PDA

View Full Version here: : Pentax 14mm XW Alternative ?


Nordo
13-11-2006, 08:38 AM
I want to start upgrading my EPs, and from what I've read the XW would be a great EP for the 13-15mm range. However, as the XW is a little out of my price range at the moment, I was wondering what EPs in a lower price range would be comparable? ie what lower priced EP comes closest to all the attributes of the XW? :)
Really, I guess I should be asking - What do you consider is the best "bang-for-buck" wide angle EP in the 13-15mm range?

wavelandscott
13-11-2006, 09:25 AM
While I've not used them myself, I've heard many people attribute the title "best bang for buck" to the Stratus line of eyepieces...but I am not sure on the eyep relief.

There is a 13 mm and 17 mm that seem to be near what you are looking for. They are available at Bintel (maybe other places too) and Rodstar has a secondhand 17 mm for sale in the Buy/Sell/Trade area of this sight.

Again, I've never used one but I've read/heard pretty good things about them.

Good Luck!

ausastronomer
13-11-2006, 09:55 AM
John,

I own the 14mm Pentax XW and like it a lot.

I have also used the Orion Stratus series in several scopes including my own 10"/F5. IMO these are clearly the best value for money eyepieces currently available. The upside is, for a budget eyepiece they perform quite well in fast scopes, with reasonable edge performance and nice bright sharp stars. They have 20mm of eye-relief in all focal lengths and are very comfortable to use. These are Chinese made almost-clones of the Vixen LVW's.

For someoene on a budget with a reasonably fast scope, these are the only option IMO for a widefield with good eye-relief. The Baader Hyperion is almost identical optically to the Orion Stratus, the coatings are a little better IMO and consequently they are a little more expensive.

CS-John B

OneOfOne
13-11-2006, 01:50 PM
I have an XW7 and Stratus 8 and comparing the views in each of them, the difference is fairly marginal, the XW by a couple of whiskers! The Stratus range have got a very good reputation for clarity etc. at around half the price of an XW. If you are on a bit of a budget, but can stretch to a couple of hundred, I would recommend the Stratus or Hyperion which are very similar.

As noted by others in the group, the XW14 does appear to have a bit of field curvature, and I can confirm this myself in mine. I don't have an equivalent Stratus though, so I can comment on how the equivalent compares. The XW14 is not as "good" as the 7 or 10 though.

ausastronomer
13-11-2006, 02:12 PM
You need to be a bit carefull there, jumping to conclusions based on a sample of 1 eyepiece in 1 scope. The 14mm Pentax XW shows worse field curvature in some scopes than in others. I have a 10"/F5 newt and an 18"/F4.5 newt. The field curvature in the 18"/F4.5 is hardly noticeable. This would appear surprising to some being of faster F-Ratio, but in fact field curvature seen in the eyepiece is not solely dependant on the F-Ratio of the scope it's used in, unlike coma and some other aberrations. We compared the views in the 18" scope between the 14mm Pentax XW and a 17mm Nagler T4 (both without a paracorr) at Kulnurra a couple of Saturdays ago and the Pentax gave a better view in just about every respect than the Nagler including field curvature and it's performance at the EOF. That wasn't just my opinion either BTW, there were about 6 other IIS forum members that all saw exactly the same thing. To be honest it wasn't even close. In fairness to the 17mm Nagler, I think its performance would have been improved a lot by the use of a paracorr, whereas the paracorr may not have been quite so beneficial in the Pentax.

CS-John B

stephenmcnelley
13-11-2006, 02:17 PM
Ditto all of the above re Stratus, for a couple of hundred $ a Stratus 13mm is a value EP. There is a little distortion in the outer edge FOV, though it has a lot of elements they give a nice flat view not much curvature, but i am no expert at judging that. They are a little down on light transmission compared to say, a simple narrow field super plossl, but contrast is very good as far as my own eyes can detect.
For a little more the Baader Hyperion 13mm- another Vixen clone- comes with slightly better (?) coatings and threads to attach stuff to it for imaging, but i dont know much about how they work.

Nordo
13-11-2006, 09:49 PM
Thanks everybody:) .
I had heard of the Orion Stratus, and was hoping to have a lend of Gargoyle_Steve's 14mm this Saturday at Cambroon, but he can't make it.
$199 sounds a lot better than $399:thumbsup: .

janoskiss
13-11-2006, 10:17 PM
Having owned a number of both types of EPs, IMO the difference between XW and Stratus is not marginal at all but very obvious from the first moment you try to focus with the eyepiece in the focuser. The Stratus (and Hyperion) are the best in their price range. Stratus, Hyperion, LVW, XW: these are all worth the investment if you can afford them. XW-14 with a typical Newt does have field curvature though and I do find it bothersome (this varies from one individual to next).

CoombellKid
13-11-2006, 11:38 PM
I sometimes wonder after hearing fairly varied accounts of the field curvature
in the 14mm XW, which I see mostly being testing in mass produced mirrors.
If the varying performance of the mirrors have something to do with this. I've
tried my 14mm XW in a variety of scopes, in some it performs better than in
others.

I have tried a Hyperion, cant remember what FL it was. But I would have to
say it was the closet thing I've seen to the performance of the XW in regards
to contrast.

regards,CS sunny days

Rob