[ap-ug] Life after the Stowaway


Roland Christen
 


You know what? Back in the day we used to make mirrors out of Pyrex because it has fairly low expansion coefficient. That means the mirror's figure would not change as the temperature dropped. If you really wanted to drop some coin on a mirror blank, you went for quartz which had a fraction of the expansion of Pyrex. Plate glass was considered bogus because it will not hold a decent figure when the temperature drops (as it does in most places).

What do we have nowadays? Well, those cheap and cheerful Asian imports use borosilicate crown (BK7 equivalent), which has the same expansion coefficient as cheap plate glass. And people are joyful as bunny rabbits in a carrot patch. I can't compete with that because people just don't know stuff any more, like what we knew back in the days of Sky&Tel with their "Gleanings for Amateurs" series. Heck, you could probably sell plastic mirrors now and claim 0.99 Strehl. I'm betting someone is already working on that as we speak.
Smile

For me, I like quartz optics in a reflector. Would not make them any other way. Quartz holds its shape even when the mirror is very thin and light weight. My 17" Quartz Cassegrain astrograph has a mirror that is only 12.5mm thick at the edges. I can hold it up in my right hand. It sheds heat so fast that it basically does not have any cooldown time. I also have  10" and 12" quartz Mak-Cass astrographs that work the same way. They have thin mirrors that shed heat quickly and are ready to use in minutes. On a typical winter day the temperature can drop from 38F to 4F in a matter of 2 hours. Focus doesn't change in these quartz-carbon fiber scopes. The problem is the expectations of amateurs to have large aperture optics at near zero cost. For that to happen you can forget getting it made in the USA. A raw quartz blank costs more than a complete finished Newtonian with a cheap and cheerful import mount thrown in for good measure (well I'm maybe stretching it a bit).

Celestron and Meade pretty much put the kabosh on anything Cassegrain. Fact is they use plate glass optics and aluminum tubes, which together pretty much insures that you are constantly fiddling with the focus knob. Plus you have those nice heat plumes that run up the baffle tubes. Do people know that's happening? Do they really care? Probably not because they got them brand new and shiny at ridiculously low cost. And somehow they can make them work, although I'm completely baffled how they manage it.

Rolando

-----Original Message-----
From: ROBERT WYNNE <robert-wynne@...>
To: chris1011@...
Sent: Tue, Jan 18, 2022 8:08 pm
Subject: Re: [ap-ug] Life after the Stowaway

I think because we all believe you probably have access to superior blanks and provide the best mirror figuring in the world. Plus, Newtonians are relatively inexpensive to manufacture but A-P as imatter stand could set its own price on Newtonians and still have the highest gross margins in the business. Unless competing projects, space and machining time is a concern. I wonder if manufacturing Newtonians would be a good introduction to the craft for new employees. -Best, Robert
On 01/18/2022 8:19 AM chris1011@... wrote:


You can buy Newtonians at a dime a dozen out of Asia. Why would I want to compete with that? Stuck out tongue winking eye

Rolando


-----Original Message-----
From: ROBERT WYNNE <robert-wynne@...>
To: main@ap-ug.groups.io; Arun Hegde <arun.k.hegde@...>
Sent: Mon, Jan 17, 2022 7:17 pm
Subject: Re: [ap-ug] Life after the Stowaway

I'll second that vote. The little I know about lens figuring a Newtonian is a relatively fast mirror to figure. I have three old Newtonians and they are all good performers but not all are compatible with my Televues. The inexpensive eyepieces that originally came with the scope are very poor except for the bargain lot of 6 I got with an old 10" Trekerscope. They were all marked Orthoscope and made at a time when Leland Barnes was the head optician for Coast. I sometimes use the Barnes eyepieces in preference to the Televiews due the sharp high contrast images. End of the lottery. I must be the luckiest person alive. My Stowaway arrived the first week of January. -Best, Robert
On 01/17/2022 7:59 AM Arun Hegde <arun.k.hegde@...> wrote:


If AP is taking requests or we are voting, mine would be for a fast Newtonian that works without complaint in cold temperatures.

