Skywatcher Startravel 120 advice

[Olli]

Hello again,

after settling on a dobsonian I think I’ve decided not to get one, and I have come across the Skywatcher  Startravel 120. This looks like a good telescope especially for wide FOV,and seems like a good grab n go scope too. However I have a few questions that I would like to ask and no better place then to ask them here  

1. People have said that there is noticeable CA when using these types of scopes. How much of a problem is this? and are there any filters that are available that can reduce the CA if I find it a problem?

2. The last question I have for this scope is on FLO they are doing a deal with the 120 on a AZ3 mount.One of the reviews (well the only review ) said that they had found it wobbly on the AZ3 Mount and decided to get an AZ4. Is this necessary or is it capable with the AZ3 Mount if it’s only for visual.

here is the link to FLO for the set up I’m looking at  https://www.firstlightoptics.com/startravel/skywatcher-startravel-120-az3.html 

Would also like your feedback on the scope too if possible 

Thanks in advance  

[alanjgreen]

The tripod is not very good. This £279 bundle includes a £239 scope!! (and therefore the tripod for £40) . So the opposite of the AZ5 and pronto bundles, where the mount is all the money and they throw in a starter scope. This one is a good scope and a starter tripod. The AZ3 will keep you going for a few months but this is not a long term combo for success in my opinion.

The AZ3 has a max capacity of 5kg. The 120 is 4.1kg. Once you add a diagonal and eyepiece and finder then thats about the max.

Some ideas in here...

 

You would be best buying the new AZ5 and then the 120 OTA on its own.

https://www.firstlightoptics.com/startravel/skywatcher-startravel-120t-ota.html

https://www.firstlightoptics.com/sky-watcher-az5-deluxe/sky-watcher-az5-deluxe-alt-azimuth-mount.html

= £199 + £239

Having had a read around even the AZ5 may struggle with the 120 frac. Need to wait for someone using a 120 frac on a decent AZ mount for advice. You may need a SKYTEE-2 or a VIXEN PORTA2 as these have a higher load capacity and will work fine. Obviously price keeps going up...

Its a case of buy once or keep buying and selling (and losing money) until you are finally happy.

Otherwise, you may be better going for a 102mm frac (available in an AZ5 bundle) depending on overall budget?

https://www.firstlightoptics.com/alt-azimuth/sky-watcher-startravel-102-az5-deluxe.html

 

[NGC 1502]

I’ve never owned a SW 120 / 500, but several years ago I was loaned one by a clubmate. I think all of these short focal length achromats work very well indeed at low to medium powers, especially on dim targets. Use one like that at a dark site and the views can be fabulous, and from town as well, although all telescopes are hampered by light pollution of course.

As to how much the inevitable CA is a problem to you is hard to evaluate, for some it will be acceptable, others may be horrified. The CA is much more of a problem with bright objects. I used the borrowed scope on Jupiter. The CA was indeed very noticeable, but for me the view was still satisfying with quite a lot of surface detail seen. If you take a look at the cost of a 120mm refractor that gets rid of the CA, then that can be even more horrifying.......?

As to the mount, my Astro Tech Voyager was barely adequate.

HTH, Ed.

[Alfian]

I've not used the 120 but had a look at one a couple of years ago and was surprised how big it was for a 120/600. It's owner rated it pretty well for an f5 achromat. I could see that an Az3 would struggle to do it justice. However I have had a Steel legged AZ4 and I could see that would be a good match for the ST120. Note that the 1.75" steel legged tripod makes a very significant contribution to its stability. You can pick a 2nd hand AZ4 up for under £100.

[Olli]

50 minutes ago, alanjgreen said:

The tripod is not very good. This £279 bundle includes a £239 scope!! (and therefore the tripod for £40) . So the opposite of the AZ5 and pronto bundles, where the mount is all the money and they throw in a starter scope. This one is a good scope and a starter tripod. The AZ3 will keep you going for a few months but this is not a long term combo for success in my opinion.

The AZ3 has a max capacity of 5kg. The 120 is 4.1kg. Once you add a diagonal and eyepiece and finder then thats about the max.

Some ideas in here...

 

You would be best buying the new AZ5 and then the 120 OTA on its own.

https://www.firstlightoptics.com/startravel/skywatcher-startravel-120t-ota.html

https://www.firstlightoptics.com/sky-watcher-az5-deluxe/sky-watcher-az5-deluxe-alt-azimuth-mount.html

= £199 + £239

Having had a read around even the AZ5 may struggle with the 120 frac. Need to wait for someone using a 120 frac on a decent AZ mount for advice.

