SW 120ed v Starfield 102

[IB20]

I do think the 5” frac is the one. If you go smaller you may always think what if, where you’re less likely to do that if you got a 5”. IME the mounting requirements between the 102ED & 120/125mms were no different.

[Flame Nebula]

12 minutes ago, russ said:

Also remember, what ever you decide to go with, it will be the wrong choice. It's a given. A couple of months or year down the road, you're start getting niggling doubts that you should have taken a different route. Then it starts all over again. It happens to us all.  

Maybe, it is a necessary path to travel on the road to enlightenment? 

[dweller25]

10 minutes ago, IB20 said:

I do think the 5” frac is the one. If you go smaller you may always think what if, where you’re less likely to do that if you got a 5”. IME the mounting requirements between the 102ED & 120/125mms were no different.

Just a data point here….

I have a 100mm F/8 refractor that sits happily on a Vixen GP (similar to a SW EQ5) mounted  on a Berlebach UNI28.

I tried my 120mm F/7.5 refractor on the Vixen GP/Berlebach combo and it was too unstable for high power planetary.

Edited March 28 by dweller25

[dweller25]

4 minutes ago, Flame Nebula said:

Maybe, it is a necessary path to travel on the road to enlightenment? 

True, But to save you some time and money…..

I have had many telescopes and all the different types and the only scope type I would recommend as truly sharp is a refractor.

But that is just me 🤣

Edited March 28 by dweller25

[IB20]

1 minute ago, dweller25 said:

True, But to save you some time and money - I have had many telescopes and all the different types and the only scope type I would recommend is a refractor.

But that is just me 🤣

Agree, if I had my time again and I had all the money I’d spent on scopes, I’d go for the TSA120. I wouldn’t even think about a reflector.

[Flame Nebula]

16 minutes ago, dweller25 said:

True, But to save you some time and money…..

I have had many telescopes and all the different types and the only scope type I would recommend as truly sharp is a refractor.

But that is just me 🤣

I think a 5" Refractor is now solidifying. The remaining fly in ointment is satisfactory planetary AP. 

[John]

14 minutes ago, dweller25 said:

Just a data point here….

I have a 100mm F/8 refractor that sits happily on a Vixen GP (similar to a SW EQ5) mounted  on a Berlebach UNI28.

I tried my 120mm F/7.5 refractor on the Vixen GP/Berlebach combo and it was too unstable for high power planetary.

On an alt-azimuth tack, I use my ED120 on a Skytee 2 or Giro Ercole on a Uni 28 and it's very steady even at 300x. 

On sharp vs mushy, I use my ED120 for outreach at my astro society regularly and the experienced members (mostly newt or SCT owners) often comment how sharp the planets look through the ED120.

If I didn't have the ED120 or the 130mm triplet I would be looking very hard at either a Stellalyra 125 ED doublet or a TSA 120 if I could stretch to one. 4.7-5 inches is a very nice aperture for a quality refractor in terms both of performance potential and relative ease of use🙂

 

[Flame Nebula]

Just now, Flame Nebula said:

I think a 5" Refractor is now solidifying. The remaining fly in ointment is satisfactory planetary AP. 

Perhaps a used C9.25 is worth a punt for that. 

[Elp]

28 minutes ago, Flame Nebula said:

satisfactory planetary AP

Define this. You do realise the output is largely dependent on your post processing skills?

[Flame Nebula]

5 minutes ago, Elp said:

Define this. You do realise the output is largely dependent on your post processing skills?

OK, so I would like to be able to see the Encke gap. I won't use the word resolve, as I think it may be correct, but if you look at Saturn images, you will see what I mean. I have seen C8 scopes do it, but usually it is most obvious from images taken in C9.25 and larger and Newts at 10" or higher. Now, taking your point, I often see a wide range of images with same scope, some better than others, and that will be where the user comes in, and to some extent the seeing, although I understand this has much less effect in planetary  AP. Going to jupiter, similarly, I'd like a scope capable of showing the various festoons, e.g. the white oval ones in southern hemisphere. Hope this gives you an idea of what the scope should be capable of: whether my processing skills will be good enough is another matter. 🤔😉

[Elp]

You need the aperture then. There's a reason Damien Peach is one of the world's best.

