Altair-EX Eyepieces

[Naemeth]

After searching far and wide over the internet, I couldn't find much, and was wondering if anyone had any experience of the Altair-EX Wide Field eyepieces, they are 70 Degrees, and to be honest they look like they may be worth a try at £30:

http://www.altairastro.com/product.php?productid=16418

http://www.altairastro.com/product.php?productid=16419

Thoughts?

[E621Keith]

A 70deg eyepiece for the price of a plossl

Go on, buy one and tell us what it's like.

[John]

Low cost wide field eyepieces can be great in slow scopes (eg: F/10) but yours is F/5. The centre 50% or so of the field will be fine but the stars in the outer parts are likely to be distorted a bit. Unless Altair have found a rival design to a Tele Vue Panoptic at 1/7th of the price !

[Naemeth]

It still has to be better than the stock eyepieces. I think I will give this one a try when I get the money .

Keith, I had those exact thoughts in my head when I posted this .

[John]

It still has to be better than the stock eyepieces.......

Yes, but thats a fairly low benchmark. Personally I reckon the BST Explorer eyepieces would be better even though they are a bit more expensive and have a slightly smaller field of view.

Still, £30 is not a lot, as you say.

[Naemeth]

Yes, but thats a fairly low benchmark. Personally I reckon the BST Explorer eyepieces would be better even though they are a bit more expensive and have a slightly smaller field of view.

Still, £30 is not a lot, as you say.

I'm planning on a 15mm BST soon-ish.. so I suppose when I have both I could compare, then sell on the one I don't like .

[Capricorn]

It is a 4 element design, the same basically as a plossl. They do not state how many groups, it would have to be at least 3 otherwise it would be a plossl. Every one I have seen/read of with this specification are 5 elements not 4.

Mind you I would expect an astronomy retailer to know how to determine the magnification of a scope and an eyepiece.

Copied from the Altais Astro page of the eyepieces mentioned:

To work out the amount of magnification this eyepiece produces with your telescope, simply divide the focal length of the eyepiece by the focal length of the telescope.

Always thought it was the Telescope Focal Length divided by the Eyepiece Focal Length. :rolleyes:

[Naemeth]

It is a 4 element design, the same basically as a plossl. They do not state how many groups, it would have to be at least 3 otherwise it would be a plossl. Every one I have seen/read of with this specification are 5 elements not 4.

Mind you I would expect an astronomy retailer to know how to determine the magnification of a scope and an eyepiece.

Copied from the Altais Astro page of the eyepieces mentioned:

Always thought it was the Telescope Focal Length divided by the Eyepiece Focal Length. :rolleyes:

I might just inform them of that when I go into the shop (it's reasonably local... sort of).

[E621Keith]

It is a 4 element design, the same basically as a plossl. They do not state how many groups, it would have to be at least 3 otherwise it would be a plossl. Every one I have seen/read of with this specification are 5 elements not 4.

Abbe orthoscopic also have 4 elements in 2 groups, a triplet and a singlet, so an eyepiece with 4 elements 2 groups is not necessary a plossl. The are a few more non plossl/abbe possibilities but I don't know whether any of them will work.

I'd guess the most likely design is a 4 elements Konig (3 group) which can have 70deg field.

[Naemeth]

I don't think Konig designs are that common, but are probably a step above MA / Kellner etc...

[John]

I think the 20mm in this review is the same eyepiece as the Altair EX 20mm:

http://www.cloudynig...hp?item_id=1293

I'm pretty sure these are 5 element eyepieces, a development on the Erfle design.

[Spec-Chum]

Seems pretty good if it is. I've got all the ep's I need for now tho, so ill pass for now...

[alan potts]

Low cost wide field eyepieces can be great in slow scopes (eg: F/10) but yours is F/5. The centre 50% or so of the field will be fine but the stars in the outer parts are likely to be distorted a bit. Unless Altair have found a rival design to a Tele Vue Panoptic at 1/7th of the price !

I don't think so John, unless it is a re-brand we were talking about earlier.

Alan.

[Naemeth]

I think the 20mm in this review is the same eyepiece as the Altair EX 20mm:

http://www.cloudynig...hp?item_id=1293

I'm pretty sure these are 5 element eyepieces, a development on the Erfle design.

