Skywatcher 102 advise on lenses

[Alysha]

Hi all,

I am looking for some advise for my skywatcher 102 telescope. 

From what I have read I understand this is a wide field scope but I was wondering if there are any lenses on the market which would give me a closer look at the planets and stars. 

I have purchased a Barlow lens which has helped greatly and I have a terrific view of the moon and wide views of the night sky. I can see the bright silhouette of Saturn/ Jupiter but would it be possible to get a closer look with this scope? 

Any help/advice would be greatly appreciate as I am very new at this. 

Kind regards

Aly

[Tiny Clanger]

There are a few skywatcher 102 models, the 102 indicates the aperture, I'll have a guess that yours is the Startravel 102 ?

If so, it has a focal length of 500 mm , and you probably got 10mm and 25mm eyepieces included with it ? A 2x barlow with the 10mm eyepiece would give you 100x magnification, in theory you could get an eyepiece to increase this , say a 3.2mm would give a decent 156x , but depending on what mount the 'scope is on, the view may be rather wobbly at that sort of magnification (which magnifies the wobbles along with the view !)

If I guessed the wrong 'scope, sorry !

Heather

[vlaiv]

Hi,

What eyepieces do you already have? I'm guessing stock 10mm and 25mm MA eyepieces?

With that scope - it is really hard to get in close to view the planets. You won't be able to get very high magnification, and even if you do - planets simply won't be as sharp as in other scopes.

Not all is lost. If you have barlow lens (I'm guessing x2 barlow lens), then try using that and 10mm eyepiece - and put cap on scope - but remove central section.

Your front cover probably looks something like this:

It means that this central section can be removed. Remove it and place cover on the scope. This will create aperture mask. It will let less light in scope - and is there fore very bad for general observing of faint things, but it will sharpen up view on high magnifications. You want to achieve this effect:

(people make aperture masks out of various bits)

If you find that you like barlow + 10mm and above scope cover on planets, then you can get dedicated eyepiece in that focal length that you'll be using without barlow that will provide you with same view (or a bit better than that 10mm + barlow):

https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-5mm-ed-eyepiece.html

That is very nice 5mm eyepiece that won't break the bank. Use it again with aperture mask to get sharp views.

 

[Nik271]

The planets are  low in the sky this year and the atmosphere rarely allows magnification much higher than x100.

I assume you have the 102mm Startravel. If it came with the erect image diagonal my advice is to get an ordinary mirror diagonal as the errcting prism does not work very well with small bright objects like Jupiter.

You could get a 6mm eyepiece which you can then barlow for x166 magnification but the scope will be at its limits.

[Cosmic Geoff]

If it is the 102mm f5 Startravel, it is not the ideal scope for viewing planets, but if you replace the terrestrial 45 deg diagonal (if supplied) with a 90 deg star diagonal, fit the x2 Barlow that most likely came with it, and add a 10mm eyepiece (not the one that came with it but a better replacement) then you will be getting the best you can out of it.

[Alysha]

Hi All, 

Apologies it is the Startravel 102. Thankyou for all of this information. It is a huge help! 

I had no idea about an aperture mask so I will certainly try that and thankyou for the suggestions. 

Could I ask with changing over the diagonal, does anyone have any recommended brands? From what I have seen so far, Celestron seem to be one of the higher prices which I don't mind as long as it is worth it. This is a very new hobby for me and the last thing I want to do is to go and spend thousands of pounds without truly knowing the difference between items. 

The mount for my scope is the AZ-GTEC mount, I live in an urban area and next week will be the first time that I travel up north to a dark site and take my scope with me so I will be able to find out how it works outside. 

I do have the stock 10mm and 25mm MA eyepieces which came with the scope. I didn't want to buy another lens without some helpful advise as there are so many options on the market. Also it is the x2 Barlow which I am using. 

I cant thankyou all enough for your support. 

Kind regards

Aly 

[Tiny Clanger]

45 minutes ago, Alysha said:

Hi All, 

Apologies it is the Startravel 102. Thankyou for all of this information. It is a huge help! 

I had no idea about an aperture mask so I will certainly try that and thankyou for the suggestions. 

Could I ask with changing over the diagonal, does anyone have any recommended brands? From what I have seen so far, Celestron seem to be one of the higher prices which I don't mind as long as it is worth it. This is a very new hobby for me and the last thing I want to do is to go and spend thousands of pounds without truly knowing the difference between items. 

