Pentax XW vs Vixen LVW

[janoskiss]

Has anyone had a chance to compare Vixen LVW and Pentax XW eyepieces of similar focal lengths? Are the Pentaxes considerably better? Is it just the obvious differences, i.e., 5 degrees extra AFOV & twist eyecup, or are they clearly superior optically? Any comments most welcome, thanks.

ps: I saw what could be very good deals on Vixen LVW and Pentax XW eyepieces, but I haven't followed them up yet. Just dreaming at this stage.

[davidpretorius]

sorry mate, all i can say is that i really like asimovs 5mm lv. talking to astroshop, he actually uses the lvw's and loves them

[matt]

I have the 6mm LV which I use with my 8" f5 and it's very nice.

I've had a look at the 13mm LVW and that's a serious lookin' bit o' gear!!! Big and lots of glass:lol:

It's the next EP on my shopping list and will work nicely with both the 8" and my Celestron 9.25.

[Starkler]

John B should have an answer to this.

I have the 10.5 and 14mm XL's and havent seen an eyepiece yet that I'd trade them for :whistle:

[janoskiss]

XWs maybe, Geoff? The XWs are 1.5x the cost of LVWs. Just wondering why when the specs are so similar and they are both meant to be "premium" EPs.

[ausastronomer]

Well I pretty much agree with Geoff. I have the 7mm,10mm,14mm and 20mm Pentax XW's and I won't be trading them on anything either. The 7mm and 10mm are about as good an eyepiece as I have ever used in these focal lengths and that includes everything uncle Al has ever made. The 14mm has a little bit of field curvature and the 20mm has slightly more field curvature in faster scopes. However, this is a necessary compromise to achieve 20mm of eye-relief and 70 deg AFOV at these focal lengths with this design. It is not obtrusive and you don't notice it in general observing, you can detect it if you specifically look for it. It causes stars in the outer 10% to 15% of the FOV to "bloat" in size by about 5% from best focus. They stay perfectly round and DO NOT become elongated astigmatic slits that are commonplace in $50 eyepieces. The upside is that on axis sharpness, contrast and light transmission are superb and superior to any premium widefield eyepiece I have used.

That having been said the Vixen LVW are also a superb eyepiece. Clearly superior to the LV's that others have mentioned as being great. They are also a completely different design to the LV's FWIW. Any observer would also be very happy to have a box full of Vixen LVW's in his observing kit.

In conclusion I possibly rate the 22mm Vixen LVW as superior to the 20mm Pentax XW. In all of the shorter focal lengths I think the Pentax XW's are about as good as it gets and superior to anything you care to throw at them. I rate them above the Nagler T6's and Radians also by a very small margin.

Whichever you choose between the Pentax XW's and Vixen LVW's you will end up with an excellent eyepiece. So don't get involved too deep in "paralysis by analsysis". If you can afford the shorter focal length Pentax XW's grab 'em, if not take comfort from the fact that the Vixen LVW's are also superb. Something else that may be important to you depending on the scopes you own is that the LVW's all have the dual 1.25"/2" barrel and fit either size focuser. This is no benefit to me but may be relevant to you.

CS-John B

[janoskiss]

Thanks heaps, John. Re the dual 1.25"/2" barrel size, don't the XWs have the same thing? I always thought they did. :shrug:

[Starkler]

Nope they dont in the shorter focal lengths, 1.25" only, and the 30mm up are 2" only.

Dual 1.25/2" configuration eyepieces can be a pain depending on focus point and travel of your focuser. If forced to use the 1.25" part in a barlow, it can be hard to get a firm mechanical coupling with the 2" section in the way also.

Well maybe I'd possibly swap for an XW, but I havent looked through any myself. DanielSun has a 22mm LVW that I looked through at the star camp, and that seemed very nice.

For those brave enough to buy second hand via astromart, I think the Pentax XL's are still a good bargain.

[ausastronomer]

Steve,

The Pentax XW's "look like" they do because of the step in the body but in fact they don't, the 2nd step is slightly smaller than 2".

CS-John B