Small ED/APO refractors - what are the options?

[Retrograde]

Hi all,

I'm thinking of purchasing a small ED/APO refractor and wondered about the pros and cons of different models. I'd prefer something below 80mm and it would do multiple duties as:

small 'grab & go'
wide-field imager
guidescope
portable eclipse rig
and possibly even as an over-sized finderscope.

So what are the pros & cons of these options?
Tak FSC60, WO Zenithstar 71, Stellarvue SV060EDS - any others worth considering?

Thanks in advance,
Pete

[glend]

Have a look at the Explore Scientific ED80 APO Triplet. I have one and the quality is great for the price, and they are on sale at Opt Corp right now for $680 USD for the white tube Essential model - so you can probably get one for less than the GST threashold. Of course if cost doesn't mean anything to you and you want to buy a Tak then do that, but the ES will do all the things you listed and give you greater aperture than those you listed.

[Slawomir]

Hi Pete,

I have also been wondering about quality wide field scope- so will watch this thread with interest.

I would also consider quality of the focuser, unless you are keen to upgrade the stock one. Poorly attached flexing focuser will spoil imaging sessions much more than not too perfect optics. I would like to think that Tak and Stellarvue would make reliable telescopes.

[Meru]

Hi Pete,

I used to own a AT65EDQ - it was a fantastic scope and the specs/price were amazing, always regretted selling it. Borg also have a range of scopes under 80mm but are pretty expensive.

[Retrograde]

Thanks Glen - 80mm is really a bit bigger than I wanted to go. I already have an ED102 triplet for more aperture (& focal length) if I need it.




Thanks Slawomir good point. I upgraded the stock focuser on my ED102 so not keen to do it again on a smaller scope.




The AT65EDQ sounds like another worthwhile option - I've heard of it but don't know much about it so thanks for mentioning it. I've heard Borg are expensive but have a good reputation - not sure where to source one from though. :shrug:

[N1]

http://www.hutech.com/

If cost is not the main concern, the FS60 probably won't disappoint. Especially the grab-and-go and eclipse bits it will do superbly. The OTA is very small and light. And for those times when you want a little bit more reach, you can attach an FC76 objective unit, which has been offered second hand on this forum. The resulting 3" f/7.5 ist still highly portable when broken down, but not quite as wide-fieldy, especially when retaining the 1.25" setup.

[blink138]

flash has a 60mm sharpstar fpl-53 doublet for sale on iis classifieds at the moment!
pat

[LewisM]

I was going to say what Pat said. I have personally looked through the EXACT scope on sale, and it was surprisingly good! I mean, REALLY good - rich view with good contrast when coupled to a good eyepiece.

Be perfect for terrestrial and WIDEFIELD astro. And well priced from Flash too.

[Profiler]

If you are considering a Tak FS-60 then you should also consider the Televue TV-60. Optically at 60mm there isn't anything between them irrespective of whether one is genuine fluorite vs FPL and given you want it for G&G etc something that is more robust than fluorite is probably better. The Tak can 'in theory' accept 2' EPs with appropriate adapters but in reality is totally impractical in such a configuration and is hopelessly out of balance for any serious observing when using 2' EPs. Instead, you will only be using 1.25 EPs which puts it back on par with the TV-60. Televue also make a specialised adpater which allows the TV-60 to be used as a finder which is fully adjustable and will fit any telescope. As far as portability there is nothing that genuinely competes with the TV-60 - you can literally carry it in your coat pocket. Although there are certainly small refractors around a traditional R&P (or any horizontal etc) focuser is a liability for portability as it can potentially be damaged whereas the TV-60 features a clever 2 speed helical focuser design which can't be snagged and thus damaged whilst on the move unlike all others.

[Camelopardalis]

I bought a Zenithstar 71 for grab and go a few years ago, it's well built and has nice optics. It's travelled with me to 4 continents at this point :D does a decent job of Jupiter at >100x, nice and crisp for open clusters, even resolves some stars in Omega Centauri. When used with a long focal length eyepiece it has swallowed Magellanic Clouds whole :lol: It has a decent rack and pinion focuser too, easy holds a hefty 2" diagonal and quality big eyepiece.

For the past year it's also served as my imaging scope, as it's nice and fast at f/4.7 with the reducer/flattener, although as it's only a doublet there's a little blue halo effect on long exposures of bright stars, which can be edited out in post for the most part.

