On Friday, December 10, 2021 at 9:30:27 PM UTC-7, Chris L Peterson wrote:

> It is a telescope designed for imaging. A dob is not.

It has an equatorial mount, that makes it more useful for imaging.

And given its large aperture, it may be that the telescope is too large
for convenient visual use. In the photos, it's certainly fitted with
equipment for imaging.

Thus, an ordinary Dobsonian isn't strictly comparable; if you
want a telescope suitable to long-duration exposures for
astrophotography, this one is better.

But unless it's one of those Cassegrains with a very large
central obstruction, it isn't useless for visual observation,
I would suspect. The real issue for an amateur would be its
weight, as portability is important if you want to take the
telescope with you to a dark sky site. It's useful to an
amateur who happens to live on a farm or an acreage.

John Savard

On Fri, 10 Dec 2021 23:38:30 -0800 (PST), Quadibloc
<jsavard@ecn.ab.ca> wrote:

>On Friday, December 10, 2021 at 9:30:27 PM UTC-7, Chris L Peterson wrote:
>
>> It is a telescope designed for imaging. A dob is not.
>
>It has an equatorial mount, that makes it more useful for imaging.
>
>And given its large aperture, it may be that the telescope is too large
>for convenient visual use. In the photos, it's certainly fitted with
>equipment for imaging.
>
>Thus, an ordinary Dobsonian isn't strictly comparable; if you
>want a telescope suitable to long-duration exposures for
>astrophotography, this one is better.
>
>But unless it's one of those Cassegrains with a very large
>central obstruction, it isn't useless for visual observation,
>I would suspect. The real issue for an amateur would be its
>weight, as portability is important if you want to take the
>telescope with you to a dark sky site. It's useful to an
>amateur who happens to live on a farm or an acreage.

It's not that it can't be used visually, any more than a dob can't be
used to some degree for imaging. But the market is very different for
the two. Almost certainly, the sort of person considering a big
observatory instrument like this isn't interested in getting a dob
instead!

On 10/12/2021 14:23, W wrote:
> On Friday, December 10, 2021 at 4:34:16 AM UTC-5, Martin Brown wrote:
>
>>> They said it would need a crane to lift it out of the observatory, but taking it apart might be possible.
>> It would easily split down to the OTA and the base. The OTA would
>> probably be a safe lift for two reasonably fit men, one guy who eats 3
>> wheatabix for breakfast or a block and tackle.
>>
>> The base and drive might be more of a problem for weight but a forklift
>> would probably not have much bother moving it around.
>
> The telescope, mount and parts thereof would need to be physically small enough to fit through the doors, stairwells, elevators and hallways that lead to the outside. That could be why they suggested using a crane.

It would be a strange building where the doorways were narrower than
30". The OTA would be the only part that might be pushing the size
boundaries but I would hazard a guess it is around 26" diameter all up.

The counterweights and base will be *very* heavy but a bit smaller.
>
> Once you got it home, you could very well have difficulties making adjustments in the mount if your latitude is different from that of its current location.

Not really. You put it on a cast slab of concrete with a very solid
wedge on top to shift the axis if you need to. It is probably good for
+/-2 degrees adjustment from the location it was originally installed.

There is usually some provision for exactly aligning the polar axis
after the thing is on site and installed.
>
> For what this bargain would really cost, I would rather go for a Dob of larger size, shorter f-ratio.

Depends what you want to do with it. The deal is for a relatively slow
imaging scope with quite a long focal length for its aperture.

Dob's are primarily a visual observers scope although you can do some
imaging on them if you try hard enough.

