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menacegtr

FIRST TIME WITH THE STARTRAVEL-120 (AZ3)

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Hi to you all. I am a complete newbie. I am getting the STARTRAVEL-120 (AZ3), and need some advise. I contacted 2 dealers with conflicting advise. I told them I wanted the scope for land but also for night time views. I told the dealers I wanted something better than what would be supplied with the telescope. Both the dealers said that a Sky-Watcher Planetary 58° UWA 1.25" Eyepieces 6 or 7mm would be great for strong land views and still be ok for night sky use. Also one of the dealers suggested the 2"/50.8mm Di-electric Coated 90 degree Star Diagonal with 1.25" adaptor and a PanaView™ 2" Eyepieces 32 or 38mm would be great for night time. I want the telescope to be able to see right up close to the moons creators and hopefully go beyond. Both the dealers were conflicting on a deluxe 2x Barlow, one said it would be to dim with the big eye piece while the other said it would be fine, and also they conflicted about using a moon filter, one said you should not need one when using the 2x Barlow while the other suggested a moon filter or the Light Pollution Filters 1.25” and 2”. As you can properly tell I am now very confused as to what to get. I don't want to just be satisfied with what comes with the 120mm telescope so I want to upgrade as I order all the stuff together, that's why I want your help. Am I being told the right advise as both dealers are saying different things. Like I said I want something very powerful in the day with a quality eyepiece upgrade and a good powerful eyepiece for night sky views. I am very sorry for the long question but I need the right advise. I hope somebody can please help me and say whether I was advised correctly or can you suggest something else to aid the startravel 120mm. Thanks in advance for any advice

                                                                                                                        Regards. Dave:

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Welcome to SGL Dave.

If that's what you have already decided on you could start by enjoying it with what comes with it and add bits as and when you choose, get a feel for what it can offer in stock form first basically.

During this time you could do what i did and become a sponge for knowledge from people with no agenda's.

Apart from the great help and advice on here, youtube can also be very helpful in showing you what will do what.

Edited by MARS1960
welcome
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As Mars1960 says, have a bit of patience and see what comes in the box.

However, along the line you might want to consider a 90 degree diagonal. You should receive a 45 degree erect image diagonal with your scope. This is great for terrestrial use, and you see everything the right way up and left/right correctly. However for viewing the night sky, the 90 degree diagonal will be much more comfortable. Image will be right-way-up but left and right will be reversed - but with the stars this is unimportant.

The relatively short focal length of your telescope (600mm) is not ideal for high magnifications and essentially means your eyepiece needs to do more work! Your scope comes with 25mm and 10mm eyepieces. The latter (the more powerful) will give x60 magnification. For much lunar and planetary observation, a magnification in the x120 range would be preferable. A 5mm eyepiece would achieve this - but many come with limited eye relief, which means your eyeball has to be very close to the glass. The alternative is to use a Barlow, this effectively doubles (or triples) the magnification of an EP while maintaining the original eye relief.

A half decent x2 Barlow (maybe 20-25 pounds) would extend your range of magnifications in the short term while you are deciding where you want to go.

The supplied 25mm eyepiece will give you quite adequate low power views for the moment - so I would recommend waiting for a while before buying a 32 or 38 EP, you may decide it's not needed. In any case I would not go beyond a 32.

Eyepieces range in price from about 20 pounds to over 400 pounds, and generally the more you pay, the better they are! But money aside, brands of EPs are also a very personal choice - if you have the chance, join up with a local astronomy club. You will be able to look through other members EPs and make the right decision for you!

Remember people in shops want your money, take their advice with a pinch of salt.

Good luck and clear skies.

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I agree with the post above, your best option is to buy the scope on its own first. Once you own the scope you can test it out for both terrestrial and astronomical use and determine what is needed to improve it rather than trying to guess now and buying accessories that you don't actually need.

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Hi

What to you does 'very powerful' mean? Your expectations.

Be careful of budget eyepieces Î an thinking with the ST120 budget might increase the observation of chromatic aberration. My little ST80 performs better with my own high powered eyepiece over the supplied 10mm, the 25mm is fine and I use mine.

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I think a 4" or 5" Maksutov would give a better land or nightsky performance than the ST120 if you are interested in high power views.

