Whats the best all round telescope currently?

[gregbradley]

A controversial question no doubt but I am interested in others thoughts about what the best all round telescope is at the moment.

I suppose that should be in 2 categories - imaging and visual although some scopes are great at both.

Also within reasonable price limits. Not $200K mountain top 60 inch RCs etc.

The trend seems to be towards largish aperture and fast F ratio. But then Corrected Dall Kirkhams and other variants are becoming popular. The venerable Newtonian seems to be popular with the F3.8 and F4 versions around. APO's are still popular as an all round good performer, mainly for wider field shots which suits many targets.

Greg.

[glend (Glen)]

You will get a lot of varying opinions on this question, sort of like asking what's the best car. It's all about what you want to do with it. As an all-rounder, and if I could only have one that can do both I'd suggest something like a 10" newt (I prefer f5) with a slightly oversized secondary for imaging work but which can still be used for visual with an extension tube. These scopes tend to be very cheap and of good quality with good limiting magnitude and resolution. I should point out that I have one, but I also have a 16" f 4.5 dob, a f12 achro refractor, and ED Triplet f6 refractor, the newt gets use the most but they all have their own advantages at times.

Personally I'd avoid very fast Newts as they are hard to collimate, so don't travel well and really don't offer any advantages to imagers - where a few seconds less sub exposure time is irrelevant when you are guiding and on a good mount; but that's just my opinion.

[Wavytone]

Greg,

IMHO for visual use f/7 is the sweet spot. It permits a selection of eyepieces giving a range 10:1 or a tad more between the lowest and highest magnification. What's more, at f/7 its easy to make a newtonian reflector that performs superbly across this range, and its not too hard to find excellent ED refractors close to f/7 as well around 100-120mm aperture.

For imaging... the answer depends on what you want to photograph. The Gegenschein, or Barnards Loop ? M102 ? Mars ? Moon ?

Fast Newtonians... As low-to-medium power wide-field light buckets they're fine but don't expect them to perform well at high magnifications. They are popular only because:

a) very low cost commercially, far cheaper than any other design of comparable aperture (SCT's or Maks);

b) its easy to mount fast ones at f/4 quite adequately on a base made of MDF, chipboard or plywood with little care given to the engineering of it (Meade lighbridges come to mind). Mounting an f/7 or f/10 Newtonian is more difficult mechanically and requires a much larger and heavier mount.

c) fits on the backseat of a small car,

d) the availability of mass produced thin mirrors at f/4 that are adequate optically. 30 years ago these were far more costly, hand-made one-offs and optical quality usually poor below f/4.5.

[glend (Glen)]

It's useful to remember that while all Dobs are Newtonians not all Newtonians are Dobs. GEM mounted Newts do not have MDF bases.

[Wavytone]

Glen,

... put it this way - if we could all buy 30cm Maksutovs for less than the price of a cheap 30cm Newtonian I'm sure they'd be the most popular scope on the planet.

But it can't happen.

Mind you Meade and Celestron SCT's have always sold well enough despite their price and limitations.

[Alchemy (Clive)]

Imaging preference deep sky

My preference is for refractors, ready to use out of the box, travel well.

An all round telescope should be one you can use frequently, so a focal length of say 1000mm or less means seeing isn't such a huge consideration, from 4-6 inches keeps cost to affordable, APO goes without saying, Somewhere from f5 to f7. I don't travel with mine but a scope of this size is transportable and can be easily setup by one person.
There would be many in that class, the TAK106 has a great following although I don't have one, but it would fit the bill, Id prefer something a little longer say 150mm F5 .....

Visual.......

No sorry, colored dots don't interest me, you need to GO BIG, but that's probably not within the parameters you specified.

[Peter Ward]

I tend to agree with Clive, a big APO is pretty hard to beat.

Given my home is prone to bushfire threats, and I'm often away from home, and despite everything being insured, I've asked the family to grab my AP refractors if we have to be evacuated...as they would be very difficult to replace.