Otherwise, you may be better going for a 102mm frac (available in a bundle)

https://www.firstlightoptics.com/alt-azimuth/sky-watcher-startravel-102-az5-deluxe.html

 

Hi after posting I did  work that out  I have been looking at the 102 also is there a big difference between the two do you know? I may have to get a 102 if the weight is an issue for the mounts which is a shame but I’ll still have a look thanks 

[Olli]

4 minutes ago, Alfian said:

I've not used the 120 but had a look at one a couple of years ago and was surprised how big it was for a 120/600. It's owner rated it pretty well for an f5 achromat. I could see that an Az3 would struggle to do it justice. However I have had a Steel legged AZ4 and I could see that would be a good match for the ST120. Note that the 1.75" steel legged tripod makes a very significant contribution to its stability. You can pick a 2nd hand AZ4 up for under £100.

Thank you, I’ll have a look around on the different mounts. If I put a weight on accessories tray or tie a bag from it and put something heavy would this help?

[JG777]

I had a 120 for a while and as a wide field scope it would serve you very well, that is the scopes strong point. For planets and bright objects the CA was too much for me but it didn't stop the scope revealing good detail, and you may find it acceptable.  It was in competition though with the ED100 pro I had at the time and that was the nicer scope . Forget the mount though an AZ3  just isn't robust enough for a 120 and there are better options. Think carefully before you choose, measure twice and cut once. 

[Olli]

2 minutes ago, JG777 said:

I had a 120 for a while and as a wide field scope it would serve you very well, that is the scopes strong point. For planets and bright objects the CA was too much for me but it didn't stop the scope revealing good detail, and you may find it acceptable.  It was in competition though with the ED100 pro I had at the time and that was the nicer scope . Forget the mount though an AZ3  just isn't robust enough for a 120 and there are better options. Think carefully before you choose, measure twice and cut once. 

Thanks for the advice, this  is exactly why I asked about the mount as I  wasn’t sure . Are there any good filters to reduce the ca I did look on FLO but wasn’t sure which one was suitable, maybe I’ll see how bad it is first if I do get it.

[JG777]

There are filters that claim to reduce CA, I never tried them, the Baader fringe killer is one I believe. Most reports I recall didn't rate them very much. I would say the only real gauranteed solution to CA is a healthy credit card waved at an Apochromatic scope. or save for something better. A second hand semi apo like an ED100 pro can be had second hand for good prices, or even the 120 version although they come around a bit less than 100s. 

[Ben the Ignorant]

Another problem with cheap achromats is the cell is not adjustable, and the lenses are sometimes misaligned. They don't try too build them too well because these scopes have too much chromatic and spherical aberration for high resolution, anyway. Look at this lab report on Sky-Watcher's other large f/5 achro, the 150mm:

http://r2.astro-foren.com/index.php/de/component/content/article/10-beitraege/02-ed-optiken-halb-apos-und-frauenhofer-systeme/793-b096a-skywatcher-150-ota-stratravel-fuer-kometen-sternhauf-und-fotografie

See the two pictures with the mention "Artificial sky test 416-fach" (416x magnification), before and after the "optimierung", the difference is huge. I can adjust a cell equipped with screws, or add these screws, but not everyone wants to get involved in that. At f/10 achromats are very forgiving of slight errors in alignment, but at f/5, they're not.

The scope tested and improved by Rohr has only a 68% quality ratio after the optimization when it should be at least 80% for a basic scope (and 95% for high-end instruments). Good enough for low and low-medium power, these are sold as rich-field scopes, not high resolution scopes.

[Ben the Ignorant]

4 minutes ago, JG777 said:

There are filters that claim to reduce CA, I never tried them, the Baader fringe killer is one I believe. Most reports I recall didn't rate them very much. I would say the only real gauranteed solution to CA is a healthy credit card waved at an Apochromatic scope. or save for something better. A second hand semi apo like an ED100 pro can be had second hand for good prices, or even the 120 version although they come around a bit less than 100s. 

True, but there are also 100mm semi-apo scopes with 51 glass instead of 53 glass, and an f/7 ratio instead of f/9. Less costly and more panoramic; from what I see in my 80mm f/7 with 51 glass, the chromatic halo in the 100mm (or 102mm?) should be quite discreet.

[JG777]

Yes, excellent point ,they could be good choices for the OP, 51 glass will likely slice something off the cost. I haven't owned one myself so cant comment. It's difficult to assess without trying different scopes and I can see why many of us can make mistakes when choosing. Personally I kept my 80 equinox for travel and added a VX 6 1/10 for a mid range scope and it really is a great performer on wide, planets and moon for a third of the cost of a 120 APO. No CA in them mirrors! 

