Telescope Mounts

Telescope Mounts

Author
Discussion

Melman Giraffe

Original Poster:

6,632 posts

182 months

Wednesday 3rd March
quotequote all
Hi All

Hope you can help...

is an alt-az mount better than an EQ mount for a scope?

And is the Celestron Astro Fi Telescope any good? Or do you have any recommendations for a motorised scope that won't cost the earth?

Thanks

Simpo Two

74,875 posts

229 months

Wednesday 3rd March
quotequote all
Science forum maybe?

Melman Giraffe

Original Poster:

6,632 posts

182 months

Wednesday 3rd March
quotequote all
Maybe, i will see what response i get here and if no joy i will try

Thanks

eharding

11,541 posts

248 months

Thursday 4th March
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Given that this is the photography forum, I'm guessing you want to try some astrophotography?

If that's the case, then the answer is generally that an EQ mount is preferred, particularly for long-exposure astrophotography - whilst you can track an object for long periods with both an Alt-Az mount and an EQ mount, the former introduces field rotation - which can be corrected for but it's a pain so best just go with an EQ mount from the start.

For visual astronomy, this isn't such an issue, and as Alt-Az mounts are much more simple to manufacture, they're much more popular, the Dobsonian mount being an example.

If you want the best of both worlds, there are some mounts which can be configured either as Alt-Az or EQ, such as the Skywatcher AZ EQ6-GT and AZ EQ5-GT mounts, and you can also purchase EQ wedges for Alt-Az mounts.

I have had an AZ EQ6-GT for getting on for three years, but have only had it configured in Alt-Az mode a handful of times - in fact of late it hasn't had much use as I decided to outfit my ancient EQ3-2 with a Synscan goto motor kit for DSLR wide-field imaging, mostly with a Samyang 135mm f/2.0 lens - gets some decent results, and a lot less setup and faffing than the deep sky telescopes - the gear stays outside in a "Shed-in-a-box" shelter mounted to some decking boards and castors so even if it only looks like being clear for a couple of hours (Ha!) I can push the shelter back and be up and running in a few minutes.

Anyway, it might help if you added some details about what you want to achieve - visual or astrophotography, deep space or planetary etc. That would also have a bearing on whether the Celestron Astro Fi would be a good choice (and which type of telescope to mount on it). That being said, I also have had a Skywatcher Alt-Az Goto mount which is essentially the same design, without the WiFi, and whilst it duly will slew to requested targets once aligned, the tracking is quite jerky and the mount and tripod are fairly flimsy and prone to vibration, as lightweight mounts tend to be, but if you're faced with moving it about each evening lugging massive heavy mounts around becomes a chore.

The other thing to note about astronomy mounts for sale online is a) they are almost all out of stock with a 2-3 month wait, and have been for the best part of a year, due to covid and b) prices have gone up significantly recently - second hand might be an option.




Melman Giraffe

Original Poster:

6,632 posts

182 months

Thursday 4th March
quotequote all
Wow thank you for taking the time to give such a detailed reply. I'm actually asking on behalf of Mrs M so I will get her to look and respond. Thank you

Melman Giraffe

Original Poster:

6,632 posts

182 months

Thursday 4th March
quotequote all
Hi, Mrs M here.

Thanks for taking the time to reply, it's very much appreciated!

You are correct, I'd like to get a new telescope to try and improve my astrophotography skills.
I currently have a Celestron powerseeker 127EQ, whilst I do enjoy using it I think it's time to upgrade (possibly motorised, I'm not too sure about the benefits of such). I've had the current one for approx 10 years. Is motorised as good as they say? Or is there more satisfaction to be had in old school tech?

I currently feel like I'm wading through a whole lot of information that is confusing more than offering clarity!!

So, I guess what I'm basically asking is which scope would people recommend?!

Hopefully I've made some sense ☺️

eharding

11,541 posts

248 months

Friday 5th March
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I'd guess that depends partly on what sort of astrophotography you'd like to explore further - this has a bearing on the type of equipment you'd need (if you don't have it already).

Planetary imaging of solar system objects generally calls for long focal lengths to extract any surface detail - the planets themselves being relatively bright but comparatively small (ditto smaller lunar features), so Maksutov or Schmidt Cassegrain telescopes are a popular choice in this application. Planetary imaging, particularly from higher latitudes, typically involves using high-speed video cameras to take as many frames as possible of the target, and then use software to reduce the effects of atmospheric disturbance - cameras such as the ZWO ASI 120MC are a good introductory choice.

Deep-sky astrophotography - nebulae and galaxies - differs in that the targets are generally relatively faint, but can cover a significant portion of the night sky, so high magnification is not a pre-requisite - you may need higher powers to go after the smaller objects, but there are plenty you can image with a standard DSLR lens. Broadly speaking, the choice is then either a reflector or a refractor. Reflectors - Newtonian or Cassegrain types - have the advantage of being easier and cheaper to manufacture than a refractor of equivalent aperture, but they have the downside that they can require regular collimation. Most types will probably require some additional corrective optics to reduce inherent errors in the particular design - field flatteners for refractors, coma correctors with Newtonian reflectors (recent advances in mirror manufacture mean that Ritchey–Chrétien telescopes - which have very little need for any correction - are widely available, the downside that the central obstruction is larger than other cassegrains). As for cameras, DSLRs or mirrorless equivalents perform very well in this role. There are dedicated cameras from likes of ZWO that use much the same APS-C or full-frame sensors as DSLRs, but offer more control over the configuration of the sensors, and active cooling to reduce noise, but stock DSLRs perform perfectly well, although a popular option is to have the camera modified to remove internal filters to increase sensitivity (and Canon will sell you a pre-modified camera, charging a significant sum to remove some bits before selling it to you).

As for a recommendation, I would say explore wide-field deep-sky DSLR astrophotography with good quality short-focal length refractors (including standard lenses - as above, the Samyang 135mm f/2.0 is my favourite at the moment) - examples are the Sky Watcher 72ED or the William Optics Zenithstar. There are load of targets you can image with these sort of optics, and everything is just easier a low magnifications.

It's worth downloading a copy of Stellarium and configuring the 'Oculars' plugin with the details of the optics and sensors you're considering using, and then comparing the projected image scale with suitable targets (useful throughout the year as the available selection changes).

As for a mount, I would say EQ all the way. The levels of motorisation and automation in mounts varies - at the most basic level a 'clock drive' on the RA axis of an EQ mount if it was well-polar aligned should suffice for the sort of 3-5 minutes sub-exposures required, and if you don't want to bring a computer into the equation something like the Sky Watcher Star Adventurer or an EQ3-2 with an optional motor drive would get you started. However, whilst just having tracking on the basis of timed motion is OK, having Go-To also makes things much easier (and has potential for doing things like auto-guidling later on) - in which case the EQ 3 Pro is a good introduction, and has potential for further integration with PC software to automate your imaging sessions.

Hope that helps - whilst all the links above are to FLO and Sky Watcher gear, other quality vendors and brands are available, but it's worth a call to FLO for some advice (not least because they might be able to tell you when - hopefully- some of this gear ever comes back into stock again!)