Aperture: 50mm (coated lens)
Type: right angle, erect image
Mount:Bracket included with 30mm wide dovetail
Supplier: Optical Vision Ltd
The Skywatcher 9×50 Right-Angled Erecting Finderscope is good quality instrument which would complement any telescope.
Its 50mm aperture reveals far more than the smaller examples often bundled with some starter telescopes.
Credit: Mark Parrish
The right-angled diagonal produces an upright and left/right corrected image so slewing the telescope to find an object, whilst looking through the finder, is very intuitive.
When setting up, the spring-loaded thumbwheels (which correspond to the two cross hairs) make it easy to centre an object in the field and thereby match the view to the main telescope.
The alignment screws are plastic, but the sturdy metal bracket and internal O-ring mean they shouldn’t need to be adjusted very often once set up, unless the equipment is roughly handled.
The objective appears to be coated on the outside and can be focused by screwing in/out, then locked in position with a knurled ring.
The inside of the tube has a matt black surface and a neat field stop, features that contributed to the good contrast we observed – a dark background sky and pinpoint stars for 75% of the field of view and revealing Jupiter as a sharp-edged disc.
Whilst the main tube parts and bracket are made from aluminium alloy, the diagonal casing and eyepiece tube are plastic which are less durable, but it does reduce the weight.
This helps with balancing so when fitted to a small telescope, the weight shouldn’t present a problem.
Credit: Mark Parrish
The cross hairs were clear and sharply focused although there is no provision for independently focussing the eyepiece.
We noticed the “cross” on our test model to be slightly rotated, relative to the diagonal.
This is not a problem but if you are fussy and like the cross hairs to line up with the mount axes, a paper shim under the eyepiece tube should help.
In summary this is a sensible upgrade or replacement finder scope which is simple to set up, enjoyable to use and good value.