Which 7/8/9mm eyepiece?

[Clouder]

I have done some searching guys, but must admit I'm lost as there's soooo many to choose from, and don't want to just buy buy buy.

Basically, I have a 200p Dobsonian, using the standard 10mm eye-piece and a 2x barlow, giving me a mag of 240x. Stuff looks good on clear nights, but I want a little more mag for those very clear evenings

So I assume that a new, good quality eye-piece will be better than swapping the Barlow out for a 3x?

Saw a recent thread about a Pentax 8.5mm, which would give me about 280x mag, I guess I'm ideally looking for an 8mm, to give me 300x mag, which I believe is about the max I could possibly hope to make use of on a good clear night in the UK? I'm guessing the 340x from a 7mm would be taking things too far?

I'm looking at getting a webcam for my dobs, so I'm looking to retain as much clarity as possible from the new eye-piece, but not spend a fortune (ideally sub £70...), so any recommendations welcome please

Apologies if I'm way off the mark with my thinking aloud, I'm only 2 weeks into all this...

[twotter]

Push another £20 odd and you could get a 8mm Hyperion I have one and it's very good in my 200P dob.

Otherwise you could consider Celestron X-Cel LX, or the BST Explorer... both get good reviews on here and are popular.

[John]

Tracking with a dob at 250x plus is a challenge, assuming that the seeing conditions allow that sort of power to be useful, which most of the time I find they don't.

If you can afford it, the Skywatcher Nirvana gives a sharp 82 degree field of view which makes manual tracking at high power easier. The 4mm and 7mm Nirvana's are £135 which I think is a bit of a bargain for the performance you get - 90% of the much more expensive Tele Vue Nagler.

Edit: in all honesty I think 300x is taking things too far - 250x is a much more usable maximum 90% of the time.

[Clouder]

The tracking does concern me, but I'm ok at it at 240x at the mo I'm thinking of giving the BST Explorer a go but I have a dillema..

Do I go for the 8mm, which when using my 2x barlow will give me 300x, or do I go for the 5mm and NOT use my barlow, giving me 240x. I'm 'happy' with the viewing of Jupiter and the moon at 240x with my barlow'd standard 10mm, but want to get a bit closer, and hopefully improve clarity, especially of mars. By getting the 5mm and ditching the barlow I'd hope the clarity would improve (due to quality of EP?), but ofcourse the mag won't. So do I try to tick both boxes and have (in theory) a better quality EP as well as a little more mag, and get the 8mm?

Both are £41, and at the mo that's about all I want to spend whilst I'm still playing with just moon/planetry viewing. Any views appreciated

[Stephen]

Beyond 240x it would have to be an exceptionally clear night to get "more" clarity, I fear you will only get less the more past that you push it

[Clouder]

Hmm, that's my concern. I guess a part of me just wants to see it with my own eyes, then settle for 240x or less but that requires buying them both, and I want to avoid that.

Basically, I don't want to buy the 5mm and notice no difference to what I can see at the mo, but I also don't want to buy the 8mm and over-mag it, so aside from buying both, I'm a little stuck.

[gooseholla]

If you save up £20 more, as someone suggested, you can get a Hyperion. If you get an 8mm or a 10mm, for example, they can be changed into 2inch 22mm and 24 mm (around that figure, I think) respectively. You can also buy a couple of rings which allow them to function at 2 or 3 other focal lengths as well.

[hemihaggis]

speak to alan at skies the limit , they have a kind of try before you buy deal , you tell him what you would like to buy and he will send you a tester ep or two , if you like em ,you send back the tester and he sends you a new one !!!

ps .. where do you stay ??

i think about 240x is as much as you can use in your scope , you could maybe get a little more mag if you stay in the highlands of scotland or a really good site in wales or kielder .

[Mr Spock]

The supplied x2 Barlow and 10mm eyepiece are both below par. You'd be better off for planets with a single quality eyepiece. The Celestron X-Cel LX 5mm at £69 is right on your budget and will provide nice crisp views.

Going for a higher magnification won't bring out any more detail except on the 2 nights a year the seeing is perfect.

[Clouder]

I'm from Cornwall, very little light pollution on the whole.

Thankyou for the advice to speak to Alan, that seems like a sensible idea I can then try an 8mm with my 2x barlow, and a 5mm on it's own, and see what happens

The only issue I can forsee is if I don't want either - it doesn't really state on their site that I can return them all, just the one(s) I don't want..

[gooseholla]

I believe you can send any piece back and get your money back. After all, you pay for them all up front. If you don't want any, then return them all for all the money back, as far as I can tell.

[michael.h.f.wilkinson]

Just a note to say that the difference between an 8 and 8.5 mm is minimal in terms of magnification. If anything, the 8.5 can be used on just a few more nights than the 8. I agree that a 5 without barlow makes more sense. If your scope is F/5 a 5 mm is not pushing it. A 4 could even be used (like I use my 8(.5) in an F/10 scope quite regularly, and sometimes go up to 290x with the 14mm plus 2x TeleXtender(very much better than a standard barlow)).