Eyepiece advice for Skywatcher 150p Dobsonian

[starforce]

Hi,

At the moment I have just the 10mm and 25mm eyepieces that come as standard with this scope.  I have been viewing Jupiter, Mars and Venus in the mornings over the past month or so.  I can make out the moons of Jupiter which appear like bright stars, and make out the stripes across Jupiter when using the 10mm eyepiece. 

I am now looking to get a closer look at the planets, so was looking for some advice.  I have narrowed down to purchasing a 2x Barlow lens, someone else mentioned on another post to buy a 8mm Plossi, not sure how that would help?

Is a 3x Barlow compatible with the 150p, and does it provide any more value in comparison to the 2x Barlow, and is there a brand that you experts can recommend to buy?

Many thanks

[dick_dangerous]

I have a set of the BST Starguider EPs for my 150P - 5mm, 8mm, 15mm and 25mm. They make an excellent upgrade to the supplied equipment - I started out with the 8mm which will give you 150x magnification, perfect for viewing small planetary nebulae, planets and the moon.

Paul

[ronin]

Your 150P is 1200mm focal length, I would follow Paul and say the BST's - I have one and a half sets of them.

However viewing planets can often mean that you need small steps between eyepieces, it is one area where you can go up in 1mm increments and the BST's have a jump between 5mm and 8mm.

Equally 150x is fine for Saturn and Jupiter, so the 8mm BST fits both, and is the one I would suggest you consider as a first increment for the supplied.

Mars will remain a small red disk, Mars is generally trouble to view so I suggest you do not have great expectations and do not go off buying something overly costly for viewing Mars. Oddly the 5mm BST may be a possible option, you will get 240x and for one night the conditions may allow it to be used. Mars will still be small at 240x. Seeing rover tracks is not an option.

The others that have slightly smaller steps are the Celestron X-Cels, 5mm, 7mm, 9mm, 12mm. If specifically wanted planets they may be better suited simply owning to the smaller increments. Slight hiccup is that X=-Cels are £60 (ish) BST's are £49.

As Venus is perpetually cloud covered all you will observe is the upper cloud surface, so I would tend to simply consider Jupiter+Saturn and if whatever you use for those renders Venus then again use that setup.

The selection Paul has himself would suit you as the 5mm may be a bit high but as said once in a while (and specifically Mars) it may be a useable addition. The other single eyepiece that gets good comments for planets is the William Optics 6mm planetary, 200x.

As you can start to realise we are already talking of 4 BST's and possibly a 6mm WO, what's that £260. :eek:

When someone says that you will spend more on eyepieces then the scope no-one seems to believe them.

[laudropb]

I use a X-cels 7mm for Jupiter and have found it very good.

[starforce]

Thanks everyone for the responses. Appreciated.

As I want to get as much magnification as possible, and not spend too much.  I steering towards going for the 5mm EP to get 240x.  The x-cels in 5mm are around £60, but I've found a Plossl 5mm for £19.99 on Amazon.  

Forgive me for the amateurish questions, but if the 5mm EP will provide 240x magnificiation; and a Barlow 2x with the existing 10mm will also be 240x.  Which is a better choice to buy? - The 5mm EP, or buy a 2x barlow and use the existing 10mm EP?

My objectives are to get closer and/or clearer viewings of Jupiter, Saturn and Messier objects.

Many thanks.

[Mrbloke]

Problem is the UK atmosphere will only allow you to use a certain amount of magnification.  There will be some (maybe many) nights when 240x will be too much.  Quite often, the closer you get, the LESS clear the view will be.  See the link below

http://clarkplanetarium.org/thinking-buying-telescope/

For most messier objects​, you wont want too much mag so the 25mm is the best one to use anyway.

​

[BritAngler]

I would opt for the 5mm instead of 10mm & Barlow (Patrick Moore hated Barlows and would never use one).

