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A tough time aligning
the telescope about 18 months after buying it convinced me to buy a right
angled finder to complement the Baader RDF and replace the straight through
finder.
For three successive nights in
freezing cold weather the GoTo system demanded alignment on stars that were
high in the sky near the Zenith. Being bundled up in layers of clothing and
having to try and crane my head round in strange angles for prolonged periods
to get a star into some faint crosshairs convinced me that good as the Baader
RDF was I also needed to seriously think about a better optical finder.
Another convincing reason was searching
for an elusive comet where the RDF could only offer limited help and I found
the normal straight through finder too tough going.
A corrected image finder is a boon in many ways as it
means the sky is orientated through the finder the same was as you are seeing
it with your eyes. I decided that for higher accuracy with the GoTo I would
prefer an illuminated finder to help me get locked on to alignment stars super
accurately without looking like a yoga adept.
After shopping around I
decided to buy the Antares 7x50 illuminated RACI finder. This finder is
sometimes stated as being 7.5x 50 or 8x50.
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| The Antares 7x50 RACI Finder - its a nice looking unit but sadly
its performance didn't match its looks. |
Out of the
box......
The Antares looked good
on arrival. Its rather solid and with its glossy black finish (its also
available in white or blue) it looked rather natty. Unfortunately it would
prove to be a problematic bit of equipment but more on that later.
The Antares has a standard achromatic lens, the edge is not blackened
nor glued into place. Surrounding the end of the finder is a long
dew-shield/lens shade which has a ridged interior to reduce reflection though
the paint finish on the interior surface is shiny rather than matted.
The long lens shade would be useful to
protect the finder from dewing up although I was bit less convinced about the
shiny paint finish on the inner surface.
The finder barrel has a knife
edge baffle and terminates with a right angled correcting prism that's locked
into place using a small Allen headed grub screw. Atop the prism is a short
barrel which the eyepiece sits in. The eyepiece can be adjusted up and down the
barrel by a locking screw which allows the eyepiece to reach focus. The prism
may also be moved in and out of the scope tube and rotated by undoing the
recessed Allen headed grub screw.
If
there is one thing that could be improved with this product it would be
replacing that Allen headed screw with a thumbscrew which would allow rotation
of the eyepiece in the field and additional focus travel without resorting to
tools.
The eyepiece itself carries a
dioptre adjustment for fine focus and for focusing the reticule. A small
aluminium illuminator is attached on this version. The illuminator works well
enough although I found it a little too bright even at its dimmest setting
-also its doesn't lock in the power off position very securely making it easy
to get switched on while in transit. Mine in fact arrived switched on in the
box!!!!
The reticule pattern is of a double cross hair useful for both
aligning to stars and also for drift alignment. The eyepiece with its reticule
are removable and useable in a standard 1.25" focuser which may be of use to
imagers carrying out drift alignment. Attachment to the telescope is via the
same quick release mount as used on the Sky-Watcher finderscopes and as with
the Sky-Watcher product provides fuss free alignment to the scopes main optics.
The fit of the finder to the quick release mount is rather tight and as a
consequence the glossy black finish of the Antares tube was quickly damaged
with scuffs.
First Light
Unfortunately the unit I was supplied with showed a large number of
defects and areas which I was very unhappy with for the price. First light a
few days days after the unit arrived revealed some rather large problems.
Firstly the finder scope refused to
reach focus at infinity. Even with all of the adjustments in as tight as they
could go there was insufficient 'in focus' to achieve focus on stars. When I
investigated I found the tube was probably about 5mm too long. Advice received
from another Antares owner suggested the tube length should have been shorter
to accommodate the illuminator element in the eyepiece. I felt it reasonable to
carry out a few checks and this was when problem number 2 revealed its
head.......
Removing the prism from the
tube I found the tube full of loose bits of flaky paint and metal. Forever
after I was unable to get the optics as clean as they should be despite
repeated blower brushing of the internal elements. As fast as one lot of debris
was removed more would replace it. Further investigation showed the scope had
even worse optical defects.
The scope
showed a lack of focus anywhere than other in the very centre of the lens.
Objects further than 10-20% from the centre showed a distinct lack of
resolution and focus. Optically I felt this unit was by far the worst of the
units I have tried to date.
Not a keeper
Given these problems I had no real
chance to evaluate the scope further and decided to return it. There are many
happy Antares owners out there so I can only assume I was on the receiving end
of a bad 'un. I would say that if the scope had worked as advertised I think it
would be a very capable unit. With some blackening of the lens edge and the
small grub screw that holds the prism to the tube replaced with a thumb screw
to give an ability to rotate the eyepiece I think this unit would be a winner
assuming that the optics are normally better than mine turned out to be.
For myself I decided to return it for a refund - a part of me really
wanted to give another unit a try but I decided to buy something else instead
rather than risk having to stump up for more postage. Sadly not a keeper.
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