The mount for my scope is the AZ-GTEC mount, I live in an urban area and next week will be the first time that I travel up north to a dark site and take my scope with me so I will be able to find out how it works outside. 

I do have the stock 10mm and 25mm MA eyepieces which came with the scope. I didn't want to buy another lens without some helpful advise as there are so many options on the market. Also it is the x2 Barlow which I am using. 

I cant thankyou all enough for your support. 

Kind regards

Aly 

Aha !

You added a location ... hello  neighbour 🙂 I'm on the southern edge of the conurbation.

I've bought a couple of diagonals for my 'scopes, one was a secondhand one of these https://www.firstlightoptics.com/diagonals/SWdiagonal-20967.html which is very nice, and there is another just  as good for £10 less https://www.firstlightoptics.com/diagonals/stellamira-1-25-90-di-electric-diagonal.html  However ,that's quite expensive !

To go in my 102mm Bresser refractor I bought a cheap Chinese mirror diagonal via Amazon , there are many available , sometimes you can find one for £10 , and I find mine perfectly adequate , I'll do a search and find the link.

Heather

[Alysha]

Haha! I thought since I am using this site so much people should know where I am based. Hello Neighbour! 

Thankyou for sending those, its a big help. Its amazing, I spent so much time browsing google but its hard to make sense of it. 

Aly  

 

[Tiny Clanger]

Goodness, how prices have increased since June ! The diagonal I bought has now quadrupled in price . There are plenty of the model available from different sellers at  around £30-£40 , they all use the same photos but it's anyone's guess if the pic.s are simply borrowed from another ad. or actually of the item (which is why I bought one dispatched from az in the UK, easy return/refund if it turned out to be rubbish) . Here's one going for £26 and another , apparently identical one for just over £30 .

An important thing to look for is that brass strip inside on the eyepiece end of the diagonal : it gets pushed unwards by the screw to hold your eyepiece tight, and is unlikely to  scratch the eyepiece barrel as a simple screw would .

There's a thread about the diagonals here

 

Edited October 14, 2021 by Tiny Clanger
added link

[Alysha]

It is still alot cheaper than the £145 diagonal from Celestron I was looking at. That is great thankyou, I will look at that link you have sent and give it a try. At least with Amazon you have the return option.  

[Carbon Brush]

A long time ago (10 years?) I owned an ST102. The view per ££ spent was very good.
At the same time I had a William Optics 80mm short tube refractor.
Put the two side by side and tried terrestrial viewing on a 2KM horizon.
Initially both had the supplied eyepeices and diagonal.

As expected the it was clear vs foggy day for the clarity of view. But look at the price tags!
But where does spending money help?

I then started swapping the eyepieces and diagonals between the scopes.
Basically spending on a better in this case WO)  eyepiece, or better diagonal, gave a significant improvemnt in view.
No surprise that low cost Skywatcher diagonal and eyepiece in the WO degraded performance.

As suggested above, a half decent mirror diagonal (less surfaces than a prism diagonal) will improve performance.
I have yet to find anyone who thinks the supplied Skywatcher 10mm eyepieces are worth anything. Though the 25mm are OK.
Probably something like a BST Starguider will help you see things a bit better.

Don't forget, eyepieces and diagonals can stay with you should you decide on a different scope.

Once your SGL post count and time have increased, you will have access to the classified ads section.
A good source of used astro parts at less money than new and usually well looked after.

If you are buying new, always go to a specialist astro retailer. They will advise you if you are buying completely unsuitable accessories.
Avoid ebay like the plague. Amazon is OK if you know what you want and it is a genuine part.
Don't forget retailers (like FLO who sponsor this site) also have no fuss returns.

Keep asking the questions,

David.

[Pixies]

1.25" dielectric diagonal here for a £24:

https://www.astrobuysell.com/uk/propview.php?view=178971

[Alysha]

@Carbon Brush Hi there, thankyou for the advice, my biggest worry was buying something which was not suitable for my scope. I did wonder where people were getting 2nd hand items from without using Ebay and now I know. I have read the eyepieces which come with the scope are very basic and not the best. 

Is there anything on the eyepiece specification which would indicate to me that it is a good quality piece or should I just keep looking for reviews? 

@Pixies Thankyou, thats great! 

