Today's winning picture of M-57 got me to thinking. What's the state of the art in large alt/az mounts or platforms? I'm not talking about mounts for tiny refractors but rather ones that can handle 12 inch class scopes and up. I know that platforms were very popular with big dobs at one time but I wonder if that's changed. yes, field rotation has to be dealt with but if you really want to carry a big payload, alt/az is the way to go. The present crop of advanced eq mounts are nice but that approach quickly hits a payload verses cost wall. I did some quick Googling and came up empty. I wonder if anyone has some insight into this question?
State of the art - alt/az mounts
Engaging
The Planewave L-series mounts are state of the art Alt-Az mounts when set up with a rotator. They come in multiple sizes. The L350 would be appropriate for a 12" class telescope. Remember that with an Alt-Az configuration, diffraction spikes rotate during the exposure so it's best to solve that problem optically. I'm personally not much of a fan of alt-az, which is why I have my L600 on an equatorial wedge. Load capacity isn't the biggest reason for Alt-Az. It's mostly for a more compact installation and to reduce the cost for a really big scope. You can carry any size load on an appropriately sized equatorial mount–if you have the room and you can afford it.
John
John
Well Written Helpful Insightful Concise
I've come across a few but only through You Tube videos put out by some enthusiastic people associated with a few of the remote observatories catering to the amateur market. Those remote observatories also host professional telescopes and its a little treat to see them up close and get a little description of the equipment on each one. I noticed a couple things with the mounts associated with these telescope. Some use equatorial mounts that you could seemingly buy but they tend to cost around $20k on up just for the mount itself. The company names were not familiar to me. Others used mounts that were purposely made for the telescope and not necessarily ones you could go out and buy. These things are being advertised to professional buyers somewhere but not through the typical channels I've seen for hobby oriented astrophotography.
Here are few:
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-equatorial-with-goto-20/rainbow-astro-rst-300-goto-mount-15135
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-azimutal-with-goto-79/10micron-az2000-hps-combi-azimuthal-goto-mount-with-dt-upgrade-kit-16289
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-azimutal-with-goto-79/10micron-az3000-hps-azimuthal-goto-mount-mount-head-16287
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-azimutal-with-goto-79/track-the-stars-tts-300-mammoth-mount-head-9594
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-equatorial-with-goto-20/rainbow-astro-rst-300-goto-mount-15135
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-azimutal-with-goto-79/10micron-az2000-hps-combi-azimuthal-goto-mount-with-dt-upgrade-kit-16289
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-azimutal-with-goto-79/10micron-az3000-hps-azimuthal-goto-mount-mount-head-16287
https://www.teleskop-express.de/en/mounts-tripods-rings-rails-power-supply-14/mounts-azimutal-with-goto-79/track-the-stars-tts-300-mammoth-mount-head-9594
John Hayes:
The Planewave L-series mounts are state of the art Alt-Az mounts when set up with a rotator. The come in multiple sizes. The L350 would be appropriate for a 12" class telescope. Remember that with an Alt-Az configuration, diffraction spikes rotate during the exposure so it's best to solve that problem optically. I'm personally not much of a fan of alt-az, which is why I have my L600 on an equatorial wedge. Load capacity isn't the biggest reason for Alt-Az. It's mostly for a more compact installation and to reduce the cost for a really big scope. You can carry any size load on an appropriately sized equatorial mount--if you have the room and you can afford it.
John
In didn't think about rotation of the spikes, I suppose the entire upper cage could be rotated but that might be a bigger engineering challenge than just rotating the camera.
Using a curved spider would get rid of the spikes altogether without having to rotate anything
Médéric Hébert:
Using a curved spider would get rid of the spikes altogether without having to rotate anything
or use the ninja weapons (binary apotizers)
Médéric Hébert:
Using a curved spider would get rid of the spikes altogether without having to rotate anything
Yes...this is one of the ways to combat that problem.
Médéric Hébert:
Using a curved spider would get rid of the spikes altogether without having to rotate anything
Not without other issues though.
Médéric Hébert:
Using a curved spider would get rid of the spikes altogether without having to rotate anything
Or an optical window...
At that point might as well make a Mak-Newt, easier than make a plane parallel optical window and don't have to contend with coma (to a large degree).
I know, none of the solutions are perfect. I did have at one time an old Meade SN-6. It was the only one of the series that was F/5 instead of F/4 and it performed really well. Sorry I let that one go.