Is It Worth The Change?

[pbyrne]

Hi everyone.

That feeling we all get in the back of the neck from time to time is causing an itch and I don't know if I should scratch.

My current set up is a 120mm f/5 Skywatcher Startravel with an older 120mm f/8 Evostar for lunar and solar work.  I have seen the Explore Scientific 127mm ED Apo, f/7.5 and my mind is starting to wander and the credit card is whining in my wallet.  

https://www.telescope.house/en/Telescopes/EXPLORE-SCIENTIFIC-ED-APO-127mm-f-7-5-FCD-1-Alu-2-R-P-Focuser.html

I can hear many people out there asking why not consider a reflector, but I am a refractor guy and it's a lens for me.

My current scopes display a lot of CA on the brighter objects, Moon, Venus, Sirius, Vega, etc. and the thoughts of colour free views is very tempting.

My fields of interest are deep-sky and double stars.  I know that the ES will have superior optics to the Skywatcher, but is it worth forking out the cash for an extra 7mm and better optics?

Any thoughts are most welcome.

 

Edited June 27, 2020 by pbyrne

[John]

What mount do you have in mind ?

These 5 inch triplets are quite heavy and long scopes - they need stout mounts.

If you need to buy another mount as well, it would well skew the equation somewhat.

 

[pbyrne]

Skytee II mount.

[John]

The Skytee II might be OK. Depends how fussy you are about stability.

On the double stars I think the 127mm triplet will be better than your current scopes. On the deep sky, the 7mm over your 120mm F/5 will make a slight difference but the scope will be a lot heavier, longer and will take longer to cool down than the 120mm achromat.

If you go for the triplet 127, make sure you have a good returns policy. If the collimation is knocked out of whack in transit it's a specialist job in sorting it out.

 

 

 

[mikeDnight]

Even if you changed to a SW 120ED F7.5 doublet apo, you will gain a great deal in performance over both your achromats, both in colour correction and in magnification range. The 120ED is an amazing visual scope.

[cloudsweeper]

12% more light gathering - not a lot!  And the triplet will be heavier and take more cooling.  For doubles and DSOs, the CA won't be a problem.  (I don't find it a problem anyway with my achros.)

Not sure what the focuser on the Evostar is, but the one on the ST is not great.  If you think the focuser on the ES is better, that would be a strong consideration.  (The focuser on my little ES ED80 Triplet is a lovely DS R&P.)

Would it be much better than the Evo for the money?  The choice is yours, Paul!

Doug.

 

[Shimrod]

12 hours ago, pbyrne said:

Hi everyone.

That feeling we all get in the back of the neck from time to time is causing an itch and I don't know if I should scratch.

My current set up is a 120mm f/5 Skywatcher Startravel with an older 120mm f/8 Evostar for lunar and solar work.  I have seen the Explore Scientific 127mm ED Apo, f/7.5 and my mind is starting to wander and the credit card is whining in my wallet.  

https://www.telescope.house/en/Telescopes/EXPLORE-SCIENTIFIC-ED-APO-127mm-f-7-5-FCD-1-Alu-2-R-P-Focuser.html

I can hear many people out there asking why not consider a reflector, but I am a refractor guy and it's a lens for me.

My current scopes display a lot of CA on the brighter objects, Moon, Venus, Sirius, Vega, etc. and the thoughts of colour free views is very tempting.

My fields of interest are deep-sky and double stars.  I know that the ES will have superior optics to the Skywatcher, but is it worth forking out the cash for an extra 7mm and better optics?

Any thoughts are most welcome.

 

 

I can't help on the scope, but I did notice that the UK website has a number ex-display ES 127mm ED Apo at just over £1,064 (1,170 EUR). At that price you could probably buy, and if it doesn't work out, you can probably sell on for not much of a loss.   TelescopeHouse ex-display

Edited June 28, 2020 by Shimrod

[Timebandit]

 

 

Save yourself some money and get yourself a nice second hand SW 120ED ,a great scope in my opinion, otherwise I would not own one 🙂. For doubles, Luna, planetary and some DSO this scope would be ideal. 

And the money you will save by getting a used SW120ED . Then for the fainter DSO then look at getting yourself a decent size aperture reflector .I know you say you are not a reflector chap. But bang for buck especially on fainter DSO then aperture with dark Sky's are where it is at. I personally prefer my refractor views on targets also. But on fainter DSO then aperture wins and  will show you so so much more, and bang for buck this means a reflector .

 

[mikeDnight]

The 127ED is a great scope but it will take 45 minutes to cool when taken out from a warm house on a winter night. The 120ED will take around 15 minutes. Also, the 127 is a bit of a beast and needs a solid mount, but visually it is excellent. I've attached a pic of a friend of mine with his 127ED to give an idea of the physical size.  My friend tried to talk me into doing a swap for my 120ED after he used his scope alongside mine, but I didn't bite. The 120ED was much more manageable and just as colour free when in focus.

[dweller25]

Well @pbyrne

As you said “any thoughts are welcome” ........

