Skywatcher 'Fracs a few questions & thoughts

[SiriusB]

Been a while since i've posted....

Seriously hankering for a larger 'Frac. Yes i know i could save money & have better views with a 200p or something, but i like fracs.

 

First the questions,

Anyone who's ever owned the Acromatic Evostar 150 f8 & the 120 f8,3. Can you quantify how much worse the CA is in the 150?

 The 120. f8 creates no unacceptable CA problems for my eyes. It's there but only on afew targets is it am issue.

Own or have owned, ST80,ST102,ST120,Evo120,omni120 xlt,80ED,skymax127.

For planets @ medium+ mag only the ST120 failed to give acceptable (sharpish/ acceptable CA) views~for me at least.

Also tube dia of  Evostar 150 & Evostar 150ed please? (oversize tubes good IMO eg 80ED)

How's the evostar 150 on an eq5 for visual use?

Had evo120/eq5 about 15+yr ago,(ali tripod)seems the tripod stability much improved on current offering.

Now a few thoughts.

I could go out & blow some serious cash,but i'm a cheapskate & @ end of day it is only a hobby, not a profession!

 

ED120 about 5x £ of Evostar 120

ED150 about 3x £ of Evostar 150. ED150 An absolute bargain?

Longstanding visual  DSO fan, now erring towards planetary/lunar.

Few thoughts on some skywatcher fracs.

ST80~ amazing for the money,great travel scope if you have access to darkish skies.

ST102~ slightly disappointing DSO wise, ED80 very close. I was suprised how well it performed for planetary/Lunar however (theoretically it shouldn't!)

ST120~ poor on planets,nice low to med lunar, my favourite DSO scope,though pretty much a one trick pony. Always 1st out the house on a clearish,darkish night.

ED80~ Visually,amazing for it's size~ mine must have been one of 1st in country(blue tube) back in 2003. Will never sell this scope! But it is only 80mm.

Evostar120/omni xlt120 A good general purpose workhorse, Some of my most memorable nights have been with a 120 f8.3. More for the backyard than jaunts out into the country however.

 

Any thoughts/help please folks?

 

ED120 not worth 5x an evostar 120 to me, maybe ED150 worth 3x an evostar 150 ?😉

 

 

 

 

 

 

[wormix]

Following with interest - I’m considering trading my 150pds for an 80ED as I like the portability / storability of the frac 

Be interesting to see others comments. 

[John]

This chart shows an assessment of the CA levels that achromats generate which might answer some of your queries:

It's not just about the CA with achromats. Quite a few also have spherical aberration, being either over or under corrected to some degree. Generally ED doublets (at least the ones that I've owned and used) are better corrected for SA as well has having lower levels of CA. SA impacts the scopes performance at higher magnifications.

Achromatic refractors can still be good  scopes to own and use though 

The "is it worth it question" is a personal one in my opinion. Each of us will have their own answer to that

 

 

[SiriusB]

Ok, thanks John.

So from chart CA of 150 f8 approx similar to 102 f5 or about 1/3 more than the 120 f8.3.

Not great, but i coped with the 102 f5.

[John]

Sounds about right.

@cotterless45 gets some great views with his 150mm F/8 - look out for his reports in the observing section

[SiriusB]

22 minutes ago, wormix said:

Following with interest - I’m considering trading my 150pds for an 80ED as I like the portability / storability of the frac 

Be interesting to see others comments. 

It is only an 80mm scope, but with dark skies; especially.....seems to punch above it's weight.

Much loved by the imagers(if you ever got that bug)

I fell in love after reading an ancient Ed Ting review of the Orion USA version. (same scope, different brand) Try to track that down on the web.

As soon as I heard Skywatcher had released it in UK, I bought one. £300 if i recall correctly, 16+ years ago, no accessories, not even tube rings,just a horrible camera tripod mounting block!

So....

https://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-ds-pro-outfit.html

Is a pretty good deal all these years later. (looks a lot better now too!)

Depends what you want it for, but for me it will always be a keeper.

[SiriusB]

12 minutes ago, John said:

Sounds about right.

@cotterless45 gets some great views with his 150mm F/8 - look out for his reports in the observing section

Thanks again John, will do!

[mikeDnight]

1 hour ago, SiriusB said:

Been a while since i've posted....

Seriously hankering for a larger 'Frac. Yes i know i could save money & have better views with a 200p 

 

ED120 not worth 5x an evostar 120 to me, maybe ED150 worth 3x an evostar 150 ?😉

 

First, it depends how you define"better views".  Brighter yes, but I've seen many smaller aperture refractors show noticeably better definition and sharper views that leave the 200p lagging obviously behind.

