Over the past year or two, there have been plenty of telescopes on simple Go-To mounts for beginners. These feature altazimuth (altaz) mounts that move up and down, left to right, taking the tilt of the Earth’s axis into account.
Now Konus has joined the gang with its Digimax-90, a 90mm (3.5-inch) Maksutov-Cassegrain telescope on a Go-To altaz mount.
It’s simple to assemble because the whole system is relatively light, yet the tripod is still sturdy enough for the job.
For the best tracking and performance it’s worth spending a little time making sure that the tripod is level, and it is nice to see a bubble level on the unit’s main base for this very purpose.
With the mount level, the telescope tube is attached with a standard dovetail bar, and we were glad to find that we could mount the tube so that the eyepiece end would miss the mount’s base when the scope was pointed vertically, so all areas of the sky could be reached.
It comes with the altaz version of the SynScan computerised controller, the SynScan AZ.
This enables 43,000 objects to be located and tracked with relative ease.
The hand controller works very well, with a soft red glow from the display and buttons.
Power comes from either eight AA batteries or a 12V power pack, which have to be purchased separately.
We used our own power pack for the majority of testing and found that it was worth wrapping the power cord round the base unit once to prevent the plug from accidentally being pulled out when the scope slewed a long way to an object.
Turning to the sky, you set up the Go-To system by inputting basic details such as your latitude, longitude, time zone, date and time.
Then you’re taken to the tube-alignment phase.
There are two alignment choices, ‘brightest star’ or ‘two-star alignment’, and we found that both worked well.
Once set up, the full database of celestial objects is available to browse.
It encompasses double stars, stars with names, and the Messier and NGC catalogues to name just a few options.
A range of views
The Digimax-90 comes with two eyepieces, a 17mm and 10mm, which give magnifications of 73x and 125x respectively.
The views were good, but we felt that including a 26mm eyepiece (giving a 48x magnification) would have given a slightly better range of magnification than you get with the 17mm.
We examined the bright star Procyon and used the telescope’s 17mm eyepiece on it.
Over the 15 minutes we tracked it, the star remained within the inner 50 per cent of the view, although there
was a slight amount of drift. Procyon was also pin-sharp across 75 per cent of the field of view, with the quality only dropping off slightly towards the field edges.
We noticed a bright oval ring of light appear as the star neared the edge of the field, which shrank and disappeared as the star moved out of view.
This suggests a reflection on an inner surface, but it didn’t affect fainter stars and objects to the same extent.
Good, clear views
Despite this, the views of the night sky were enjoyable: the components of the double star Castor were easily split with the 10mm eyepiece, while Algieba in Leo provided a lovely sight, with its two golden-yellow stars clearly separated.
The Orion Nebula was a joy to view and the central Trapezium stars sparkled when we swapped in the 10mm eyepiece.
The Moon fits well in the field of view with the 17mm eyepiece, and with both eyepieces it displayed plenty of detail.
In addition, Saturn’s rings could be seen crossing in front of the disc as a thin dark line, while three of its moons were visible as well.
There was also a hint of the differing shades of pale yellow in both of the planet’s hemispheres.
Overall, the Digimax-90 works well on most types of object, but its long focal length is better suited to the planets and double stars, as opposed to fainter things like galaxies.
Lightweight and portable, it’s an ideal setup if you’re a beginner, or for use as a quick-look scope if you’re a more practised astronomer.
The SynScan Go-To system is the gem in this setup.
The hand controller is simple to operate, with relatively large buttons for ease of use in the dark.
The layout of the menu is straightforward and all the buttons have their basic function marked with text that stands out when illuminated by red light.
We found the alignment process and Go-To functions worked very well.
Every object we selected showed up in the main field of view of the 17mm eyepiece, although this accuracy depends on how thorough you are when you initially set up the telescope.
Its database of 43,000 objects offers a huge choice of things to examine, although asteroids and comets are missing.
However, you can input your own object data and store it for future reference, or even connect the controller to a laptop running planetarium software to get the positions of even more objects – including asteroids and comets.
The sky’s the limit with this system.
The Maksutov-Cassegrain optical assembly worked well and gave clear views of a wide variety of night sky objects.
The quality of the field of view was good, but we noticed some internal reflections when bright stars were viewed near the edge of the field.
The red-dot finder is simple and easy to use, with a dimmer switch to vary the brightness of the red dot, which made the alignment process much easier. It is conveniently positioned at the back of the telescope.
Star diagonal and eyepieces
The 1.25-inch star diagonal allows the eyepieces to be used at a more comfortable position, so viewing objects high in the sky doesn’t cause neck-ache.
The 17mm and 10mm eyepieces gave good views with their respective magnifications of 73x and 125x.
The focusing knob is at the base of the telescope tube.
We found it easily in the dark and it was quite smooth when focusing, although there was a little play in the mechanism.
The base unit is compact, fits easily on the tripod, and holds the telescope assembly well.
There’s a bubble level on top of the unit where the battery compartment is also located.
Aperture: 90mm (3.5 inches)
Focal Length: 1250mm; f/13.9
Eyepieces: 17mm, 10mm
Mount: Altazimuth Go-To
Supplier: Evergreen Optics
Telephone: 01588 620717
This review originally appeared in the May 2009 issue of BBC Sky at Night Magazine.