171 replies to this topic

[astroneil]

Thanks Neil, if you ever find yourself this way, just let me know. We are very lucky  with the sky here. It is still odd, though, to see Polaris so low in the Northern Sky, and The Plough almost literally tilling the earth

 

Mrs H (Now officially Dr) is content to look through one of my scopes about once a year. I have higher hopes for our boy to become an observing companion - that would be great

 

And so to business: last night I put the 3.8" achro (102mm XLT) through the same obstacle course. Seeing was much improved over the previous evening, and of course the Mak gives 50% larger images with my lowest power EP, so I really need to do this side-by side. The doublet is very nice though, I think the two are very close in performance, with only a little trading between the two on different aspects of the presentation. The slightly wider field afforded by the 1000mm focal length did offer a bit more context to some of the Messier Objects and at f/10, and ~28x  absolutely gorgeous sharp stars across the field of view. I spent most of the night at this power, save for a peek at The Double-Double, resolved nicely,  and the Ring Nebula where I bumped to ~133x. Seeing let me see much more than on the 20th

 

The one thing I am certain of, as I've accumulated and used 'scopes like these is that I value all of them and enjoy the design and individual character of each. There is no burning desire to spend a fortune in search of perfection. Moreover, they are a toolkit, each with slightly different capabilities and suitability for different conditions. That is my interpretation of culture, and hopefully that means I get out more!

 

Cheers

 

Ed

Hi Ed,

 

I would be delighted to hook up with Clan Holland at some stage. Life is long and we find ourselves in unexpected places.

 

Fondest congrats to your other half on securing her Ph.D.

 

4" f/10 achromats are generally excellent. I spent years using one as virtually my only instrument. Indeed, the first thing that rang alarm bells in my head about apochromats was when I saved up to buy a 4-inch Televue Genesis f/5 refractor. One evening, I was comparing an old Tal 100R achromat to the Genesis at ~200x on the Red Planet and the achromat delivered a better image to my eye, no question. 

 

Incidentally, the chap whom I bought the Genesis off was a retired reverend who told me that he had an ETX 125 in his stable. I now see why he kept his ETX!

 

Apochromats are forever tainted in my eyes. Their builders promised the Earth, and they delivered next to nothing!

 

Regards,

 

Neil.

Edited by astroneil, 23 August 2014 - 04:30 PM.

[astroneil]

Neil, I tested an ETX 80...wow was that thing sharp. I had it well above 50x per inch and was thinking it was blowing my Orion out of the water. Turns out, once I got the magnification sorted, my Orion was up even higher. But, I tell ya, that ETX was impressive. I was looking at a moth on a street light at a long distance (afraid to guess), you could count the hairs on that moth, bright wing "spars", eyes, everything was crisp - Nat Geo quality image. In mine, too, but that ETX image is still fondly etched in memory.

 

Ed, in Panama at 8 degrees north, Polaris was so low and I was so lucky to spot it at all through a break in the trees. So far south, the milky way lay across the horizon instead of dropping below it. You could stare right into her belly. If you ever get the chance...

 

There is no burning desire to spend a fortune in search of perfection.

 

 

I feel the same way.

 

Eric, okay, deep sky, huh? No complaints.

Hi Norme,

 

I'm  with you!

 

Great sketch! There is something deeply satisfying about finding a low cost telescope and using it until it falls to pieces. Folk don't follow equipment profiles, they follow enthusiasm, which you obviously have in bucket loads.

 

Regards,

 

Neil.

[DesertRat]

Hi Neil,

Enjoying your exchange.  And I always thought culture was listening to Segovia while observing.  Who knew? 

 

I would add to your Televue Genesis comment the following.  Not sure how it was advertised but it was not an APO by any stretch.  In fact it was not really a visual scope but more of an astrograph.  A better comparison with respect to the TAL 100 would be vis-a-vis the TV-102.  That was not an APO either in the strictest sense but close and a great visual scope.

 

By the way the largest Maksutov in the US is the John Gregory built 22" he donated to the Stamford Museum:
http://stamfordmuseu...bservatory.html

 

Glenn

[astroneil]

Hi Glenn,

 

I had a TV 102 as well.... the Genesis was just the genesis of it all.

 

The review of that telescope can be found in the CN review archives.

 

Have you ever looked through a 4" f/15 Fraunhofer achromatic?

 

Thank you for the Gregory link!

 

best,

 

Neil.

Edited by astroneil, 23 August 2014 - 05:08 PM.

