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I want a 6 inch refractor. What can I see?

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#1 David Stevenson

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Posted 17 April 2021 - 05:30 AM

I like refractors. I don't want to mess up with a big Newtonian, so I am wondering if a six inch refractor could still give some nice views, also on deep sky. What about clusters and nebulae? What can I expect to see? Any experiences there? I could reach a bortle 4 sky in 30min and bortle 3 in one hour.. otherwise I am in a city pulluted area..
Thanks
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#2 t.r.

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Posted 17 April 2021 - 05:52 AM

Refractors are an excellent choice for the city and a 6”, while not particularly portable, will at least show you every class of object. It will reveal detail in all that you ask about. It is considered the minimum for a lifetime of enjoyment and can be kept as a sole use instrument. If I only had a 6” refractor I would be content. There would be a lifetime list of objects to explore.

Edited by t.r., 17 April 2021 - 05:55 AM.

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#3 CHASLX200

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Posted 17 April 2021 - 05:55 AM

A 6" refactor can be just as much a job to set up than a bigger Newt. Ask me how i know.  If you have good seeing a good 6" ED will show you the planets at 450x without breaking a sweat. Deep sky will also look very nice in darker skies.


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#4 Astrojensen

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Posted 17 April 2021 - 05:59 AM

How much you can see in a telescope strongly depends on how skilled and experienced you are as an observer. It is therefor quite difficult to predict how much YOU will see, based on other people's experiences, though they may serve as a general guideline. 

 

Under a dark sky, and in the hands of an experienced observer, a 6" refractor is a surprisingly powerful deep-sky telescope. I have one (APM 152 ED) and in my roughly Bortle 3 sky, I can take it down to around magnitude 15 on stars. This means that many globular clusters are at least partially resolved and numerous galaxies begin to show some structure. The very sharp optics mean that I'm often using MUCH higher magnifications, than I do with my reflectors (my 12" dob has very poor optics). This brings in fainter stars and allows better resolution of clusters, globular clusters in particular. 

 

BTW, be aware that a 6" refractor, especially if it's f/7 or longer, is a very heavy instrument that needs a suitably strong mount. You will need AT LEAST an EQ-6 class mount, preferably with an upgraded tripod, as the 2" steel pipe tripod on the EQ-6 mounts is their weakest link, by far.   

 

 

Clear skies!

Thomas, Denmark


Edited by Astrojensen, 17 April 2021 - 06:02 AM.

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#5 bobhen

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Posted 17 April 2021 - 06:31 AM

As others have said, a 6” refractor is no slouch on deep sky and is of course an excellent lunar planetary telescope.

 

If portability and a quick set up is a concern, consider an alt/az mount like a DiscMounts DM6 or something similar.

 

Living in a city you might want to consider a 5” refractor on a GEM but add an inexpensive camera (like the Revolution II or similar) for quick shot EAA. Or you could take the money you saved by getting a 5” refractor and lighter mount over the 6” refractor and purchase an image intensifier. Both of the above will show you more deep sky objects and details from your light polluted location than traveling to a dark sky will.

 

Anyway, just some suggestions to consider.

 

Bob


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#6 David Stevenson

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Posted 17 April 2021 - 07:05 AM

Regarding the mount, would it be the same for a newt on an equatorial I guess, I don't want Dobson mount

#7 John Fitzgerald

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Posted 17 April 2021 - 07:45 AM

A six inch refractor is a beast to set up and haul around, especially if f/7 or longer.  I would not have my 6 inch refractor and G11 mount if not for the dome to house it.

 

Those who set them up nightly are very dedicated and usually young and strong.

 

Edit:  They are generally harder to set up on an equatorial or alt az mount than a newt because the attachment point is much higher, sometimes above head height.


Edited by John Fitzgerald, 17 April 2021 - 07:59 AM.

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#8 CHASLX200

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Posted 17 April 2021 - 07:57 AM

My 6" ED with a AP800 mount was a 7 trip scope to set up. My 18" Obsession can be rolled out my door all set up in one lick. So i guess we know what i kept. My house is not set up to roll out a big refractor or i would have a 8" F/15.  Even a cheap 6" F/8 achro is very good on deep sky with poppy contrast and a dark sky background.  You can get by with a smaller mount but i am very picky about a steady mount and i like a over size mount. These scopes are top heavy and have to be hung low on the mount so reaching SLO- MO controls can be a long reach for a ape even. Also viewing can be a pain since you need to be on your knees in some parts of the sky. So a bigger and higher mount is best.


