However, having aligned many times using a polar scope Down Under, I can attest that just aiming a mount's polar axis
at the right area of sky, then identifying Sigma, can be a real challenge, particularly for those visiting from the north.
Described in the Guinness Book of Records as 'the world's greatest living explorer', the Old Etonian was the first man to circumnavigate the globe on its polar axis
and was one of the first to walk unaided across Antarctica.
When set up as a star-tracker, the included polar-alignment scope inserts into the polar axis
. The scope comes with a separate bright-field illuminator and an excellent reticle suitable for both the northern and southern hemispheres.
1969 Travels the length of the White Nile by hovercraft 1970 Traverses Norway's Jostedalsbreen Glacier 1979 to 1982 Travels globe on its polar axis
by land transport 1992 Discovers lost city of Ubar 1993 Attempts to cross the Antarctic unaided 12000 On solo walk to North Pole his sleds fall through ice 2003 Four months after double heart bypass, he does seven marathons in seven days 2005 Attempt on Everest ends when he has a heart attack 2007 Climbs north face of Eiger 2008 Exhaustion ends a second attempt on Everest 2009 Reaches Everest summit
The mount then automatically offsets a calculated amount from the star, and you manually shift the azimuth and altitude of the polar axis
to re-center the star in the eyepiece.
In 1982, a round-the-world expedition led by Sir Ranulph was the first successful circumnavigation of the globe on its polar axis
. And in 1993, he became one of the first men to walk unaided across Antarctica.
Once installed, the unit produces an 11[degrees] x 8[degrees] field of view and its PoleMaster software then quickly identifies the star field and locates your mount's true polar axis
--allowing you to adjust your alignment until you are within 30 arcseconds of the pole.
However, the design of the AZ-EQ5 precludes any polar alignment scope mounted within the polar axis
For example, the all-important polar-alignment instructions that are mandatory when setting up for astrophotography (the ones that scroll across the hand control), while technically correct, are almost physically impossible to do--you can't point the OTA to declination 90[degrees] and look through the eyepiece while spinning the telescope "rapidly" on its polar axis
. My neck hurts just thinking about it.
Once installed, the unit functions in conjunction with the included PoleMaster PC software, which quickly plots your polar star field and marks where the true polar axis
is, allowing you to adjust your alignment until you are within 30 arcminutes.
A major problem was deterioration of the massive bearing wheel at the bottom of the polar axis
. Eighteen inches in diameter and 3 inches wide, supporting three tons of moving parts, it was made of relatively soft cast iron; large steel bearings weren't available in 1895.