[Paz]

I have a ST120 that I got in a bundle with an AZ3. In respect of your queries my take is this...

I do notice CA on bright objects - for example blue and yellow fringes around the limb of the moon and around bright stars. I have a Baader semi apo filter that does dampen these down and improve CA but it does not eliminate CA. The way I prefer to reduce CA in the ST120 is to stop the aperture down to about 52mm by using the aperture stop build into the lense cap. At low and medium magnifications if anything is bright enough to cause annoying CA then it's bright enough to show well with a smaller aperture. I you stop down the aperture and use a semi apo filter the CA is further reduced. At higher magnifications full aperture becomes more necessary. All of this said, the ST120 is not great at color correction and all of these things are trying to make the best of it. Other types of scope avoid CA more fundamentally by their design.

The AZ3 mount is not much use for astronomy with the ST120 but it worked out very cheap to buy that in the bundle. With the ST120 altitude balance is a pain because the centre of gravity of the scope is displaced away from the centre of rotation of the altitude axis and the weight of the scope means you have to jam on the friction control and then take it off and put it back on again when you want large altitude changes. Since I got alternative alt/az mounts (AZ4 and Porta 2) the AZ3 has never had another outing with the ST120. For completeness I would say the AZ3 is fine for terrestrial observing and fine with the ST80 for astronomy, but not wth a ST120.

I like the ST120 but it is one of a few scopes I have and I can pick the best tool for any particular job, but I would say if I could only have one scope for visual there are better general purpose scopes.

[Olli]

32 minutes ago, Paz said:

I have a ST120 that I got in a bundle with an AZ3. In respect of your queries my take is this...

I do notice CA on bright objects - for example blue and yellow fringes around the limb of the moon and around bright stars. I have a Baader semi apo filter that does dampen these down and improve CA but it does not eliminate CA. The way I prefer to reduce CA in the ST120 is to stop the aperture down to about 52mm by using the aperture stop build into the lense cap. At low and medium magnifications if anything is bright enough to cause annoying CA then it's bright enough to show well with a smaller aperture. I you stop down the aperture and use a semi apo filter the CA is further reduced. At higher magnifications full aperture becomes more necessary. All of this said, the ST120 is not great at color correction and all of these things are trying to make the best of it. Other types of scope avoid CA more fundamentally by their design.

The AZ3 mount is not much use for astronomy with the ST120 but it worked out very cheap to buy that in the bundle. With the ST120 altitude balance is a pain because the centre of gravity of the scope is displaced away from the centre of rotation of the altitude axis and the weight of the scope means you have to jam on the friction control and then take it off and put it back on again when you want large altitude changes. Since I got alternative alt/az mounts (AZ4 and Porta 2) the AZ3 has never had another outing with the ST120. For completeness I would say the AZ3 is fine for terrestrial observing and fine with the ST80 for astronomy, but not wth a ST120.

I like the ST120 but it is one of a few scopes I have and I can pick the best tool for any particular job, but I would say if I could only have one scope for visual there are better general purpose scopes.

Thanks for that, exactly what in wanted a review from someone who has used both the mount and scope together. I think it sounds a lot of trouble with the ca and the mount I’m sure the scope is great but I think for my budget between 200-300 I can get a good scope with less problems. I appreciate the help ( and also from the others). At least I’m slowly narrowing down on the scopes. The hunt continues ...

[Alfian]

Have you had a look on Astrobuysell.com/uk? If you put a search in the Browse Ads for a refractor, reflector, mounts etc there are some good buys. Depending on which part of the country you live in will probably govern whats available in terms of the practical  collection distance but its a good source of astro' gear. I've bought several items via ABS and I know many folk here use it to sell stuff. Buying second hand would make your budget go much further and you may just be able to put together the right combination you are looking for. There is, of course also the for sale/wanted section here.

[M Astronomy]

Why were you put off the idea of buying a dobsonian? For £285 you can get a Skywatcher Skyliner 200p, which give you much better views of deep sky objects due to the larger aperture and apparently still gives great planetary views as well. It also doesn't have the problem of chromatic aberration as it is a reflector. The mount wouldn't have to be upgraded and therefore money could be spent on eyepieces and other accessories. I understand the issue of portability, but it can be split into two parts; the base and the scope. Instead of sacrificing aperture and going for a 102mm that has CA that could distract you from the views, with a mount you may still find wobbly, I'd get a 200p. But that's just my opinion. 

[alanjgreen]

13 hours ago, Dinoco said:

Thanks for that, exactly what in wanted a review from someone who has used both the mount and scope together. I think it sounds a lot of trouble with the ca and the mount I’m sure the scope is great but I think for my budget between 200-300 I can get a good scope with less problems. I appreciate the help ( and also from the others). At least I’m slowly narrowing down on the scopes. The hunt continues ...

