It is like using an apochromatic refractor at a fraction of the cost. The high focal ratio (11.8) also means it is short and easy to carry (at 8.2kg it is fairly heavy for its size) and it is very robust. It is a bonus that it doesn’t require collimation. The main weakness of this model is the tripod, the plastic casing around the legs started to crack after three years and the power plug of the go-to easily pops out. The tripod is only just strong enough for the mak. The go-to works (I usually use two-star alignment), but it is only just accurate enough with an accuracy of about 30 arcmin.  The main drawback of a mak is the narrow field of view, but the corresponding high magnification means it is excellent for planets and double stars. I can easily see 9th magnitude stars locally and occasionally 10th magnitude. Despite my reservations about the tripod and go-to, I would recommend this telescope on cost grounds. Current cost: £599. 

Peter Morris, February 2023

Explore Scientific AR102

I wanted a rich-field telescope (RFT) with a good aperture and this scope fitted the bill. It is a simple achromatic doublet with a crown-flint objective but I have not had any major problems with chromatic aberration despite the short focal length (6.5), which means it is better than the equivalent Skywatcher models. The joy of this model is the excellent two-inch Crayford focusser which is very smooth. Many telescopes of this type have a long focal length which makes them awkward to use, but this one is nice and compact, and light at 5.2kg. This means I can use it on the superb Vixen Porta II tripod which I bought for an 80mm Skywatcher, but only just. But the lightness of the whole set-up trumps the slight wobbliness. Unsurprisingly, this scope has a wide field of two degrees or more, and I can observe the Pleiades with ease. This also means that a finderscope is rarely needed. However, the low focal ratio means you cannot easily crank up the magnification – the realistic maximum is 94x. My only grumble is I cannot use my beloved Orion 9x50 right-angle finderscope with the non-standard bracket. In a dark sky area, this would be a superb RFT. It is also remarkably cheap at £558 (tube only) at Widescreen.



Peter Morris, February 2023