I have finally learnt how to reply to people specifically haha 

[Franklin]

17 hours ago, vlaiv said:

It means that this central section can be removed. Remove it and place cover on the scope. This will create aperture mask. It will let less light in scope - and is there fore very bad for general observing of faint things, but it will sharpen up view on high magnifications. You want to achieve this effect:

(people make aperture masks out of various bits)

What's that Vlaiv? 

Is it a Frankenstein scope?

[Tiny Clanger]

You need to have 25 posts and a month elapsed since signing up to access the buy/swap  area , so not too distant a prospect for you.

Eyepieces (as you'll have seen by browsing around here) are a huge topic, the only limit is how much you can spend . Decent, basic plossls (from a reputable make) are OK , and start at around £20-£30 each , OK for lower magnifications, but the eye relief (how close your eye has to be to the top of the glass) is very small in higher magnification ones , so not ideal , especially for glasses wearers.

The usually suggested next step up are BST Starguiders, which are around £50 new, , and come up for around £35 second hand. The 25mm you get with skywatcher 'scopes is OK, no urgent need to upgrade that yet , but that 10mm is notoriously poor. There is no 10mm BST, but there is an 8mm and a 12mm. I have both, and can confirm they work well in my 102 refractor (and my other 'scopes too) .An 8mm would give you 62.5x and adding your barlow would double that to 125x , a bit more magnification than your 10mm (50x/100x) . Trying that would give you an idea if you'd find a 5mm eyepiece useful, or if it is pushing your setup and skies too far .

Heather

[Alysha]

@Tiny Clanger Ok brilliant, thankyou for that. As you can see, I am still learning this site. 

 

So I have seen, what is the difference on a Plossls eye piece? I have seen them in a few sets I was looking into but decided against it as I wanted to look into and understand the various pieces first. Do you use filters at all? I have been reading some people say it is essential to get a moon filter and one to reduce light pollution but I am not sure if that is for a more powerful scope. 

[Cosmic Geoff]

15 minutes ago, Alysha said:

I have been reading some people say it is essential to get a moon filter and one to reduce light pollution but I am not sure if that is for a more powerful scope. 

Using a moon filter is purely a matter of personal choice. I have never bothered with one.  Light pollution filters are a more complex subject.  The older design of light pollution filters were designed to counter yellow sodium street lighting, and are useless against white LEDs.  There are filters that are claimed to have a slight benefit vs LEDs, but they cost as much as your scope did, if not more.  Then there are narrowband filters designed for imaging nebulae, which work for that purpose even in the presence of light pollution.

In short, don't bother with either.

Plossls are inexpensive eyepieces and work fairly well in most scopes, but there are reasons why some observers prefer more exotic designs.

Some people consider that using a coloured filter with scopes like the Startravel ST102 makes the chromatic aberration less evident.

Edited October 13, 2021 by Cosmic Geoff

[Alysha]

@Cosmic Geoff With the eye pieces I have, I get a really good view of the moon so I am quite happy. I have noticed a bit of Chromatic aberration but it didn't impact my viewing as I was still blown away by it.

Thankyou for explaining the filters, have you ever used a narrowband filter? Eventually once I feel comfortable with my understanding of the scope, I want to get into trying some astrophotography but considering how much there is to learn for both subjects I thought it was best to stick to the most important piece of equipment first. 

 

[Tiny Clanger]

Avoid sets, you are bound to get things included which you'll only ever use once . Much better to decide where your interests lie & there are shortcomings in what you already have, and upgrade / add a little at a time , less chance of wasting cash .

Plossls are decent , but are seen as basic, simple eyepieces , the name is a general one referring to the arrangement of lenses within the eyepiece . They have a field of view ( like the size of window you are looking through) of around 50 degrees, which is OK, the BSTs have a field of view of 60 degrees and a different internal arrangement of lenses.

This is a good page for info on eyepiece types http://swindonstargazers.com/beginners/eyepieces.htm

A Moon filter is like  sunglasses, you put it on the eyepiece if you find the Moon uncomfortably bright through that 'scope. Different people have different tolerance for the dazzle, I don't need a filter for the Moon with my 102 refractor, but I absolutely do with my bigger 150mm heritage dob. So only get one if you really need it. Light pollution filters are a matter of debate, some folk think they work, but I suspect they are much more effective where older street lights (the yellowish sodium ones) are still in use.  I think Leicester City Council have updated most of the streetlights  , so I doubt a filter would help.