--
Regards,
Martin Brown

On Friday, December 10, 2021 at 11:30:27 PM UTC-5, Chris L Peterson wrote:
> On Fri, 10 Dec 2021 15:58:05 -0800 (PST), W <wsne...@hotmail.com>
> wrote:
>
> >On Friday, December 10, 2021 at 3:03:31 PM UTC-5, Chris L Peterson wrote:
> >> On Fri, 10 Dec 2021 06:23:18 -0800 (PST), W <wsne...@hotmail.com>
> >> wrote:
> >> >On Friday, December 10, 2021 at 4:34:16 AM UTC-5, Martin Brown wrote:
> >> >
> >> >> > They said it would need a crane to lift it out of the observatory, but taking it apart might be possible.
> >> >> It would easily split down to the OTA and the base. The OTA would
> >> >> probably be a safe lift for two reasonably fit men, one guy who eats 3
> >> >> wheatabix for breakfast or a block and tackle.
> >> >>
> >> >> The base and drive might be more of a problem for weight but a forklift
> >> >> would probably not have much bother moving it around.
> >> >
> >> >The telescope, mount and parts thereof would need to be physically small enough to fit through the doors, stairwells, elevators and hallways that lead to the outside. That could be why they suggested using a crane.
> >> >
> >> >Once you got it home, you could very well have difficulties making adjustments in the mount if your latitude is different from that of its current location.
> >> >
> >> >For what this bargain would really cost, I would rather go for a Dob of larger size, shorter f-ratio.
> >> Apples and organges. This is an imaging system. A Dob is for people
> >> who want to look through an eyepiece.
> >
> >It is possible to have an "imaging system" and a Dob. The Model 131 is a telescope, not an "imaging system."
> It is a telescope designed for imaging. A dob is not.

You completely missed the point.

One can choose between an "imaging system" and a Dob, choose neither or choose both.

The cost of buying, transporting and setting this scope up in a new location is not going to be trivial. So most people will find a better way to spend the money and choose something more powerful or more practical.

On Saturday, December 11, 2021 at 8:55:39 AM UTC-5, Martin Brown wrote:
> On 10/12/2021 14:23, W wrote:
> > On Friday, December 10, 2021 at 4:34:16 AM UTC-5, Martin Brown wrote:
> >
> >>> They said it would need a crane to lift it out of the observatory, but taking it apart might be possible.
> >> It would easily split down to the OTA and the base. The OTA would
> >> probably be a safe lift for two reasonably fit men, one guy who eats 3
> >> wheatabix for breakfast or a block and tackle.
> >>
> >> The base and drive might be more of a problem for weight but a forklift
> >> would probably not have much bother moving it around.
> >
> > The telescope, mount and parts thereof would need to be physically small enough to fit through the doors, stairwells, elevators and hallways that lead to the outside. That could be why they suggested using a crane.
> It would be a strange building where the doorways were narrower than
> 30". The OTA would be the only part that might be pushing the size
> boundaries but I would hazard a guess it is around 26" diameter all up.
>
> The counterweights and base will be *very* heavy but a bit smaller.
> >
> > Once you got it home, you could very well have difficulties making adjustments in the mount if your latitude is different from that of its current location.
> Not really. You put it on a cast slab of concrete with a very solid
> wedge on top to shift the axis if you need to. It is probably good for
> +/-2 degrees adjustment from the location it was originally installed.
>
> There is usually some provision for exactly aligning the polar axis
> after the thing is on site and installed.

There was an update by the seller. The telescope is located in a stand-alone dome, off campus. There is a picture that shows the exit door, second from the left, second row.

Reality check, for a 16-inch:
http://www.mnastro.org/how-the-onan-observatory-came-about/

WONDERFUL NEWS!!!!!!!!!!!
Another Chicom launch today with two new spy satellites added:

https://www.youtube.com/watch?v=4EoAHdwGBvU

On Wednesday, December 8, 2021 at 11:01:49 AM UTC-5, RichA wrote:
> On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
> > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
> > <'''newspam'''@nonad.co.uk> wrote:
> >
> > >On 07/12/2021 16:44, RichA wrote:

> Check this out then!
>
> https://www.govdeals.com/index.cfm?fa=Main.Item&itemid=1127&acctid=9002

Check THIS out:
https://optcorp.com/products/planewave-cdk600-6-meter-telescope-system

Now, who could be so foolish as to order this telescope, and not get the "polishing cloth" to go with it?

On Saturday, December 11, 2021 at 8:34:47 AM UTC-8, W wrote:
> On Wednesday, December 8, 2021 at 11:01:49 AM UTC-5, RichA wrote:
> > On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
> > > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
> > > <'''newspam'''@nonad.co.uk> wrote:
> > >
> > > >On 07/12/2021 16:44, RichA wrote:
>
> > Check this out then!
> >
> > https://www.govdeals.com/index.cfm?fa=Main.Item&itemid=1127&acctid=9002
> Check THIS out:
> https://optcorp.com/products/planewave-cdk600-6-meter-telescope-system
>
> Now, who could be so foolish as to order this telescope, and not get the "polishing cloth" to go with it?