[Profiler]

Excluding cost as a variable the TV-60 coupled with a 1.25 everbrite and 2-4mm Nagler Zoom set at 2.5fl will easily reach 144x magnification and give a sharp, bright image of Saturn with Cassini plainly visible and doesn't require exceptional conditions to achieve such results.

I must however stress that to achieve these results does come at a disproportionate cost:(

[Retrograde]

Thanks for all the great information guys.



Thanks Mirko. The main thing that puts me off Tak is the cost of accessories etc. I've never owned a Tak (or even looked through one :sadeyes:) so would have to collect flattener & anything else I'd need from scratch (although I'd still need a flattener for the other options).





Thanks for the heads-up guys.
From a brief search it seems that Sharpstar provide donor telescopes for Stellarvue & this model should be functionally identical to the SV60EDS?
I understand Stellarvue provide added value with QC & warranty-support etc (although luckily we have Lewis in this case ;) ).

At 330mm it's a bit shorter than I'd ideally like & for photography it's FOV would be similar to lenses I already own (although likely would give better results at that FOV)





Good info thanks Profiler. I wondered about the TV60 (& also the TV76). I'm quite happy using 1.25"eyepieces with it & already have a good diagonal that size.
Is the helical focuser a real option with a DSLR + flattener?



Cheers Dunk - the WO seems like an attractive option. I can get one with reducer/flattener landed for under $1k. I've seen some shots with it & some do exhibit the blue halos though. I guess most people do a little star reduction on their images anyway so fixing halos isn't a huge extra step (however I'm just not very good at it yet).

[LewisM]

There is always the relatively new Vixen ED70SS - seems like Vixen's answer to the venerable Tak FS60.

I shot our local Vixen dealer an email asking price.

Here is an image of it: http://blogs.c.yimg.jp/res/blog-6c-d0/giheymaru/folder/232110/70/18454970/img_0?1407119064

Looks like an FS60, only bigger, with Vixen's focuser and decals :P

[PlanetMan]

The mechanical design and specs which I can find online for this new Vixen ED70ss seem eerily similar to a WO Megrez 72. It's almost as if someone took a M72 and painted it plain white with a few red Vixen stickers and their stock R&P focuser:D

[Camelopardalis]

Yeah it's not a bad scope for the money, although if I was buying again now purely for imaging I'd probably stretchy the piggy bank a bit more and go for the GTF81 or [swoon] Star71. As I said, I originally bought mine for grab-and-go/travel scope as it fits in a (padded) laptop bag.

The reducer/flattener works really well though, and is threaded for 2" filters. The halos are pretty easy to fix, once I got to grips with processing a bit ;)

See some of my pics...

Orion and the Running Man (http://www.iceinspace.com.au/forum/showthread.php?t=128452) - beware, stretched like mad!
Alnitak and friends (http://www.iceinspace.com.au/forum/showthread.php?t=126683) - could use a repro!
Two winter favourites (http://www.iceinspace.com.au/forum/showthread.php?t=125075) - ditto above :D
Surf and turf (http://www.iceinspace.com.au/forum/showthread.php?t=124465)

[brian nordstrom]

:) I have owned and loved the sweet FS60 but stupidly sold it. , that scope performs way above a 60mm should. , I missed it so much and couldn't justify the 1k plus price and wanted a 60mm class scope again .
Enter the 60mm f7 Long Perng triplet from Andrews Com. and I am now the owner of truely world class small scope , this little beauty performs 98% of what the Tak did for less than 1/2 the price, built very solid with awesome ( for 60mm ;) ) optics , its great .

I have noticed that these are not on Andrews web page but the ED 60mm doublet is and if these are as good as my triplet you can't go wrong , worth a look as they have a no question return policy . Great people to deal with.

Brian.

[MortonH]

Hey Brian,

I think you mean the 66mm ED doublet. It's the same scope as the William Optics ZS66 (and my SV66ED). Plenty of stuff on the web about the ZS66. Maybe not quite so well colour corrected as your triplet but still good.

[Wavytone]

Pete, according to your OP you already have a 102mm f/7 refractor and an 80mm f/10 Mak. To be honest it leaves me scratching my head as to why you really want another small scope than is within a factor of 2 of the aperture/focal length of scopes you already have...

[Retrograde]

I guess that even within seemingly quite narrow sub-categories no one scope can really do it all perfectly although all the suggestions will do a reasonable job of most.




Nice pics Dunk! I hadn't heard of the star 71 before but it sure sounds nice. Kind of expensive though.
Any idea about the old Megrez 72 FD? Similar to the Zenithstar colour-correction wise?




