||VIXEN DOVETAIL SIDE BY SIDE ACCESSORY PLATE
The SX DX accessory plate from Vixen Japan is a highly rigid, breadboard
style accessories adaptor that will fit directly to any Vixen 45mm style dovetail mounting
receptor such as Great Polaris, SXP plus external brands like Synta (Sky-Watcher) and
their HEQ5 and EQ6 range of mount as well as Celestron and others. It can be used to mount
a host of different adaptors including piggybacking a DSLR or hosting several telescopes
at once both for visual or astrophotography purposes.
Above: A typical side by side
system on a HEQ5 Pro equatorial mount using the Vixen #2576 SX DX accessories mounting plate
with guide scope mounted on the Vixen XY guide mount. Seen here is the classic Vixen
AX103S optical tube and a ProStar 80mm refractor used as the guide scope.
Now we all know that basic auto-guide scope can be as simple as a cheapy finderscope
arrangement however in many parts of the sky, available stars of significant brightness
can be hard to find (the like of say the star field around M83 and others). But aperture
and focal length are important for a.) allowing your guide camera to detect and track a
faint star in the field and b.) being able to detect subtle drift from periodic error at a
single pixel level to ensure corrections to the mount are made effectively and timely. So
in a serious set-up, discerning astro-photographers will use at least an 80mm scope for
best guided astro-photography results.
Guide scope tube mounting rings with adjustable 3 pivot points on each
tube ring is a common set-up. However as the angle of the telescope changes throughout the
night, sifting of weight can lead to minor or even major flexure issues resulting in a
poorly tracked object (elongated stars). To remove this 3 point shifting risk of slippage,
using the solid clamping tube rings that come with the telescope is often preferred and
thus.. enter the Vixen X- Y guide mount.
The Vixen X - Y Guide mount
A close up view of this set up shows how adjustments to the guide scope
can be made using the fine adjustment knobs that also double as position locking bolts.
Not labelled in the centre of the X-Y guide mount is
are two release clamps that allow for course adjustment and locking just like the RA and
declination clamps found on an equatorial mount. These are generally used only at set up
time to set the guide scope "on axis" to the main scope that will be used for
What I really like about the X - Y guide mount used with the accessory
mounting plate is that there are indeed four possible positions along the plate to take
the X - Y guider so that centre of weight can be balanced as close as possible over the
fulcrum point of your equatorial mount. Thus, if the primary (imaging) optical tube is say
a 8 inch OTA (quite fat) then the guide scope can be spaced away from it leaving room for
you to get your hand access to the fine tuning X - Y azimuth knobs. But if using two
refractors as shown in figure 1 then the scopes can be set close to one
another for best centre of balance which is important to lessening strain on motors when
slewing to other parts of the sky.
In practice, I found the fine adjust knobs of the X - Y guide mount an
absolute pleasure to use after battling for many years with adjusting front and rear 3
prong guide tube rings. The fine adjustment movement of the Vixen X -Y was silky smooth
and with 6 degrees or so of adjustment on both axis, finding a suitable nearby guide star
quickly was a breeze... no horrible shifting as in the old way!
Above: The primary imaging telescope
can be mounted to the Vixen accessory mounting plate using either a Vixen dovetail
mounting block or a square style ProStar dovetail
receiver. The fitting holes match the Vixen mounting plate identically.
Above: From the underside of
the Vixen accessory mounting plate, we see the incredible strengthening rib design which
is so important for minimising flexure in an optical mounted system intended for serious
long exposure astro-photography. Note at the ends of the 16cm dovetail plate the safety
bolt heads to avoid the whole thing slipping out of the dovetail mount head when loosening
to make balance adjustments. Vixen have thought it all out and it is excellent.
The whole guide mount system can be bought here.
I would highly recommend the Vixen accessory mounting plate fitted with
their new light-weight though sturdy X- Y guide platform for anyone seeking to minimise
flexure in their astro-photography set up. Lessen the frustration and enjoy more
productive time under the stars. - SM
|To learn more about the hole spacing and thread sizes
provided in the Vixen SX DX accessory plate
See Plate specs here
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