Guiding is essential for taking long exposure images of such celestial objects. Long gone are the days when your guidescope was a telescope that would be similar in focal length as your imaging scope and you would guide by looking at a star through a high power cross-hair eyepiece making rapid adjustments manually! Nowadays with high resolution, sensitive image sensors and advanced software imaging algorithms that allow sub pixel star centroiding, smaller aperture shorter focal length telescopes can be used for guiding. If you want a lightweight and compact guidescope to complement your imaging setup QHYCCD's miniGuideScope (mGS) could be just for you. The mGS is available as OTA only and also as OTA with mounting bracket.
The telescope: size and weight
The mGS comes in a sturdy aluminium container with foam inserts to keep the telescope safe during transport or storage. The outside of the telescope body and its finderscope dovetail mount are finished in an attractive stylish matt silver finish. The interior of the telescope is painted matt black to minimise internal reflections.
The scope itself is 31.6mm diameter (similar to a 1.25" eyepiece barrel) and is small in length at only ~115mm with the focuser fully inward. With a QHY5P-II-M camera attached and focussed ready for guiding (as shown) the length of the overall scope and camera combination was only 170mm (without dew shield). The OTA itself weighs a mere 118g without dew shield and camera attached. With its mini-dovetail mounting bracket the complete unit is still lightweight at just ~220g, and with a small guidecamera such as QHY5-II series attached ~260g. It's small, compact and light weight form factor means that it is ideal for using on set ups where (additional) weight of a larger guidescope and associated accessories may be an issue. Furthermore, the mGS is ideal for long exposure astrophotography with small (ultra-)portable tracking platforms (see photo for an example set up).
On the rear of the telescope there is a male CS screw thread for direct camera attachment and many guide cameras use this type of mount. The guidescope is compatible with the current QHY Series II and Series III cameras such as the QHY5L-II-M, QHY5-III-178 and QHY5-III-290 as well as a range of other cameras using the Cs lens thread attachment. This mGS is also a great match for StarAid Revolution Standalone Autoguiding - Revision B (#1485001 , € 890) which works best with guidescopes with focal lengths of 100mm-150mm. In this case, the black threaded adapter at the end of the mGS must be replaced with StarAid 1.25" to C-Mount adapter ring, 5mm height (#1485010 , € 30) . For those doing astrophotography using a camera tracking platform and a DSLR/Mirrorless camera, the combination of the small lightweight mGS and the "without-a-pc operation" of the StarAid Revolution for guiding and camera control contribute towards a truly portable grab-and-go astroimaging system.
Objective end and focus:
Moving towards the objective end of the telescope, the mGS uses a high quality 30mm aperture doublet achromat lens with a focal length of 130mm (f/4.3) and features a broadband anti-reflective coating. Focusing is achieved with a simple screw-twist of the end barrel of the OTA and a single focus locking screw allows you to lock the focus position. The telescope can focus from 1.5m - ∞ and focus position indicator markings assists in helping to achieve focus and also refocus positioning if the camera has been removed or changed. A small aluminium screw-on dew shield completes the objective end of the mGS.
The mGS mounting bracket features two tube rings each with a plastic tipped locking screw to secure the OTA in place. The inside diameter of the tube rings are just slightly larger that the guidescope tube so no positional adjustment of the guidescope can be done. However the telescope's large field of view means this is not an issue as as suitable guidestar can be located in just about any part of the night sky. The rings are attached to a mini dovetail base that allow it to be attached to a wide range of telescopes that feature this common type of finderscope/guidescope shoe-bracket attachment. For telescopes that either require such a shoe or if you need an additional bracket, we offer our Baader Standard Base - for MQR III & IV & for V-Bracket, and for all Vixen-style finderscope mount bases (#2457000 , € 34) , which can be attached to most telescopes with tubes 130-400mm in diameter, and features two locking screws for secure guidescope attachment. The mGS base also features a standard 1/4" UNC tripod threaded hole so that the mGS can be attached to e.g. telescope tube rings.
Field of view:
With the mGS's short 130mm focal length, what field of view will you get on the sky? That will of course depend on the camera and its sensor being used.
However, to give you some idea of FOV, below we present a table that lists a few of the current popular guidecameras along with the sensor pixel array, pixel size and the resulting pixel scale and field of view in degrees.
(" / pixel)
|QHY 5-III 174M / ASI174||1920x1200||5.86 x 5.86||9.30 x 9.30||4.96 x 3.10|
|QHY 5-III 178M||3072x2048||2.40 x 2.40||3.81 x 3.81||3.25 x 2.17|
|QHY 5-III 290 / ASI290 / StarAid Revolution||1920x1080||2.90 x 2.90||4.60 x 4.60||2.45 x 1.38|
Below, we have shown these camera F.O.V's superimposed on a celestial image of Messier 31 (Andromeda Galaxy) to give you a more "visual-orientated view".
In summary, QHY miniGuideScope with mount (#1932051 , € 162) is a high quality, small and lightweight guidescope that is easy to set up and use and can be used with many imaging setups. With it, and a compatible camera, it can help you obtain long exposure images of celestial deep sky objects.
QHYCCD also design and manufacture a wide range of high quality, excellent performance and reliable cooled CMOS and CCD astronomical imaging cameras ranging from entry level up to professional astronomy grade that are used in research programs. To complement their cameras they also produce dedicated accessories including filter wheels, off-axis guiders and adaptor kits. You can find out more about QHYCCD and their product catalog here.
About the author
Dr. Lee Sproats has been interested in astronomy since watching Star Wars in 1977 and has appeared on the UK Sky at Night TV programme. He then went on to study Astronomy where he obtained a degree and then a PhD in the subject at University College London/Mullard Space Science Laboratory. He has worked in Australia in radio astronomy and used optical/infrared telescopes on Hawaii and La Palma and Lowell and Kitt Peak observatories in the USA. After working for the University of Surrey to promote the use of computers for teaching in UK higher education and then as an IT trainer for a stock market company, he went on to work for Greenwich Observatory Ltd where he ran their northern branch and then worked for David Hinds Ltd dealing with our and Celestron products. He is often involved in flight excursions that take passengers to observe the northern lights, has led trips to see the great USA 2017 eclipse near Hopkinsville and was lead astronomer onboard a specially chartered 737 to view the 2015 total solar eclipse at 38,000ft. Lee`s astronomical interests include Lunar observing, astrophotography, photometry and pro-am collaborations.
Since David Hinds stopped operation in December 2020, Dr. Sproats works for Baader Planetarium as our UK representative/consultant and is responsible for looking after our UK/Eire dealers, dealing with Baader Planetarium/PlaneWave/10Micron product support, writing articles and also is involved in our large telescope and observatory instrumentation projects.View all posts from