Comparing 'scope performance

[Planetesimal]

So, I had a go at resolving epsilon Lyrae this evening with the 150PL. Max magnification attempted was 120x. I could see the double clearly through the 6x finderscope (at least I assume I was looking at the right binary system!), but all the way to 120x I still couldn't resolve the double double.

My question is, should it be possible to split the double double at 120x with a 6" newt? Or am I being too ambitious?

[Marki]

http://stargazerslou...-double-double/

This links to a thread where splitting the double double has recently been discussed : this is worth a read. I'd have thought you can definitely be able to split it with a 150mm scope and at x120, although "seeing" conditions and experience can affect this. I believe that the record claimed on SGL is a split at x48 ! Closest I've got is x76 with a 125mm achromat in very steady and good seeing - more usually I can split is at x90 or higher. Keep at it - if you're on the right target you'll get it soon enough and its well worth the effort.

[Planetesimal]

Thanks for the encouragement Mark - I'll keep trying, maybe I need to look again at the collimation!

[John]

You should be able to do it easily with that aperture. Fast newtonians don't present such tight star images as maks and refractors do though so this can make splitting tight doubles more challenging, especially if seeing conditions are poor.

[Qualia]

As Mark and John suggests it should very much be possible but I think seeing plays an important part. For me (in Spain) seeing tonight was awful and I couldn't even guarantee that I split M 45 (that's a joke - but only just) . Try another night and when you're there abouts in Lyra try going for the other double-double of Struve 2470 and 2474, they're easier to split, have a beautiful contrasting colour of light golden yellow and blue hues and infinitely more beautiful to contemplate in their spectacular stary field.

[brantuk]

What eyepiece were you using? At 120x I would guess it's the supplied 10mm. I reckon your problem lies there - it really isn't a good eyepiece at all - especially not for splitting double doubles. I reckon a better quality eyepiece would do the job for you - something in the range of £40-£60 will make the view come alive at 8-10mm. Also ensure you are well dark adapted - 20 mins in pitch black will make a huge difference before viewing.

[Planetesimal]

Thanks, I've been suspecting that the supplied 10mm is not that great, but I'd hoped given the slow focal ratio (f8) that the 'scope would be able to handle the lower quality lenses.

Oh well, back to the bank manager!