Astro club for the filthy rich can buy it, I think?

On Sat, 11 Dec 2021 07:06:09 -0800 (PST), W <wsnell01@hotmail.com>
wrote:

>On Friday, December 10, 2021 at 11:30:27 PM UTC-5, Chris L Peterson wrote:
>> On Fri, 10 Dec 2021 15:58:05 -0800 (PST), W <wsne...@hotmail.com>
>> wrote:
>>
>> >On Friday, December 10, 2021 at 3:03:31 PM UTC-5, Chris L Peterson wrote:
>> >> On Fri, 10 Dec 2021 06:23:18 -0800 (PST), W <wsne...@hotmail.com>
>> >> wrote:
>> >> >On Friday, December 10, 2021 at 4:34:16 AM UTC-5, Martin Brown wrote:
>> >> >
>> >> >> > They said it would need a crane to lift it out of the observatory, but taking it apart might be possible.
>> >> >> It would easily split down to the OTA and the base. The OTA would
>> >> >> probably be a safe lift for two reasonably fit men, one guy who eats 3
>> >> >> wheatabix for breakfast or a block and tackle.
>> >> >>
>> >> >> The base and drive might be more of a problem for weight but a forklift
>> >> >> would probably not have much bother moving it around.
>> >> >
>> >> >The telescope, mount and parts thereof would need to be physically small enough to fit through the doors, stairwells, elevators and hallways that lead to the outside. That could be why they suggested using a crane.
>> >> >
>> >> >Once you got it home, you could very well have difficulties making adjustments in the mount if your latitude is different from that of its current location.
>> >> >
>> >> >For what this bargain would really cost, I would rather go for a Dob of larger size, shorter f-ratio.
>> >> Apples and organges. This is an imaging system. A Dob is for people
>> >> who want to look through an eyepiece.
>> >
>> >It is possible to have an "imaging system" and a Dob. The Model 131 is a telescope, not an "imaging system."
>> It is a telescope designed for imaging. A dob is not.
>
>You completely missed the point.
>
>One can choose between an "imaging system" and a Dob, choose neither or choose both.
>
>The cost of buying, transporting and setting this scope up in a new location is not going to be trivial. So most people will find a better way to spend the money and choose something more powerful or more practical.

No, you missed the point. But you always do.

On Saturday, December 11, 2021 at 9:34:47 AM UTC-7, W wrote:

> Check THIS out:
> https://optcorp.com/products/planewave-cdk600-6-meter-telescope-system
>
> Now, who could be so foolish as to order this telescope, and not get the "polishing cloth" to go with it?

This compares favorably with a similar product offered by Apple...

https://www.pcmag.com/reviews/apple-polishing-cloth

John Savard

On Saturday, December 11, 2021 at 5:48:07 PM UTC-5, Chris L Peterson wrote:
> On Sat, 11 Dec 2021 07:06:09 -0800 (PST), W <wsne...@hotmail.com>
> wrote:
>
> >On Friday, December 10, 2021 at 11:30:27 PM UTC-5, Chris L Peterson wrote:
> >> On Fri, 10 Dec 2021 15:58:05 -0800 (PST), W <wsne...@hotmail.com>
> >> wrote:
> >>
> >> >On Friday, December 10, 2021 at 3:03:31 PM UTC-5, Chris L Peterson wrote:
> >> >> On Fri, 10 Dec 2021 06:23:18 -0800 (PST), W <wsne...@hotmail.com>
> >> >> wrote:
> >> >> >On Friday, December 10, 2021 at 4:34:16 AM UTC-5, Martin Brown wrote:
> >> >> >
> >> >> >> > They said it would need a crane to lift it out of the observatory, but taking it apart might be possible.
> >> >> >> It would easily split down to the OTA and the base. The OTA would
> >> >> >> probably be a safe lift for two reasonably fit men, one guy who eats 3
> >> >> >> wheatabix for breakfast or a block and tackle.
> >> >> >>
> >> >> >> The base and drive might be more of a problem for weight but a forklift
> >> >> >> would probably not have much bother moving it around.
> >> >> >
> >> >> >The telescope, mount and parts thereof would need to be physically small enough to fit through the doors, stairwells, elevators and hallways that lead to the outside. That could be why they suggested using a crane.
> >> >> >
> >> >> >Once you got it home, you could very well have difficulties making adjustments in the mount if your latitude is different from that of its current location.
> >> >> >
> >> >> >For what this bargain would really cost, I would rather go for a Dob of larger size, shorter f-ratio.
> >> >> Apples and organges. This is an imaging system. A Dob is for people
> >> >> who want to look through an eyepiece.
> >> >
> >> >It is possible to have an "imaging system" and a Dob. The Model 131 is a telescope, not an "imaging system."
> >> It is a telescope designed for imaging. A dob is not.
> >
> >You completely missed the point.
> >
> >One can choose between an "imaging system" and a Dob, choose neither or choose both.
> >
> >The cost of buying, transporting and setting this scope up in a new location is not going to be trivial. So most people will find a better way to spend the money and choose something more powerful or more practical.
> No, you missed the point. But you always do.

