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It's another "which eyepiece" question


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So I have my skywatcher 10" f4.7 manual dob, and it's doing everything I expected of it. But! Various people on this forum have suggested that the 10mm plossl it comes with leaves a bit to be desired. Last night's shock discovery of unrecorded nebulosity around *every* open cluster suggests they're right.

Also, Saturn is getting awfully close to being an evening object and I want to do it justice when I first clap eyes on it.

So I'm in the market for a new eyepiece at the planetary end, and I was thinking of the 6mm TMB clone on offer from Sky's the Limit. I should add that there is definitely a budget at work. Will this EP work well at f4.7?

I would also like to get a wider FOV at the lower mag end, but I can't afford to get into TV/Nagler territory. I could stretch to a ton, and I'd like to support my local 'scope merchant Charles at MC2 Telescope in Frome. He stocks Baader Hyperions, would one of those be up to the job? And if so, what size? I was thinking 17mm, or should I go closer to 10mm?

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Click on "Stargazers Lounge" in the header, scroll down to equipment reviews, enter, and on page 5 near the bottom there's a comparison of Baader Hyperions and Vixen LVWs by "jahmanson". I don't have any Hyperions, but I do have a couple of the Vixens which are fabulous, so if the Hyperions are as good as the review suggests they're going to be a good buy.

My 17mm Vixen is my most used eyepiece.

Edited by KenG
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Saturn holds up too high magnification quite well so a 6mm ep would do the job nicely. As for another ep depends what you want to do with it, if your currently happy with the 25mm ep that came with your scope the something in the 12 or 13mm focul length would be a good buy. When I got my 10" Dob the first ep I bought was a 12mm, it gives me x100 and is now my most used ep (the others are a 28mm, 17mm, 8mm and 5mm) I find it excellent on DSO's. Here's a thought you could always skip the 6mm and get a 12mm plus a good x2 barlow.

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Thanks for the advice everyone. I'll think I'll go for the 6mm TMB and a 17mm Hyperion, and then maybe a 12mm Hyperion later on when cash is a little looser. And then I'll buy a 25mm Nagler!

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Thanks spaceboy - but £130 is a bit rich for me, I have a mental issue with paying £xxx for an EP! ...

I know exactly where your coming from. When I set out to build a new collection of EP's I had a budget of £300 in mind. Unfortunately I ended up getting TV addiction and spent 4 times that amount. :)

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With an F4.7 scope you could stretch to a 4.5 - 5mm EP for evenings of good seeing (I use my 8mm Radian quite a bit, and it gives 250x in my 8" scope). A 4.5mm would yield 265x and a 5mm about 240x.

Don't forget I have a hand-powered dob - wiser heads than mine have advised that 200x is about the point where it becomes very difficult to keep the object in the EP. I'll see how I get on with the 6mm....

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Hi guys,i've just ordered me a Celestron omni 4mm eyepiece to build up my miniscule collection so it should take me to just under my highest useful mag on my scope. Does anyone one know if these EP's are good quality?

Hi Big daddy I think you may be a little optimistic at 250x magnification given the UK's usual seeing conditions. The rule of thumb is to keep around 200x which would be a 5mm in your scope but even this may be pushing your setup to it's maximum practical potential. More magnification doesn't always mean better and sometimes you will gain more from a smaller steady image than you would from a larger distorted one.

This may help http://www.buy-telescope.com/guides/telescope-power-calculators/

SPACEBOY

Edited by spaceboy
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I'd recommend the TMB clones from Sky's The Limit too. I have the 6mm and it works really well in my 200P dob and Tal 100RS when seeing conditions allow!

I used to have a set of the Celestron Omni Plossl's, they were actually quite good from what I recall and very nice build quality, although looking through the 4mm was a little like looking through the end of a straw - quite a small lens to peer into!

Doc

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