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@Peter Drew . Thank you for you suggestion, that's why I came here for advise. I never even gave the Maksutov a thought. Are you saying this telescope is far and away a better scope than the one i had in mind?. The one thing I would say is there are hardly any reviews on the skytravel 120mm, but there are loads on the Maksutovs so that must say something to me. I will take a serious rethink on what telescope to buy now. Thanks for yours and everybody's suggestions

                                                                                            Regards. Dave:

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1 hour ago, menacegtr said:

@Peter Drew . Thank you for you suggestion, that's why I came here for advise. I never even gave the Maksutov a thought. Are you saying this telescope is far and away a better scope than the one i had in mind?. The one thing I would say is there are hardly any reviews on the skytravel 120mm, but there are loads on the Maksutovs so that must say something to me. I will take a serious rethink on what telescope to buy now. Thanks for yours and everybody's suggestions

                                                                                            Regards. Dave:

I think the difference in this case is not the quality of the scope, but the focus length. Long focus length is good for high power views, but it gives a narrow field of view. Short focus length gives a wide view. In watching the night sky, a narrow field of view is no problem when you are looking at a planet, which you typically look at with high power. Some Deep sky objects (DSOs) however are quite big and they are best viewed with a wider field of view. E.g. my Maksutov doesn't show M31 as nicely as my binoculars that give a wider field of view. Also the double cluster is quite difficult to get all the way into my view. On the other hand there are many deep sky objects that are smaller and that are even tiny in my telescope with magnification.

For daytime viewing I use an Amici prism (that shows left and right the correct way). I can easily watch boats on the fjord that are approx 25km away. For astronomy, I use a star diagonal, which shows left and right mirrored. That last thing is a bit confusing and is a matter of practice to get used to. If you want to, you can also use am amici prism for astronomy, but it might take away a little more light than a star diagonal.

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Gosh there are pros and cons for both, if I stick with the skytravel 120mm and get myself a very good long eye relief  5 or 6mm EP would that work and also would I need a good barrow, as I believe one does not come with the skytravel 120mm. Have just seen some pretty good up-close creator shots of the moon with the 120mm ON YOUTUBE. Or do I go with the 127 sky scan Maksutov, I think that's what it is. The only thing putting me of is powering it by some 12volt means, and carrying it around with you, and the dew problems they have. I am not sure. See how much I have learned by visiting this site. Like I said at the start I want it for  strong day use and to see the moons creators at night. I will keep researching.

                                                                     Regards. Dave

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The maksutov-cassegrain design will produce sharper and colour free views of the moon and planets at high power. The Skytravel 120 is designed as a wide field scope. You can use high power with it but it gets outside it's "comfort zone" really in that role.

 

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Having had an ST102 for years and now an ST120 (which i am still waiting for first light with, damn clouds!). I can only echo what has been said here. There is no "one scope for everything" I have a 127mm Mak and on planets/moon its great and as others say, you can really push the mag with this scope. But for star clusters, galaxies, nebulas etc the Startravel is the weapon of choice for these targets.

I got the ST as my first scope. The moon gives more than acceptable views in it imho. I have also had a look at Jupiter with it on occasions where i couldn't be bothered to swap scopes. lol

I would get the ST again in a heartbeat, then when funds permit, get yourself a little Mak for planetary work. I used to have a 90mm one and it was a good little scope. Mars, venus, Jupier and Saturn all looked good in it, i even took some images of these targets with it and they were quite surprising for such a small scope. 

 

 

 

 

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@Bobby1970 . finally someone that used the ST 120mm. Can you please recommend a good 6/7mm EP to add to what will be in the box of the startravel and would you recommend a Barlow? and if so what type

                                                              Regards. Dave:

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Knighty2112 on the forum has done quite a bit of work on his ST120, he'll have some advice. Hasn't been on lately though.

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2 hours ago, menacegtr said:

@Bobby1970 . finally someone that used the ST 120mm. Can you please recommend a good 6/7mm EP to add to what will be in the box of the startravel and would you recommend a Barlow? and if so what type

                                                              Regards. Dave:

If we ever get some decent cloud free nights, i will happily report my findings on this scope. I have a TMB Planetary II eyepiece so will give it a go with that at some point. 

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A 120mm f/5 achromat is going to exhibit oodles and gobs of false colour on every bright object you observe.  Do you remember kaleidoscopes as a kid, and it gets worse as the magnification is increased.  A fast achromat however excels at observing the dimmer deep-sky objects; not too terribly bright, mind you.  If you want to observe mostly at higher magnifications, then go with either a 150mm f/12 Maksutov, or a 150mm f/5 Newtonian combined with a barlow.  The Maksutov would be a near-simulation of a 120mm f/15 planetary refractor, and perfect for observing everything up close.  Similarly, a 127mm Maksutov would mock a 90-100mm long-focus refractor.  On the other hand, a 150mm f/5 Newtonian would imitate a 120mm f/6 apochromatic refractor...

http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-ota.html

Newtonians are apochromatic, meaning "totally without colour"; that being false colour, or chromatic aberration.  With a better-quality 2x barlow, the 150mm f/5 would enable magnifications up to 250x and beyond, in good and better seeing conditions; and all the way down to 23x with a 32mm ocular for wide-field deep-sky objects and vistas. 

