I'm considering a wide-angle eyepiece in the neighborhood of 30x for my 65mm ED Pentax scope.
Before I shell out the $$, I'd really like to know what the essential difference would be between the XF (very much in my budget) and XW (stretching the budget) eyepieces.
Tell me all you want about the quality of the glass, ED vs. non-ED. I appreciate the aesthetics of the argument. BUT, will it make a difference in my birding in the field?
Yes, it is worth the difference. As with all things, there are tradeoffs between cost/quality and only you can really decide it it's worth the budget "stretch".
I have tried the XF12, XL14, and XL10 and directly compared all three. The XL's are the predecessor to the XW and extremely similar, except the XW's are a teensy bit brighter/sharper and have a wider field of view. My thoughts on the XL should apply to the XW pretty well.
When I tested the XF12 vs. XL14 vs. XL10, I ended up keeping only the XL14 and selling the other two. Do some searches on this forum and you can dig up some of my older posts comparing them, this has been discussed a few times before.
My thoughts in brief:
1. In the center of the field, there is very little difference between any of them as they are all excellent, excellent eyepieces. The XF has a slightly different color cast (a little cooler?) but it's not significant. The XL is maybe a hair sharper in the center.
2. As you move to the edge of the field, the XL dominates the XF. The XF starts to get blurrier and has increased chromatic aberration out in the outer 20-30% of the FOV. An XL stays sharp and well-resolved almost to the edge.
3. The wider field of view is significant, and perhaps it's a perceptual thing but the XL always felt significantly "brighter" than the XF.
Now, don't get me wrong, the XF is an EXCELLENT eyepiece.
However, the XL was clearly superior: wider field of view, brighter, sharper, and held the image out almost to the edge. And this has practical implications for birdwatching. The wider field of view makes scanning for your bird much easier. On a seawatch, I can be focused in on one bird and catch a different bird zooming by at the edge of the field.
The sharpness out to the edge is very helpful when, for example, scanning a flock of shorebirds or gulls. I can just set the scope on group of birds and move my eye around to examine the flock, and the bird out at the edge is just as sharp as the one in the middle. With the XF, I would have to reposition the scope more frequently.
The XF's biggest advantages are that it is tiny and light, and I found it to be extremely comfortable and easy to position the eye. The screw-up eyeguard is exceptionally comfortable, moreso than the XL.
The only thing I have heard with regards to the XW (as opposed to my thoughts on the XL) is that the XW is a little less forgiving with eye placement, easier to get "kidney beaning" or "blackouts". This seems to be true of most super-wide-angle eyepieces, as in order to get that much apparent FOV resolved at the same spot involves a few compromises. Naglers (with 80 degree + AFOV's) are notorious for being highly sensitive to eye position.
So in summary: the superior brightness, sharpness to the edge, and wider field of view of the XL/XW make it a superior all-around birding eyepiece over the XF. If I could have only one eyepiece for a PF-65, it would no doubt be an XL or XW 14mm. The view at 28x is exactly in the sweet spot of the scope, and it's still wide enough for general use.
However, if you don't want to shell out for an XW, there are several options:
1. The Baader Hyperion or Orion Stratus 13mm that others have suggested is an excellent option. They are bulky, but give a wider field of view than the XF with equal sharpness. I briefly compared my scope with XL14 to a friend's PG-65 with Stratus 13mm, and the views were very similar. These are considered the #1 "bang for the buck" wide angle eyepieces.
2. A used XL14 can be had for $180-200 or so. Check the classifieds at Astromart.com and ebay. The XL is almost as good as the XW, just sacrifices a little bit of AFOV.
3. A used XW14 will save you 15-20% off the new price, although people do not like to let go of these!
And, as others have said, the XL/XW as higher-end eyepieces will hold their value better.
Hope that helps!