For deep sky/lunar and planetary a 10” Dob :

https://www.firstlightoptics.com/bresser-telescopes/bresser-messier-10-dobsonian-telescope.html

And for double stars/lunar and solar a long focal ratio refractor :

https://www.firstlightoptics.com/scopetech-telescopes/scopetech-stl-80a-maxi-80mm-f15-classical-refractor.html
 

That’s £964 for the pair 😀

However of the two scopes you mentioned I would chose the lighter, cheaper, quicker cooling 120ED doublet.

Edited June 28, 2020 by dweller25

[niallk]

For less money you could get a 12" and gain 2 orders of magnitude over a 120mm for DSOs 😮  Yeah I know you say you don't like a mirror, but if DSOs are a favourite a mirror is hard to beat.

[mikeDnight]

18 hours ago, pbyrne said:

I can hear many people out there asking why not consider a reflector, but I am a refractor guy and it's a lens for me.

[John]

If my main field of interest was the deep sky I would go for a reflector every time. I can't afford, house or handle the sort of aperture in refractors that I can in reflectors.

12" in reflector:

12 inch refractor:

[pbyrne]

Thanks for the responses.  I am liking what I am hearing about the Skywatcher 120ED and I will keep my eye open for any second hand options.

[dweller25]

There is also the SW 150ED......

https://www.firstlightoptics.com/pro-series/sky-watcher-evostar-150ed-ds-pro-ota.html

[AstroPhil]

Bit more pricey, but the WO equivalent is an option I have my eye on myself:

https://www.firstlightoptics.com/william-optics/william-optics-zenithstar-126-apo-telescope.html

 

[John]

The price is rising !

We started with a circa £1K scope 

I have a Skywatcher ED120 and it is a fine scope. Compares well with my much, much more expensive Takahashi 100 fluorite doublet and TMB/LZOS 130 triplet.

You can get the ED120's in nice pre-owned condition for £600-£700.

 

 

[dweller25]

18 minutes ago, John said:

The price is rising !

We started with a circa £1K scope 

 

 

That’s OK - it’s not our money 😂😂😂

Edited June 28, 2020 by dweller25

[Timebandit]

5 hours ago, niallk said:

For less money you could get a 12" and gain 2 orders of magnitude over a 120mm for DSOs 😮  Yeah I know you say you don't like a mirror, but if DSOs are a favourite a mirror is hard to beat.

 

If you have a mirror diagonal in the refractor, then you are introducing a mirror into the optical chain of your refractor anyway, so may as well look at a reflector 🙈🙊🙉 

 

 

 

3 hours ago, John said:

If my main field of interest was the deep sky I would go for a reflector every time. I can't afford, house or handle the sort of aperture in refractors that I can in reflectors.

12" in reflector:

 

 

That's a nice grab and go set up for your dark site trips away 😁

 

 

[Dippy]

3 hours ago, John said:

If my main field of interest was the deep sky I would go for a reflector every time. I can't afford, house or handle the sort of aperture in refractors that I can in reflectors.

12" in reflector:

12 inch refractor:

John, is that a kitchen knife magnet at the bottom of your 12” Dobsonian telescope ? What kind of weights and what size you add to it to balance the tube?

[mikeDnight]

2 hours ago, Timebandit said:

If you have a mirror diagonal in the refractor, then you are introducing a mirror into the optical chain of your refractor anyway, so may as well look at a reflector 🙈🙊🙉 

If you use an eyepiece, not to mention a coma corrector, in a reflector, then you might as well consider a refractor. Prisms are better anyway in F7 and above. 

 

 

[niallk]

2 hours ago, mikeDnight said:

If you use an eyepiece, not to mention a coma corrector, in a reflector, then you might as well consider a refractor. Prisms are better anyway in F7 and above. 

 

 

... don't prisms work by total internal reflection?!! 😂😜

Sorry, couldn't resist 😁

[Alien 13]

Reflectors will always be hybrid refactors unless someone invents an eyepiece using mirrors, lots of people especially in Japan use refactors "straight through" so no contamination there 

Alan

[mikeDnight]

1 hour ago, niallk said:

... don't prisms work by total internal reflection?!! 😂😜

Sorry, couldn't resist 😁

And yet, unlike mirror diagonals, they have virtually no scatter effect and so produce better defined and more contrasty views. 😊

[bomberbaz]

21 hours ago, mikeDnight said:

The 127ED is a great scope but it will take 45 minutes to cool when taken out from a warm house on a winter night. The 120ED will take around 15 minutes. Also, the 127 is a bit of a beast and needs a solid mount, but visually it is excellent. I've attached a pic of a friend of mine with his 127ED to give an idea of the physical size.  My friend tried to talk me into doing a swap for my 120ED after he used his scope alongside mine, but I didn't bite. The 120ED was much more manageable and just as colour free when in focus.

blooming heck that's a beastie for a 127, never realised they were quite that big. I am so glad I resisted the temptation to got for one a while back.