What’s the Best Option for Bigger Aperture?

[PeterC65]

7 hours ago, Captain Scarlet said:

I seem to be in the minority that uses a newt on an alt-az mount. And at the big end of things too: a 12” on an AZ-EQ6. Although I now have reduced the weight of the OTA with a carbon tube, it used to be a full-blown SW 300p with steel tube, coming in at over 27kg including eyepieces finder etc. I was and am able to attach it to the mount without risk on my own: I attach the rings first, then with clutches locked and OTA horizontal held with one hand at each end, I “walk” the tube into the open rings, close the rings whilst gently holding the tube in place with my body and I’m done.

A 10” being so much more wieldy should be even simpler should you go down that route.

Cheers, Magnus

I hadn't thought of doing it that way. Thanks for the tip! I carry the OTA, tubes and dovetail, in my arms, lower the dovetail into the clamp and then manage to tighten the clamp with a spare hand. I'd been concerned that the spare hand may be needed to support the OTA in the case of a 10". Your method would be much safer.

 

[PeterC65]

6 hours ago, Carbon Brush said:

My take, which is not necessarily correct.

A goto dob (I used to own one) can mean storing and carrying everything in one lump.
I used to separate the mount and tube on my 10" SW flextube.
But you can only use the mount for this scope. Alright depending on your DIY skills and patience, you can put something else on there.

If you buy a big goto mount, you swap scopes as often as you like, without having to learn a new goto system.
It is as easy as dropping something different into the dovetail. Are you really only going have one scope - ever?

EQ is a littlle less intuitive than AZ. But you only have to learn once.
This choice opens the door to astro. Whether it is low cost wide field DSLR, or money pit is your choice.
I have in the past used EQ5 with a DSLR on 800/1000mm FL 8" newts for a couple of minutes with good (to me) results.
This was unguided and before all this complicated fiddling and stacking in the computer was so popular.

Most important whichever you choose. Is it still easy enough to set up quickly?
The best scope is the one used most and all that.

HTH, David.

 

I should also have mentioned that I only observe at home and that involves moving the scope less than 10m on the flat just through a patio door. So portability isn't a big issue but I do need to be able to setup and dismantle on my own.

The wife does have an issue with storing a Dobsonian. She calls them the MFI mount! I have pointed out that the Flextube models can be shortened but so far that isn't proving to be persuasive!

I completely agree with your point that a Dobsonian wouldn't do anything to enhance my other scopes (I have three others) and that's why an AZ EQ5-GT is so appealing. On the other hand, that mount alone (without a new OTA) doesn't gain me much!

 

[PeterC65]

2 hours ago, catburglar said:

Just one comment on observing comfort…The eyepiece height on a 10 or 12 inch dob will vary with altitude much more than it will with your 150- a longer tube and balance point closer to the mirror will almost guarantee it… I suspect you’d need to swap between standing/seated observing as you move between objects…In my experience a mak/SCT or short focus refractor is most likely to give you observing comfort across a broad swath of sky.. 

You could stick a 10inch SCT on an AZ-Eq5 if your budget would allow…or the Evolution9.25… and both would give you an beefier mount for your other scopes if you wanted it.

Good point! I hadn't thought of that.

Putting cost to one side, I'd probably choose an AZ EQ5 GT and a C11, but that would set me back £4k, more than twice the cost of a 12" GOTO Dobsonian. 

[PeterC65]

1 hour ago, Paz said:

This is a difficult one as it involves trading off different things,  but I would say a big Newtonian on an eq mount would be a serious undertaking, quite difficult and physical to set up due to weight, bulk, awkwardness, more hassle balancing everything off, the eyepiece rotating all over the place, etc.

I think there's a lot to be said for a go-to dobsonian although it may not tick every box perfectly. 

It is true eyepiece height varies a lot on a big dobsonian but my observing chair (a bog standard skywatcher one) allows me to go from almost sitting on the floor to almost fully standing just fine.

I currently use a kick stool as my seat which is low and fixed height. Great for moving around and just the right height for diagonal enabled scopes though.

I could try an adjustable observing chair with the Explorer 150PDS. I hadn't considered using a Newtonian from a seated position, and as you mention, an adjustable chair is probably essential to be seated at a large Dobsonian.

 

[Stu]

@PeterC65 Just a few random thoughts as they come to me…..

