I think they are still being made...hence replaceable ...that said...as an imaging machine..it's like using a really short tubed, perfectly corrected 12" APO.....and is without doubt, one of he finest imaging 'scopes I've had the pleasure of using.
Visually that big secondary is noticeable...hence to be fair, it doesn't fit the "all rounder" moniker quite so well...
To add to my woes it won't be able to live in the dome with the new Alluna (simply not enough room). Bugger.
I think they are still being made...hence replaceable ...that said...as an imaging machine..it's like using a really short tubed, perfectly corrected 12" APO.....and is without doubt, one of he finest imaging 'scopes I've had the pleasure of using.
Well... if it's ever going to burn, let me know. I'll pick it up for you. No drama.
bit out of left field, but has anyone used a Skywatcher 190/f5.3 Mak Newt?
By all accounts these perform visually like a very big APO (small central obstruction and no aberrations to speak of). The aperture is probably large enough to pull in a range of the brighter DSOs. For imaging, they have enough aperture to provide seeing-limited resolution (with small pixels) and have a short enough fl and are inherently well enough corrected, to provide a fairly wide flat field with a large camera or DSLR.
The downsides might be that they are heavy and that viewing may be inconvenient on an EQ mount. Also, Skywatcher's QC sometimes seems to be a bit iffy - but their optics are pretty good and, fitted with a decent focuser, this could be a useful choice as an all-rounder. Of course these scopes would lack mystique, bragging rights and premium build quality (= pleasure of ownership), but if they work OK....
Does anyone have any experience with one of these? - would this design meet Greg's criteria?
I'm quite enjoying the amenity of my 20" f4 Ultralight at the moment actually. A lovely Zambuto mirror 2" thick. Cooldown time is practically straight away and coupled with TV wide angle eyepieces the views are superb. Jupiter the other night was the best I've seen it. Setup/teardown time is in minutes. At f4 most of the time I'm standing on the ground with only an occasional hop up near zenith. No Argo or Servocat (yet). 12v hairdryer sometimes required .
My scope of choice would be a Mak, and given my age it would
unfortunately be limited to a 10". I've just started my 63rd year of
owning and/or using scopes, and have enjoyed my 150 and 180mm
Maks more than any other scope I've owned. I've never owned anything
really large, a 17 1/2" Dob being the largest.
raymo
I did a lot of experimenting with different collimation methods, including lasers, but found the best way to collimate these Mak Newts was with a long Cheshire and the extension tube pulled right out as far as it will go.
This will give you a much better view to see if the focuser is correctly placed over the secondary mirror.
There are so many circles in the view but once things become clear in your mind as to what goes where, it becomes easier. (there is a faint circle on the secondary)
The hardest part was centering the focuser over the secondary correctly - it took a bit of persuasion.
It was very easy to see in your images if the collimation was correct - star colours would be even around the star instead of off to one side.
If contemplating buying one of these scopes (even brand new)please make sure it is the latest model and not the earlier with single speed focuser.
for visual i would think something like an acf/edge 8"..reasonable price, easy to mount/transport
big refractors give great star views but are heavy/expensive not that portable
Having used telescopes of all designs from 2" aperture to 36" aperture and from F3 to F16 in F-ratio, if I could only have one telescope for visual astronomy it would be a high quality Newtonian of 12" to 16" aperture and about F4.5 in F-ratio. This to me is the perfect compromise between visual performance and storability and transportability. I am yet to use a better "all round visual telescope" than my 14"/F4.5 SDM. It is a high quality product with a Zambuto mirror, Feathertouch Focuser, Servocat and Argo Navis. Set up as such they aren't cheap compared to the mass produced scopes (about $15K) but they give exceptional all round performance with accurate GOTO and tracking and high quality optics and functionality.
I am not an imager but one of my favourite scopes which I am sure would work very well for a large number of imaging chores is the Takahashi TOA 130. Excellent small aperture visual telescope which I am sure is a great imaging scope as well.
Cheers,
John B
Sorry to be late in my in adding my comments. I agree with John's take on this...12-16 inch reflector (properly cooled and collimated is tough to beat visually. However, I will concede that portability for some might be an issue.