No, you missed the point from the moment you butted in.
What a little child you are.

ALL MEMBERS - PLEASE READ - IMPORTANT ANNOUNCEMENT!!!

WONDERFUL NEWS!!!!!!!!!!!
Elon Musk Is TIME's 2021 Person of the Year.

https://www.youtube.com/watch?v=4EoAHdwGBvU

On Sunday, 12 December 2021 at 02:44:51 UTC-5, Quadibloc wrote:
> On Saturday, December 11, 2021 at 9:34:47 AM UTC-7, W wrote:
>
> > Check THIS out:
> > https://optcorp.com/products/planewave-cdk600-6-meter-telescope-system
> >
> > Now, who could be so foolish as to order this telescope, and not get the "polishing cloth" to go with it?
> This compares favorably with a similar product offered by Apple...
>
> https://www.pcmag.com/reviews/apple-polishing-cloth
>
> John Savard

Lets you know how pathetic people get when they're reviewing polishing cloths. Anyone who knows anything about optics knows only an idiot
would re-used a cloth to clean any glass or optical surface. Especially something you might shove in your pocket. That is, unless they are offering
the home Apple Polishing Cloth Storage Case for $20....

On Wednesday, 8 December 2021 at 11:01:49 UTC-5, RichA wrote:
> On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
> > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
> > <'''newspam'''@nonad.co.uk> wrote:
> >
> > >On 07/12/2021 16:44, RichA wrote:
> > >> https://www.ebay.ca/itm/154726532372?hash=item24066b8514:g:uP4AAOSwIyxhpeEh
> > >>
> > >Price is a bit steep for a 0.5m observatory class instrument but then it
> > >is a Maksutov so a hell of a lot of glass has to be ground to make one.
> > Yeah, pretty hard to justify when you can get a new 0.5 m PlaneWave
> > CDK for $34,000 or a 0.7 m CDK on a computerized fork mount for
> > $195,000 (both with guarantees, support, and service).
> > >He now states on the listing and his website ships worldwide but does
> > >not ship to UK.
> > It says that because you're seeing it from the UK. From here it says
> > he doesn't ship to the U.S. Indeed, look at the exclusions after
> > "worldwide" and he basically doesn't ship anywhere. Not even to
> > Germany, where the telescope is located!
> Check this out then!
>
> https://www.govdeals.com/index.cfm?fa=Main.Item&itemid=1127&acctid=9002

Big used Cassegrain went for $10,200. Add around $1000-$2000 to prep and ship it plus $25,000 or so for the observatory. And maybe re-aluminizing.

On Monday, December 13, 2021 at 9:24:43 PM UTC-8, RichA wrote:
> On Wednesday, 8 December 2021 at 11:01:49 UTC-5, RichA wrote:
> > On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
> > > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
> > > <'''newspam'''@nonad.co.uk> wrote:
> > >
> > > >On 07/12/2021 16:44, RichA wrote:
> > > >> https://www.ebay.ca/itm/154726532372?hash=item24066b8514:g:uP4AAOSwIyxhpeEh
> > > >>
> > > >Price is a bit steep for a 0.5m observatory class instrument but then it
> > > >is a Maksutov so a hell of a lot of glass has to be ground to make one.
> > > Yeah, pretty hard to justify when you can get a new 0.5 m PlaneWave
> > > CDK for $34,000 or a 0.7 m CDK on a computerized fork mount for
> > > $195,000 (both with guarantees, support, and service).
> > > >He now states on the listing and his website ships worldwide but does
> > > >not ship to UK.
> > > It says that because you're seeing it from the UK. From here it says
> > > he doesn't ship to the U.S. Indeed, look at the exclusions after
> > > "worldwide" and he basically doesn't ship anywhere. Not even to
> > > Germany, where the telescope is located!
> > Check this out then!