I wouldn’t try a 10” newt on an AZ-EQ5. I’m not a huge fan of these mounts, particularly in altaz mode as they can have a bit of backlash which makes them a bit frustrating. Also the way the cable connects between the two halves of the mount can end up getting caught if the mount keeps going too far in one direction. I think a 10” would be a bit much for it, so would go for an AZ-EQ6 if trying this sort of thing, much more substantial (but also a heavier lift).

A C8 on one of the better altaz mounts would be a decent option. I’ve heard the Celestron SE mounts are a bit marginal for the C8, and the CPC dual arm mounts are heavy beasts, so the Evolution is probably the happy medium.

With an adjustable observing seat, a dob can be used from a seated position quite comfortably (except perhaps towards the zenith when standing may be needed depending your height vs the tube length). The range of movement is larger so if skipping around the sky, more changes are needed but with a good seat this is very quick.

Finding things manually with SkySafari is actually not so hard, particularly with a TelRad and RACI combination of finders. Setup SkySafari so it matches the fov, orientation and limiting magnitude of your scope/eyepiece/sky combination and star hopping becomes trivial. Tracking manually is something you get used to, but certainly an EQ platform is well worth considering as they do make a big difference. I’ve never used a platform with a push to dob, but I believe this can be made to work. Might be a little complex to align, not sure.

Do you have fences around your garden? If so, then a dob can feel a little more limited for lower targets as it pivots in alt from the base. A tripod mounted scope gets you up a bit higher and may be easier in this particular respect.

Don't forget the AZ75 or AZ100 as options. The 100 has slow motion controls and would take a C8 or C925 very nicely on the right tripod. Not cheap, though could be upgraded to goto/tracking later.

If Goto is a must, then out of your list I would probably go with the 10” goto dob, or a C8 Evo. I agree with Mr Spock that I have found newts to give more consistent images than SCTs, particularly in veritable conditions; I’ve split much tighter doubles with my 8” f8 than I ever managed with a C8 or C925.

I’ll be quiet now 😉

 

[Stu]

Just found these of my 8” f8 (ie 1600mm f/l) dob on EQ Platform with observing seat.

[Cosmic Geoff]

Of the suggested items, a AZ-EQ5 + 10" Newt costs around £1814, an AZ-EQ6 + 10" Newt costs £2284, and a Celestron Evo 8 costs around £1970. 

A CPC800 is ~ £2025.

An Evo 925 is around £2449, a CPC925 £3249

A CPC1100 is £3995.

Note that used SCTs seem not to hold their prices well, so can often be had for far less than the new price (as I can personally confirm 🙂) ie arounf 50%.  So many C8's have been made that if you want to buy a used one you can always find one.

As is widely quoted, for other astro gear it's more like 66%.

The new CC scopes look good, but seem to be available as OTA only - attractively priced (in 8" size) but look like they would need a substantial mount.

[Mr Spock]

Before I had the C9.25 on an EQ-6, I had a 250mm Newt on there. Getting a 250mm onto an EQ-6 requires forearms like Popeye 😜

[Stu]

14 minutes ago, Mr Spock said:

Before I had the C9.25 on an EQ-6, I had a 250mm Newt on there. Getting a 250mm onto an EQ-6 requires forearms like Popeye 😜

Have you seen @Captain Scarlet? 😉

[PeterC65]

56 minutes ago, Stu said:

@PeterC65 Just a few random thoughts as they come to me…..

I wouldn’t try a 10” newt on an AZ-EQ5. I’m not a huge fan of these mounts, particularly in altaz mode as they can have a bit of backlash which makes them a bit frustrating. Also the way the cable connects between the two halves of the mount can end up getting caught if the mount keeps going too far in one direction. I think a 10” would be a bit much for it, so would go for an AZ-EQ6 if trying this sort of thing, much more substantial (but also a heavier lift).

A C8 on one of the better altaz mounts would be a decent option. I’ve heard the Celestron SE mounts are a bit marginal for the C8, and the CPC dual arm mounts are heavy beasts, so the Evolution is probably the happy medium.

With an adjustable observing seat, a dob can be used from a seated position quite comfortably (except perhaps towards the zenith when standing may be needed depending your height vs the tube length). The range of movement is larger so if skipping around the sky, more changes are needed but with a good seat this is very quick.

Finding things manually with SkySafari is actually not so hard, particularly with a TelRad and RACI combination of finders. Setup SkySafari so it matches the fov, orientation and limiting magnitude of your scope/eyepiece/sky combination and star hopping becomes trivial. Tracking manually is something you get used to, but certainly an EQ platform is well worth considering as they do make a big difference. I’ve never used a platform with a push to dob, but I believe this can be made to work. Might be a little complex to align, not sure.