But you do need good seeing to support the aperture and I believe the larger you go the more problematic it becomes and you'll hit a limit depending on the sky conditions.

Edited March 28 by Elp

[dweller25]

I think Damian Peach does a lot of his imaging from some of the premium seeing sites all over the world ?

Edited March 28 by dweller25

[Elp]

5 minutes ago, dweller25 said:

I think Damian Peach does a lot of his imaging from some of the premium seeing sites all over the world ?

Hence my point about seeing. I've read it a few times that UK skies are suited to 8 inch or so, don't know if there's any truth to that as people are using larger.

Edited March 28 by Elp

[John]

When I've occasionally experienced truly excellent seeing conditions, while the scope that I happened to be using at that time (different designs over the years) showed superb planetary views, I got the feeling that practically any scope would also be excelling under such conditions. 

It always concerns me a little when someone is looking for some sort of "guarantee" of what they will be able to see or image. There are so many factors involved and only a few of them relate to the telescope used. Suiters "wobbly stack" concept illustrates this I think, even if we debate the relative impact of the various components within it.

Make a decision, acquire the chosen equipment, familiarise yourself with it's operation then devote everything you have to using it as often as possible on a wide variety of targets / uses and under a variety of conditions. Practice, practice, practice, there is no substitute for it 🙂

 

Edited March 28 by John

[Flame Nebula]

29 minutes ago, John said:

When I've occasionally experienced truly excellent seeing conditions, while the scope that I happened to be using at that time (different designs over the years) showed superb planetary views, I got the feeling that practically any scope would also be excelling under such conditions. 

It always concerns me a little when someone is looking for some sort of "guarantee" of what they will be able to see or image. There are so many factors involved and only a few of them relate to the telescope used. Suiters "wobbly stack" concept illustrates this I think, even if we debate the relative impact of the various components within it.

Make a decision, acquire the chosen equipment, familiarise yourself with it's operation then devote everything you have to using it as often as possible on a wide variety of targets / uses and under a variety of conditions. Practice, practice, practice, there is no substitute for it 🙂

 

Very true John, 

Although I must point out that I'm not looking for any guarantees, even if it may come across that way 😉, and I can understand it might. 

I'm looking for a 'balance of probabilities', based on gathering as much data as I can from reviews, speaking to knowledgeable people such as yourself and looking at lots of images. I know there is no guarantee (this applies to many things in life), but I also know from years of experience that lack of preparation usually leads to failure too. 😉

I am grateful for your advise and everyone else here, and for all your patience! 👍😊

 

[mikeDnight]

On 28/03/2024 at 16:33, Flame Nebula said:

OK, so I would like to be able to see the Encke gap. I won't use the word resolve, as I think it may be correct, but if you look at Saturn images, you will see what I mean. I have seen C8 scopes do it, but usually it is most obvious from images taken in C9.25 and larger and Newts at 10" or higher. Now, taking your point, I often see a wide range of images with same scope, some better than others, and that will be where the user comes in, and to some extent the seeing, although I understand this has much less effect in planetary  AP. Going to jupiter, similarly, I'd like a scope capable of showing the various festoons, e.g. the white oval ones in southern hemisphere. Hope this gives you an idea of what the scope should be capable of: whether my processing skills will be good enough is another matter. 🤔😉

 Imaging or visually observing the Encke gap may be difficult at present due the the current angle of Saturn's rings. Not many know this, but when the rings are fully open, linear features such as the Encke gap (not to be confused with the minima) - although technically beyond resolution - is entirely observable visually in the anse through a good 5" scope as a fine dark division about a quarter to a third of the way in from the outer edge of the A ring on a night of good seeing. 

Edited March 29 by mikeDnight

[Flame Nebula]

27 minutes ago, mikeDnight said:

 Imaging or visually observing the Encke gap may be difficult at present due the the current angle of Saturn's rings. Not many know this, but when the rings are fully open, linear features such as the Encke gap (not to be confused with the minima) - although technically beyond resolution - is entirely observable visually in the anse through a good 5" scope as a fine dark division about a quarter to a third of the way in from the outer edge of the A ring on a night of good seeing. 