I dunno, I have a 25" f/5 Newtonian for about that same value, and it is a LOT more portable... and the views are fantastic when taken to a dark site.... no crane required... I can load and unload it by myself from my trailer and it takes about 15 or 20 minutes to assemble in the field... and I would not trade it straight across for this thing, no way... but then, I have no intention of imaging with my telescope, since I can get umpteen thousand really nice images from the internet of virtually any target that you might want to see... it is my natural eyeballs on a target that get me all excited... and there are way too many things to see, enough to easily last my own lifetime... of course, YMMV...

On Tuesday, 14 December 2021 at 00:53:56 UTC-5, palsing wrote:
> On Monday, December 13, 2021 at 9:24:43 PM UTC-8, RichA wrote:
> > On Wednesday, 8 December 2021 at 11:01:49 UTC-5, RichA wrote:
> > > On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
> > > > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
> > > > <'''newspam'''@nonad.co.uk> wrote:
> > > >
> > > > >On 07/12/2021 16:44, RichA wrote:
> > > > >> https://www.ebay.ca/itm/154726532372?hash=item24066b8514:g:uP4AAOSwIyxhpeEh
> > > > >>
> > > > >Price is a bit steep for a 0.5m observatory class instrument but then it
> > > > >is a Maksutov so a hell of a lot of glass has to be ground to make one.
> > > > Yeah, pretty hard to justify when you can get a new 0.5 m PlaneWave
> > > > CDK for $34,000 or a 0.7 m CDK on a computerized fork mount for
> > > > $195,000 (both with guarantees, support, and service).
> > > > >He now states on the listing and his website ships worldwide but does
> > > > >not ship to UK.
> > > > It says that because you're seeing it from the UK. From here it says
> > > > he doesn't ship to the U.S. Indeed, look at the exclusions after
> > > > "worldwide" and he basically doesn't ship anywhere. Not even to
> > > > Germany, where the telescope is located!
> > > Check this out then!
> I dunno, I have a 25" f/5 Newtonian for about that same value, and it is a LOT more portable... and the views are fantastic when taken to a dark site... no crane required... I can load and unload it by myself from my trailer and it takes about 15 or 20 minutes to assemble in the field... and I would not trade it straight across for this thing, no way... but then, I have no intention of imaging with my telescope, since I can get umpteen thousand really nice images from the internet of virtually any target that you might want to see... it is my natural eyeballs on a target that get me all excited... and there are way too many things to see, enough to easily last my own lifetime... of course, YMMV...

I think that was part of the sale, the mounting is probably very high precision, or as high as the era permitted, it also had some kind of encoders added at some point. So it's likely a good imaging scope. Only thing is I don't know if it had a widefield imaging port of any kind.

On Mon, 13 Dec 2021 21:53:54 -0800 (PST), palsing <pnalsing@gmail.com>
wrote:

