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Another Eyepiece Help Thread!


tomw28

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Hi!

Sorry for starting yet another thread asking for help with eyepieces but it seemed easier than sifting through the millions of others looking for others with the same question.

Next month I am hopefully getting a Skywatcher Explorer 150P on and EQ 3-2 mount. It comes with the usual 10mm and 25mm EP's, as well as a 2x barlow. I know these won't be great quality, but they'll do for the timebeing. However, if my maths is right the maximum magnification available from the 10mm with the barlow is 150x. This leads onto the first part of my question which is... is 150x high enough to see planets well?

If not I've been looking at getting a 6mm EP which would give 250x when barlowed. I was looking at a Vixen NPL, but these look like they have a scarily low eye relief of 3mm. Is that a reasonable amount for an EP of that size or is there anything out there that would be better? My budget is pretty low, preferably below £40 so please could someone offer a bit of advice?

Thanks!

Tom

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150x is enough to see planets.

I don't use short focal length plossl, because I need to wear glasses to observe, but 3mm does sound very close even for non specs wearer. If you are concern about eye relief, you can get the Skywatcher LER eyepiece on your budget. Alternatively, you can get a TAL barlows from FLO. This would half your eyepiece's focal length, but maintain the same eye relief.

Hope this helps

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Yes 150x gives very good views of planets. During this current Jupiter apparition,

now drawing to its end, I've used 120x, 150x, 170x and 200x, according to the

steadyness of the atmosphere. I prefer smaller and sharper views, rather than

larger and fuzzier. On very rare occasions, I've used 240x to good effect on Mars,

when the atmosphere was steady enough.

Regards, Ed.

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I am happy with the TMB Planetary II eyepieces which have reasonable eye relief and are available from a couple of UK sources at £40 to £50 (look on eBay). I bought them instead of Vixen NLV eyepieces which are now too expensive for me.

Chris C

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Thanks, I'm glad 150x will be alright. Would a 3x Tal barlow be a good idea then which would give 225x with the 10mm EP? I can then upgrade the supplied EP's when I've got the cash instead.

I was thinking about trying webcam imagng planets at some point as well. I think I read that an f-ratio of about 20 is needed. Would I be able to stack barlows to get this, by putting the 2x barlow that comes with the scope in the 2x one I already have, or does it have to be a single 4x barlow with a F-5 scope?

Thanks for your patience!

Tom

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The TMB's are probably a better option as they go down to quite small focal lengths.

Assume that the 150P is f/5 so you will need a decent eyepiece, if the TMB's work OK then I would suggest just eyepieces and not a barlowed eyepiece.

With the barlow you are banking on the scope, the barlow and the eyepice all working well together. Just one bit that doesn't match up with the others will deteriorate the image.

Personally I wouldn't expect good images above 200x probably less on the majority of evenings.

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Hi. I have exactly the same set up, 150P. I wanted a shorter FL EP and eventually (after lots of ums and r's) plumbed for a Baader hyperion 5mm. It's expensive but, knocks the spots off the 10mm/barlow in terms of contrast and detail. Jupiter just lights up and I don't regret the purchase! I find 150x is about the limit with the seeing around me (rural but fields have a lot of heat haze even in winter) but gives me the option to go to 3.2 (234x) with an extra ring (£7) for the few days a year the atmosphere will let me, and it's only a few. Mostly, any more power than 150x, the image degrades dramatically. Don't think though you can just chop and change betwen 5 and 3.2 during a session, it's not that slick to add the ring and changing in the cold can introduce condensation. Im very pleased with the Baader. Tom.

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