185 replies to this topic

[25585]

Most posts here are about the Moon, planets and imaging. 

 

Are refractors with their small apertures but excellent optics really only good for detailed views of solar systen objects, and for imaging?

 

I suppose as higher magnification monoculars, taking over from binoculars, the grab & go hassle free side ipof smaller sizes is good. But beyond that, refractors' apertures are limiting.

 

So refractors seem more specialised than average sized Newtonians & SCTs, and less good for general viewing of deep sky.

 

 

[Sam M]

I especially like mine for wide field views of DSOs.

[bobito]

The notable exceptions are large DSOs.  Things like the Double Cluster, Andromeda, the Pleiades are all fantastic in refractors.

[Jeff B]

Most posts here are about the Moon, planets and imaging. 

 

Are refractors with their small apertures but excellent optics really only good for detailed views of solar systen objects, and for imaging?

 

I suppose as higher magnification monoculars, taking over from binoculars, the grab & go hassle free side ipof smaller sizes is good. But beyond that, refractors' apertures are limiting.

 

So refractors seem more specialised than average sized Newtonians & SCTs, and less good for general viewing of deep sky.

No!  I believe that refractors, achromats in particular, are vastly underated for lower power deep sky observing.  Inch per inch they excel at light gathering and contrast.  Even the standard Synta 6" sample achromats can provide some truly excellent, low power deep sky viewing.  My 6" F5 Jaegers certainly does.  Trouble is as the inches inch upwards in aperture, refractors can get kinda big and heavy once you get past 6" in aperture.   

 

Jeff

[M11Mike]

And don't forget --- they are great on DOUBLE STARS.  And hard to beat the FOV.  Try M24 in a Mak!!!   :-)  

Leo Triplet - M81/82 (same FOV) - M31 and the list goes on. 

 

M11Mike 

[Diana N]

Every object on the Messier list can be observed, and observed well, with a 4" refractor.  So can quite a few NGC objects.

 

But (like any telescope) to truly appreciate what a refractor can do on DSOs, you have to use it under a dark sky. 

[bobzeq25]

Most posts here are about the Moon, planets and imaging. 

 

Are refractors with their small apertures but excellent optics really only good for detailed views of solar systen objects, and for imaging?

 

I suppose as higher magnification monoculars, taking over from binoculars, the grab & go hassle free side ipof smaller sizes is good. But beyond that, refractors' apertures are limiting.

 

So refractors seem more specialised than average sized Newtonians & SCTs, and less good for general viewing of deep sky.

It's far more complicated than that.  Some people _prefer_ refractors for viewing DSOs.  High contrast and sharp stars are a couple of reasons.  They are willing to sacrifice aperture.

 

What kind of telescope to use is usually just a personal decision, not some cosmic right/wrong deal.

[turtle86]

The notable exceptions are large DSOs.  Things like the Double Cluster, Andromeda, the Pleiades are all fantastic in refractors.

 

The Veil is pretty good too.

[tog]

Globular clusters are a real treat with my refractor!

[Sketcher]

. . . depends on who's using the refractor and what their sky is like.

 

I own several refractors.  Each of mine might, possibly, have been used more often for visual deep-sky observation than for any other purpose.  I consider all my refractors to be multi-purpose visual instruments -- suitable for solar, lunar, planetary, and deep-sky visual use.

 

If a 1-inch refractor can provide deep-sky views like the following, what do you suppose could be seen with a 2-inch, 3-inch, 4-inch, etc?

 

 

 

 

 

 

So far I've observed 83 Messier objects with only 1-inch of (refractor) aperture.  Soon I expect to "catch" most, if not all, of those that remain.

[noisejammer]

I have a 6" f/7.3 refractor. I can run it a f/6.3 and fully illuminate a 41 Panoptic. That's a 3^o true field. I can remove the reducer and (atmosphere permitting) resolve 0.8 arcsec.

 

For completeness, a 3^o TFOV is possible in some - admittedly scarce - reflectors. As an example, consider the Epsilon 160. The thing is, a perfectly collimated Epsilon runs out of mojo at around 4 arcsec resolution, something that any 2" refractor can better.

 

Getting equal performance would mean an Epsilon and another 8" scope, and maybe another mount ...

 

The reason I like refractors, even for deep sky viewing is they are low-hassle instruments. My free time is very precious and I want things to work. The image quality is just a sweetener.

[mikeDnight]

Refractors are renowned for delivering high contrast high definition views. If they do this with the moon and planets, they also do it with DSO's.

 

 

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[Shorty Barlow]

Are refractors really mainly solar system & imaging instruments?

 

 

 

 

No.

 

 

 

I rarely look at solar system objects with my titchy little 72mm refractor, and the only cameras I own are on my phone and tablet. OK, I occasionally view the Moon with the ED72, but I'm more likely to use a Newtonian or Maksutov for a dedicated lunar session.

 

 

I've split doubles, seen faint comets, galaxies, nebulae, open clusters and a plethora of objects with the Evostar 72ED DS Pro. I recently read somewhere a 70mm telescope is 100x better than the naked eye. I don't know how true it is, but I can believe it.