>On Monday, December 13, 2021 at 9:24:43 PM UTC-8, RichA wrote:
>> On Wednesday, 8 December 2021 at 11:01:49 UTC-5, RichA wrote:
>> > On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
>> > > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
>> > > <'''newspam'''@nonad.co.uk> wrote:
>> > >
>> > > >On 07/12/2021 16:44, RichA wrote:
>> > > >> https://www.ebay.ca/itm/154726532372?hash=item24066b8514:g:uP4AAOSwIyxhpeEh
>> > > >>
>> > > >Price is a bit steep for a 0.5m observatory class instrument but then it
>> > > >is a Maksutov so a hell of a lot of glass has to be ground to make one.
>> > > Yeah, pretty hard to justify when you can get a new 0.5 m PlaneWave
>> > > CDK for $34,000 or a 0.7 m CDK on a computerized fork mount for
>> > > $195,000 (both with guarantees, support, and service).
>> > > >He now states on the listing and his website ships worldwide but does
>> > > >not ship to UK.
>> > > It says that because you're seeing it from the UK. From here it says
>> > > he doesn't ship to the U.S. Indeed, look at the exclusions after
>> > > "worldwide" and he basically doesn't ship anywhere. Not even to
>> > > Germany, where the telescope is located!
>> > Check this out then!
>
>I dunno, I have a 25" f/5 Newtonian for about that same value, and it is a LOT more portable... and the views are fantastic when taken to a dark site... no crane required... I can load and unload it by myself from my trailer and it takes about 15 or 20 minutes to assemble in the field... and I would not trade it straight across for this thing, no way... but then, I have no intention of imaging with my telescope, since I can get umpteen thousand really nice images from the internet of virtually any target that you might want to see... it is my natural eyeballs on a target that get me all excited... and there are way too many things to see, enough to easily last my own lifetime... of course, YMMV...

Of course. And I have virtually no interest in peering through
eyepieces. So a large portable scope is of little use to me. On the
other hand, a large aperture scope with a high quality tracking
mount...

I use a large tracking telescope that observes orbital motions minus any of the problems associated with tracking planets on the surface of a rotating Earth-

https://sol24.net/data/html/SOHO/C3/96H/VIDEO/

Just before Mercury passes beyond the range of the telescope tracking with the slower moving Earth, the focal point is the central/stationary Sun.

Identification and magnification are splendid exercises, however, the real satisfaction is putting the observed motions of the planets in context presently and in future. That former exercise compliments the more productive and creative use of a telescope, imaging and so on.

You should try it yourself as Venus will pass between the slower moving Earth and central Sun soon enough and obviates the need to wait for transits.You don't even have to appreciate the old terms of Venus in retrograde motion against the background stars as it changes position relative to the central Sun faster than the motion of the Earth than the relative change in position of the stars due to the slower motion of the Earth.

On Saturday, December 11, 2021 at 8:31:02 AM UTC-5, Chris L Peterson wrote:
> Almost certainly, the sort of person considering a big
> observatory instrument like this isn't interested in getting a dob
> instead!

With absolute certainty, you are wrong. A person interested in a "big observatory instrument" can pass on this one and buy some other telescope instead, including a large Dob.

On Tuesday, December 14, 2021 at 5:39:51 AM UTC-8, Chris L Peterson wrote:
> On Mon, 13 Dec 2021 21:53:54 -0800 (PST), palsing <pnal...@gmail.com>
> wrote:
> >On Monday, December 13, 2021 at 9:24:43 PM UTC-8, RichA wrote:
> >> On Wednesday, 8 December 2021 at 11:01:49 UTC-5, RichA wrote:
> >> > On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
> >> > > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
> >> > > <'''newspam'''@nonad.co.uk> wrote:
> >> > >
> >> > > >On 07/12/2021 16:44, RichA wrote:
> >> > > >> https://www.ebay.ca/itm/154726532372?hash=item24066b8514:g:uP4AAOSwIyxhpeEh
> >> > > >>
> >> > > >Price is a bit steep for a 0.5m observatory class instrument but then it
> >> > > >is a Maksutov so a hell of a lot of glass has to be ground to make one.
> >> > > Yeah, pretty hard to justify when you can get a new 0.5 m PlaneWave
> >> > > CDK for $34,000 or a 0.7 m CDK on a computerized fork mount for
> >> > > $195,000 (both with guarantees, support, and service).
> >> > > >He now states on the listing and his website ships worldwide but does
> >> > > >not ship to UK.
> >> > > It says that because you're seeing it from the UK. From here it says
> >> > > he doesn't ship to the U.S. Indeed, look at the exclusions after
> >> > > "worldwide" and he basically doesn't ship anywhere. Not even to
> >> > > Germany, where the telescope is located!
> >> > Check this out then!
> >
> >I dunno, I have a 25" f/5 Newtonian for about that same value, and it is a LOT more portable... and the views are fantastic when taken to a dark site... no crane required... I can load and unload it by myself from my trailer and it takes about 15 or 20 minutes to assemble in the field... and I would not trade it straight across for this thing, no way... but then, I have no intention of imaging with my telescope, since I can get umpteen thousand really nice images from the internet of virtually any target that you might want to see... it is my natural eyeballs on a target that get me all excited... and there are way too many things to see, enough to easily last my own lifetime... of course, YMMV...