As has been said however, the nights when you can get 240x magnification plus a good view will be few and far between.

[Northern Soul man]

Hi Ya Starforce and a warm welcome to the SGL.  Its really hard to advise and recommend upgrades for beginners,  to get the best views from your scope may not always mean getting the highest powered EP combination, the Planets need aperture and long focal lengths to begin to get detail that I think your after.  Mars is going to be very low on the horizon over this next apparition, so your going to be viewing Mars through a large amount of dirty and fuzzy atmosphere - at best there's going to be very little detail to discern with the Planet so low in the sky this time around - its going to be at its best around Opposition - this is when its at its closest to the earth - so its going to be I think going from memory around 18 Seconds of Arc in size - compare this to Jupiter at around 40 Arc seconds - so Jupiter is going to be twice the size in the EP - Mars is a very difficult target to observe and so low down in the sky this time around that your probably just going to make out the brighter Polar Caps and maybe - and its a very big maybe, the larger land masses like Syrtis Major for maybe just a couple of seconds of steadying atmosphere every minute or so.

The higher power will work very well on the Moon as its so close and bright - but as others have said, Mars will be a very small bright disk in the EP and even with my 11" F10, some nights its really hard to get any good, steady views of Mars - on these nights I just go DSO hunting - there are so many factors which need to be just right to get the best out of your scope and over time you will get used to the really good nights and of course, the really bad nights.

The best advice I was told when I first got into the hobby was that a smaller brighter view was much more pleasing than a very high power dull, mushy view due to too much magnification - the much steadier nights allows the mag to be increased - over time you will get to know the atmosphere and within a few minutes of setting up and having your first look at your Planetary target for the night, you will be able to choose your best EP and Mag from your EP case - if your anything like me, just the thought of pointing your scope at that "bright star" you keep looking at whilst setting up, knowing that your the only person around your area that its a Planet and not a Star, just does it for me and has done for the last 30 years or so.

Enjoy the scope, the views and just keep getting out, setting up and spending time at the EP - this is probably the best advice I was given a long time ago an I'm still trying to achieve it.

Paul.

[Charic]

Hi and welcome to SGL...re-read the text from dick_dangerous. Its spot on for your telescope, but its what your eyes  perceive as a good image, that counts, and your eyes alone,  Only after trying an eyepiece will you appreciate it.

......Your telescope has an aperture of 150mm. Please assume that this is your best maximum limit, and going beyond will only impair your image rather than improve it, believe me.

I have the 8" and 200x is my maximum from a 6mm eyepiece, and you want to get 240X from a smaller scope than mine. Its doable, infact 300x is doable on your scope  but won't look nice?

yes, I  can achieve 375x from my  3.2mm but hey come on, its like chasing the Enterprise when  tracking  craters on the Moon,  trying to keep up with the speed?  yet   If you Barlow  say 2x the 8mm eyepiece,  you achieve the same result as if using a 4mm eyepiece , that's 300X, the extreme of your scope, and to be honest, probably the least  used  eyepiece in your collection? The reason I have so many eyepieces is to frame the subject to get the best visual image with regards to contrast shape and definition, and because the eyepieces are available to me as a set. Every target  up there is different and requires a different eyepiece, and more often than not, its the lower powered EP that wins, at the loss of image size, but with more detail.

That 8mm BST Starguider is an awesome eyepiece for your needs with 60°afov (apparent field of view) it just blows the supplied 10 mm away (IMHO) Look on your telescope and you may find a small label telling you three of the dimensions of your scope. F = focal length, A=-Aperture and possibly f/ focal ratio? It should say f/8?  Buy an 8mm and it will suit the telescope. The difference in field of view is better, and if your not happy with it, send it back, get your money back. The field of view and eye-relief will be more comfortable to use with a BST Starguider over an 8mm or 5mm Plossl. Like I said, my 9mm Plossl provides a nice sharp and bright image, but I prefer the wider view of the BST.