The AP155 with the 4" field flattener is a superb imaging/solar/visual instrument. Sure, I've used bigger/wider/shorter 'scopes...but none more beautifully finished or corrected.

[GeoffW1 (Geoff)]

Hi,

After stuffing around for years, visual only, I settled on a 200 mm SCT on a go to alt az mount. Like all such solutions it lacks a bit here and there.

Horses for courses truly here.

Cheers

[Paul Haese]

My best views of Jupiter in near perfect seeing were as good as looking at an image in good seeing and that was through an 18" Newtonian just after an imaging session. I saw this with Anthony through my SDM scope. Still vividly etched in my mind.

However for imaging, refractors just make life easier. If I could afford an 12" refractor I would buy one. And if they made them at f5, it would be near perfect.

Though for angular resolution you cannot beat diameter. Either RC or CD are more affordable now for imaging and give you good imaging speed without have the moment that is associated with Newtonians. That said Newtonians have good contrast and less problems with collimation.

To be perfectly frank I could not guess which is the best all round scope currently. If money was no object then a very large aperture refractor would be the go, otherwise each has its limits and issues if your budget is under 25K.

[gregbradley]

Yuri at TEC is making 250mm APOs at the moment. He also makes a 20 inch RC that Roland Christian thought was the best he'd ever used. Images from it looked good but it needs extra baffling or something minor to correct some odd flaring on bright stars.

Looking over images posted on the net though 20 inch RCOS images are at the very top in my opinion. Crawford, Croman, Gabany (yes even with the colour). The 20 inch RCOS boys.

Peter, shouldn't you update that request to take the Honders first?

Officina Stellare have a whole range of fast astrographs up to 20 inch and F5 or F3.8.

Agreed, a good refractor does make life easier.

Greg.

[The Mekon (John Briggs)]

Greg, assuming "there can be only one" I think you have the scope for sale right now and the only reason I'm not buying as it is too soon after offloading my own AP130, and I can still manage my large reflector and a smaller refractor quite well.
So when I want to reduce to just one scope it will be a 140mm APO. I'm on the wait list but don't hold out much hope - Roland may well be in a nursing home before my name comes around.

Advantages of such a sized refractor?

1. Portability (no ramps needed for transport)
2. Perfect for double stars and planter.
3. Performance on deep sky is worth double its aperture (never saw a 8' SCT that came near my 130 on deep sky)
4. Photographic capability.

-that's 4 P's in a row, so if you are talking just one all round scope it would be a 140 APO for me.

[marc4darkskies (Marcus)]

I honestly don't think there is such a thing as an "all-rounder" telescope. But if there is Greg, you probably own one!

[LewisM]

Both categories - REFRACTOR in my opinion.

I am not a fan at all of artificial inclusions in images like diffraction spikes, so that rules out MOST reflectors save the corrector plate types.

Whilst I would LOVE to own a Tak CCA250, at the end of the day, I will always come back to refractors.

[strongmanmike (Michael)]

Hey Greg, I have an even better question with a much simpler answer:

"how long is a piece if string?"

That said and if $200K is your limit, I'd opt for a 12" refractor for visual and a well made fork mounted 20" F3.5 Corrected Newt (that has image plane tilt adjust) for imaging

Have to say, at least from an imaging perspective and keeping the price actually affordable and delivery time realistic, I have been very happy with my AG12 though ... it can do both THIS and THIS just change the camera. Of course if you add a 1.8X dedicated barlow then you can cover almost all bases and it is still quite fast . It is portable enough for many people, is surprisingly easy to collimate (with Catseye tools) and holds collimation well and having used a 6" Starfire APO (the worlds finest refractor) to image with at F8, data acquisition speed is streets ahead and under good seeing conditions, the resolution is better

Now back to that piece of string, thing is......

Mike

[Slawomir (Suavi)]

AG12 is on special offer at the moment... about 15% discount at Orion Optics!

[strongmanmike (Michael)]

Originally Posted by Slawomir

AG12 is on special offer at the moment... about 15% discount at Orion Optics!