> Of course. And I have virtually no interest in peering through
> eyepieces. So a large portable scope is of little use to me. On the
> other hand, a large aperture scope with a high quality tracking
> mount...

Well, Chris, my 25" does have tracking (ServoCat)... which only means that it can keep an object within the FOV for a number of hours, but not so accurately that a long-exposure picture would be successful...not to mention that with an alt-az telescope there is no field de-rotation capability... but then, I have virtually no interest in taking photos through this guy... he/she is strictly for visual amateur astronomy... and he/she has long lines at star-parties, your own non-interest in visual peeks notwithstanding :>) I myself find it to be mind-blowing, even after 5 or 6 decades of regular observing...

On Tuesday, December 14, 2021 at 2:55:53 PM UTC-8, W wrote:
> On Saturday, December 11, 2021 at 8:31:02 AM UTC-5, Chris L Peterson wrote:

> > Almost certainly, the sort of person considering a big
> > observatory instrument like this isn't interested in getting a dob
> > instead!

> With absolute certainty, you are wrong. A person interested in a "big observatory instrument" can pass on this one and buy some other telescope instead, including a large Dob.

Sure... as long as he doesn't want to image to much!

On Tuesday, December 14, 2021 at 3:55:53 PM UTC-7, W wrote:
> On Saturday, December 11, 2021 at 8:31:02 AM UTC-5, Chris L Peterson wrote:
> > Almost certainly, the sort of person considering a big
> > observatory instrument like this isn't interested in getting a dob
> > instead!

> With absolute certainty, you are wrong. A person interested in a "big observatory
> instrument" can pass on this one and buy some other telescope instead,

That's absolutely true.

> including a large Dob.

But this part, crucial to the conclusion that he was wrong, is not so
certain. After all, a Dobsonian is, by necessity, on an alt-azimuth mount.

There _are_ computerized motorized Dobsonians out there. For long-exposure
photography, of course, anything that's alt-azimuth needs image rotation. But
given that "lucky imaging" has now basically replaced long exposures, as it
allows bypassing much of the effects of Earth's atmosphere (of course, for
anything much over 11 inches in aperture, you actually need adaptive optics
instead, but that's available too...) perhaps that's not too much of an issue either.

So, on reflection, you are correct: a Dobsonian _is_, these days, potentially
an alternative to a large equatorially-mounted instrument for nearly all purposes.

John Savard

On Tue, 14 Dec 2021 20:24:33 -0800 (PST), Quadibloc
<jsavard@ecn.ab.ca> wrote:

>On Tuesday, December 14, 2021 at 3:55:53 PM UTC-7, W wrote:
>> On Saturday, December 11, 2021 at 8:31:02 AM UTC-5, Chris L Peterson wrote:
>> > Almost certainly, the sort of person considering a big
>> > observatory instrument like this isn't interested in getting a dob
>> > instead!
>
>> With absolute certainty, you are wrong. A person interested in a "big observatory
>> instrument" can pass on this one and buy some other telescope instead,
>
>That's absolutely true.
>
>> including a large Dob.
>
>But this part, crucial to the conclusion that he was wrong, is not so
>certain. After all, a Dobsonian is, by necessity, on an alt-azimuth mount.
>
>There _are_ computerized motorized Dobsonians out there. For long-exposure
>photography, of course, anything that's alt-azimuth needs image rotation. But
>given that "lucky imaging" has now basically replaced long exposures, as it
>allows bypassing much of the effects of Earth's atmosphere (of course, for
>anything much over 11 inches in aperture, you actually need adaptive optics
>instead, but that's available too...) perhaps that's not too much of an issue either.
>
>So, on reflection, you are correct: a Dobsonian _is_, these days, potentially
>an alternative to a large equatorially-mounted instrument for nearly all purposes.

Lucky imaging has not replaced long exposure imaging. It only works
with very bright targets- the Moon and planets. It is useless for deep
sky imaging.

