Refractor For Purely Visual Astronomy?

[John]

15 minutes ago, mikeDnight said:

I'm not sure I'd agree about that John. I have quite vivid memories of how I felt when sweeping the milkyway using a SW150 F5 Star Travel at my local astro centre. It was twenty years ago but its still emblazoned in my mind. Despite the greater aperture of the many larger reflectors and SCT's, not one scope could match the beauty of the wide, rich, piercingly sharp star fields of the ST150, and DSO's seemed to glide effortlessly into the field of view. It was quite a sight to see under a dark sky, and the memory of that night still makes my heart race. 💓

Fair enough Mike - I've not used the F/5 version of the 150 achromat. My personal feeling is that a 200mm F/6 dob would still go deeper (though not as wide) and also be excellent for planetary and lunar observing so a better all round scope rather than the "1 trick ponies" of the fast achromats.

But I could be wrong - it's been known

 

[Ian McCallum]

On 28/09/2021 at 09:15, Stu said:

I actually have both of these on trial from FLO at the moment. They are actually exactly the opposite of what you said ie they are dedicated visual instruments, not really suited to astrophotography at all.

They have a long focal length and slow focal ratio, with well figured optics so are good planetary and lunar and double star scopes, but don’t have the widefield capability you would get with a 100mm f7 for instance. They also only have 1.25” focusers so the maximum field of view in the f15 would be about 1.3 degrees, vs around 3.8 degrees with a 40mm 2” eyepiece in the f7. Personally I wouldn’t recommend one as your first/only refractor as they are quite specialised although I have had some lovely lunar and double star views with both scopes.

If you had to choose between the 2 models, which would you choose and why?🤔

[johninderby]

Apparently there is not a lot of difference but I chose the 80mm f/15 version. Great lunar / planetary scope and visually no noticeable CA at all. Very light weight as well although it’s length means it needs a decent mount.

 

 

And a smartphone image

Edited September 29, 2021 by johninderby

[John]

17 minutes ago, Ian McCallum said:

If you had to choose between the 2 models, which would you choose and why?🤔

Sounds like you have a "refractor itch" that needs scratching

[IB20]

There is something extremely pleasing with the views through a refractor. Having both scopes has definitely made me a better observer, a better user of both scopes and I can access more targets.

[Stu]

1 hour ago, Ian McCallum said:

If you had to choose between the 2 models, which would you choose and why?🤔

Not a lot on it as my findings here show:

I probably need to add some more to this which I will try to do now I’m a bit more settled in my new location. The scopes are still in storage though so need to bring them down on my next trip.

If I had to choose, I would go F15, just because optically it is a smidge better corrected but there’s not a lot in it and the 12.5 is just that bit easier to mount.

[woldsman]

In my (limited) experience, a Skywatcher 200P reflector out performs a Tal 100RS achro refractor in a head to head but the latter is more easily transportable to a darker site, unless you have a van. So definitely worth having a second scope for visual.  

[Sunshine]

No matter what type of scope you are used to using, everyone needs a refractor. Sooner or later everyone has one in their collection.

Edited September 30, 2021 by Sunshine

[Stu]

The only thing I would add to my previous comments for the OP, are that the Scopetech f15 has the same focal length as an f6 200mm dob, so you will get the same field of view in both.

The way refractors complement dobs is often by showing a wider view of the same (or different) scenes, so an f7 100mm ED refractor would, to my mind, be much more flexible, and ultimately have higher resolution and a wider field than the 80/f15.

[wookie1965]

12 hours ago, wibblefish said:

Id be curious if anyone has used the ar127s (and what it would take to mount it). I keep looking at it to upgrade my 90/660 though in my head I know a 200p (or equivalent) dob would probably end up more bang for buck but I do enjoy my refractor! (Apologies for butting into your thread!)

I have a Meade 127mm on a EQ5 mount with a EQ6 tripod adapter plate and pier extension works very well for visual only as it is at the top end on the mounts load capacity.