Hi Mike, 

Interestingly, I was actually reading an old post of yours, where you reported that, and vlaiv's interesting response. 

[Flame Nebula]

On 28/03/2024 at 14:45, bosun21 said:

Three years! And you still haven't decided. If I were you I would narrow it down to the serious contenders, then list their pros and cons. Any reviews you read for the said telescopes try and ensure that they are from experienced observers. Even on this forum while I read every comment on equipment purchase and observing results etc, I only ingest and allow myself to be guided by those comments coming from experienced members whose many years at the eyepiece with different scopes forms the basis of their knowledge. I'll say it once again. If you can allow for the cool down time of an 180mm Maksutov then you will have the closest to apo refractor performance in my experience. They are sharper both for visual and planetary imaging than an SCT. They are also good for doubles. They are also compact and easy to transport. The other choice you mention is the ED120 or the SM125. Buying new then the 125 would be my choice simply for the extra 5mm aperture and the better 2.5" R&P focuser fitted as standard. When I'm personally deciding on buying a new telescope  it's on the particular model I'm purchasing, as I have decided on scope design and manufacturer some time prior. I also am a planetary enthusiast and have viewed and imaged the planets with refractors (both apo & achro), reflectors, SCT's as well as Maksutovs. The best views were from my 4" apo refractor with lovely colours and sharpness all round. The Maksutovs (once cooled) were snapping at the heels of the refractors along with the Newtonians. Slightly behind the Newts came the SCT's solely due to the views being softer. As you increase aperture the playing field changes in my opinion. Ideally we would just want to increase the size of our apo refractor scope but cost throws a proverbial spanner in the works. For planetary imaging then it's all about resolution to tease out the details on the planets surface which means aperture basically. For this reason it's large Newts and SCT's that are the scopes of choice. As you are already aware the seeing conditions here in the UK hinders the performance we can achieve with larger apertures. So I have found it to be something of a balancing act between conditions and equipment regarding the planets. I have captured images of the planets with a 180 Mak that I haven't beaten with a 300mm Newt. I know that this is solely due to the seeing conditions not being conducive to the larger scope.But I have started asking myself am I getting more enjoyment from several nice images with the smaller scope or perhaps the one excellent image (if any at all) from the larger scope. I am now in the smaller scope camp. I think I will settle on my existing 10" go to dobsonian and I will add a 180mm Maksutov onto my AZ-EQ6 for the nights of poorer seeing. Either that or a SM25 apo and I can then open the sky up to a multitude of amazing views and targets. The only thing that I do know for sure at this second is that it won't take me three years to decide. Good luck with whichever avenue you decide to venture down.

Hi Bosun, 

I've been deliberating further, and quite like your idea of a 180 mm mak and 10" Newtonian combo, on a AZ-EQ6 mount. I can see how these would complement each other and be a big jump from my current scopes. I have researched two 10 inchers. The OO 10VX and SW 250pds. I'm favouring the OO, with option of 1/10 wave mirror. I've also discovered that the secondary in the OO is 25%, compared to 29% in SW. I couldn't find the SW secondary diameter mentioned anywhere in specs, but chat gpt tells me 73mm.😉The OO is 3 kg lighter too! I reckon it would go well with AZ mode on mount 

I was wondering what dob you had, and what you think of it, for planetary AP and visual observation? 

Thanks 

Mark 

[bosun21]

I have the SW 10" go to dobsonian which is very good for planetary imaging in my opinion. There are several very good planetary imagers on the forum that use these scopes of varying sizes. The reason that the secondary is larger on the SW PDS and Flextube dobsonians as opposed to the OO  is to allow for a camera to reach focus easily without the need for a barlow etc. Visually they are also very good, and the PDS with a coma corrector fitted makes a competent AP scope. I was actually thinking of getting an OO tube to mount on my AZ-EQ6 but the fact that I already have a new 10" go to dobsonian renders this a mute point.

[Flame Nebula]

29 minutes ago, bosun21 said:

I have the SW 10" go to dobsonian which is very good for planetary imaging in my opinion. There are several very good planetary imagers on the forum that use these scopes of varying sizes. The reason that the secondary is larger on the SW PDS and Flextube dobsonians as opposed to the OO  is to allow for a camera to reach focus easily without the need for a barlow etc. Visually they are also very good, and the PDS with a coma corrector fitted makes a competent AP scope. I was actually thinking of getting an OO tube to mount on my AZ-EQ6 but the fact that I already have a new 10" go to dobsonian renders this a mute point.