--
Roland Christen
Astro-Physics


W Hilmo
 

Now you are just teasing us :)

On 1/18/22 7:51 PM, Roland Christen via groups.io wrote:

...For me, I like quartz optics in a reflector. Would not make them any other way. Quartz holds its shape even when the mirror is very thin and light weight. My 17" Quartz Cassegrain astrograph has a mirror that is only 12.5mm thick at the edges. I can hold it up in my right hand....
Rolando




Terri Zittritsch
 

Roland, I love my refractors but I have to admit that the commercial SCTs are the best bang for the buck of any telescopes I have.    I have an 8" meade ACF and an 11" Celestron edge and both perform, to my eyes, amazingly well given their price point.    Un-forked they're amazingly portable for the aperture and forked are incredibly versatile with excellent goto.     I have ordered a premium 7" refractor but I expect to keep my Meade for outreach.    Lots of WOW for the buck and the vast majority in this hobby can't afford the price tags for premium 10" optics even if they were available.

Terri 


mjb87@...
 

Some people (beyond Astro-Physics) still care about quality. My CFF 300 Cassegrain has a cellular fused-silica glass mirror. It is, unfortunately, a better telescope than my seeing will accommodate.


fernandorivera3
 

Was there a long wait time for the CFF 300 to be completed, then delivered?

Fernando


mjb87@...
 

About six months, but this was pre pandemic. Excellent support and communication throughout. 


Dan Purjes
 

Roland,

Any Cassegrain you produce will likely have a long order list and a long wait time, so why be bothered about "competing" with Asian imports?
You do not compete with them.
No one thinks of Astro-Physics as a competitor to Asian equipment. They're not in the same galaxy, much less the same ball park.

Dan


Emilio J. Robau, P.E.
 

Dan,
I agree completely.  With the exception of some of the run of the mill adapters and dovetail plates, nothing that AP produces competes with Asia.


Andrew J
 

On Tue, Jan 18, 2022 at 07:51 PM, Roland Christen wrote:
Celestron and Meade pretty much put the kabosh on anything Cassegrain. Fact is they use plate glass optics and aluminum tubes, which together pretty much insures that you are constantly fiddling with the focus knob. Plus you have those nice heat plumes that run up the baffle tubes. Do people know that's happening? Do they really care? Probably not because they got them brand new and shiny at ridiculously low cost. And somehow they can make them work, although I'm completely baffled how they manage it.
I agree. It is kind of a shame that the EdgeHD (or equivalent for Meade) is the best SCT we can get right now. It would be nice if someone could make a better mouse trap. An SCT that didn't have all the cooling issues if for once and for all the could solve the mirror flop issue while still being able to focus without locking the mirror and useing an external focuser. It would be a game changer. That said, I am sure it would end up costing 3 or 4x what a EdgeHD or simular would cost, so seems we are stuck with what we have..


dvjbaja
 

You just described the Takahashi TSC 225.  

Despite mass produced Schmidt cass shortcomings, astrophotographers have been producing exceptional images with them.  

You mat be shocked to learn that even the 254mm f/14.5 Mak-cass has a tiny bit of image shift.  

AP should build more Stowaways and Mach 1 mounts.  LOL. 

Actually, I would love to see a premium Mak-newt like the 6" f/4 Robert Jones Vega.  

J



Sent via the Samsung Galaxy Note9, an AT&T 5G Evolution capable smartphone


-------- Original message --------
From: Andrew J <andjones132@...>
Date: 1/24/22 7:08 AM (GMT-08:00)
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] [ap-ug] Life after the Stowaway

On Tue, Jan 18, 2022 at 07:51 PM, Roland Christen wrote:
Celestron and Meade pretty much put the kabosh on anything Cassegrain. Fact is they use plate glass optics and aluminum tubes, which together pretty much insures that you are constantly fiddling with the focus knob. Plus you have those nice heat plumes that run up the baffle tubes. Do people know that's happening? Do they really care? Probably not because they got them brand new and shiny at ridiculously low cost. And somehow they can make them work, although I'm completely baffled how they manage it.
I agree. It is kind of a shame that the EdgeHD (or equivalent for Meade) is the best SCT we can get right now. It would be nice if someone could make a better mouse trap. An SCT that didn't have all the cooling issues if for once and for all the could solve the mirror flop issue while still being able to focus without locking the mirror and useing an external focuser. It would be a game changer. That said, I am sure it would end up costing 3 or 4x what a EdgeHD or simular would cost, so seems we are stuck with what we have..


fernandorivera3
 

Andrew a while back Takahashi made the TSC 225 & people say it's the best SCT that is out there, 2nd to none. I have not used one personally, BTW. I do know they are expensive & rarely come up for sale. They made the scopes in very limited quantity- only 100 of them. 

Fernando