[banjaxed]

15 hours ago, Ian McCallum said:

That's a problem, as we're not getting any younger.  🤣

Would I have to buy new eyepieces or would my existing BST's do the job? 

The BST eyepieces work very well for me.

[Louis D]

6 hours ago, wookie1965 said:

I have a Meade 127mm on a EQ5 mount with a EQ6 tripod adapter plate and pier extension works very well for visual only as it is at the top end on the mounts load capacity.

All I can say is, it's a good thing the Dobsonian mount was invented if that frac is at the top end of an EQ5's capacity.  Can you imagine how big of a GEM it would take to mount a 24" Newtonian?  It's no wonder all modern giant observatory telescopes have gone to alt-az mounts.

[Ian McCallum]

7 hours ago, Stu said:

The only thing I would add to my previous comments for the OP, are that the Scopetech f15 has the same focal length as an f6 200mm dob, so you will get the same field of view in both.

The way refractors complement dobs is often by showing a wider view of the same (or different) scenes, so an f7 100mm ED refractor would, to my mind, be much more flexible, and ultimately have higher resolution and a wider field than the 80/f15.

Although I get some nice views of Jupiter and Saturn, I do find much above 150x magnification, they tend to get a bit indistinct using my Sky-Watcher 200P. 

Would the  Scopetech give me better views at higher magnifications at 150x and above? 

[Stu]

3 hours ago, Ian McCallum said:

Although I get some nice views of Jupiter and Saturn, I do find much above 150x magnification, they tend to get a bit indistinct using my Sky-Watcher 200P. 

Would the  Scopetech give me better views at higher magnifications at 150x and above? 

I would say no. At x150 the 80mm would give an exit pupil of 0.53 vs 1.33 for the 200p. The 200mm would give a brighter image with better resolution.

It’s a complex, nuanced situation though; seeing conditions play a role, and one benefit of smaller refractors is that they tend to cut through poor seeing better than larger scopes. Under good conditions, a good big scope will beat a good small scope. Under poorer conditions it will be much closer, and there is the convenience factor of the small scope to take into account too; fast cool down, quicker setup etc.

I love good refractors but have had multiple occasions where top quality apos costing thousands (Tak FC100DC and Vixen FL102S) have been humbled by a £200 Hertitage 150p.

My Orion Optics 8” f8 generally shows more planetary detail than my fracs if conditions allow.

EDIT I should add that I haven’t yet compared my new LZOS 130mm f6 apo triplet to the 8” f8.

[John]

3 hours ago, Ian McCallum said:

Although I get some nice views of Jupiter and Saturn, I do find much above 150x magnification, they tend to get a bit indistinct using my Sky-Watcher 200P. 

 

Obviously I don't know your observing situation but I think your 200P should be doing a bit better than that, certainly on Saturn. On Jupiter 130x-160x often does give the best (sharpest and most contrasty) views but with Saturn 200x-250x should be delivering nice sharp views, if the seeing is anywhere near decent.

I hate to mention the "C" word (collimation) but some mis-collimation can impact sharpness and contrast rather negatively ?

 

[Deadlake]

14 minutes ago, Stu said:

My Orion Optics 8” f8 generally shows more planetary detail than my fracs if conditions allow.

How often to seeing conditions (or you viewing style, such as waiting for cool down) mean this is possible?

[wookie1965]

13 minutes ago, John said:

Obviously I don't know your observing situation but I think your 200P should be doing a bit better than that, certainly on Saturn. On Jupiter 130x-160x often does give the best (sharpest and most contrasty) views but with Saturn 200x-250x should be delivering nice sharp views, if the seeing is anywhere near decent.

I hate to mention the "C" word (collimation) but some mis-collimation can impact sharpness and contrast rather negatively ?

 

I was thinking the same and flocking to help with contrast. 

[Ian McCallum]

The collimation on the 200P is okay, just my memory that's faulty. 🙄

It's towards the higher end of the magnification scale, where I get larger but indistinct images, as you'd expect... I'm thinking for example of the 5mm eyepiece and smaller, etc. 