On Tue, 14 Dec 2021 20:21:03 -0800 (PST), palsing <pnalsing@gmail.com>
wrote:

>On Tuesday, December 14, 2021 at 5:39:51 AM UTC-8, Chris L Peterson wrote:
>> On Mon, 13 Dec 2021 21:53:54 -0800 (PST), palsing <pnal...@gmail.com>
>> wrote:
>> >On Monday, December 13, 2021 at 9:24:43 PM UTC-8, RichA wrote:
>> >> On Wednesday, 8 December 2021 at 11:01:49 UTC-5, RichA wrote:
>> >> > On Tuesday, 7 December 2021 at 16:53:41 UTC-5, Chris L Peterson wrote:
>> >> > > On Tue, 7 Dec 2021 17:08:44 +0000, Martin Brown
>> >> > > <'''newspam'''@nonad.co.uk> wrote:
>> >> > >
>> >> > > >On 07/12/2021 16:44, RichA wrote:
>> >> > > >> https://www.ebay.ca/itm/154726532372?hash=item24066b8514:g:uP4AAOSwIyxhpeEh
>> >> > > >>
>> >> > > >Price is a bit steep for a 0.5m observatory class instrument but then it
>> >> > > >is a Maksutov so a hell of a lot of glass has to be ground to make one.
>> >> > > Yeah, pretty hard to justify when you can get a new 0.5 m PlaneWave
>> >> > > CDK for $34,000 or a 0.7 m CDK on a computerized fork mount for
>> >> > > $195,000 (both with guarantees, support, and service).
>> >> > > >He now states on the listing and his website ships worldwide but does
>> >> > > >not ship to UK.
>> >> > > It says that because you're seeing it from the UK. From here it says
>> >> > > he doesn't ship to the U.S. Indeed, look at the exclusions after
>> >> > > "worldwide" and he basically doesn't ship anywhere. Not even to
>> >> > > Germany, where the telescope is located!
>> >> > Check this out then!
>> >
>> >I dunno, I have a 25" f/5 Newtonian for about that same value, and it is a LOT more portable... and the views are fantastic when taken to a dark site... no crane required... I can load and unload it by myself from my trailer and it takes about 15 or 20 minutes to assemble in the field... and I would not trade it straight across for this thing, no way... but then, I have no intention of imaging with my telescope, since I can get umpteen thousand really nice images from the internet of virtually any target that you might want to see... it is my natural eyeballs on a target that get me all excited... and there are way too many things to see, enough to easily last my own lifetime... of course, YMMV...
>
>> Of course. And I have virtually no interest in peering through
>> eyepieces. So a large portable scope is of little use to me. On the
>> other hand, a large aperture scope with a high quality tracking
>> mount...
>
>Well, Chris, my 25" does have tracking (ServoCat)... which only means that it can keep an object within the FOV for a number of hours, but not so accurately that a long-exposure picture would be successful...not to mention that with an alt-az telescope there is no field de-rotation capability... but then, I have virtually no interest in taking photos through this guy... he/she is strictly for visual amateur astronomy... and he/she has long lines at star-parties, your own non-interest in visual peeks notwithstanding :>) I myself find it to be mind-blowing, even after 5 or 6 decades of regular observing...

Sure, lots of people do. But I don't get the attraction. I find little
of interest in the eyepiece. What blows me away is capturing and
processing an image.

Different strokes...

On Tuesday, December 14, 2021 at 11:23:11 PM UTC-5, palsing wrote:
> On Tuesday, December 14, 2021 at 2:55:53 PM UTC-8, W wrote:
> > On Saturday, December 11, 2021 at 8:31:02 AM UTC-5, Chris L Peterson wrote:
>
> > > Almost certainly, the sort of person considering a big
> > > observatory instrument like this isn't interested in getting a dob
> > > instead!
>
> > With absolute certainty, you are wrong. A person interested in a "big observatory instrument" can pass on this one and buy some other telescope instead, including a large Dob.
> Sure... as long as he doesn't want to image to much!

Let's all say this together now:

THERE ARE OTHER IMAGING TELESCOPES AVAILABLE ASIDE FROM THE GROUP 128 24-INCH FROM THE 1960s.

And let's all say this too:

IT IS POSSIBLE TO DECIDE BETWEEN AN "IMAGING TELESCOPE" AND A DOB SINCE IT IS POSSIBLE TO BE INTERESTED IN THE ACTIVITIES TO WHICH EACH IS BEST SUITED.