As for the 120ED vs 120 evostar, with regard to lunar and planetary  the 120ED is truly in a whole different league. And even on deep sky the 120ED is sharper and brighter, so it might be a mistake to side line it at this stage.

[SiriusB]

14 minutes ago, mikeDnight said:

First, it depends how you define"better views".  Brighter yes, but I've seen many smaller aperture refractors show noticeably better definition and sharper views that leave the 200p lagging obviously behind.

As for the 120ED vs 120 evostar, with regard to lunar and planetary  the 120ED is truly in a whole different league. And even on deep sky the 120ED is sharper and brighter, so it might be a mistake to side line it at this stage.

Duly noted Mike.

Had a 200p on loan, thought the views were pretty good. Certainly excellent bangs for your buck.

Found the locating & tracking of objects less than exciting, all down to personal preference i guess.

For me, EP needs to be @ bottom of tube & need some  slow-mo's whether it's, alt-az or Eq.

Re ED120, if i were to spend >£1k I might as well splurge the extra for an ED150,unless i'm missing something?

Still hoping an achro 150 might scratch the itch.....

for less £.

Still waiting for an appraisal on eq5/ 150 ota visual viability, as being of the old school a non goto mount is pretty much essential.

Can you de-goto & manual slo mo a heq5/ eq6 i wonder? 

@ My last home location, seeing seemed to get pretty shaky @ =>120mm,(in hollow) current home location is looking more promising thus far.... might justify extra aperture?

 

[Timebandit]

 

The 120ED should not be ruled out. Optics are very sharp especially on luna and planetary. Great at handling CA and for DSO then the extra aperture is useful. Can be mounted on a half decent mount, so you do not need at heavy duty expensive Mount. Got mine on a AZ4 and works just great for me. Also the SW 120ED do come up second hand and can be had for very sensible money for such a high quality refractor, quite a saving can be made from purchasing a new one. Do not rule out the 120ED very capable and very affordable used, for such a capable refractor. 

[mikeDnight]

8 hours ago, SiriusB said:

Duly noted Mike.

Had a 200p on loan, thought the views were pretty good. Certainly excellent bangs for your buck.

Found the locating & tracking of objects less than exciting, all down to personal preference i guess.

For me, EP needs to be @ bottom of tube & need some  slow-mo's whether it's, alt-az or Eq.

Re ED120, if i were to spend >£1k I might as well splurge the extra for an ED150,unless i'm missing something?

Still hoping an achro 150 might scratch the itch.....

for less £.

Still waiting for an appraisal on eq5/ 150 ota visual viability, as being of the old school a non goto mount is pretty much essential.

Can you de-goto & manual slo mo a heq5/ eq6 i wonder? 

@ My last home location, seeing seemed to get pretty shaky @ =>120mm,(in hollow) current home location is looking more promising thus far.... might justify extra aperture?

 

I had a SW 150 F8 (Helios) for years and it was very nice. The CA didn't really bother me, in fact I thought it was pretty well controlled considering the scopes short F ratio. Three of my friends bought the 150 F5 version, which was terrific as an RFT/comet seeker and in many ways hard to beat. I though, wanted the F8 as I wanted a more general purpose scope that would perform well for lunar and planetary viewing. One evening though, while at my local astro club, someone with a twisted sense of humour decided it would be good to pit the 150mm F8 refractor against a Vixen FL102  fluorite apo. The target was Saturn and the 102mm Vixen left the 150 Helios in the dust. The level of fine detail in the Vixen simply wasn't there in the Helios. However, as a rich field comet seeker, the 150mm F8 achromat was spectacular. Deep sky in the 150mm was gorgeous, and galaxies, tiny globulars I'd never seen before, and nebulae just glided effortlessly into its field of view. The Orion nebula put on quite a show, displaying a beautiful pearlescent green hue, and the spiral structure to the Whirlpool galaxy M51 was seen with ease from a dark site, as was the bridging arm linking it to its satellite galaxy. Horses for courses I suppose! Comets were my first love and for years i anchored after a nice 6" F8 achromat, a desire fuelld after reading Leslie C. Peltiers Starlight Nights.

My 150mm F8 was mounted on an EQ4, which just about handled the tube, although the Chinese tripod was not really up to the task. I later replaced the tripod for one that was much more substantial. Ideally though, such a scope would come into its own mounted on a good altazimuth.

