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What to do


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Hi all

As an enthusiastic but passive astronomer for the past 40 years I have finally stepped out and bought a scope.

I have got a Celestron Nexstar SLT 102 refractor.

Fl - 660

F/r - 6.5

Highest useful magnification is 240x

The EP's that came with the scope are 25mm (mag 26x) and 9mm (mag 73x). Obviously this just won't do.

Does anyone have any opinions on me purchasing the following:-

- Celestron (93230) 8 to 24mm (1.25) Zoom Eyepiece

- Celestron (93428) X-Cel LX 3x Barlow Lens (1.25)

If my research is correct using these two bits of kit I would get a comprehensive range of magnification without compromising on the field of view.

Any alternatives or suggestions would be welcome.

Rgds

N

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Speaking as someone who spent a fortune on eyepieces after purchasing my scope, only to sell most of them on at a loss after a few months, I would suggest you put off e/p purchases until you know what you want and why you want it. Get used to using what came with the scope and as you find out where they are being 'stretched' and you want to achieve something specific more, you will be better placed to make a purchase that will be of value to you.

Just my 2p ...

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Just a good quality barlow would be a good starting point as you would then have 26x, 52x, 76x, and 154x

A 3x barlow on it's own will only give you three different mags as 3x 25mm will give you a mag only marginally greater than your 9mm on it's own, and 3x 9mm will give you a mag that may only be useful when the seeing is really good.

This is my experience anyway. Better quality EPs than the ones I have may allow for slightly greater mags than I achieve with my 127mm mak

As for the particular EP and barlow you mention I'll let someone else advise you as I have no experience of them.

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I can't edit my previous post for some reason but I should have said '2x Barlow.'

The basic cheap one I had with my SW1145pm wasn't very good. But the Skywatcher 2x Deluxe one that I got as part of the 'DEAL' with my current scope is pretty good. I can't compare it to any others, but many favour the TAL Barlows. If I had £36 to spare I'd certainly try one to compare it.

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Hi Demonperformer

Your 2p I’m sure is worth a lot more.

If I understand correctly my scope arrangement is not "perfect" for either planetary or deep sky observation with an f/r of 6.5. Kind of a one size fits all arrangement.

My thinking is that the zoom would give me the equivalent of 17 EP’s for about £80 versus only being able to buy 3-4 separate EP’s for the same money.

My understanding is that most observing is done between 80 – 140 magnification. So with a 3x Barlow and the zoom, I would get 11 different magnifications between 83 - 141 and an additional 6 magnifications up to the limit of 240x. In addition I would also get 17 different magnifications between 28 and 83 using the zoom as a standalone.

This equates to 33 different magnifications from 28 – 248 for about £170.

I would like to focus on planetary observation and some of the brighter objects simply because where I am there is a vast amount of light pollution making deep sky observation quite difficult.

The zoom has been on the market for quite some time however the barlow is only due to be released this month.

Does this address the why and what or am I off the mark?

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OK, I see where you're coming from. But I would caution against getting too tied up with how many magnifications you are getting. I have never used the zoom, but I would guess that you would actually have an infinite number of magnifications as you can presumably stop in between a whole number of mm in focal length. But that isn't really my point.

I have a 10mm e/p and a 14mm e/p, nothing in between, but I can honestly say I have never bemoaned the absence of a 13, 12 or 11mm e/p. I have found one or other always to be satisfactory (unless I want to go up to the 5 or down to the 32). Yes, there are additional e/ps on my wishlist - a 7 would be nice for those times when I want a bit more magnification than the 10 but conditions do not really allow the power of the 5 (I have an f/10 scope) and a 20 would be nice for better widefield views.

I suspect that most people using a zoom, will choose either one end or the other or a point in the middle which is usually pretty much the same point in the middle. That may be unfair and some may choose exactly the right magnification to frame the object exactly in the fov and you may be such a person, which is fine. So the question becomes, does the ability to fine-tune the magnification that much outweigh the (albeit) small drop in quality that is inevitable when you get a zoom eyepiece.

Having said that, you suggest 3-4 separate e/ps for £80, equating to £20-30 each. Without wishing to offend, the quality that you are getting for that price, it probably won't make that much of a difference quality-wise. I strongly suspect that if you were to compare the zoom with, say, a pentax, the difference would be much more noticeable.

HTH

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