The 102mm is simply too big and heavy for grab and go and way too big to take to an overseas eclipse. I did manage to drag it up to Cairns by plane :screwy: but never again.
The 80mm Mak isn't exactly high-quality (it was all I could afford in 1988) or fast (f11) but it's light and easy to carry.
The next eclipse I'm planning on is the US in 2017 so there's no great hurry to buy something.
Having a good widefield astrograph might give me the chance to collect some data on M31 & the like whilst I'm over there.
Mind you I'm planning to take the family on the trip so I probably need more than just one extra scope for that trip :lol:

[Wavytone]

Ah Ok. I wouldn't bother with the small refractors - you might as well buy a pair of 70mm binoculars.

As for eclipse chasing... A whole different matter. A long time ago I had a Meade 102mm f/10 SCT with the tripod base (not the fork mount) for that purpose, a robust camera tripod was entirely adequate. IMHO it was the perfect choice - small enough to go on a plane, could be backpacked anywhere along with whatever you need, yet enough to do something reasonable.

My next choice - if you can afford it - is a Questar 3.5".

[OzEclipse]

I both agree and disagree with Wavytone. I agree that, a long time ago, eclipse chasers used and favoured small SCT's or Maksutovs.

However, this is no longer the case. These days with the proliferation of reasonably priced small ED refractors, eclipse chasers overwhelmingly favour small refractors with apertures in the 60-90mm range and focal lengths in the 350mm-600mm range. A larger field allowing visual or photographic views of the outer corona with some "dark space" around it for contrast is ideal. Portability is key. If you chase a lot of eclipses, you will invariably be subject to strict luggage limits when you need to use smaller aircraft. In Svalbard last March we had a 15kg limit. On light aircraft it can be 10kg.

At one stage I was using an ED 80, 600mm fl 80mm f7.5. Now I have switched to a more compact William Optics 70mm f6.3. FL=430mm and prefer its wider field both at the eyepiece and with an APS DSLR.

Some people love binoculars for eclipses, others hate them. They are hard to support and look through comfortably unless the eclipse altitude is low to to horizon. A diagonal or flip mirror on a small refractor allows comfortable viewing for any altitude eclipse.

I use an APS DSLR with a 1.25 inch flip mirror and a parfocalized 1 1/4 inch 16mm 65 deg eyepiece so I can flip between photographic and visual during totality. This gives me a 1.9x3.0 degree photographic field and a 2.4 degree visual field in a reasonably compact package. Any of the small refractors - Stellarview, Willam Optics among many others are fine as of course are any of the premium brands.

A Meade ETX will only image the inner corona 0.7 x1.1 degree field in an APS. A full frame camera will probably vignette.

You can see examples of solar eclipse images with the 70mm f6.3 and ED80 on my website -
http://joe-cali.com/eclipses
I used the 70mm f6.3 440mmFL with APS DSLR for these eclipses
2015 TOTAL with APS DSLR
2010 TOTAL with APS DSLR

I used the ED80 80mm f7.5 600mm FL for
2013 ANNULAR with APS DSLR
2008 TOTAL with APS DSLR
2006 TOTAL with 35mm film DSLR

Cheers

Joe

[Wavytone]

Ah... joe I forgot to mention I was only interested in Baily's beads and the chromosphere - not the corona. A 0.7 degree field turned out just fine. The other aspect is full frame vs APSC dslr... I was using full frame and for 2017 probably will do again. This makes a significant difference with respect to the focal length - I agree if you're going to use an APSC sensor 500-600mm do will be plenty.

If you want the corona yes you want a wider field - and a shorter focal length.

[Retrograde]

Hi Joe - thanks for telling us about your eclipse setup. I also use a Pentax K-5 (aps-c)
The flip-mirror idea sounds really good and something I'll certainly investigate although I'm a little unsure how to go about getting a camera and eyepiece parfocal via this arrangement.

[OzEclipse]

Sorry I didn't explain that. The camera needs more back focus than the eyepiece. The William Optic M70 refractor's Crayford focuser has a mm scale on the barrel. I focussed the camera, took a reading, then the eyepiece then I machined my own custom extender for the eyepiece. I machined it a little short then I focus the camera, pull the eyepiece up until focused and then lock it in place for the duration. If your refractor doesn't have a scale, use a vernier caliper to make the measurements.

One more thing, With the eyepiece, flip mirror and camera on the back, it doesn't balance on the dovetail foot. However the foot can be removed and rotated 180 degrees which extends the dovetail backwards towards the camera. This reversed foot also works when I use a 2 inch diagonal and eyepieces for visual.

