Recommended Eye piece for Skywatcher Skyliner 200p

[bebuuk]

Hi all,

 

I have recently purchased a skywatcher skyliner 200p, however I am considering adding a lense or two to the current set that is provided 10mm and 25mm. My question is around what is the recommended lense to get for planet viewing and deep space objects.

Many articles suggest a variety of option but it only adds to the confusion, do I focus my search on 6mm lense for planet viewing or simply get x2 barlow to be used with 10mm and so on.

Apology in advance if it seems like a silly question as it may appear to be a very novice question.

[brantuk]

Nope - not a silly question at all - we all started somewhere and we're all at different stages in the hobby.

The dobsonian you have purchased has a highest practical magnification limit of x406. But I see you're living in London - and the UK weather will limit that to around 250x max. So I would suggest a small range of eyepieces giving equal steps of magnification between x50 and x250. You work out power or magnification by dividing eyepiece size (in mm) into the scope focal length (in mm). E.g. your 10mm eyepiece gives 1200/10 = 120x and your 25mm eyepiece gives 1200/25 = 48x magnification.

To complete the set with other powers I would add maybe 90x, 180x, and circa 200x to 220x. These are only suggestions and by no means cast in stone - only you can decide what suits you best. The problem then is which make/model to go for. That's a big question because there are so many different types and quality of eyepiece available.

The supplied eyepieces are basic - enough to get you going out of the box. But £30-£40 per eyepiece will get a decent upgrade and much better views - clearer, crisper, and better corrected. Stick with main brands to begin with Skywatcher, Celestron, Meade, etc, and join a local astro soc where you can go out observing with other members who are usually happy to let you try an eyepiece or two in your scope before you buy.

The Baker Street Irregulars meet in Regents Park at the end of each month - check their website for specific date/times.

Hope that helps - and remember - the only daft question is the one you didn't ask.

[spike95609]

I've got the 10" version of your scope which works along the same focal length. A 6mm eyepiece will give you 200x magnification, and may be about as far as you'd want to push it with planets, I believe a 5mm at 250x can be used but you need a night of exceptional atmospheric conditions to get the benefit of it. Even so a 6mm can be a bit wobbly on the average night, and since buying a replacement 10mm I've found that its views at 120x are superb for planets when this happens. It's also my go-to eyepiece for very small DSOs, my 15mm at 80x being used on larger ones, with the 32mm at 38x as a finder and for very large objects.

So I'd say your 25mm covers your low power requirements, and your 10mm the medium-high end. Adding a 6-8mm for high power and maybe something in the 12-15mm area for medium would by and large complete your range. Ultimately I'd recommend doing what I did and try using your 10 and 25mm on a wide range of objects over a few weeks or months. With each object you can ask yourself the question of whether you'd like a bit more or a bit less power than what you're seeing, and over time you'll start to figure out in your head precisely what eyepieces are right for you. Not just in terms of magnification, but field of view too - your current ones give you +/- 50°, and you might find you're happy with that, or might fancy something bigger. If you look at most any eyepiece on the FLO website, towards the bottom of the page there's a field of view simulator, where you can specify what scope you're using and play around with a few eyepiece choices against a background of messiers objects and it'll help to give you a little more understanding of what each one can do.

[bebuuk]

Hi,

 

Thank you brantuk and spike95609, this information has really helped me out. My next question is where does on consider a barlow lens or would it be advisable just to stick with lens with the appropriate magnification. 

[brantuk]

If you find the need for a barlow - get a good one. Adding coated glass into the light train can only diminish the views and you often find the extra magnification only amplifies the atmosphere making the views more grainy. A single eyepiece of the same quality is nearly always better than a longer barlowed eyepiece.

But against that you have to weigh your budget - a barlow will double the number of magnifications in your set (eg 3 pieces with a barlow will give 6 different magnifications if you check the maths carefully). This is very typical of astronomy - everything is a compromise of performance against budget.

[Louis D]

Barlows sound good on paper, but they are a pain to swap in and out.  When I use one, I tend to leave it in the focuser and just magnify every eyepiece for a while.  Look for a good, used long (not shorty) Japanese made 2X barlow like the Orion (USA) Deluxe or the Meade 140 2X.  I like them better than my TV 2x.

[Pyrodave]

Hi Bebuuk 

Before you spend any more  money get yourself out to a local astro club's observing session they're usually a friendly bunch and most will let you try  an eyepiece in your scope to let you see if it suits you and the scope , as what is good for some may not suit others as our eyes are all different . Hope this helps 

[Jimtheslim]

thought I would drop in on this thread as I am considering the same scope or the 10". I already have a variety of Meade 4000 series which work well with my refractor. Would these transfer well to a scope with such a shorter focal ratio?