Edited by CHASLX200, 17 April 2021 - 07:59 AM.

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#9 John Fitzgerald

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Posted 17 April 2021 - 08:13 AM

My original 6 inch f/8 achro was about six trips to set up.  Tripod, eq head, counterweights, table, ep case and charts.  Putting in the yard pier eliminated the first trip.  Putting the dome over it several years later eliminated most of the trips in and out, and increased the equipment safety factor manyfold due to less handling.


Edited by John Fitzgerald, 17 April 2021 - 08:15 AM.

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#10 JMW

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Posted 17 April 2021 - 08:27 AM

We use a TEC 140 ED when camping under dark skies. At home I mostly use a SVR90T to look at the brightest stuff such as open clusters, doubles, planets and moon.

 

The 5.5 inch refractor gives us much pleasure looking at all kinds of objects including DSOs. We use it on a DM6 mount with a Planet tripod. It takes about 15 minutes to setup.


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#11 j.gardavsky

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Posted 17 April 2021 - 08:32 AM

My 6" F/5 achro

is light weight, and when fully accessorized on a Cullmann Titan tripod with the central geared column for optimal height adjustment, it makes 15kg, and I can easily move it just with one hand.

 

During the star parties, I am the first ready to observe, whereas the others are checking the collimation, and waiting on the cooldown of the mirrors.

 

Am I missing something?

Yes, a bigger aperture, but this would defy the purpose of light weight and portability.

 

Best,

JG


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#12 John Fitzgerald

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Posted 17 April 2021 - 08:37 AM

A 6 inch f/5 somehow seems much easier to set up than a 6 inch f/8.


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#13 Astrojensen

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Posted 17 April 2021 - 08:48 AM

Regarding the mount, would it be the same for a newt on an equatorial I guess, I don't want Dobson mount

No. The tripod would need to be much higher and correspondingly stronger, to eliminate vibration. The tube assembly of a refractor is usually also much heavier, because the optics are heavier in themselves (more glass, much more complicated and stronger housing cell). The mount usually needs to be much stronger, than for a similar size newtonian. 

 

While my Vixen GP mount can carry my 6" f/8 newtonian quite well, it's woefully inadequate for my 6" f/8 ED, which needs an EQ-6, at the bare minimum.

 

 

Clear skies!

Thomas, Denmark



#14 TOMDEY

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Posted 17 April 2021 - 09:07 AM

Hi David; I completely agree!

 

Six-inch has always been my favorite. Possibly because my first really excellent scope was six decades ago, a 6" F/12.5 Newtonian entirely of my own making. Yet Refractor all the better, for reason subtle --- no ~central obstruction~. Therefore, I now use the 6-inch F/8 APO Refractor as my favorite! This allows cavalier selection of eyepiece; all working equally-well. Even those "too long" that the exit pupil spans so large as to surpass the darkened eye and magnification so low as to encompass too much sky. In that sense, your main scope becomes the "finder" just by popping in the two-inch 55mm Plossl, or 41mm Pano, or even the three-inch 80mm (15x, 3.3o field). I can then change eyepieces to get up to 300x --- seamless progression from 15x to twenty times that... all with the same scope! No more fussing over exit pupil size and other arcane distractions.    Tom


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#15 StarAlert

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Posted 17 April 2021 - 09:09 AM

Why does a question about what can be seen in a 6” refractor turn into a discussion about portability? 


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#16 dagadget

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Posted 17 April 2021 - 09:15 AM

A 6" refactor can be just as much a job to set up than a bigger Newt. Ask me how i know.  If you have good seeing a good 6" ED will show you the planets at 450x without breaking a sweat. Deep sky will also look very nice in darker skies.

Yes Chas is correct in this sense as a 6 inch Triplet Refractor is quite nose heavy very long and not the easiest thing to mount on a GEM. In this case it is on a Ioptron GEM 45 with not enough counter weight as those are on back order. 