Indeed, a good time to buy I guess?

After thoroughly enjoying the AG12 for 4 years now, I wanna try one of OO's ODK's now (long focal length envy )...so who knows?

Mike

[ausastronomer (John Bambury)]

Originally Posted by Wavytone

Fast Newtonians... As low-to-medium power wide-field light buckets they're fine but don't expect them to perform well at high magnifications. They are popular only because:

I think this is a very old fashioned approach and shows some narrow-mindedness and naivety in regard to modern Newtonian telescope design, construction and performance.

I don't particularly like Newtonians faster than F4, for a whole range of reasons, the main one being the fact that I have seen more poor quality sub F4 mirrors, than I have seen decent ones and these have all been from reputable US opticians. Myself and a large number of other observers share the view that some of their best lunar and planetary views have been in medium to large aperture Newtonians ranging in size from 12" to 20" and in F ratio from F4 to F6.

I have used all types of telescopes including Maks (Questar, Quantum, Intes & Intes Micro) ; countless SCT's from both Meade and Celestron, some of the best refractors money can buy up to 15" aperture (AP, Takahashi, TMB, Televue, TEC and D & G) and countless Newtonians ranging in quality from abysmal to exceptional in in aperture from 3" to 36" and in F-ratio from F3 to F12.

My best lunar and planetary views have come in my own 18"/F4.5 Obsession (OMI mirror) , my own 14"/F4.5 SDM (Zambuto Mirror) and James Pierce's 16"/F4 SDM (Lockwood Mirror). The problem is for a Newtonian to deliver its best images everything has to come together all at the same time. The scope has to be well built, it has to be properly cooled and collimated and the seeing has to be very good as large aperture scopes are more severely affected by poor seeing than small aperture scopes. To get a medium to large aperture fast Newtonian to properly strut its stuff takes some know how and patience, which many people that own them can't accommodate because they don't have the know how, patience, or both. Unfortunately 90% of Newtonians on the field at public star parties are poorly set up and will not be capable of delivering top quality high power views because of a combination of poor set up, poor collimation and inadequate cooling and air circulation.

When you get a newtonian in the 12" to 20" class that has a high quality thin mirror (faster cooling), in a good telescope structure with a good mirror cell that is properly collimated under excellent seeing, it will deliver better high power views by virtue of its greater aperture, hence greater resolution, than a smaller telescope of a different design.

An 18" AP refractor would undoubtedly give slightly superior views to my 18" Obsession under the same conditions, but unfortunately Roland isn't making them at the moment and I couldn't afford one if he was.

Cheers
John B

[ausastronomer (John Bambury)]

Originally Posted by gregbradley

A controversial question no doubt but I am interested in others thoughts about what the best all round telescope is at the moment.

I suppose that should be in 2 categories - imaging and visual although some scopes are great at both.

Also within reasonable price limits. Not $200K mountain top 60 inch RCs etc.

The trend seems to be towards largish aperture and fast F ratio. But then Corrected Dall Kirkhams and other variants are becoming popular. The venerable Newtonian seems to be popular with the F3.8 and F4 versions around. APO's are still popular as an all round good performer, mainly for wider field shots which suits many targets.

Greg.

Hi Greg,

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

[Peter Ward]

Originally Posted by gregbradley

.....

Peter, shouldn't you update that request to take the Honders first?
....

Greg.

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.

[ausastronomer (John Bambury)]

Originally Posted by Peter Ward

Visually that big secondary is noticeable...hence to be fair, it doesn't fit the "all rounder" moniker quite so well...

This is another important aspect of visual performance and Newtonians that Peter has highlighted here. For a Newtonian to deliver high quality high power views it needs a small secondary obstruction. Typically it needs to be under 20%. The MTF curves show that a scope with a <20% central obstruction (regardless of design) has close optical performance to an unobstructed scope. The AG 12 has a CO over 30% as do most SCT's and MCT's.

Cheers,
John B