[DesertRat]

Hi again Neil,

 

Your quick on this exchange!  Yes I observed through a Unitron 4" so many years ago its hardly useful to compare against today's scopes.  I know I was impressed however, and it looked very cool.  

 

Best refractor I observed with was an early Christen 6" f/12 Super Planetary.  It was magnificent.

 

Glenn  

[astroneil]

Hello Glenn,

 

I don't doubt for a minute the Christen  6" f/12 Super Planetary would deliver nice images. The 130GT I recently tested was super nice.

 

But it is not an inconsiderable fact that there are many telescopes of non-refractive design that would outperform these telescopes and at far less expense to the consumer.

 

The promulgation of  the "refractor only" mindset is somewhat irrational IMO.

 

See you guys next week.

 

Best,

 

Neil.

[Ed Holland]

I would like to say how much I am enjoying this thread. Although we are in Cats and Casses, with a Maksutov as the focus of the discussion, it has ranged across the gamut of optical designs without chafing. Excellent!

 

We live in interestimg times for hobbies. Anyone and his dog is able to discuss preferences, budgets, abilities etc. with the whole wide world, from the safety of his or her living room. Not surprisingly, things can take a wry turn or two . Yet CN does a good job establishing order.

 

Astronomy, for good reasons, attracts people who have a taste for perfection. The internet lets us mix socially regardless of wallet thickness. It is funny (to me) that some of us find a version of perfection at one end of the scale, and some at the other, whether thst scale is aperture, price, optical perfection or a host of other parameters too long to list here.

 

With the right attitude, however, one can derive enjoyment from almost any telescope. This thread embodies that notion.

[astroneil]

 

With the right attitude, however, one can derive enjoyment from almost any telescope. This thread embodies that notion.

Couldnae agree more Ed.

[astroneil]

Date 25.08.14
Time 00:25 h
Ambient: 8.5C at 22:30h (Sunday), 1015mB falling,  7C at 00:15h(Monday), seeing excellent (<1”) earlier in the evening, deteriorating to ~1.5” after midnight, as judged by the inability of either my 5 inch glass or the 180mm Mak to cleanly resolve Pi Aquilae. Transparency excellent; distinctly autumnal.

 

Another good test for Cornelia and Tiberius this evening. I turned both instruments on Psi Cassiopeiae at just after 11pm local time. The primary is a 5th magnitude K spectral class star and just east of it lies the faint magnitude 9.1 and 10.0 (C & D components) separated by 2.3” (2007 data). Looking first through the the big Mak at 340x,  I knew it was too much power, so I backed down to the 16mm zoom setting yielding 169x and refocused. Voila! No problem. The exceedingly faint pair was readily seen at this medium magnification. The challenge here is that the C and D components are both very close and very faint and the bright orange glow from the primary right next door doesn’t help.

In comparison the 5 inch glass really struggled. I convinced myself that it was doable – but only just! I wonder also whether precognition was at work here? Dinnae ken.

 

Clear performance difference between the instruments here.

 

Attempted BU63 (I’m sure I located it this time)  at 23:30h, as Delphinus was now culminating. Heehaw seen at any magnification. This is a 6th and 9th magnitude pair separated by 0.9”. I think you’d need the eyes of a very young S.W. Burnham and more besides to crack this chestnut. Gave up after ten minutes of scrutiny.

 

Big Mak, guid graith!

 

Thanks,

 

Neil.

Edited by astroneil, 24 August 2014 - 07:28 PM.

[astroneil]

Cornelia is doing well thus far don't you think? There is little to distinguish her from a medium aperture poodle costing many times more.

 

All of the above can be put to the test and I warmly welcome such tests from other individuals in order to establish a more general truth.

 

I observe on grass, that living carpet of green which exhibits excellent thermal properties. Soil that is barren fairs much worse and so does concrete.

 

 

http://www.cloudynig...n-fiction-r2452

 

 

So, being a sceptical individual, I ask again; how much of the thermal 'issues' Maksutovs are said to have are attributed to;

 

1. Laziness?

 

2. Ill-preparedness?

 

3. Wilful scare mongering?

 

 

Thanks,

 

Neil.

[Asbytec]

Following this thread, you seem to be enjoying the Mak as much as I do. Congrats. As for thermals, no doubt some folks experience them. However, I usually do not, so...

[astroneil]

Hi Norme,

 

Thus far, I can find little fault in the 7-inch Orion Mak.

 

When the seeing cooperates, it's all been good.

 

Regards,

 

Neil.

