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Which eyepiece to spend money on?

freelander86

By freelander86
in Discussions - Eyepieces

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freelander86

freelander86

Posted
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Hi,

I have a Celestron 130EQ MD and I'd like to spend some money on a good eyepiece to accompany my setup...

I am going to buy a TAL 2x Barlow lense and one other???

My scope came with a 10mm and 20mm eye piece.

I was thinking either a 6mm or 9mm Celestron?

Surely I only want to increase magnification from my 10mm? Some people seem to suggest 15 or 32mm! Surely thats less magnification?

Freelander86

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Damo636

Damo636

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If you are buying the barlow i would suggest something in the 13-15mm range. This will give you a good workhorse eyepiece and when combined with the barlow will double up as a planetary eyepiece. Regarding choice, it depends how much you want to spend really. Decent plossls or orthos can be had from around £30 upwards.

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gazmass

gazmass

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What about a zoom eyepiece. i brought a televue 8-24 and used it more than my eyepiece set. sky at night did a review on them and the meade one came out on top. although not sure if it maybe a little heavy

Sent from my GT-I9100P using Tapatalk

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John

John

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Surely I only want to increase magnification from my 10mm? Some people seem to suggest 15 or 32mm! Surely thats less magnification?

Freelander86

Low and medium magnifications are very useful for viewing deep sky objects. Higher magnifications are really only used on the planets, the moon and binary stars.

The ideal situation is to have a set that spans low - medium - high powers.

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rwilkey

rwilkey

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Hi Freelander86, it all depends what you want to view, planets, Moon, DSO's? The possibilities are endless. Magnification is not always the answer, as has already been hinted at, quality of image is what matters to most people I think, certainly to me.

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Tinker1947

Tinker1947

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If your going to use a 2x Barlow then getting EP's that when doubled don't clash with EP's you allready have, so something like a 24mm with a Barlow will go to 12mm, maybe a 15mm with a barlow makes 7.5 and a 5mm goes to 2.5mm, so a 24,15,5 will give you 6 magnifacations, the 2.5mm will properly blur every thing..:)

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freelander86

freelander86

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Ive decided to go with a Revelation Eyepiece kit.

After much deliberation I think it will be a good way to get a feel for what really works for me...

I was worried that I might spend £65 on a Barlow and 6mm EP and still not be happy.

At least I should have a few to try now :)

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newman

newman

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One of the first things you should get rid of is the beginner's idea that more magnification = better, always.

The best way to look at it is to remember that an eyepiece with higher mag does not suddenly make a telescope collect more light. Light gathering capability is the same, and is one of the most important features of a telescope. This means that an eyepiece with higher magnification will show your targets bigger, but to do that it will distribute the collected light over a larger area, resulting in a dimmer image.

In addition, there are two limiting factors regarding magnification: your own aperture, and the atmosphere. A general rule of thumb is to take your aperture in mm, multiply by 2, and that is your maximum practical magnification. This will, however, vary, depending on atmospheric conditions, the quality and type of your optics, and the target you're observing. The seeing will limit you as well, making you unable to go much over 200x on most nights.

Some DSO's are really faint. For instance, when looking for the Crab Nebula I'll use my lowest mag because it's really faint in my scope anyway. Magnifying would only make it a really dim, maybe even invisible smudge. M42 or M13, however, can tolerate more magnification since they're brighter objects. With planets, I find that I want to use the lowest magnification that allows me to make out detail. Just works best for me that way. Each time you go over the limit of what your optics, target and atmosphere allows, you'll get less than satisfactory results.

Another thing that is often overlooked by beginners is contrast, directly connected to the exit pupil. The exit pupil is the width of the light cone going out of your eyepiece and into your eye. The sweet spot is usually regarded as about 2mm exit pupil. You calculate the exit pupil by dividing your eyepiece's focal length with the focal ratio of your scope. Since your scope is f/5, a 10mm eyepiece would give you an exact 2mm of exit pupil, while giving you 65x magnification. A quality, wide field 10mm would give you optimal DSO results and would probably become a workhorse, with occasional switches to higher mag when needed. The ep's that come with the scope.. well, let's just say I have yet to see one I actually like. Especially after having looked through, and eventually owning premium quality. My Skywatcher super MA 25mm and 10mm ep's don't stand much of a chance of being used anymore, since I put stuff like Orthos and an Ethos in the collection. They're just completely redundant, and the only reason I've kept them around is because I intend to sell them off alongside the scope when I decide to get the second one.

In short, magnification is just one part of the equation, and if you overlook the other important factors you're likely to get less than satisfactory results. If I were you I'd steer clear of kits and take my time, building my eyepiece collection one quality eyepiece at a time, starting with the ones I'm likely to use most and moving to more specialized ones as I go along. An eyepiece is half your optical system, and a lot of people would argue it's the more important half - since most people who stay in the hobby eventually outgrow their beginner scope and get a better one. A quality ep set will last you through such a change and will be usable on the next scope as well.

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freelander86

freelander86

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Thanks for the post Newman.

Its staring to make sense that I cant expect to see Jupiter at full resolution at the same size as the eyepiece i'm looking through!

I have however ordered the revelation kit and I hope it will give me a good insight as to what I need.

It includes a 9mm (down from my 10mm with the scope) so hopefully that will be all the magnification Ill need for a while. (Especially with the barlow!)

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