Divide the F/A and you should get 8. f/8 focal ratio, and using an 8mm eyepiece will give you the 150x power your scope was designed for with an exit pupil of 1mm. perfect for the highest magnification, staying within the designed limits of your scope!

If you want a decent Plossl, look for the GSO Revelation Plossl from Astroboot, extremely cheap, and extremely good, to my eyes. Remember a 5mm Plossl is very hard to use, your eye has to be touching the lens to see anything, and some brands like TeleVue ( probably the best) don't  produce a Plossl less than 8mm, due to the shortness of the eye relief?

I have a 9mm Plossl from said site, its stunning,  only a few quid, and to me very usable!......what is there to loose?

There is already some excellent advice/comments (as always from the folk here )  mostly  all from experience, so take it or leave it, but the choice can only be your decision in the end.

[dick_dangerous]

Thanks everyone for the responses. Appreciated.

As I want to get as much magnification as possible, and not spend too much.  I steering towards going for the 5mm EP to get 240x.  The x-cels in 5mm are around £60, but I've found a Plossl 5mm for £19.99 on Amazon.  

Forgive me for the amateurish questions, but if the 5mm EP will provide 240x magnificiation; and a Barlow 2x with the existing 10mm will also be 240x.  Which is a better choice to buy? - The 5mm EP, or buy a 2x barlow and use the existing 10mm EP?

My objectives are to get closer and/or clearer viewings of Jupiter, Saturn and Messier objects.

Many thanks.

Because of the expense of the eyepieces I bought them over the period of a year or so - starting with the 8mm, then the 15mm, the 25mm and finally the 5mm. The 5mm gets minimal usage because of our atmosphere but is great in my 80mm refractor. I would also suggest getting hold of a UHC filter - one of my favourite bits of kit, it brings out emission and planetary nebulae.

I have a 10mm lens and a 2x barlow (Kit stuff) but would pick the 5mm BST over them every time!

Paul

[starforce]

Thanks to everyone for their input and advice.  It was very useful, and much appreciated.  The Clark Planetarium link was a very informative site.  Thanks for the Astroboot site info as well.

I think I will end up buying an 8mm EP and a pair of 25 x 70 binoculars.

Thanks everyone.

[Northern Soul man]

Hi Ya Starforce - great mate nice 1, the Bino's are just a great piece of the Astronomers arsenal - set up in seconds - I have a pair of cheap 15x 70's and they really work well - especially for sweeping around the night sky, it just takes a minute or so to check the sky and set them up on a monopod - then your off!!.  They just give you more of a perspective where these DSO's are situated marvellous on the looser star fields and clusters and then you've got the scope to set up if its clear to dig deep into the close compact star clusters and fainter DSO's - just take the dumbbell nebula (M27) - from my back garden I can just make it out with the Binoculars within a large field of stars with two sets of doubles pointing right at it - then go in for a closer look with the scope - gives you a good indication of how clear and transparent the sky is, when you can get up really close, being able to pick detail out in either of the lobes and just how good the sky is.

I think I paid £50 for my Revelation 15 x 70's and I must admit, that, for the money, they really do compliment the telescopic views of each object - your not going to get up close to many of the Nebulae - most of the DSO's are just smudges of grey against a large open Field Of View - it may be worth your while if you can try different binoculars before you commit to buy - for the 25 x 70's your going to need a very sturdy mount to hold them especially at mags of 25 - I mentioned the monopod - I think I paid about £8 for it, and after using it for a few times you can really hold the Bino's steady with it - I can also make the Galilean moons around Jupiter - puts the whole Planetary system into context - and all with just x15 mag.

Paul.

[Mrbloke]

I agree, 25x is going to need some support. Anything above 10x is going to get shaky before too long if you are just using your hands.

[Chris]

Thanks everyone for the responses. Appreciated.