[BillP]

Who among you would deny that a bog standard 10-inch Dobsonian will give you a far more compelling view of say a majestic globular cluster compared with the finest 5- or 6-inch refractor money can buy? You can strain and train your eyes all you want, but one glance through the big ‘ugly’ Dob will convince you of the truth.

 

 

Ummmm...

 

I have too many scopes....so an putting some up on the chopping block, but had to decide which.  So lately I have been bringing 3 scopes out at once...6" Refractor, 8" SCT, 10" Dob and comparing views on various objects I enjoy.  In the comparison I have been viewing the targets in two ways, one with the exit pupil equalized between the scopes so brightness is similar, the other way with magnifications equalized.  Of course the 8" went a little deeper than the 6" and the 10" a little deeper than the 8".  But when comparing the 6" to the 10", the deeper that the 10" went just was not a wow by any stretch on the several globs I observed.  So it was nice, but not a compelling difference for me.  And given the greater demands the larger scope has on ergonomics, thermal management and collimation, just not impressing me sorry to say. 

 

So guess there are, like the adage goes, at least two sides to any story.  In the case of telescope aperture preferences, many sides I think.  So for some of us, bigger is not always better.  So it is a preference, not a truth.

 

btw - I've had 127 Maks, and have always been curious about how a 180 would behave for me.  Perhaps something to acquire to play with once I rid the other scopes.

Edited by BillP, 25 August 2014 - 01:22 PM.

[astroneil]

Hello Bill,

 

Thanks for your comments.

 

The quote of mine you took merely emphasised what is generally known; a 10-inch Dob is far better than a 6 inch refractor for looking at globular clusters. That is not a preference, it is an easily verifiable truth and I doubt you would meet many who would disagree with that assertion.

 

I don't wish to comment on the SCT.

 

The problem with refractor culture is that it gets all too defensive when other telescope types are brought to the fore. I recognise that all too easily because I'm guilty as charged for cultivating this for several years, but the 180mm Mak is clearly superior to my 5 inch refractor on double stars and DSOs.  And my previous (though brief) experience with the SkyWatcher incarnation of the same instrument convinced me it will do the same on planets in due course.

 

That's why I won't be considering a larger refractor. I don't think they make any sense in apertures above 6 inches.

 

Best wishes,

 

Neil.

Edited by astroneil, 25 August 2014 - 02:34 PM.

[jrbarnett]

Following this thread, you seem to be enjoying the Mak as much as I do. Congrats. As for thermals, no doubt some folks experience them. However, I usually do not, so...

I think it really depends on where you observe.  If you observe under conditions where your daytime and night time temperatures differ by just a few degrees C, the thermal issues will be different than if your locale suffers much larger temperature swings.

 

I'll give you an example.  For many years I owned and traveled with an Intes-Micro M715D.  That's a 7" f/15, 25% CO, 1/8.5 wave RMS Russian Gregory-Maksutov.  It was a great scope in late summer and early winter from home, when the day vs. night temperature delta might only be 15F.  Taken out to the high desert in early fall with a 40-50F high-low temperature delta, though, it was a miserable scope for at least a couple of hours after sunset, despite being a vented design with a fan.  If I lived in the desert southwest and had to store my scopes at ambient (in a garage or shed, for instance), I would favor the design less than if I lived in a more stable, and slowly changing temperature zone. 

 

I don't think there's any clandestine Cabal out to maliciously besmirch the reputation cats and casses in a cynical effort to mislead and to deprive the masses of any particular design within that category.  Instead, I think telescopes are tools for tasks and circumstances.  Not every tool is suitable for every task or for every task or every circumstance.  But when tools fall out of general favor and become less available commercially, it usually has nothing to do with the promotional efforts of either design fans or detractors.  The market speaks; the invisible hand rules all.  Items in commerce just like living species move toward extinction because better solutions for particular tasks and circumstances have evolved into a specific task and circumstances niche and displaced them.  "Better" could be in an absolute performance sense or a value (performance per dollar) sense, or both.  

 

I think the important thing is for observers to see telescopes for what they are, tools, and to understand how the requirements of a given set of tasks and circumstances map to the characteristics of a particular scope under consideration.  

 

- Jim 

Edited by jrbarnett, 25 August 2014 - 03:25 PM.

[BillP]

Hello Bill,

 

Thanks for your comments.

 

The quote of mine you took merely emphasised what is generally known; a 10-inch Dob is far better than a 6 inch refractor for looking at globular clusters. That is not a preference, it is an easily verifiable truth and I doubt you would meet many who would disagree with that assertion.