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#17 StarAlert

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Posted 17 April 2021 - 09:15 AM

I like refractors. I don't want to mess up with a big Newtonian, so I am wondering if a six inch refractor could still give some nice views, also on deep sky. What about clusters and nebulae? What can I expect to see? Any experiences there? I could reach a bortle 4 sky in 30min and bortle 3 in one hour.. otherwise I am in a city pulluted area..
Thanks

I have a TEC160ED. I live in Bortle 7/8 skies east of LA. It is my favorite scope for lunar, planets and doubles. A six inch refractor in any sky will keep you busy and happy for a very long time. 


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#18 John Fitzgerald

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Posted 17 April 2021 - 09:25 AM

Why does a question about what can be seen in a 6” refractor turn into a discussion about portability? 

A lot can be seen in a six inch refractor.   The portability issue comes up because it can prevent frequent set up, and therefore, enjoyment of the wonderful views.


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#19 Astrojensen

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Posted 17 April 2021 - 09:31 AM

Why does a question about what can be seen in a 6” refractor turn into a discussion about portability? 

Because people tend to underestimate just how big those things are. Those of us who own one, wants to make prospective buyers aware of this potential problem. 

 

On the other hand, I would like to point out, that a well-functioning 6" refractor system (the telescope as a whole) is NOT particularly difficult to handle, provided the individual components aren't heavier than you can handle them safely. If you don't have to carry each component a long distance, say, from your house and 50 feet down the garden, then assembling the scope doesn't take long and isn't difficult or particularly heavy. 

 

I can set up my 6" f/8 almost right outside the door on many evenings, when studying the Moon and planets, and then it doesn't take me more than around five minutes. I do keep the mount and tripod set up as a single unit, but without the counterweight shaft attached. 

 

I'm using an old Vixen Saturn mount (fully manual German Equatorial Mount) and it doesn't have a dovetail adapter, but a flat plate with four holes for attaching tube rings. The tube rings from the APM didn't have matching holes, so I've made an adapter plate with four stud bolts that matches the Saturn mount. This is CONSIDERABLY safer, faster and easier to assemble, than a dovetail system. I just put the scope on the mount, aligning the stud bolts with the holes and let them slide in. The scope then sits safely on the mount and can't slide backwards, while I attach the knobs. This works so well, that I'm seriously wondering why the dovetail systems are so popular on larger scopes. Especially since it's also vastly more expensive... 

 

gallery_55742_4772_508875.jpg

 

 

 

Clear skies!

Thomas, Denmark 


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#20 gjanke

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Posted 17 April 2021 - 10:02 AM

I like refractors. I don't want to mess up with a big Newtonian, so I am wondering if a six inch refractor could still give some nice views, also on deep sky. What about clusters and nebulae? What can I expect to see? Any experiences there? I could reach a bortle 4 sky in 30min and bortle 3 in one hour.. otherwise I am in a city pulluted area..
Thanks

I like refractors too! I like them a lot and have owned a number of 6" refractors.  Remember this; its only 6" after all. Your DSO's are for the most part gonna be smudges. Others are going to argue the merits of high magnification and how it'll bring out so much more in the viewing experience but most of this thinking is just telescope lore.

You want sharp planetary views and star splitting fun? Own a refractor but if you want to resolve DSO's buy something else. 

The PSA on portability is something definitely to consider because to enjoy viewing with a 6" refractor, and not experience a boat load of jiggle, you need a stout mount.

This was my last 6" ED F/8, 94% strehl, it was a solid performer. Giant pain to set up and breakdown. I sold it to a gentlemen in Chicago in 2017 and he sold it last year and so goes the story of the 6" refractor. 

Clear Skies

- Gerald

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#21 astrohamp

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Posted 17 April 2021 - 10:20 AM

My rather mediocre 152mm OTA was revived by incorporating EAA observing as well as migrating from DSC push-to and tracking to GOTO and track.  From my local Bortal 5+ visible clusters yes, not so much nebula although on occasion the Horse Head will appear. Never in an eyepiece.  My more remote site Bortle 4 (4- maybe) shows so much more in all areas.

Setting up something this large for one night, having to return in the dark or dawn is not for me any more. YMMV


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#22 vahe

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Posted 17 April 2021 - 10:25 AM

A 6" APO is a lifetime scope.

.
I received mine, AP155EDT f/9 in 1993, it was upgraded by Roland in 2001.