There's a lot of love for a filter called a Baader Neodymium (my spelling may be a bit approximate there)  , apprently it increases contrast in all manner of things, but it costs around £60 ...

Coloured filters can be used to make the contrast between .say, bands on Jupiter appear greater, but again, it's a bit of a debateable thing . I bought an ultra cheap set of half a dozen filters (amazon again!) to try the idea out, and find that sometimes a filter may help pick out a detail on a planet, and I've bought a few better/different ones to try out, but the improvement (for me) is marginal and occasional. Whatever the advertisers claims, filters do not perform magic ,  and they lose some of the light ... not a bad thing for Jupiter, where you can be dazzled by the brightness , but much of the time ...meh !

I saw it suggested that a yellow/green filter can usefully reduce the chromatic aberration on an achromat refractor at a 102 aperture, so splashed £10 on one , can't say it helps much !

Ha, as per usual, my slow typing has made a lot of my wittering redundant, I could have just said 'I agree with Cosmic Geoff' ! 🙂

[Cosmic Geoff]

2 minutes ago, Alysha said:

Thankyou for explaining the filters, have you ever used a narrowband filter?

I have an OIII filter which makes planetary nebulae and the Orion nebula easier to see, if rather green. 🙂  I tried imaging a planetary nebula with it and it lengthend the exposure time a lot and the result - a monochromatic blob - was uninspiring.

BTW the Startravel 102 is quite good for trying some basic imaging and electronically assisted observing - I have imaged all sorts of stuff with mine + an ASI224MC camera.

[Franklin]

Your scope is a short focal length refractor and is more suited to low power widefield viewing such as star clusters and the brighter Messier objects in general. So I would go the other way and get a longer focal length eyepiece such as a 32mm Plossl which would perform very well for this kind of observing. As Vlaiv has noted above you already have a 10mm and a barlow for high power.

[Louis D]

16 minutes ago, Tiny Clanger said:

There's a lot of love for a filter called a Baader Neodymium (my spelling may be a bit approximate there)  , apprently it increases contrast in all manner of things, but it costs around £60 ...

It's basically the same thing as the generic Moon & Sky Glow filters that go for under $20.  Just do your homework and look for the pale blue filter color and the spectral chart.

[Alysha]

@Tiny ClangerNot at all, the more I am reading from the replies, the more it is making sense to me. I find that on the internet, a lot of people will use the correct terminology without explaining it is to a newbie like me I have no idea what it means. I am so glad I asked about the filters as it was something I was really considering. Thankyou for helping me to decide on the sets, I kept going back and forth and I thought I would wait until I know a bit more than parting with £200 to get eyepieces I wont use. 

@Cosmic Geoff Oh that is a shame about the filter! I will be using an old DLSR camera and I have a T-ring which fits onto my scope as well as a Tripod so I will be taking it with me next week to try out, I am not holding my expectations too high haha

@Franklin Would a 32mm eye piece be better than a 25mm for wide viewing? (I know this probably sounds like a dumb question) 

[Tiny Clanger]

2 minutes ago, Alysha said:

@Tiny ClangerNot at all, the more I am reading from the replies, the more it is making sense to me. I find that on the internet, a lot of people will use the correct terminology without explaining it is to a newbie like me I have no idea what it means. I am so glad I asked about the filters as it was something I was really considering. Thankyou for helping me to decide on the sets, I kept going back and forth and I thought I would wait until I know a bit more than parting with £200 to get eyepieces I wont use. 

@Cosmic Geoff Oh that is a shame about the filter! I will be using an old DLSR camera and I have a T-ring which fits onto my scope as well as a Tripod so I will be taking it with me next week to try out, I am not holding my expectations too high haha

@Franklin Would a 32mm eye piece be better than a 25mm for wide viewing? (I know this probably sounds like a dumb question) 

Okay, so the 32mm plossl, with it's 50 degree field gives a view almost exactly as wide as a 25mm but 60 degree BST starguider ( I have both !)

You can get an approximate comparison by using a tool which is linked to on some of the FLO eyepiece pages like this one :

https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-25mm-ed-eyepiece.html

scroll down the page a bit, to astronomy tools field of view simulator. You can change it to your telescope (by the drop down menu) , swap to a different target, delete the circles of the eyepieces you don't care about, add circles for other eyepieces ... you'll be there for hours 🙂

Heather

[Alysha]

@Tiny Clanger Oh wow! Thankyou for sending that link, that's a huge help