For travel, I prefer the M70. It fits in my carry on camera back pack with all my other camera gear and the shorter tube sits with less vibration on the small mounts I travel with. The ED80 had to travel in my checked luggage. One day in Shanghai, I watched the luggage handlers throwing my suitcase up to the luggage hold, they missed and it fell down to the tarmac. ED80 was ok. Good suitcase and padding.

They are both nice scopes. If I were recommending a car portable instrument, the ED80 would be my pick but you will want to upgrade the focuser. I got both brand new some years ago for around $500 each so I've kept them both. Use the ED80 for lunar and annular and general grab and go scope and the WO for total eclipse travel.

cheers

Joe

[dannat]

the Borg are great units -cheaper than Tak , 71Fl would be very good, can be bought from peter tan in HK www.tan14.com.gears.htm [cheaper than hutech]

the WO would not disappoint either

[OzEclipse]

Daniel is correct and understated. Borg are a premium quality instrument and can be good value for money.

Be warned, the Borg are modular telescopes. You buy bits and pieces to put together what you want. This makes them very flexible but also a bit confusing. Their modular design also break down well for travel. You can carry the tube components in checked luggage and the objective unit in your carry on.

If you buy the #6071 kit HK$7200=A$1260 you get a 400f5.6 telephoto. There is a helical focuser in the middle of the train. However you'll need to buy tube rings to support it. If you want a visual scope, you'll have to buy a visual back end plus diagonal etc. Not trying to put you off Borg, just warning you to cost out all the bits and pieces before you make a decision.

I considered Borg many years ago but was buying during the GFC at a time when the A$ was very weak which made buying Borg via Hutech a relatively expensive undertaking and decided to go the William Optic route instead. If you can afford the Borg, they'll be better than the WO and that helical focusser won't sag or slip.

If you can't afford the Borg, Andrews is currently selling the MEGREZ 72 ED f/6 FD for $500. Except for 2mm extra aperture, this looks identical to the M70 instrument I have. The Focuser on the M72 is the same as mine, it's ok when tension is properly adjusted, but not great when the tension gets loose. It is much better than the awful slippery Synta Crayford focusser that came with my ED80.

The WO ZS71A at $800 is supposed to have a better 2 speed R&P focuser if you believe the advertising. I have no experience with this focuser and can't make an informed recommendation whether it's worth the extra money.

cheers

Joe

[Retrograde]

Thanks for the info Daniel and Joe.

The Borg certainly sounds great as an astrograph but maybe not quite so functional as an eclipse scope as far as mounting options go etc.
That Megrez seems like quite a bargain but probably isn't ideal as an astrograph.
Whilst I may not be closer to making a decision I'm certainly more informed about the choices. :)

[glend]

I still think the Explore Scientific ED80 Triplet ticks all your boxes. With its retracting shield the total length for transport can be only 335mm , by 140mm wide, with the diagonal and tube extension removed. It can be both visual and astrograph. It's very cost effective if you buy from Optcorp or Telescope.net and bring in directly (under the GST treashold). Gives you more flexibility in terms of use.

[Camelopardalis]

I've not had the chance to look through or image with a Megrez, but depending on how much weight you put on each of your requirements, the Zenithstar may or may not be good for you. The focuser is solid...I've never experienced any slippage, and with a fringe killer you can keep the blue halos minimised.

But I can't help thinking a triplet would be better all round for a little more $$. For example, the Orion ED80 triplet seems to have a good reputation. It's small, light(ish) and well corrected by all accounts.

[Retrograde]

A quick update on this.
Whilst I was very tempted by the Borg 71fl the cost was just a bit too high to justify for the aperture I was looking at (especially once you added one of their field-flatteners at an extra $500+)

Yesterday I picked up an Astrotech 65 EDQ from an IIS member at a reasonable cost. It is pretty much the exact focal length I was after and with the in-built flattener it represented great value & should be a great little astrograph.

Down-sides are it's a bit hefty with four pieces of glass and a bit slow at f6.5 but still fits on the camera tripod and is small enough to pack in hand-luggage for travel so overall a good compromise.

[Atmos]

I have recently been thinking about a Sky Watcher Esprit 80mm which comes with a 0.85x flattener reducer. Makes a 80mm F/4.2 wide field scope at a pretty reasonable price.

[Camelopardalis]

None of the Esprit come with a reducer - it's a field flattener only. The 80mm is f/5 native. No doubt there's a reducer that would work fine though.