 

 

Hi Neil.  Well...glad to be counted then in the not so many    Only bias for me is what my eyes have been telling me the past several evenings looking at Globs with my 3 scopes.  Just not a big deal difference to my eyes between the two.  A difference yes...but not one that is big enough for me to be chasing the larger aperture.

[Asbytec]

Jim, no doubt one's climate plays a big role in cooling to ambient, along with some prep. That's my experience in the tropics. Combined with excellent seeing, my current scope simply rocks my world. It happens to be a MCT, and it so happens I've discovered lunar and planetary and even double stars, ironically enough.

 

I am not sure why the MCT fell out of favor. When you can observe it performing nicely, it's a great design. It may be that it cannot compete with the SCT in terms of cost per aperture. 

 

It may not be the right tool for all uses, but it does shine in the area of observing I have neglected for far too long. Both experiences of rediscovering something other than deep sky and doing so in modest climates using a MCT has reinvigorated a love for observing like no other endearing me to the MCT culture. 

[Ed Holland]

Given the ever growing trend in astro-imaging, we have the high end (certainly in terms of $$$) occupied by faster telescopes with well corrected large fields. Shorter focal lengths go hand-in-hand due to the high cost of aperture and serve the desire for wider fields. Many seem as much to be super expensive telephoto lenses as they are visual instruments.

 

A Maksutov of f/12 or maybe more can offer the aperture, but the long focal length might cause trouble for the imager (no experience here but I could well be talking rubbish). Also much longer exposures would be needed for a given target.

 

They are different tools. I have no reason to disbelieve those who praise expensive refractors for visual use, but I am happier to view the skies more economically and still retain many of the same qualities of the APO. Also the slower cheaper optics have the native focal length desirable for planetary targets. I might be interested in an ED scope, were one to be made in longer focal lengths to take advantage of the greater colour correction possible and to suit my observing tastes. Until then, there are MCT and SCT optics

[BillP]

I am not sure why the MCT fell out of favor. When you can observe it performing nicely, it's a great design. It may be that it cannot compete with the SCT in terms of cost per aperture. 

 

 

I think cost may be part of the reason...the front element has to cost more.  But also the focal ratio.  Once you get over f/10 I think it falls into a highly specialized instrument class as it it is more difficult to use.  For refractors the length is also an added problem.  But resulting small TFOVs because of the long focal ratios just makes them a more difficult instrument to navigate with...especially for the less experienced. 

[Asbytec]

Nice point, Bill, there may be something to the inexperienced user and specialized observing, coupled with the popularity of SCTs and costs, that drives the MCT out of favor. I wish they would manufacture more of them, though, I'd certainly be in the market for a mass produced 8" (if one can be mass produced well enough. Please...don't answer that! )

 

The point being, I wish they made them plentiful so one might upgrade and others would share the pure excitement I get from mine, that Neil get's from his, and an old friend with his Questar got from his. It's a great design when cooled and collimated in good seeing - even if it's specialized. 

 

Pete, down in the deep sky forum, though, is having a blast with his 6" SCT observing variations in the Ring nebula's annular structure. I've seen it, too. (So, what gives on the difference?) That's the excitement I am talking about, though, among other observations. Observations that motivate an intense desire to observe the night sky.

[dotnet]

Focal ratios slower than f/10 used to be par for the course. In fact, f/15 used to be (still is?) regarded as the optimal focal ratio for visual. The race to the bottom (fast focal ratios) was probably driven by the explosion of amateur astro imaging, and the DSO hunters' desire for ever bigger Dobs while also keeping their length manageable. Makers of premium eyepieces rubbed their hands with glee, since fast scopes are much more demanding of eyepieces.

 

I still have a modest 8" f/6 Dob that I drag out occasionally, and I'm harbouring plans to get a bigger one, if only for a few times a year at our dark sky site. I also have an AT 80ED which hasn't seen star light in well over a year. There is nothing the little refractor does particularly well, I might as well get rid of it or replace it with a pair of binoculars. The scope I'm totally infatuated with is my 6" Intes Mak. I've had it since 1998 or so, and it just never ceases to amaze and delight me. This is the scope I use well over 90% of the time.

 

Cheers

Steffen.

[BillP]

I wish they would manufacture more of them, though, I'd certainly be in the market for a mass produced 8" (if one can be mass produced well enough. Please...don't answer that! )

 

 

Yup...would be nice to see them more mainstream.  The Mak and APOs (along with RCs) do share something inherently special...maybe that's why people are taken to the Maks?  As RC posted...