.
It weighs @ 23 pounds, according to AP catalog, weight wise it is manageable, it rides on my 1992 G11 mount with fixed tall legs, Since I am strictly visual the G11 is ok for that purpose.

.

Vahe

 

 

 

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#23 BarrySimon615

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Posted 17 April 2021 - 10:35 AM

I like refractors. I don't want to mess up with a big Newtonian, so I am wondering if a six inch refractor could still give some nice views, also on deep sky. What about clusters and nebulae? What can I expect to see? Any experiences there? I could reach a bortle 4 sky in 30min and bortle 3 in one hour.. otherwise I am in a city pulluted area..
Thanks

Original post quoted above -

 

A 6 inch refractor can work very well give what your scenario is as outlined in your post above.  You say nothing about planetary or lunar observation, but you do mention deep sky including clusters and nebulae.  You talk about getting to Bortle 4 and 3 skies which tells me that dark skies are important to you.  You mention nothing about cost limitations for telescope or mount.  So based upon all of this I think a 6 inch ED or apo triplet properly mounted would best fulfill your requirements.  I would go no lower than 140 mm (5.5 inches) on aperture and no longer than f/7.  Most people will find that manageable.

 

If budget is limited a 6 inch f/8 achromat refractor can be handled by most and the tube length is such that it will fit across the back seat of most cars.  Chromatic aberration can be minimized with appropriate filters and if you stick mostly to deep sky at lower magnifications (visual - not photographic) chromatic aberration is not a real concern.

 

I have a home constructed Jaegers 6" f/5 which was home built by me back in 1978/79 and it is great on deep sky.  My weapon of choice these days for observation under dark skies is my TMB SS 130 f/7 triplet apo (5.1" diameter) on an AP Mach 1 mount.  When more portability is needed I have an Astro Tech AT 111 triplet f/7.

 

Barry Simon


Edited by BarrySimon615, 17 April 2021 - 10:39 AM.

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#24 kmparsons

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Posted 17 April 2021 - 10:41 AM

I am currently very tempted by the TS-Optics 6" f/5.9 achromat. The price is not too bad at 922 Euros (currently $1105). The weight is 8.5 kg (about 19 pounds), which is a chunk, but not too unwieldy with a length of 900mm (about 36"). I think my heavy-duty SkyWatcher alt-az mount would handle it pretty well. I imagine that it would shine on the brighter clusters and nebulae and provide excellent wide-field views. Gathering over twice the light of a 4" refractor, it should have a real advantage with the brighter DSO's, and for that I would be willing to tolerate some CA on the Moon and planets. 



#25 BillP

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Posted 17 April 2021 - 10:41 AM

A six inch refractor is a beast to set up and haul around, especially if f/7 or longer.  I would not have my 6 inch refractor and G11 mount if not for the dome to house it.

 

Those who set them up nightly are very dedicated and usually young and strong.

 

Edit:  They are generally harder to set up on an equatorial or alt az mount than a newt because the attachment point is much higher, sometimes above head height.

 

All depends on how you mount it really.  I do not image or bother with automation so I just star hop to everything I want to see.  As a consequence of that my mounting for my 6" f/8 Apo is a simple fork-type alt-az mount head on a tripod from a CG5 mount.  Entire thing is rather light and I can pick it up and move it mounted without much problem and have carried it in and out of the house to yard fully mounted.  When I do use 2 trips to set it up, I many times leave the tripod with legs collapsed.  Once the scope is on it I just tilt the tripod and extend one leg, then repeat the process with the other legs until all are fully extended.  Not difficult or dangerous process.  Other times I just fully extend the legs first and lift the OTA.  Again, depends on the OTA but I believe mine is about 25-30 lbs with rings and finder and diagonal so not all that heavy.  Having a fork with cradle alt-az makes the lifting and attaching of the OTA much easier as well as just have to place it into the dovetail and it sits there stable unsecured, then tighten things up.  If the dovetail was on the side, as it is for non-fork alt-az mounts, then it would be a major pain for one person.  The wide base of the fork is also very handy as I just dip down and put that on my shoulder then stand up and easy as pie to lift the entire rig that way with shoulder taking all the weight and walk it around the yard or into the house.

 

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Edited by BillP, 17 April 2021 - 10:47 AM.

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