Eyepiece selection help

[dcwales2012]

Hi,

Unfortunately my eye sight is not that brilliant - short sighted with astigmatism. I use a tal 2 x barlow but cant get decent viewing of planets with a 7mm EP, cant pick out any detail. If I use my Revelation 15mm and 32mm; say on Jupiter I cant see all its moons quite bright. So basically what I'm asking is, how much higher could I go in EPs to be able to see Jupiters in better detail, or Saturns rings, or Mars polar caps?

Telescope SW Explorer 150p.

Been looking at Celestron Cel-LX, WO Swan and SPL and Vixen NPL, but not sure if these will Improve my viewing. Could I go to a 4mm or 5mm?

Assistance gratefully appreciated

Regards

David

[damnut]

Hi David,

If you have a local astro group, then I would go to one of their meets and ask to try out some of the ep's being used.!

The BST Explorer / Starguider ep's are good value for money and have large eye lens for ease of viewing and a screw up rubber eyecup which is great for specs !.. They can be found here :-- http://www.skysthelimit.org.uk/telescope%20eyepieces.html Also the chap who runs this is a good guy and will let you try and buy.

The 5mm will give you 150x (from memory your scope has a focal lentg of 750mm). You should be able to easily see the cloudbelts on jupiter , the four Galilean moons and the rings of saturn. However do not expect 'photograhic' quality viewing!.

If things are blurry, check your signature!(the collimation bit...)

Hwyl!

[bingevader]

If things are blurry, check your signature!(the collimation bit...)

Agreed, I'd stop shaking it about too!

If I'm right in thinking you're using the 2x tal barlow with the 7mm EP, then you're probably overdoing it a bit. You'd need very clear steady nights to work at over 200x magnification.

A 4mm EP should give you about 187x magnification, so would depend more on conditions and the site you're viewing from.

As Damnut has said, the 5mm would be good and a sound safe bet. Can't go wrong with a BST. But The Celestron comes in a 5 too. WO don't do a 5mm in swan or spl and the Vixen is a plossl so at that size the eye relief will be tight.

Cheers

[Oddsocks]

Hi David,

Like you, I have poor eyesight, astigmatism, retinal damage, torn vitreous humour (floaters), and have been struggling with this for the last ten years or so.

These days I mostly only deep sky image with ccd cameras but I still on occasion look at the planets visually using a W.O FLT 110 or with an Orion Optics ODK 10.

I found the best eyepieces to help cope with my eyesight problems have been the Televue Radians and Panoptics but both in conjunction with the Televue Dioptrix astigmatism corrector.

Being able to view directly at the eyepiece without glasses to correct my eyesight defects has been a great help.

Also found turning the diagonal to view horizontally and seated rather than standing and looking down into the eyepiece helps keep all the rubbish in my eye from drifting across the field of view.

If you get a chance to try before buying any one of the Radian, Ethos or Panoptic eyepieces together with the Dioptrix corrector I think you will be amazed how much clearer your view becomes.

Regards

William.

[ronl]

I find the BST Starguider and wide angle planetary eyepieces very good,

and are easy on the eye, like yourself my eyes are not that good, but with

these I get great views, Saturn is superb.

Clear Sky's

[ronin]

If the scope is f/5 then I suggest not considering the WO SWANS, WO say they are not good at faster then f/6.

The Vixen NPL's are plossl's so eye relief will be a problem at the shorter focal lengths, so suggest those are dropped.

Would it be right to guess that the 7mm you have is part of the Revelation set and therefore a plossl?

So that leaves Celestron Cel-LX and SPL from your original list.

The WO SPL's are only 3 in the set and the 3mm is too short I would say, but I don't have your scope and don't have the SPL's.

The 6mm should be good and give 125x.

The Celestrons have the best selection of focal lengths at the short end for magnification, 5mm, 7mm, 9mm.

They have good/reasonable eye relief of 16mm.

The BST Skyguiders are similar to the X-Cels and come in 5mm, 8mm and 12mm at the lower end.

A lot will depend on whether or not the barlow is good - Tal's have a good reputation, however I stick to single eyepieces.

What detail can you see on Jupiter ?

I can see banding quite clearly at 60x, and my eyes are no different to yours, this was with the BST's.

The 7mm wil have given 107x so would have expected a fair bit of detail. You could need 120x for Saturn.

Problem I have is that you have a 7mm otherwise I would have said the Celestron X-Cels, however you will be doubling up on 7mm as the 7mm should really do both Jupiter and Saturn. For cost and a little less magnification how about the 8mm BST ? Another option is the 12mm BST and then throw in the barlow, giving 12mm and 6mm.

A 5mm should be usable in your scope.

Both the Celestrons and the BST are good at f/5, maybe the 7mm (if plossl) just cannot handle f/5, that is about boarderline for most plossl's.