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2 hours ago, Alan64 said:

A 120mm f/5 achromat is going to exhibit oodles and gobs of false colour on every bright object you observe.  Do you remember kaleidoscopes as a kid, and it gets worse as the magnification is increased.  A fast achromat however excels at observing the dimmer deep-sky objects; not too terribly bright, mind you.  I

I think some of this is a little unfair. There are several members who have owned or do own fast achromat scopes and I for one would not say it exhibited "oodles and gobs" of false colour. 

If you went down the reflector route, be advised you will need to be more careful when transporting the scope and it will also need collimating now and then. 

Some people do not find CA a problem. Some find it more so. I got myself a semi apo filter for next to nothing second hand and it does diminish the CA somewhat. But the flip side is a slightly yellow cast to the objects you are viewing. 

The best course of action is to try one of the scopes for yourself and decide if you find it acceptable. I do think that ultimately you will end up with more than one scope though. Most people seem to   

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Owning a newtonian, mak and refractor the newtonian is the least suited to land use, I would say very unsuited.

Edited by happy-kat

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I had an ST120 for many years. It's a good basic scope for widefield views, and the eyepieces it came with, and the diagonal ( a 90 degree one, not 45 degree erect image one which you will need for terrestrial views) were fine....not the best by any means, but fine for starting out. Trying to get decent results at higher magnifications than you can get with the supplied 10mm eyepiece is a waste of time. It's a basic achromatic short focal length lens, and these sufferfrom chromatic abberation and can only take so much magnification before the image becomes a blurry mess.

Don't get a barlow with it.....the last thing you want is more magnification. Used for what it's designed for, widefield views of star clusters etc,  it's a great scope for the price, but if you want high magnification views of the moon and planets, then get a Mak or similar, as has been suggested here earlier.

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I'm pretty certain that the AZ mounted version of the Startravel 120 comes with a 45 degree diagonal, whereas the EQ mounted version comes with the 90 degree diagonal.

Between a refractor and a reflector, I definitely agree the frac is a thousand times better for terrestrial viewing. As a previous poster said, before editing it out, a reflector is about as useful as a chocolate teapot. I loved that!

The size-price relation is one of the main advantages of a short-tube refractor, and perhaps to be honest the only one.

If you really want to get close and personal with the Moon you need higher magnifications than a 600mm focal length is capable of giving. I have a frac with the same aperture, 120mm, but a focal length of 1000mm, with this I have no problem achieving good magnifications of x250 or well above (always depending on seeing conditions). As the Moon is so bright, I don't need the light gathering properties of a larger aperture, and in my opinion a frac gives better contrast.

Chromatic aberration is a problem with Achro fracs. The problem increases with shorter focal ratios. CA on my telescope (f8.3) is present but I can live with it, and the good news is the older you get the less you notice it! There are filters which can reduce this effect such as "fringe killers". Otherwise you have to spend a whole lot more money for an Apo which generally use a triplet lens made from expensive glasses.

However if you want to look at very faint objects such as the dimmer DSOs, you do need aperture. Without this ability to gather light, your range of object magnitude is much more restricted. An 8 or 10 inch reflector will, sadly, give my frac a sound thrashing!

For visual observing (as opposed to astrophotography, which is another kettle of fish) short-tube refractors have the worst combination: lack of aperture and lack of magnification. A short focal length is also much more demanding on eyepieces, often you just can't get away with the cheaper options, and this can translate into serious money. Others may disagree but that's my personal take.

If you really want a good 6mm EP with excellent eye relief, you might consider a Pentax. But then again, as this will cost as much as your whole telescope, you might pass!

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Is a 180mm Mak also suitable for Deep Sky? In the sense that it could be a better alternative then a 8 inch reflector? Or is again the narrow FOV very limiting?

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I have used 6mm TMB Planetary EP in my ST102 and it seems fine, not sure how much these are these days. I also used 9mm Celestron Xcel-Lx, which also seems fine in pretty much any scope i have ever used it in.

 

 

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6 hours ago, Bobby1970 said:

I think some of this is a little unfair. There are several members who have owned or do own fast achromat scopes and I for one would not say it exhibited "oodles and gobs" of false colour. 

If you went down the reflector route, be advised you will need to be more careful when transporting the scope and it will also need collimating now and then. 