I think you are right, I believe it is a GSO rebrand:

http://www.teleskop-express.de/shop/product_info.php/info/p2643_GSO-SuperView-20mm---1-25--WA-eyepiece---70--FoV.html

Around the right price too..

[John]

I think you are right, I believe it is a GSO rebrand:

http://www.teleskop-...---70--FoV.html

Around the right price too..

GSO make stuff for loads of folks it seems - decent stuff for the money too

Thanks for the link - my German vocabulary has increased:

Umklappbare Gummiaugenmuschel = Fold Down Rubber Eyecups

Might not crop up in regular conversation much though ......

[Naemeth]

GSO make stuff for loads of folks it seems - decent stuff for the money too

Thanks for the link - my German vocabulary has increased:

Umklappbare Gummiaugenmuschel = Fold Down Rubber Eyecups

Might not crop up in regular conversation much though ......

With a German Astronomer it would

It was a coincidence really, as I was looking for a 32mm Plossl, went on eBay, then went to there. If it is just a rebrand of the GSO, it should be of good quality. May be worth getting. I will see in probably September-ish when I'm looking at getting my next EP.

[russ.will]

I'd agree it looks like a re-branded GSO Revelation Astro Superview EP. I had the 2" 26mm for a very short while - It's eye relief was too long (kidney beaned like a goodun) and astigmatism was very obvious in the outer 50% of the field of view. I didn't like it, replacing it with the BST Explorers which were far superior in my F5 200p.

Russell

[Capricorn]

You mean these GSO Super View Eyepieces:

http://www.gs-telescope.com/content.asp?id=147

Cannot see any detail on them however.

[russ.will]

If not those ones (where's the 26mm?) then definitely these ones.

Russell

[Naemeth]

If not those ones (where's the 26mm?) then definitely these ones.

Russell

They are the 2". The Altair/GSO 15mm and 20mm are 1.25".

[russ.will]

Indeed, but it's still that old nugget of squeezing a wide FOV out of a cheap eyepiece - Fast scopes find them out.

At £30, I'd go GSO Super Plossl (or any of the major branded Plossls - Vixen NPL, Skywatcher, etc) simply because whilst the total FOV will be smaller, the sharp FOV will be wider.

Russell

[Naemeth]

Indeed, but it's still that old nugget of squeezing a wide FOV out of a cheap eyepiece - Fast scopes find them out.

At £30, I'd go GSO Super Plossl (or any of the major branded Plossls - Vixen NPL, Skywatcher, etc) simply because whilst the total FOV will be smaller, the sharp FOV will be wider.

Russell

I'm still unsure of what to go for as my finder EP. A good 70 degree 20mm EP will show 2.2 degrees of sky (or thereabouts), my current 25mm shows 2 degrees. I've found a nice EP (TMB Style Design) at 25mm with 58 AFOV which gives 2.23 degrees and a nice design and adjustable eye relief. I don't know what exit pupil to go for, but know it shouldn't be over 7 certainly, and as I live in a quite heavily light polluted area, I think 25 - 27mm is my maximum (5 - 5.4mm exit pupil). Thoughts?

[russ.will]

2 degrees is loads - An extra 0.2 isn't going to add anything significant. My SW Panaview 32mm (6.5mm exit pupil) is my finder EP and gives me 1.493deg TFOV in the Flextube and I manage just fine.

I still stand by a decent Plossl for £30. A faint DSO fuzzy will be invisible in the mush that is the outer edges of a cheap wide angle EP, which doesn't really help. I'd hang on for second hand bargains as we've discussed before. After all, there's little chance of any decent viewing for at least the next two weeks...

Russell

[Naemeth]

2 degrees is loads - An extra 0.2 isn't going to add anything significant. My SW Panaview 32mm (6.5mm exit pupil) is my finder EP and gives me 1.493deg TFOV in the Flextube and I manage just fine.

I still stand by a decent Plossl for £30. A faint DSO fuzzy will be invisible in the mush that is the outer edges of a cheap wide angle EP, which doesn't really help. I'd hang on for second hand bargains as we've discussed before. After all, there's little chance of any decent viewing for at least the next two weeks...

Russell

I am hanging on .