WHAT EYEPIECES

[Newbs2215]

Hi All,

 

Recently bought a Celestron Nextstar 4se, which came supplied with a 25mm plossi eyepiece. I would like to know what eyepieces i would be best off buying to supplement this model. I also have a Celesrtron 2 x Barlow. I would like to cover as broad a spectrum as is possible, but would like to future-proof any purchases i make.

All suggestions gratefully welcome.

[Ricochet]

What sort of budget are you thinking of per eyepiece? I would probably start with the fact you've got a long focal ratio Mak with a 1.25" focuser and so plan a 32mm Plossl (maybe even a 40mm) for maximum exit pupil at the bottom end. Above that I would swap your 25mm Plossl for a 24mm 68° and above that look for something at about 17mm and then at about 12mm. You might want to consider an 8-24mm zoom instead of the 12mm so that you can adjust lunar/planetary magnification depending on the exact conditions.

The cheapest move would be to just buy the 32mm Plossl and then barlow that and your existing 25mm to give you a set of 32-25-16-12.5 but barlows extend the eye relief and this may be an issue with those eyepieces.

[ronin]

First is that a decent plossl shoiuld do fine in a 4SE, but get a 30/32mm or maybe better a 40mm. BAsically simple biggest field of view possible. Lets sasy you get a 40mm.

So yu have 40 + 25 next consider a 15mm and eventually a 10mm. You can more or less stop there but personally I would just go 40, 25, 20, 15, 10.

Good plossl's are TV (£££) and Vixen (£50ish). I have lost touch with the plossl options.

Next the future proof and in a way the Vixens. Many myself included use BST Starguiders (£50). They have a bit wider field of view but stop at 25mm. So a 25mm BST gives the same field as a 30mm plossl. The Vixen involment is that they went up in cost and are now the same cost as a BST some in monetary terms no real difference. The BST's come in other focal lengths and mave a fixed eye relief. They likely both operate to the same focal ratio's.

I have the full set of TV plossl's and the full set of BST's. Do npt think you will necessarily only end up with one set of eyepieces. I also have assorted others.

That covers the lesser cost area. Next wold be the Meade 5000 HD, about (£100). No idea how good but good reports, I do actually need one to fill a gap. Next  up in cost are ES 82's but being wide the focal lengths are limited. So you will end up with some ES 82's and some others.

That is where I stop. Supply a budget, essential.

You want long focal lengths's 40 to 10 in plossl or 25 to 12 or 8 in BST, even the 8mm may get little use. Ignore the claims of magnification.

In general I have the opinion you need enough to see Saturn, say 125x maybe 150x IF the scope delivers a good image. 80x will oddly be about average use, maybe a bit less.

[Newbs2215]

Was thinking about buying Baader Hyperion eyepieces. Starting with the 32mm and working towards an 8mm at about one eyepiece per month, rather than the cheaper Celestron models. My thinking is that if i invest in quality eyepieces at the start of my journey, i will not have to pay out later on. I am also thinking about getting an 12 Dob for DSO's.

Not really bothered about the money part of it.

[ronin]

Hyperons will not be much good on a 12". They are fast and hyperons do not perform well in a fast scope.

If the idea is 4SE now and 12" in future then I suggest the BST's now and later a couple of the ES82's for the width at the shorter focal lengths.

[alanjgreen]

Newbs,

It’s hard to future proof eyepiece purchases as they are very scope specific. Your scope has a focal length of 1325mm. You divide this number by the eyepiece focal length to calc the magnification you will get at the eyepiece.

you should be looking to get a spread of magnifications with gaps around x50 as you go, so something like x50, x100, x150, x200 or x75, x125, x175, x225.

A difference of less than x50 will not really be noticeable at the eyepiece and is therefore not worthwhile.

You scope has 4” aperture and a magnification maximum of x50 per inch puts you at a top end of x200.

your 25mm EP is giving you 1325/25 = x53 magnification (in this scope)

i would start with a x100 (12mm) then a x150 (8mm) and lastly x200 (6mm)

Budget is next, you want decent EPs, these will be around £50 each for something like a BST Starguider.

You need to consider

- eye relief. If you wear glasses then the EP you buy needs minimum 15mm eye relief. Check the spec. Eye relief is distance from eyeball to top lens of EP

- field of view. This is how wide a piece of sky you get at the EP. Less than 50 degrees is tiny. More than 60 degrees would be wise. The wider FOV will push the price up

Once you start considering another scope then if that new scope has a wildly different focal length to the 4se then your current EPs will provide totally different magnifications and need to be sold and replaced so there is a limit to “future proof”

Alan

 

[Newbs2215]

Hi Ronin,

Many thanks for the info. Looks like BST's at a rate of one a month. Also seem good for glasses wearer. However largest BST FLO offer at the moment is the 25mm. Maybe more in the future, or buy somewhere else.

[alanjgreen]

38 minutes ago, Newbs2215 said:

Was thinking about buying Baader Hyperion eyepieces. Starting with the 32mm and working towards an 8mm at about one eyepiece per month, rather than the cheaper Celestron models. My thinking is that if i invest in quality eyepieces at the start of my journey, i will not have to pay out later on. I am also thinking about getting an 12 Dob for DSO's.

Not really bothered about the money part of it.

Buy the first ones to cover the KEY magnifications then you get more out of the scope.

remember these three x50, x100, x150 gives a great useable spread.

the 25mm is giving you x53. A 32mm will give x42 !

Making this somewhat pointless as a first EP purchase in my opinion. As the Americans say, do the math!

Alan

[Newbs2215]

Sub Dwarf & Ronin,

 

Many thanks for the advice. Very new to this. Was just looking at BST Starguider's.

 

 

[cloudsweeper]

You might want a slightly longer focal length EP if you wish to see a wider field of view, for example to enjoy larger clusters.  (Plus the view might help you find your way round.  GoTo is all very well, but to confirm what you are looking at, again, a wide field is useful.)

A 32mm would give you about half a full-Moon's extra view.  I wouldn't try to go much higher though, since this benefit decreases owing to the smaller inherent field of view of say a 40mm eyepiece.

Doug.