@Dinoco what was wrong with the 130mm reflector on the az5. Why did you change tack to a refractor (which are heavier)?

That 150p star discovery is great value  

 

[Olli]

27 minutes ago, alanjgreen said:

@Dinoco what was wrong with the 130mm reflector on the az5. Why did you change tack to a refractor (which are heavier)?

That 150p star discovery is great value  

 

I haven’t  honestly I’m quite lost on the scopes been looking for ages and still haven’t made a decision those two are still scopes I’m considering and maybe a mak as well. Not really sure what I’m looking for lol. I’m just trying to get as much infor as possible about the scopes I can realistically afford and suite my needs. so I know I’m getting the best choice. 

[Olli]

46 minutes ago, M Astronomy said:

Why were you put off the idea of buying a dobsonian? For £285 you can get a Skywatcher Skyliner 200p, which give you much better views of deep sky objects due to the larger aperture and apparently still gives great planetary views as well. It also doesn't have the problem of chromatic aberration as it is a reflector. The mount wouldn't have to be upgraded and therefore money could be spent on eyepieces and other accessories. I understand the issue of portability, but it can be split into two parts; the base and the scope. Instead of sacrificing aperture and going for a 102mm that has CA that could distract you from the views, with a mount you may still find wobbly, I'd get a 200p. But that's just my opinion. 

Hi, I know The dobs are great value for the money I’m just thinking about storage reasons and ease of use. Even though they can be separated I’m still put off by them ( including the weight) maybe I’ll have another re think I’m not sure.

[M Astronomy]

Dobs are probably the easiest telescope to use. Just plonk it down and put an eyepiece in it. No tripods to worry about. I have a small reflector on a what I thought was an adequate tripod and mount. Despite the scope being very light, it shakes like anything, especially when there's a breeze. So I'm looking to upgrade and the 200p seems right for me after the research I've done. If storage is an issue, there's no reason why you can't go for a smaller dob. A 150mm still has better light gathering abilities than a 120mm and a lot better than a 102mm. Or go for a Skywatcher Heritage 130p. Its small, collapsible with its flex tube design and only £137. Bear in mind that it needs to be on a table or something though. Hth!

[Olli]

6 hours ago, alanjgreen said:

@Dinoco what was wrong with the 130mm reflector on the az5. Why did you change tack to a refractor (which are heavier)?

That 150p star discovery is great value  

 

Edit to my older reply : Have decided to go for the 130p on az5 just been writing down pros and cons of each scope I’ve looked at and made a decision to get this. The scope seems a good all rounder for what I want and also the Mount seems great have just watched a video on the mount and scope itself. Seems like a good combo and perfect to get into the hobby properly   

[alanjgreen]

2 minutes ago, Dinoco said:

Edit to my older reply : Have decided to go for the 130p on az5 just been writing down pros and cons of each scope I’ve looked at and made a decision to get this. The scope seems a good all rounder for what I want and also the Mount seems great have just watched a video on the mount and scope itself. Seems like a good combo and perfect to get into the hobby properly   

I am sure you will be happy with it. My first scope was a 130mm reflector and I saw a lot of targets with it.

I would also get "turn left at orion" (book) which has all the best targets and how to find them, plus sketches of what you will see in a small scope. Get the spiral bound version as its made to take outside (free postage on Amazon)

https://www.amazon.co.uk/Turn-Left-Orion-Hundreds-Telescope/dp/0521153972/ref=tmm_other_meta_binding_swatch_0?_encoding=UTF8&qid=1517762083&sr=8-2

https://www.firstlightoptics.com/books/turn-left-at-orion-book.html

Alan

[cloudsweeper]

I have - and like - an ST120, but I wouldn't want it as my main workhorse.  The widefield views are great, but sometimes you want more aperture or magnification.  The CA is to me not a problem since it is only present with bright objects, and masking the aperture removes it (at the expense of resolution).

A smallish Dob would probably be better to start off with, or - for a bit more money - a 127 Maksutov (very portable) with GoTo.

Doug.

[Geoff Lister]

I bought the ST120/AZ3 combination to get both at the best combined price. I agree with Doug.

The AZ3 uses (one size fits one only, 116mm diameter) rings to attach the OTA. To use the ST120 on a variety of mounts, I fitted the rings to a dovetail plate, and fitted a dovetail clamp to the AZ3. The AZ4 & AZ5 use side-mounting dovetail attachment as standard.

So, I now have a cheap manual mount for most of my OTAs, and can use the full Synscan GOTO with the ST120 on the Skymax mount.

Geoff