I have come into birdwatching from astronomy. This means I have a slightly different view on telescopes than a lot of other birding enthusiasts (I guess!). In my time as an astronomer, I have now had 6 different scopes, starting with a huge 8inch reflector, working down in size to this little beauty, and definitely my last scope. I could not handle the bigger scopes due to a worsening disability, so size became more important as time went on.
Right, so what is it?
It is a small but fairly heavy 80mm diameter air spaced fully multicoated doublet objective mounted in a heavily baffled, flat black interior tube, 500mm focal length, f6.2 scope, with a foot mount for std photo tripod mounting, and a two inch focuser receptacle for eyepieces and diagonals. 18inch overall with dew shield/lens hood extended, 15inch when retracted. Bought as new, you would have got a 2inch 90 degree diagonal and a 2inch to 1.25inch adaptor, as most popular astro eyepieces are one of these two diameters. I decided to get a 25mm (20x) and a 15mm (33x) with 1.25inch fitting to start, shortly to be adding 9mm (55x) and 5mm (100x) eyepieces. The mag is calculated (if you didnt know) by dividing the focal length of the scope (500mm) by the focal length of the eyepiece, so 500mm/25mm=20x etc. Close focussing is easily achieved down to 2m with an extender tube.
For visual work I use a 45 degree diagonal, giving me a comfortable viewing position, similar to other proper spotting scopes. This also gives me an erect image (whereas a star diagonal would be upside down/back to front, or any combination of those two).
Visually the scope never disappoints, and recently I had the chance to compare it to some top names (Leica, Swarovski, Opticron, Zeiss etc). Yes, the other scopes gave a flatter field, but the eyepieces had strange kidney beaning and blackouts, so Im guessing their exit pupils were very small. I can move my eyeball about and not get any blacking out at all with any of my eyepieces. Chromatic aberration is present but only if viewing against a high contrast background e.g. - bird on branch against white/blue sky , at high power magnification. At low powers it is NOT noticeable at all.
As f6.2, it has a good depth of field, esp when using my Nikon D70 at what we call prime focus - attaching the camera *directly* to the scope, with no eyepiece in between. For this you would need a T2 mount and an eyepiece nose adaptor, so the camera pretends to be a 1.25inch eyepiece. All of my bird photos with the scope are taken this way. It also has velvety smooth a rotatable Crayford focuser : Instead of repositioning your camera for various orientations, the entire focuser rotates without any loss of focus.
OK, its a totally manual set up, so Im fixed at f6.2 and have to guess the exposure time, but that comes with practise, and underexposures can often be fixed in Photoshop anyway.
Other really nice features :
* solid aluminium construction, no plastic anywhere.
* a pull out sunshade/lens hood.
* focus lock.
It is fairly well known that this is a clone of one of the famous Williams Optics scopes, and has several brands offering just about the same thing (Antares GB230, Revelation (was GB256, but no longer available), Astronomica GB295, Orion Express US$400, Astronomy Technologies Astro-Tech US$379 etc etc). Some are 480mm f6, some are 500mm f6.2. To find one, just google for 80mm semi apo.
To summarise :
A nice easy to use scope, very versatile, cheap eyepieces, easy to use as 500mm lens for DSLR, (but afocal projection only with smaller lensed digital cameras e.g. Nikon 4500). A bit heavy at about 6lbs. Generally comes with carry case, a 1.25inch or 2inch diagonal and at least one (usually 20mm) eyepiece.
Me ? I am finally happy with a small scope I can carry about and use at a moments notice (well, almost).
David Harris