Deciding on a telescope

[Dan Petzen]

I spent days trying to decide on my first 'serious' telescope that I hope will keep me busy for years to come, but I'm more out of touch with the telescope market than I thought - and could really do with some help.

 

Short version:

What 8"-10" reflecting telescope (Cassegrain) would give me most for my money if the primary purpose is astro-photography of (initially) planetary objects, but more importantly deep sky objects (long exposure)?

 

Longer version:

Two fairly different telescopes have survived my scrutinisation:

Meade LX90 ACF 8", because:

•  I can (barely) afford it
•  ACF will make it suitable for AstroPhotography
•  A wedge will allow me to use it in equatorial mode

or

A 8" Ritchen-Chrétien with a CEM25P mount, because:

• It'll ruin me, but I can afford the budget version: https://www.astronz.nz/shop/item.aspx/astrophotography-telescope-package/251/
• It's perfect for AstroPhotography
• The mount is capable of long time equatorial exposures straight off the bat

 

You get much more aperture with the LX65 and some Celestron models, but there always seem to be trade-offs with Alt-Az mounts, optics or other things.

 

Background:

My only telescope for the last 15 years has been a Meade ETX-90 UHC. I used to live in London, but the electronics didn't survive the move to New Zealand some 5 years ago. As such, I've done virtually no astronomy at all over the last 5 years. I now really want to get back into it and I want an upper-medium range telescope for AstroPhotography. I thought I knew my way around telescopes, but the last few days of research has proven otherwise. It has been incredibly frustrating. I really need help here.

 

I took most of my pictures with a Kodak (yes, Kodak) digital camera on a fiddly mount. I eventually got a Meade Deep Sky Imager Pro CCD, but really struggled to get it to work very well. I never managed to get any deep sky images. I think it was partly the small aperture, the FoV (the brighter object tends to be a bit bigger), Alt-Az mount (I had stack images to get any results) and my own abilities.

 

I've not even started looking into (or figuring out how to afford) an imaging solution, but any advice here would be much appreciated, even though I may not deserve it yet, as I haven't done my homework ;-)

 

I would really like to get to a point where I can do deep sky imaging from my desktop in my house (or, if possible, from my van). My plan is to build a little structure/platform for the telescope, so that I can set it up, align it, and then control it remotely (wired or wireless depending on what's available).

 

Most things are incredibly expensive in New Zealand, so I need to get this right.

[Cosmic Geoff]

SCTs are the instrument of choice for planetary imaging, but I should have thought that using one for deep sky imaging would be a challenge.  Small APO refractors seem to be favoured. No doubt experienced DSO imagers will advise.  What I have read about wedges is that they are a problem area unless the outfit is permanently mounted, and that some users adopt wedges with enthusiasm then a while later give up and buy a German equatorial mount..  For what you hope to do, buying a German equatorial at the outset is clearly indicated. The Celestron SCTs are all available as OTAs or bundled with a German equatorial.

14 minutes ago, Dan Petzen said:

I would really like to get to a point where I can do deep sky imaging from my desktop in my house (or, if possible, from my van). My plan is to build a little structure/platform for the telescope, so that I can set it up, align it, and then control it remotely (wired or wireless depending on what's available).

That seems like a technologically challenging project.  But some members here have done that sort of thing.

[jonathan]

KISS - Keep it simple, stupid! 

If you want to photograph planets, buy equipment for photographing planets.  If you want to photograph DSOs, buy equipment for photographing DSOs.  While I'm sure it's possible to photograph both with one piece of kit, neither will be optimal and you'll hit snags and compromises when you try pushing in one direction or the other.

Check out the book Making Every Photon Count, it should tell you everything you need to know to get started.  I think the more you go down a specialist route (e.g. photographing Saturn or Jupiter), the easier you may find things.  Later you may be able to re-purpose some of the equipment you acquired to other target types, but I think you will find it easier to have two sets of equipment with perhaps some cross-over parts.

[Dan Petzen]

1 hour ago, Cosmic Geoff said:

SCTs are the instrument of choice for planetary imaging, but I should have thought that using one for deep sky imaging would be a challenge.  Small APO refractors seem to be favoured. No doubt experienced DSO imagers will advise.  

I'm guessing this has to do with the focal ratio. I should have spent more time on this rather than just jog my memory.

OK, I've fine tuned my wants and needs according to reality, and I think that the Cassegrain still comes out on top. I'm a bit nervous of leaving all planetary astronomy behind, as that is all I know, but the Cassegrain should still be good for small deep sky objects and if I feel up for trying on large deep sky objects, then I can always try my luck with focal reducer.