[SiriusB]

2 hours ago, mikeDnight said:

I had a SW 150 F8 (Helios) for years and it was very nice. The CA didn't really bother me, in fact I thought it was pretty well controlled considering the scopes short F ratio. Three of my friends bought the 150 F5 version, which was terrific as an RFT/comet seeker and in many ways hard to beat. I though, wanted the F8 as I wanted a more general purpose scope that would perform well for lunar and planetary viewing. One evening though, while at my local astro club, someone with a twisted sense of humour decided it would be good to pit the 150mm F8 refractor against a Vixen FL102  fluorite apo. The target was Saturn and the 102mm Vixen left the 150 Helios in the dust. The level of fine detail in the Vixen simply wasn't there in the Helios. However, as a rich field comet seeker, the 150mm F8 achromat was spectacular. Deep sky in the 150mm was gorgeous, and galaxies, tiny globulars I'd never seen before, and nebulae just glided effortlessly into its field of view. The Orion nebula put on quite a show, displaying a beautiful pearlescent green hue, and the spiral structure to the Whirlpool galaxy M51 was seen with ease from a dark site, as was the bridging arm linking it to its satellite galaxy. Horses for courses I suppose! Comets were my first love and for years i anchored after a nice 6" F8 achromat, a desire fuelld after reading Leslie C. Peltiers Starlight Nights.

My 150mm F8 was mounted on an EQ4, which just about handled the tube, although the Chinese tripod was not really up to the task. I later replaced the tripod for one that was much more substantial. Ideally though, such a scope would come into its own mounted on a good altazimuth.

Thankyou Mike,

                           That's exactly the sort of helpful personal experience that could help me or others avoid a poor choice & buying twice(or more). 👍 SGL.

So from What you & others have input so far:

Could 'get away with' a 150 f8 on a EQ5.

Need to weigh up the balance of DSO vs Planetary observing. vs how much i'm prepared to spend.

A smaller ED would be more fulfilling on planetary/lunar observing  than the big achro.

Sounds like a 120 ED would be snapping close at the heels of the Evostar 150 even on DSO?

[John]

10 hours ago, SiriusB said:

...Re ED120, if i were to spend >£1k I might as well splurge the extra for an ED150,unless i'm missing something?

 

Be aware of the size difference and therefore mounting requirements of the ED150. The gold scope is my ED120. An EQ5 is right at it's limit (even with the steel tube legs) of a 150mm F/8. I used a driven CG5 (EQ5 with 2 inch steel tube legs) with the 150mm F/8's that I owned (I've owned 3 or 4 over the years) and that was just about OK. Probably a motorised focuser would have helped keep vibration down more. The get the most from a 150m F/8 refractor something more substantial is needed really such as an HEQ5. The Celestron AVX is a bit more sturdy than the EQ5 and has 2 inch steel tripod legs.

 

[dweller25]

I had a 150 F/8 helios refractor on a Vixen GPDX and it was only just ok - an EQ5 would not be very stable whilst focusing at high power.

I also found CA was too much for me and none of the CA filters helped much.

A 7” Mak - which is a folded frac 🤪 would be a better option perhaps ?

Edited July 12, 2020 by dweller25

[John]

7 minutes ago, dweller25 said:

I had a 150 F/8 helios refractor on a Vixen GPDX and it was only just ok - an EQ5 would not be very stable whilst focusing at high power.

I also found CA was too much for me and none of the CA filters helped much...

 

I reached similar conclusions here eventually.

The best "big achromat" experience that I had was with the Bresser 127L which is F/9.4 so not a lot of CA really and pretty well corrected.

[SiriusB]

4 hours ago, John said:

Be aware of the size difference and therefore mounting requirements of the ED150. The gold scope is my ED120. An EQ5 is right at it's limit (even with the steel tube legs) of a 150mm F/8. I used a driven CG5 (EQ5 with 2 inch steel tube legs) with the 150mm F/8's that I owned (I've owned 3 or 4 over the years) and that was just about OK. Probably a motorised focuser would have helped keep vibration down more. The get the most from a 150m F/8 refractor something more substantial is needed really such as an HEQ5. The Celestron AVX is a bit more sturdy than the EQ5 and has 2 inch steel tripod legs.

 

That ED120 looks tiny! ( but i know it's not.)

   Thanks again John, the practicalities of lugging a 150 in & out regularly start to become apparent.

Maybe better for those with an obsy.

[SiriusB]

4 hours ago, dweller25 said:

I had a 150 F/8 helios refractor on a Vixen GPDX and it was only just ok - an EQ5 would not be very stable whilst focusing at high power.

I also found CA was too much for me and none of the CA filters helped much.

A 7” Mak - which is a folded frac 🤪 would be a better option perhaps ?

 

4 hours ago, John said:

I reached similar conclusions here eventually.

The best "big achromat" experience that I had was with the Bresser 127L which is F/9.4 so not a lot of CA really and pretty well corrected.

When you're trying to make a decision, always one or more people throw something extra into the mix 😃

Worth mulling the extra options over.

I'm now better informed thanks to SGL members, but no more clear on deciding!