As I want to get as much magnification as possible, and not spend too much.  I steering towards going for the 5mm EP to get 240x.  The x-cels in 5mm are around £60, but I've found a Plossl 5mm for £19.99 on Amazon.  

Plossls are great budget eyepieces above say 11-12mm, but below this the eyerelief becomes very tight. A 5mm Plossl would be my worst eyepiece nightmare and I don't even need glasses to obvserve. 

If it absolutely has to be a 5mm the BST would be much much better. My vote goes with the 8mm BST because you can use it most clear nights at 150x. Much above this and the seeing has to be very good and these nights can be few and far between. I'd say 240x with a 5mm is just too much 95% of the time.

Sometimes less is more in that you can see things clearly at 150x but it would be a horrible mess at 240x. 

I have a 1200mm focal length 5" refractor and a 5mm high end eyepiece, they have never met each other but the 6mm has on very good nights. I remember one time not so long ago, my 7mm Luminos put up a noticably better view than my 6mm even though the 6mm is better optically. It's just simply that the seeing conditions favoured the 7mm better. An 8mm you could use every clear night I bet

[Moonshane]

My recommendation would be to buy a 2x barlow lens. If you buy a reasonably cheap one, you can use it to gauge which focal lengths work best for you. With your existing eyepieces and a 2x barlow you'd get 25mm (48x), 12mm (96x), 10mm (120x) and 5mm (240x) however, a neat little trick of barlows is to unscrew the element on the end and this can usually be screwed into the bottom of any eyepiece. This reduces the barlow effect to 1.5x giving an additional two magnifications at  approx. 17mm (71x) and 6.7mm (179x). Worth trying this before splashing out a lot of money on eyepieces. Rather, buy once you know you'll use the focal length. In truth for lunar and planets even the humble standard eyepieces, whilst cheap, are perfectly adequate. 

[starforce]

On 11/9/2015 at 18:47, Moonshane said:

My recommendation would be to buy a 2x barlow lens. If you buy a reasonably cheap one, you can use it to gauge which focal lengths work best for you. With your existing eyepieces and a 2x barlow you'd get 25mm (48x), 12mm (96x), 10mm (120x) and 5mm (240x) however, a neat little trick of barlows is to unscrew the element on the end and this can usually be screwed into the bottom of any eyepiece. This reduces the barlow effect to 1.5x giving an additional two magnifications at  approx. 17mm (71x) and 6.7mm (179x). Worth trying this before splashing out a lot of money on eyepieces. Rather, buy once you know you'll use the focal length. In truth for lunar and planets even the humble standard eyepieces, whilst cheap, are perfectly adequate. 

Thanks for the informative reply.  I am going to buy this 2x Barlow - http://www.amazon.co.uk/gp/product/B006631Z4A?psc=1&redirect=true&ref_=ox_sc_act_title_1&smid=AC0Z9SY209HFV as it has some good reviews and is reasonably priced compared to others I've seen.  Your comment about removing the end of the barlow, can this be done on all barlows or only certain ones?  Which part can be removed is it the part at the top or bottom?

[Alan64]

When placing a barlow into the optical train, if it doesn't match the quality of the telescope's mirrors and the eyepieces, the performance will suffer; and the scary part is: you may not ever notice it...

http://www.rothervalleyoptics.co.uk/antares-x2-twist-lock-barlow-lens-125.html

A barlow is purchased only once, and for life.  I've had the one illustrated here, center, since the early 1990s...

  

Incidentally, I've read of at least one individual who removed the lens-element from their 2x/1.5x barlow, dropped it onto concrete, in the dark, and chipped and cracked the lens.

One can never have too many barlows and eyepieces, whilst striving for better quality in each, and to be used and enjoyed with each and every telescope that comes along in future.

[rwilkey]

Hi Starforce, Jupiter excels at 150x mag, so going any higher will not make the view better for you, just fainter and fuzzier.  So my advice is to stick to a lower mag.