1 hour ago, Cosmic Geoff said:

What I have read about wedges is that they are a problem area unless the outfit is permanently mounted, and that some users adopt wedges with enthusiasm then a while later give up and buy a German equatorial mount..  For what you hope to do, buying a German equatorial at the outset is clearly indicated. The Celestron SCTs are all available as OTAs or bundled with a German equatorial.

I've never used a wedge, so that is very useful information. Obviously, the people selling wedges won't mention any issue with them.

The OTA's are quite affordable, so if I can get hold of a reasonably priced equatorial mount, then perhaps that is a better option. I'm going to do a bit of research into this.

1 hour ago, Cosmic Geoff said:

That seems like a technologically challenging project.  But some members here have done that sort of thing.

This is an optional project. I still remember all the nights I've been standing there shivering by my telescope. The idea has a certain appeal 😉

Edited July 27, 2020 by Dan Petzen

[Shimrod]

1 hour ago, Dan Petzen said:

I've never used a wedge, so that is very useful information. Obviously, the people selling wedges won't mention any issue with them.

The OTA's are quite affordable, so if I can get hold of a reasonably priced equatorial mount, then perhaps that is a better option. I'm going to do a bit of research into this.

 

I have an LX90 and wedge - it is an older model and at some point I must sell it because it has turned into an ornament. If you are using the LX90 on a permanent pier, then a wedge might be worthwhile, but if you are setting up each night then it just adds extra time and complexity to the set up of the telescope. It could take me 40mins upwards to get set up and ready to go.

I now have a Celestron AVX equatorial mount with both an EdgeHD and Skywatcher 80ed to use depending on what I want to observe or image. An 8" SCT on an equatorial mount is only going to be same (or maybe even less) than the LX90. I find the AVX fine,although you will often see the Skywatcher HEQ5 Pro recommended as the entry point. Both are around the same price, and the HEQ5 does offer an upgrade path with the Rowan Belt mod which improves tracking. With a couple of additions (Ioptron ipolar and starsense), I can be set up in little more than 15 minutes.

Going down the separate mount and OTA path makes it much easier to add to your telescope collection (just accept it will happen!) than the fork mounted LX90.

For imaging, if you have a DSLR, I would buy the appropriate T mount to use that for imaging, see how you get on and what you enjoy imaging first - then buy the astro camera to best fit your needs. I am just starting down the imaging route, and I have to resist the urge to buy an astro cam - but looking around at the DSLR images of DSO that are so much better than mine is an easy reminder that it's about more than just the kit.

[Dan Petzen]

On 27/07/2020 at 23:29, Shimrod said:

I have an LX90 and wedge - it is an older model and at some point I must sell it because it has turned into an ornament. If you are using the LX90 on a permanent pier, then a wedge might be worthwhile, but if you are setting up each night then it just adds extra time and complexity to the set up of the telescope. It could take me 40mins upwards to get set up and ready to go.

I now have a Celestron AVX equatorial mount with both an EdgeHD and Skywatcher 80ed to use depending on what I want to observe or image. An 8" SCT on an equatorial mount is only going to be same (or maybe even less) than the LX90. I find the AVX fine,although you will often see the Skywatcher HEQ5 Pro recommended as the entry point. Both are around the same price, and the HEQ5 does offer an upgrade path with the Rowan Belt mod which improves tracking. With a couple of additions (Ioptron ipolar and starsense), I can be set up in little more than 15 minutes.

Going down the separate mount and OTA path makes it much easier to add to your telescope collection (just accept it will happen!) than the fork mounted LX90.

For imaging, if you have a DSLR, I would buy the appropriate T mount to use that for imaging, see how you get on and what you enjoy imaging first - then buy the astro camera to best fit your needs. I am just starting down the imaging route, and I have to resist the urge to buy an astro cam - but looking around at the DSLR images of DSO that are so much better than mine is an easy reminder that it's about more than just the kit.

Sorry for the time it took to respond. I've had a bit of a busy period.

Thanks for sharing your experience in regards to this. It helped a lot. However, every time something is cleared up, something new has to be investigated.

I know what I want now, but there are loads of options. I called the company that sold the RC for advice and they walked me through loads of options, but suggested I joined the local astronomy organisation before making a decision.

So I'm going to the first meeting tomorrow and am planning to join them at a dark site outside town in a week and a bit.

Thanks for your reply!