Do you have fences around your garden? If so, then a dob can feel a little more limited for lower targets as it pivots in alt from the base. A tripod mounted scope gets you up a bit higher and may be easier in this particular respect.

Don't forget the AZ75 or AZ100 as options. The 100 has slow motion controls and would take a C8 or C925 very nicely on the right tripod. Not cheap, though could be upgraded to goto/tracking later.

If Goto is a must, then out of your list I would probably go with the 10” goto dob, or a C8 Evo. I agree with Mr Spock that I have found newts to give more consistent images than SCTs, particularly in veritable conditions; I’ve split much tighter doubles with my 8” f8 than I ever managed with a C8 or C925.

I’ll be quiet now 😉

 

This is all really useful information. Thanks!

I was concerned about the external cable on the AZ EQ5 mount as it seems to connect parts of the mount that move independently and I was thinking that a 10" Newtonian would be too much for the AZ EQ5. The AZ EQ6 would be nice but it is quite a bit more expensive. If I did go for an AZ EQ6 would it handle a 12" Newtonian?

I've looked at the AZ75 and AZ100 many times. They are beautifully engineered but I'd like to see the GOTO version released before I give them serious consideration.

I observe from a terrace in front of the house which is on the side of a hill. There are clear views to the south east across about 120° and from the horizon to the zenith, but the north and west are obscured by the house. I don't think a Dobsonian would be any different from a tripod mount for me.

A GOTO Dobsonian does seem to be the most sensible option, which is the conclusion I was coming to myself. I think I need to try using my Explorer 150PDS with a tall stool and then maybe invest in an adjustable observing chair.

[PeterC65]

40 minutes ago, Cosmic Geoff said:

Of the suggested items, a AZ-EQ5 + 10" Newt costs around £1814, an AZ-EQ6 + 10" Newt costs £2284, and a Celestron Evo 8 costs around £1970. 

A CPC800 is ~ £2025.

An Evo 925 is around £2449, a CPC925 £3249

A CPC1100 is £3995.

Note that used SCTs seem not to hold their prices well, so can often be had for far less than the new price (as I can personally confirm 🙂) ie arounf 50%.  So many C8's have been made that if you want to buy a used one you can always find one.

As is widely quoted, for other astro gear it's more like 66%.

The new CC scopes look good, but seem to be available as OTA only - attractively priced (in 8" size) but look like they would need a substantial mount.

My issue with buying a used scope is that it's still a lot to pay for something with no warranty / support / backup. I've bought customer returns from FLO (the Explorer 150PDS was one) and still had good support from them and this feels like a better option. In fact what prompted me to start this post was a customer return AZ EQ6, sadly now gone!

 

[Stu]

4 hours ago, PeterC65 said:

If I did go for an AZ EQ6 would it handle a 12" Newtonian?

Magnus ( @Captain Scarlet) uses one of his AZEQ6. It’s got a lightened CF tube but I think the original skywatcher tube worked fine on the mount.

I can’t quite get my head around the observing position of newt on an AltAz but it seems to work. A dob is certainly likely to be quicker and easier to setup though.

[Captain Scarlet]

19 minutes ago, Stu said:

Magnus ( @Captain Scarlet) uses one of his AZEQ6. It’s got a lightened CF tube but I think the original skywatcher tube worked fine on the mount.

I can’t quite get my head around the observing position of newt on an AltAz but it seems to work. A dob is certainly likely to be quicker and easier to setup though.

Yes indeed. I do need a step or two for the higher elevations but I like the setup.

The pics below are of my old steel-tubed 300p, nearly 28kg all in and no slewing problems. My current 12” is carbon tubed and comes in around 21kg. I’ll be using that tonight I think.

Magnus

[PeterC65]

I tried using the Explorer 150PDS in daylight yesterday while perched on a tall stool. The OTA needed rotating in the tube rings so that the focuser was much closer to the horizontal but after making this adjustment I could comfortably sit to observe. As others have mentioned, the vertical movement of the focuser is more limited with the Explorer 150PDS than it would be with a larger Dobsonian so even with the fixed height stool I could observe across 20° to 70° altitude without bending too much. The stool seat is probably not quite as stable as my usual kick stool but much better than standing. It will be nice to try this setup at night although that may be a while away.

In the meantime I've ordered a Geoptik Nadira Astronomy Observing Chair from RVO. It's considerably cheaper than a sheet of 24mm Birch Plywood!