Congrats on the new scope Pete, should put out some might fine views :thumbsup:

[Atmos]

Thanks for that, I do remember reading recently that there was a 0.85x flattened reducer specifically for the 80mm so I assumed that was what it came with.

[Camelopardalis]

FWIW, Skywatcher says the field flatteners included (in Aus) with the Esprit are tuned to their scopes.

I read somewhere (a while back) that the APM reducer works well... but I'd looked at it and shrugged it off because of the price... http://www.teleskop-express.de/shop/product_info.php/info/p5120_Riccardi-Reducer-and-Flattener---42mm-field---0-75x-for-Refractors-and-RC.html

I don't have any reducers to hand so can't really test, but it'd be interesting to see if any of the generic reducers like the Orion or the TV TRF2008 worked :question:

[Slawomir]

Stellarvue is about to release a new 70mm f6 triplet, that with a dedicated reducer could potentially be a very neat wide field triplet at f/4.8.

[castor]

I disagree about the statement that small refractors are near useless.

My Takahashi FS-60c provides wonderful views of the planets and sweeping views of the Milky Way and the Magellanic Clouds and the brighter DSOs. In terms of Jupiter and Saturn it can handle near 200x without image degradation. It is literally like a lightly built short person who has been on steroids.

The Orion 80ED provided immense value when it appeared and does go deeper in accordance with its aperture.

[N1]

Yep, I think everybody on this thread so far would agree with you. Even Wavy, who, instead of just one small frac, is recommending a pair of them (aka binoculars). A valid proposition. So all good :thumbsup:

[MortonH]

Stellarvue have just announced a 70mm f/6 triplet with 2.5" R&P focuser. A bit pricey though at US$799.

http://www.stellarvue.com/sv70t-apo-triplet-refractor/

[Camelopardalis]

But no doubt strategically less pricey than the WO Star71...until you add the cost of the field flattener...essential for imaging with a short focal length refractor.

[Andy01]

Looks like a very nice 'scope, and Stellarvue have a great reputation.

Although by the time you add the approx $295 for the reducer/flattener, the estimated Fedex shipping cost of $185 and import costs ie: Customs entry, Airport terminal fee, Documentation fee, Currency adjustment fee, Airport fuel surcharge & GST you're looking at around $2050Au. which is rather more than what I paid for the WOStar71 that I ordered last week :)

[Slawomir]

It adds up very quickly, doesn't it?

Looking forward to reading your review of your new 'scope Andy :thumbsup:

[Camelopardalis]

Me too :thumbsup:

[Andy01]

Looks like its going to a while before anyone sees a review of the WOStar71.

My order was placed 3 weeks ago when the factory production was running again after running out of stock worldwide earlier in the year, but my dealer was just informed by WO after a lengthy delay that they're out of stock, again!
(Sigh)

So no sign of it in the immediate future. :(

Also, heads up that there's a new WO four element 71 coming in January.

[Camelopardalis]

Andy, Agena astro are showing them as in stock, although no doubt at a higher cost with import etc. :shrug:

I'd love to see one of these with a full frame chip, like a Canon 6D or similar...

[Andy01]

Update:
So anyway, having ordered and paid for my WO star71 back in Dec last year, and expecting delivery in 10 days- my Oz dealer informed me three weeks later that WO had it seems run out of stock (again) and he had no idea when I could realistically expect to recieve my 'scope.

So I emailed the WO factory today to express my disappointment and politely ask wtf was going on.

Seems that they claim that they didn't recieve my order, sold out of all Star 71's and now it's discontinued! Zip, nafa, no more.

Was told there's a new design, replacement four element model arriving in March, (maybe).

Sorry WO. I'm done waiting after three months of lost imaging time and poor communication. Refund requested, potential purchase email sent to Stellarvue.

Moving on, hoping for a better outcome :)

[MortonH]

That's disappointing from WO, Andy.

You considering the new Stellarvue 70mm triplet now?

[Andy01]

Yes, it was originally plan 'b' but the WO was around 10-15% more cost effective at the time. Hoping SV can deliver as it's also a popular item :)

[casstony]

There were issues reported on CN with more than one of the WO Star 71's; perhaps the scope was discontinued because they couldn't guarantee the quality?
It seems to be harder to make a quadruplet or 5 element scope than the more common designs.

[MortonH]

Yet now Stellarvue and others are bringing out SIX element scopes! :eyepop:

[Camelopardalis]

Yeah that sucks, I fancied one myself :D

Six elements...hmmm should be an interesting optical design...