[dcwales2012]

Hi,

Thanks for your replies. I think the Televue's are out of this pensioners price range.

Checked fleabay and there are no BSTs lower than 8mm at present. How would that compare with a Cel-LX 7mm. If I got a 5mm and 7mm Cel-LX should I see an improvement.

Regards

David

[valefor]

At the monent there are 2 bst explorer 5mm on ebay.

380679674710

370782587867

[Andrew*]

Hi,

Unfortunately my eye sight is not that brilliant - short sighted with astigmatism. I use a tal 2 x barlow but cant get decent viewing of planets with a 7mm EP, cant pick out any detail. If I use my Revelation 15mm and 32mm; say on Jupiter I cant see all its moons quite bright. So basically what I'm asking is, how much higher could I go in EPs to be able to see Jupiters in better detail, or Saturns rings, or Mars polar caps?

Telescope SW Explorer 150p.

Been looking at Celestron Cel-LX, WO Swan and SPL and Vixen NPL, but not sure if these will Improve my viewing. Could I go to a 4mm or 5mm?

Can you just confirm this is the short tube version? It will make a big difference in eyepiece selection if it's f/5 or f/8 - definitely easier if it's the latter... If it's f/5, of those you've mentioned I would only really consider Celestron X-Cel LX as the SPL don't offer the focal lengths you need, the WO is not good in f/5 and the NPL will have very tight eye relief.

I'd say you could easily get away with a 4mm, but not much lower. Did you use the 7mm with the 2x barlow? This would give 3.5mm or 214x which should give a fair view if the eyepiece is good. If it's not, or if your eye's astigmatism isn't corrected, you would do well to upgrade to a better eyepiece with enough eye relief to use your glasses.

Going too high in magnification is as bad as not going high enough - you will not get enough resolution.

I think a 7mm Celestron LX may be your best bet, but if you can push your budget a bit, consider a 4mm Vixen NLV http://www.firstligh...-eyepieces.html

or even a 3.7mm or 4.7mm or 8mm Televue Delos - they are £250 at the moment which is quite good value.

[cotterless45]

The 5mm Bst gives super eye relief and will give you enough magnification. Be aware that at this high end seeing conditions must be the very best as must collimation. You might see more clearly using the flat field 8 mm from the same source.

Good 2nd hand eps are the Meade 4000 and GSO,

Nick.

[AlexB67]

Hi,

Thanks for your replies. I think the Televue's are out of this pensioners price range.

Checked fleabay and there are no BSTs lower than 8mm at present. How would that compare with a Cel-LX 7mm. If I got a 5mm and 7mm Cel-LX should I see an improvement.

Regards

David

http://www.ebay.co.uk/itm/1-25-5mm-BST-Explorer-Dual-ED-eyepiece-Branded-Starguider-/380679674710

I think they are available if you are talking about the Starguider ( as opposed to the other BST at 58 degrees, which often get mixed up in discussing these eyepieces ). It is not always obvious finding the items directly on his site though I've missed them too previously in a search.

For the BST Starguider, f/5 it is suggested as the sort of cut off point to not really go much below that focal ratio, not that it wouldn't work of course, but as a rough guide if you do not want to suffer from too much distortion at the edges of the view. My eye sight is not great either once I remove my specs and I have no issue with them . I observe mostly with my specs off, but the BST Starguider works fine with them on too.

[Andrew*]

Thanks for your replies. I think the Televue's are out of this pensioners price range.

Sorry, I missed this.

[dcwales2012]

Andrew, no problem.

Went for 5mm and 8mm BST in the end. Just waiting for some darker nights, now to get in some seeing.

[hippie]

:glasses8:I wear glasses and fall into the older stargazer problems of deteriorating eye's, After reading on hear about the BST eyepieces I got in contact with Alan at Skies unlimited  he was very helpfull and recomended the BST lenses so  I went ahead and  purchased the BST 25mm, 18mm, 8mm, eyepieces, I have only used them briefly the other night looking at the moon & stars using with my 2x telvue barlow before the clouds came over again, I am very impressed with them  and looking to get the 12mm, & 5mm, next to complete my eyepiece set,  There Great value for money and i recommend that you try them, Alan will gladly refund your money if not satisfied.    

[cotterless45]

I rate my 12mm Bst above my Vixen NLV, it's sharper with more contrast. The 25 mm Bst is my finder ep,

Nick.

[LeeB]

I also have astigmatism and floaters and find the best is as above, try to not look steeply down into the eyepiece and make sure you don't go to small on the exit pupil, which means more deep sky, low mag and less planetary stuff. or of cause a massive scope. I find that my 8.5 and 10 inch scopes are far more comfy on the planets and notice the floaters less. Also if observing the moon use a dark filter as it allows the pupil to open better again reducing floaters. As for astigmatism I just put up with it.