Edited by Shorty Barlow, 21 November 2019 - 07:03 PM.

[turtle86]

Most posts here are about the Moon, planets and imaging. 

 

Are refractors with their small apertures but excellent optics really only good for detailed views of solar systen objects, and for imaging?

 

I suppose as higher magnification monoculars, taking over from binoculars, the grab & go hassle free side ipof smaller sizes is good. But beyond that, refractors' apertures are limiting.

 

So refractors seem more specialised than average sized Newtonians & SCTs, and less good for general viewing of deep sky.

 

O’Meara made amazing observations of Messier objects with a 4” refractor from his dark site in Hawaii.

 

I have an NP 101 and find it to be a wonderful complement to my Dobs with its wide well-corrected field of view.  It’s a joy to pan the Milky Way with it. Sometimes I want to go deep, but sometimes I want to go wide.  My 18” Dob is great for faint galaxies but the Pleiades sure looks a lot better in my NP 101.  

[nicoledoula]

Refractors are BETTER at everything IF one can afford the apertures and their mounting requirements. But yeah, I guess those other designs (all compromises due to large refractor costs and mounting issues) do OK though.

[macdonjh]

When my 6" achro was my main scope, I used it for everything: lunar, planets, double stars, open clusters, globular clusters, nebulae, galaxies...

 

I just kept my expectations in line with what 6" of aperture is capable of pulling in.  I will say, my best ever view of M51 was under what so far has proved to be once-in-a-lifetime sky one frigid March night at my club's dark site.  Even with bigger scopes it's never looked better.

[Jeff B]

I really like these sketches gentlemen and they are spooky in their realism.  Well done!

 

Jeff

[Mitrovarr]

Fast refractors are good dedicated widefield instruments, and larger (5-6" or bigger) refractors are pretty decent at everything.

 

The only real problem with refractors is that they're cost and size prohibitive in sizes over about 6".

[ChrisGTS]

+1 on large, wide-field objects.  The main reason I got a 102mm refractor was to see objects like the North America Nebula, Veil Nebula, Pleiades, etc., and it is wonderful for that. I also have a 72mm refractor that I use as a travel scope, and it really impressed me under very dark skies in Africa recently.  I had a great time looking at the Messier objects in Sgr, as well as the SMC and 47 Tucanae with it, and I even looked at a comet (Africano), and found it with no problem.  For lunar and planetary, I personally prefer my dob, which gives much more detailed and higher-resolution views.  But also, as noted above, the hassle factor with a refractor is very low.  Easy to carry and set up, and no collimation needed!

 

Chris

[jaraxx]

I go on long trips across the country, camping for weeks at a time, traveling light and fast. I like the dark skies, but I also like to look at birds, landscapes, and a moose once in a while. A small refractor for me. And a 127mm Mak . And 8x42 binoculars. And 12x50 binoculars. And a monopod.

#^&%#! This always happens...

[StarBurger]

Charles Messier (of the Messier catalog) discovered what he did with a 4" refractor which in those days (1750's) was probably not approaching modern day achro's in quality.

So there are at least 110 objects attainable visually.

Given modern cameras and tracking or guided EQ mounts the sky is your playground.

Most of our mediocre scopes (I include my own 80 mm f 7.5) are capable of wonderful DSO images if wielded properly even in poor Bortle skies.

As for visual of course, a 80 mm frac is never going to compete with a 200 mm reflector.

Said many times, but it's horses for courses.

For a sanity check I often forgo imaging on the 80 mm and haul out the 200 mm DOB for a relaxed night out star hopping to remind myself where I came from. 

[Jared]

Most posts here are about the Moon, planets and imaging. 

 

Are refractors with their small apertures but excellent optics really only good for detailed views of solar systen objects, and for imaging?

 

I suppose as higher magnification monoculars, taking over from binoculars, the grab & go hassle free side ipof smaller sizes is good. But beyond that, refractors' apertures are limiting.

 

So refractors seem more specialised than average sized Newtonians & SCTs, and less good for general viewing of deep sky.

All telescope designs have their strengths and weaknesses.  Refractors, on the whole, are good as spotting scopes, wide field/rich field scopes, good for solar system objects, good for open clusters, good for double stars, and generally perform better than other scopes even when they have not yet equilibrated.  They also need less maintenance than other designs, i.e., no collimation requirements.  They have relatively few and mild off axis aberrations.  They are an excellent choice for imaging and for photometry.  That isn’t exactly a small list of things they are good at.  Again, no telescope is good at everything.  
 

SCT’s, Newtonians, Maksutov Cassegrain, Dall Kirkhams, and Schmidt Newtonians all have a comparable list of strengths. 

[csrlice12]

According to the reflector forum, refractors make excellent finder scopes.

[Shorty Barlow]

According to the reflector forum, refractors make excellent finder scopes.

A lot of reflectors have finders bigger than 72mm lol.

 

 

102mm Mak/50mm finder!

[mikeDnight]

A few more fuzzies through a little frac. M27, M57 & Flame Nebula. Not bad for a guide scope! 

Edited by mikeDnight, 22 November 2019 - 01:06 PM.