Some people do not find CA a problem. Some find it more so. I got myself a semi apo filter for next to nothing second hand and it does diminish the CA somewhat. But the flip side is a slightly yellow cast to the objects you are viewing. 

The best course of action is to try one of the scopes for yourself and decide if you find it acceptable. I do think that ultimately you will end up with more than one scope though. Most people seem to   

Physics is incapable of being "unfair".  It is what it is....

I have an 80mm f/6 achromat.  It even came with its own vampire-star...

56acddbc7c3b4_Antares805.jpg.cb05accb7b0

 

At f/6, the aberration is well controlled, up to a moderate magnification...

100515e.jpg.3f8a4645dd82e59363353bfa00ae

 

However, research the colour-suppression performance of the faster Synta 80mm f/5 achromats(Orion, Sky-Watcher, iOptron, et al).  Then, add an extra 40mm to said f-stop.  The aberration increases with aperture when the same f-stop is maintained.  Again, a 120mm f/5 achromat should offer, at times, wonderful if not stellar deep-sky performance, and that is its strong suit.

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4 hours ago, Linda said:

Is a 180mm Mak also suitable for Deep Sky? In the sense that it could be a better alternative then a 8 inch reflector? Or is again the narrow FOV very limiting?

An 180mm Maksutov-Cassegrain would make for a splendid celestial "microscope"; for the Moon and the planets and double-stars, and would simulate a 140mm f/19 refractor.  Observing quite a few of the smaller, single deep-sky objects should be possible, too.  Now, a 30mm ocular, which gives a wide-field low-powered view at 25x via my 6" f/5 Newtonian, would realise 90x with said Maksutov: a considerable magnification, and one of the lowest practical powers.  Perhaps more people than we know look upon the short tubes of the Cassegrains thinking that one would make for a capable deep-sky instrument, until it's there before them.  Notice how the 2700mm focal-length of the 180mm Maksutov is folded into three sections within the optical tube...

makcass_scope.jpg

Therein, its true nature is revealed.

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1 hour ago, Alan64 said:

Physics is incapable of being "unfair".  It is what it is....

I have an 80mm f/6 achromat.  It even came with its own vampire-star...

56acddbc7c3b4_Antares805.jpg.cb05accb7b0

 

At f/6, the aberration is well controlled, up to a moderate magnification...

100515e.jpg.3f8a4645dd82e59363353bfa00ae

 

However, research the colour-suppression performance of the faster Synta 80mm f/5 achromats(Orion, Sky-Watcher, iOptron, et al).  Then, add an extra 40mm to said f-stop.  The aberration increases with aperture when the same f-stop is maintained.  Again, a 120mm f/5 achromat should offer, at times, wonderful if not stellar deep-sky performance, and that is its strong suit.

My mistake, i never realised "oodles and gobs" was a widely used term in the world of Physics. lol

My statement had nothing to do with physics. But everything to do with your opinion, which is in stark contrast to myself and others personal view of using these scopes over many years.

As i said, some people are clearly more sensitive to some purple fringing than others, hence why so many people own or have owned these scopes, many of whom recognise their limitations but also recognise their strengths. I used to have an 8 inch Dob myself, the views were better than any short tube achromat, however, it is often said that the best scope is the one you use the most and this means portability and ease of set up, for many people. This is where a short achromat excels at a very low price point.

 

Taken with an ST102 and a DSLR, on ALT/AZ GOTO mount, not done by myself, but certainly not too shabby either. Even with the oodles of fringing ;-)

gallery_4016_903_51432.thumb.jpg.90d2d0d

Edited by Bobby1970

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16 minutes ago, Bobby1970 said:

My mistake, i never realised "oodles and gobs" was a widely used term in the world of Physics. lol

My statement had nothing to do with physics. But everything to do with your opinion, which is in stark contrast to myself and others personal view of using these scopes over many years.

As i said, some people are clearly more sensitive to some purple fringing than others, hence why so many people own or have owned these scopes, many of whom recognise their limitations but also recognise their strengths. I used to have an 8 inch Dob myself, the views were better than any short tube achromat, however, it is often said that the best scope is the one you use the most and this means portability and ease of set up, for many people. This is where a short achromat excels at a very low price point.

I see lots of false colour when I use F/5 achromats to view brighter objects as well. It's just how they are. I see quite a bit of CA when I use a 150mm F/8 achromat too. It's there as the physics of optics says it should be. In the same way that newtonians have coma, it's just a characteristic of the design.

All scope designs have strengths and weaknesses. We pick those that best suit our needs and either accept some compromise when we use them in different roles or get another scope which is stronger in that area.

 

 

 

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