Focal Length: 1,400mm; f/9.3
Eyepieces: 25mm, 6.5mm; 1.25-inch fit
Finderscope: 6×30, straight-through
Supplier: Optical Hardware
Telephone: 01226 203275
The Visionary Mira Ceti 150 1400 comes with a basic EQ3 equatorial mount, aluminium tripod, 25mm and 6.5mm eyepieces and a 6×30 finderscope.
It has quite a long focal ratio of f/9.3, which means the field of view using the 25mm eyepiece isn’t as wide as with some other 6-inch Newtonians.
However, the tube is much shorter than models with ‘faster’ focal ratios, which is the opposite of what you’d expect.
The long focal ratio is achieved with an extra lens built in to the focuser, which allows the tube itself to be very compact.
The mount has play in both axes and you have to really tighten the locking screws to make sure the telescope doesn’t move off target when you release the controls to look in the eyepiece.
The EQ3 mount can’t have a polarscope fitted (the difference between an EQ3 and an EQ3-2 mount), but aligning the mount is still quite straightforward.
Roughly aligning this telescope in the direction of the Pole Star was enough to allow objects to be reasonably tracked using the slow-motion hand controls.
We were disappointed with the 6×30 finderscope.
We’d come across it before in a January 2007 Group test and we had hoped there would be an improved model by now.
But this finder was still the same poor quality, with strong colour fringing – we could only just see the brightest stars.
We’d recommend a red-dot finderscope instead for this type of telescope.
The supplied 25mm and 6.5mm eyepieces give magnifications of 56x and 215x, but the latter produced quite soft, fuzzy views.
This meant that we tended to rely on the 25mm, and when extra magnification was needed we added a 2x Barlow.
We felt that the 6.5mm could be replaced with a 10mm eyepiece or even something between 15 and 18mm to give a better range of magnifications.
Stars in sight
Using the 25mm eyepiece on the star Capella, the field of view was sharp across the inner 50 per cent, with acceptable views out to 65 per cent.
But by 75 per cent out to the edge of the view the star became quite distorted with strong coma.
The 25mm view was also more magnified due to the longer focal length, which meant that the Pleiades, or M45, was just a little too large to fit in the view.
Indeed we could only just see the central box-shape of this open star cluster.
However, we could just make out the Merope Nebula using averted vision, so the optics could still draw in its faint light.
Jupiter displayed its two main belts and four moons quite clearly with the 25mm eyepiece, and the Moon looked good; this scope can show off the Solar System reasonably.
The double star Castor was just split with the 25mm eyepiece, and the 2x Barlow improved the view.
The galaxy M82 showed quite strong mottling along its disc and the Orion Nebula was also quite pleasing with the stars of the Trapezium Cluster immersed in nebulosity.
Despite the niggles with the mount and finder, the Mira Ceti still offers acceptable views of a range of subjects as long as you don’t push the magnification too high.
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This review first appeared as part of a Group Test in the March 2010 issue of Sky at Night Magazine