OK, thanks Bosun. So, I have to ask; if you didn't have the goto Dob, which one would you go for? 🤔And you mention a coma corrector - this was something I wondered about, as the f ratio is 4.7 (4.8 in the OO), so borderline. Do you need one for visual? As a side note, I read that the 300pds has the same diameter secondary as the 250pds,which would make it only 24%, similar to the OO 10". I've seen superb images of Saturn taken with the SW 300pds on an EQ mount. 

Edited March 29 by Flame Nebula

[bosun21]

The reason that the secondary is the same size in the 300PDS as it is in the 250PDS is due to its longer focal length. 1500mm as opposed to 1200mm. The extra focal length allows the light cone to be narrower. The only reason I would maybe lean towards the OO is for the 1/10th wave mirror and if weight saving is an issue. Some people have experienced flexure with the larger aluminium tubes of the OO. Coma correctors for visual are subjective. Some folk hate any edge of field distortion whereas some folk don't mind too much as they mainly observe on axis. For myself F5 and below benefit from a CC.

[Flame Nebula]

2 hours ago, bosun21 said:

The reason that the secondary is the same size in the 300PDS as it is in the 250PDS is due to its longer focal length. 1500mm as opposed to 1200mm. The extra focal length allows the light cone to be narrower. The only reason I would maybe lean towards the OO is for the 1/10th wave mirror and if weight saving is an issue. Some people have experienced flexure with the larger aluminium tubes of the OO. Coma correctors for visual are subjective. Some folk hate any edge of field distortion whereas some folk don't mind too much as they mainly observe on axis. For myself F5 and below benefit from a CC.

Thanks. Indeed, it is the weight and option of the 1/10 wave. Yes, I heard about the flexure issue. Maybe it wouldn't be too bad with the VX10, as it's not so long as the vx10L. 

[Joe G]

I’ve enjoyed reading about your dilemma & the various interesting responses so far so I thought I throw another suggestion to you. There’s a nice used 4” fluorite refractor going for a bargain on ABS & he might take an ONO which if I didn’t have the Vixen model it would already be on it’s way here now . Test it against your present scopes & if you like it, store it away safely. With the money left over buy whatever you fancy & after a number of years when you’re my age you might find, like me, the 4” scope may be the only one you’ll need 

[Flame Nebula]

5 hours ago, Joe G said:

I’ve enjoyed reading about your dilemma & the various interesting responses so far so I thought I throw another suggestion to you. There’s a nice used 4” fluorite refractor going for a bargain on ABS & he might take an ONO which if I didn’t have the Vixen model it would already be on it’s way here now . Test it against your present scopes & if you like it, store it away safely. With the money left over buy whatever you fancy & after a number of years when you’re my age you might find, like me, the 4” scope may be the only one you’ll need 

Hi Joe, 

Glad you have enjoyed the posts👍

Since the last one, I have to report that I've contracted a serious dose of Bacillus Aperturitis. The symptoms have come on rapidly. I was warned there was a risk, but I kept researching and now...... 😬

I did think the symptoms had plateaued yesterday at 10", but this morning it's progressed to stage 2, 12". 😞

I don't know if there's a cure now, but this could be chronic. 

I suspect the only cure now, will be to accept my fate, get a 12" and then as the fever recedes, and clarity returns, I'll be ready for 4-5 inches of apo sanity. 😀😜

Mark

Edited March 30 by Flame Nebula

[Louis D]

It can be a slippery slope if not treated properly.  This poor chap named Mike Clements in Utah is reportedly suffering from the worst case of Bacillus Aperturtitis ever documented:

https://archive.sltrib.com/story.php?ref=/sltrib/news/57034821-78/telescope-clements-mirror-inch.html.csp#gallery-carousel-446996

https://jaysastronomyobservingblog.blogspot.com/2013/02/mike-clements-70-inch-reflector.html

Let us all pray he has a full recovery some day.