 

In other words, optical designs with inherent zero coma - RCs, Mak-Cass and Apo refractor - are very forgiving, relatively speaking, for the flattening/correcting optics near the film plane. You can be off a few millimeters plus/minus and still have excellent edge performance. Newts and classical Cassegrains are next up and require much tighter specs on exact spacing. D-Ks require even more control, and may need fancy zero expansion optics and carbon fiber tubes to work over a typical temperature range. Even a 1mm difference in placement of the corrective optic can produce quite noticeable off-axis coma/astigmatism and field curvature. (Ref - http://www.astromart..._post_id=681994)

[jrbarnett]

Given the ever growing trend in astro-imaging, we have the high end (certainly in terms of $$$) occupied by faster telescopes with well corrected large fields. Shorter focal lengths go hand-in-hand due to the high cost of aperture and serve the desire for wider fields. Many seem as much to be super expensive telephoto lenses as they are visual instruments.

 

A Maksutov of f/12 or maybe more can offer the aperture, but the long focal length might cause trouble for the imager (no experience here but I could well be talking rubbish). Also much longer exposures would be needed for a given target.

 

They are different tools. I have no reason to disbelieve those who praise expensive refractors for visual use, but I am happier to view the skies more economically and still retain many of the same qualities of the APO. Also the slower cheaper optics have the native focal length desirable for planetary targets. I might be interested in an ED scope, were one to be made in longer focal lengths to take advantage of the greater colour correction possible and to suit my observing tastes. Until then, there are MCT and SCT optics

Look on the bright side, Ed.

 

You'll be enjoying the merits of a sturdy Ankylosaurus long after the other boys have moved on and are struggling with the nightmare of respacing mirrors on their Bovinus Tauri.  

 

I do wonder though at why the SCT seems to have "won out" over the Maksutov in the marketplace.  Ease of fabrication (and therefore wide availability) of larger apertures may be a factor, though I'd say lots of 5" to 8" SCTs are sold each year, which is certainly MCT aperture territory.

 

MCTs with their wickedly curved menisci, too, look much cooler.

 

 

- Jim  

[astroneil]

Given the ever growing trend in astro-imaging, we have the high end (certainly in terms of $$$) occupied by faster telescopes with well corrected large fields. Shorter focal lengths go hand-in-hand due to the high cost of aperture and serve the desire for wider fields. Many seem as much to be super expensive telephoto lenses as they are visual instruments.

 

A Maksutov of f/12 or maybe more can offer the aperture, but the long focal length might cause trouble for the imager (no experience here but I could well be talking rubbish). Also much longer exposures would be needed for a given target.

 

They are different tools. I have no reason to disbelieve those who praise expensive refractors for visual use, but I am happier to view the skies more economically and still retain many of the same qualities of the APO. Also the slower cheaper optics have the native focal length desirable for planetary targets. I might be interested in an ED scope, were one to be made in longer focal lengths to take advantage of the greater colour correction possible and to suit my observing tastes. Until then, there are MCT and SCT optics

Hello Ed,

 

I'm not into imaging. Purely visual. That said, other folk have gotten fine planetary images out this nice, economical Maksutov. What I'm trying to establish long term is whether or not the thermal issues some folk have claimed about these telescopes are really attributed to other factors unrelated to their physical environment.

 

With humankind's global technical civilization now established, I can use the internet to instantly see most anyone's daily weather cycle and the temperature changes that are occurring there and how fast they change. I can also see their climate as well - winter and summer.

 

Man and his Technology!

 

Regards,

 

Neil.

Edited by astroneil, 26 August 2014 - 04:56 PM.

[astroneil]

Date: 26.08.14

Time 22:30h
Ambient: Temperature 9C, 1016mB, rising, fully clear sky, excellent transparency, seeing fair to good as judged by the inability of either my 5-inch refractor or 180mm Mak to cleanly resolve Pi Aquilae  but Epsilon Lyrae was well resolved in both (thus ~ 1.5 to 2”).

 

What a sterling night to visit an icy interloper from the frigid depths of the outer Solar System and well placed in my northern skies- C/2014 E2 (Jacques).

Tiberius will be given an early night. Gaius my trusty 80mm f/5 achromatic will be accompanying Cornelia, acting as a super finder and mounted side by side on my ergonomic SkyTee Alt-Az.

It’ll be a hoot!

 

Thanks,

 

Neil.