There are a few 130 mm (or so refractors) that I could also suggest fit that "sweet spot"...not too big and not too small
Personally I am leaning the discussion more towards imaging rather than visual.
If equatorial mounts were sold for free then nothing would beat a Newtonian dollar for dollar. Being that they are not, the equation slews more towards the RC and corrected DK designs.
If narrow band imaging is the intent then the fastest focal ratio wins.
Refractors are unchallenged up to 4" of aperture, but pretty much untennable (from a cost/performance basis) beyond a 6" objective.
Last edited by clive milne; 06-04-2015 at 06:53 PM.
I'm a bit sour towards AP...I checked their website and it looks like Roland has dropped the 12" f12.5 Maksutov-Cassegrain from his product line....looks like his focus is on the 12" f3.8 Riccardi-Honders Astrograph.
If equatorial mounts were sold for free then nothing would beat a Newtonian dollar for dollar. Being that they are not, the equation slews more towards the RC and corrected DK designs.
If narrow band imaging is the intent then the fastest focal ratio wins.
Refractors are unchallenged up to 4" of aperture, but pretty much untennable (from a cost/performance basis) beyond a 6" objective.
The Busack-Riccardi-Honders formula is the only 21st century design when it comes to amateur astrographs , and as such, not many people have used them yet. I think this design will grow in popularity due to its ultra compactness and excellent corrections. Once the Far East manufacturers start making them, the price should come down a lot because the design is rather simple.
I totally disagree with Maksutov lovers: Maks are the ultimate good for everything but excellent for nothing scope. They suffer from severe thermal problems. For those who disagree, let me tell them that planetary observing is not done at 150x - try 400x and more.
A proponent of the Officina Stellare brand might disagree.
OS RHA you mean? I like the extensive use of carbon fibre on the OS range. I also notice the 10 inch RHA is now F5.6. Perhaps F3 was over optimistic and the requirement for perfection on the mechnicals was an issue. Bert had all sorts of rigs and stuff to correct flex on his etc. Mind you has was overloading it beyond its specification. Roland and Massimo worked together when making the AP RHA. So it has Massimo's optical genius coupled with Roland's optical genius but also Roland's decades worth of engineering excellence and quest for perfection. The difference is Roland makes the scopes, I don't think Massimo does, he designs them. Correct me if I am wrong. F3.8 is still very very fast but probably that little bit more workable. The Tak Epsilon F2.8 is famous for being difficult to collimate. So F3 is adventurous.
That is a huge difference. Also compared to other scopes I have used, you can tell Roland has done a lot of imaging and that know how ends up in the scopes. So I have never heard of flexure issues with focusers made by AP yet I have with every other brand. The AP RHA does not require collimation as well, a big plus. The mirror coating is on the rear side of the glass so it can't degrade, another big plus.
That attention to detail and the obvious standard that there is no compromise on quality is what makes them special.
I don't know the Mak Cass is not going to be made. There was a prototype 12 inch one a few years back. It may be a lot of work tooling up to make all these different models and you'd have to get a return on the Honders investment first. I am sure it took a lot of tooling up.
Anyway its all speculation. Why don't you ask Roland direct on the AP Yahoo Group. He's likely to answer you.
Greg.
Last edited by gregbradley; 07-04-2015 at 07:46 AM.
Given F3.8 is the ratio of FL to width, which in refractors does give some comparison, but given the central obstruction and the interest in light gathering capability..... What is the central obstruction diameter and therefore the percentage variation in collecting ability in comparison to a refractor of equal dimensions and FL .....
Just trying to get an idea of its photon gathering capability, might be similar to F5 in a refractor.
Given F3.8 is the ratio of FL to width, which in refractors does give some comparison, but given the central obstruction and the interest in light gathering capability..... What is the central obstruction diameter and therefore the percentage variation in collecting ability in comparison to a refractor of equal dimensions and FL .....
Just trying to get an idea of its photon gathering capability, might be similar to F5 in a refractor.
.
