Alt-azimuth Mounts vs German Equatorial Mounts

You need a German Equatorial Mount to do proper Astrophotography…

This used to be true but with modern alt-azimuth technology new options have opened up. Professionals have been working with alt-azimuth mounts for years. Now with Track The Stars Telescope Mounts you can get the same advantage in a compact and mobile solution.

The Alt-Az Mount has a vertical and a horizontal axis. Therefore balancing the mount is limited to one axis making it more straightforward and less critical than balancing a German Equatorial Mount. The vertical Azimuth axle can also be placed directly over the pier centre giving optimal load conditions. Additionally, the movement patterns make the mount more compact leading to smaller domes for observatory mounts and more accessible transport for travel mounts.

Picture of a TTS-160G rOTAtor

Taking astrophotos of the night sky with either a german equatorial or an alt-azimuth mount demands precise continual tracking. Normally this would be reached in the set-up process of polar-aligned mounts by carefully aligning the polar axis to be parallel with the earth’s rotation axis. The alt-azimuth mount on the other hand doesn’t need any polar alignment. When powered up the mount must be aligned on 2 known objects in the sky. This gives it enough info to calculate the precise location of other objects in the sky and to precisely track those objects as they move across the night sky.  When tracking objects with an alt-azimuth mount what is known as field rotation will happen. That can be handled by using the telescope rOTAtor, rotating the whole telescope.

For more comparisons between alt-azimuth mounts and german equatorial mounts check out:

PropertyPanther MountGEM
Storage and transport2-3 compact bagsBulky transport cases
Setting up time3-4 minutes3-15 minutes
Levelling pier and mount head0 minutes3-5 minutes
Polar alignment time0 minutes10-60 minutes
Starting up mount and star alignment2-3 minutes2-3 minutes
Total Start up time5-7 minutes18-80 minutes
Setting up and tracking in daylight (sun, planets)Yes right awayPossible using a compass
Suited for long exposure astrophotographyYesYes
Suited for Autoguiding with guide telescopeYesYes
Suited for Autoguiding with off axis guiderYesYes
Suited for piggybacking equipment (telephoto lenses)Yes – balancing can be done with normal counter weightsYes – balancing demands extra counterweight mounted on the OTA. Piggybacked equipment sits below OTA after meridian flip.
Avoids Meridian flip that turns telescope upside down placing equipment in awkward positions and stresses telescope collimationYes – OTA always stays in the same angleNo
Continuous tracking of an object before readjustment of mount 1-3 hours between derotation of telescope rOTAtor. Continuous tracking through south possible.6-8 hours east or west of south. Continuous tracking through south not possible
Eyepieces stays in an optimal angle at all timesYesNo
Useful for binocular telescopeYesNo
Mounting of more telescopes parallelYes - can be done with side-mounted dovetail saddles without extra counterweightsYes – demands dual dovetail saddles or special tube rings. Extra counterweights must be added
Internal object cataloguesYesYes
Automatic precise GOTO functionYesYes
Computer control via ASCOM interfaceYesYes (most GEMs)

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