Perhaps it's time to look at the bigger DOB's again... 🤔

[IB20]

4 hours ago, Ian McCallum said:

Although I get some nice views of Jupiter and Saturn, I do find much above 150x magnification, they tend to get a bit indistinct using my Sky-Watcher 200P. 

Would the  Scopetech give me better views at higher magnifications at 150x and above? 

Agree with Stu, almost certainly no. The image in the Scopetech will be smaller and dimmer and although I’ve found reduction of brightness on these planets improves contrast and makes some detail easier to see, the dob will out-perform a smaller scope when seeing is better than average. 

The brightness of these planets can also wash out detail in the dob, have you tried using a moon filter or even maybe think about binoviewers? 
 

 

 

[IB20]

Also don’t underestimate the importance of seeing and their current position in the sky. I’ve had some nights this year when both planets have truly knocked my socks off in both my scopes. However, last night the conditions were woeful and if it were my first time viewing, I’m not sure I’d have tried again! 

[Alan64]

2 hours ago, Ian McCallum said:

The collimation on the 200P is okay, just my memory that's faulty. 🙄

It's towards the higher end of the magnification scale, where I get larger but indistinct images, as you'd expect... I'm thinking for example of the 5mm eyepiece and smaller, etc. 

Perhaps it's time to look at the bigger DOB's again... 🤔

I don't know if the question has been asked: have you ever owned or observed through a refractor?

I've seen globular-clusters through this wee 50/600 achromat...

But for those who have never experienced a refractor, 80mm is the minimum to suggest; yea, even a 70mm is praiseworthy...

A reasonably-priced gamble...

https://www.firstlightoptics.com/evostar/sky-watcher-capricorn-70-eq1-refractor.html

[Ian McCallum]

6 minutes ago, Alan64 said:

I don't know if the question has been asked: have you ever owned or observed through a refractor?

I've seen globular-clusters through this wee 50/600 achromat...

But for those who have never experienced a refractor, 80mm is the minimum to suggest; yea, even a 70mm is praiseworthy...

A reasonably-priced gamble...

https://www.firstlightoptics.com/evostar/sky-watcher-capricorn-70-eq1-refractor.html

Nope.🙁

[Alan64]

20 minutes ago, Ian McCallum said:

Nope.🙁

Refractors differ from reflectors(Newtonians, Newtonian-Dobsons, Cassegrains) , and in very important ways.  Don't think for a moment that you have to have an 8" or 12" refractor, which has nothing whatsoever to do with price, absolutely not, for the refractive experience stands alone, and regardless of aperture.

I have reflectors, several types, up to 150mm in aperture.  I have a Newtonian at 200mm, but I've yet to observe with it.  But there's just something about my refractors that keeps me coming back for more, from the beginning, to the end...

Smaller refractors are more fun than you can imagine.

Edited September 30, 2021 by Alan64

[johninderby]

I think it’s simply that sometimes I prefer the views through a refractor and nothing to do with the fact that a bigger reflector may actually give better views the refractor simply is the one I prefer sometimes IE: forget logic. 😁

125 APO and an 8” CC on the AZ100 make a great combo. 👍🏻👍🏻👍🏻

[mikeDnight]

I know the following is labouring the point that a good 4" refractor is a very capable instrument, and I can hear some seasoned SGLers mumbling "here he goes again"!  but I can't help myself. The first image compares the view of Mars on the same night as seen through an 200mm F6 Newtonian followed by that observed through a 100mm refractor.

100mm refractor and Jupiter:

100mm refractor and the Moon:

Here's a lunar sketch using a 10" F6 reflector:

100mm refractor on brighter deep sky and comets:

Here are some of the telescopes through which the above sketches were made:

250mm F6 reflector

Below the 200mm reflector used in the first Mars sketch:

And finally the 100mm refractor both in an observatory and as an easily portable grab and go:

Whatever you do, don't let me try and influence you!!! 

Edited September 30, 2021 by mikeDnight