| review: Newton Reflector equatorial TAL-2M ( appr. € 850,- ) |
The TAL-2M is also known as Siberia 150. It is produced in Russia. The whole look and feel is a bit like in the fifties.
But the overall quality is definitive good. It can be
used as a beginner's scope for serious visual work and even for photography of moon and planets and piggy-backed wide
fields. It is not at all like a warehouse scope! (Refer to photos in gallery here)
The tube is a 6" diameter f/8. In the manual is written about a resolution of 1.0" (arcsecs). This would
mean the OTA is close to be diffraction limited. I have never tested it with a close double star but I can say that the image quality is really good. The mirror is
professionel mounted in an aluminum cell with three Screws to adjust for collimation and a fourth, centered one to lock the position. A good idea I missed
on even much more expensive scopes! There is a lot of back-focus realized thru a 5cm long expansion tube acting as the eyepiece holder. It has not only one
locking screw for eyepieces but a ring. So eyepiece tubes cannot be scratched by locking them. The whole focuser is made of metal and is operating smoothly
but with a bit of too much play for astrophotography. However it is very good for visual work. When you screw away the eyepiece holder,
you can find a M42x1 thread for connection with a t-ring and a camera.
Included are three eyepieces: a 42mm Kellner, a 25mm Plossl and a 15mm Kellner. The Kellners are well choosen for
magnification and exit pupils. The quality is correct but like all Kellners the field of view is quite narrow. They are
multicoated to reduce reflection. The plossl
is a really good one! It has a nice eye relief,
good field of view and gives bright and contrasty images, sharp to the edge. This is the major work horse for this telescope. There is an
Intes Barlow lense giving an amplification of 4x.
Again there is good optical quality with multicoated lenses and so minor image degradation. There are several color glass filters with plastic holders
to be placed in front of the eyepieces. Well, being
in front of the eye lense they are smeared with liquids coming from the eye very quickly. But they work and optical
quality is somehow OK. There is a black filter too originally intended for
use when watching the sun. DO NEVER USE THIS ONE! The energy going from the sun to the 6" mirror is way too much for
this resulting in too much heat! The filter might break and your eyes might be seriously
hurt without warning. Instead use a cheap solar filter available from Baader to cover the whole 6" of aperture to keep
energy out.
The mount is fixed on a rigid three legged aluminum tube. For transportation the legs can be dismounted with a single
screw each. The mount has a drive for RA only and acts with
classical worm and wormwheel. The DEC has no wormwheel but works with a screw on which a hand wheel is connected to. So if
you correct DEC you will always introduce some
vibration to the scope. Not a real problem for visual work or photos with short exposure like moon and planets. But the end of dreaming about long
exposure deep sky photography. The amount of correcting DEC is +/- 4 degrees because of restriction
by the screw system. The overall stability is above average. While tracking the RA drive produces some noise but not too
loud to disturb neighbours. The only one tracking speed
available is for the stars. There is some variation in speed meaning sometimes the scope is too fast, sometimes it is
too slow. But I think this is more coming from the
errors induced by the worm and not by the drive itself. Again no real problem for visual work, but visible when watching
planets with huge magnification.
The TAL comes with a superb 8x50 finder scope of 7 degrees FOV. Fully coated and with reticle it allows precise position
of the main scope. This can be done in RA and DEC
only by moving the scope itself because there are well functioning fricion clutches always engaged. The DEC one can easiliy be adjusted
near the DEC handwheel but the RA one is inside the mount behind the wormwheel. It can
only be reached by opening a little door in the back of the mount and using a screw driver to adjust the three screws - one by one with turning in RA for 270 degrees.
Well, it works. And has only to be done from time to time when the friction has become to low.
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