After my recent exposure to Pentax XF 8.5mm eyepieces, I ordered and recently took delivery of the Pentax XF 12’s and yesterday I finally got a chance to try them…
I really wanted to see how they compare to the Televue Delite 11mm’s with a view to selling the Delites if the XF’s are as good…
targets were some glob and open clusters around ETA Carinae and the moon.
ERGONOMICS - These eyepieces are significantly smaller and lighter than the Delite 11’s. The XF’s come in at around 150g each which is next to nothing. Achieving focus in the Lunt 100’s was not an issue with plenty of focus travel left in either direction.
They are par focal with the 8.5’s.
Comfort wise i’ve had to remove the outer barrel of the Delites to make them comfortable. While this worked, I never enjoy having to modify an eyepiece to be able to use it (that’s part of the reason I’ve since been considering the XF’s) The XF’s on the other hand fit my eyes perfectly straight out of the box. The eye guard is a twist top with 3 stops between being being fully extended and fully retracted.
Eye relief is generous - the XF literature puts it at 18mm. I’m dont wear glasses so this is plenty for me. Once i found the most suitable position on the eye guard, eye placement became easy with no blackouts or kidney beaning when rolling my eyes around the FOV.
I cant say the Delites are any LESS comfortable in the way I use them however this is with parts of the eyepieces removed. Factory standard, the Pentax’s are definitely more comfortable to use for binoculars/binoviewing for me.
THE VIEW - The XF’s are 60* FOV and the Delites are 62*. To my eye the slight difference in FOV between the two was in line with the slightly higher magnification of the 11mm (50x vs 46x on the XF).
Comparison in the Lunt 100’s was done over several hours in both bino mode (same eyepieces in both barrels) and telescope mode (different eyepiece in each barrel for direct comparison)
Contrast is equally superb on both eyepieces with the background being presented equally dark.
Other than this, colour representation was also excellent. The moon looked identically white in both eyepieces. Stars also presented similarly however I thought the view through the XF’s showed a bit more intensity if that makes sense.
CA was the one that surprised me. On axis both show no CA whatsoever, however when looking at the Moon off-axis, probably in the last 15% of the FOV, a faint purplish line appears at the edge of the moon in the Delites. The XF’s on the other hand show a clear break with the dark background giving a nice clean edge to the Moon. This really surprised me as I was expecting similar performance from both.
To compare the similarity between the 2 eyepieces, I also had my Swarovski ATS 80 spotting scope out with the 25-50x eyepiece. Viewing the moon through this showed nil CA, however the colour of the moon was noticeably warmer which (in my experience) is typical of the Swaro eyepiece in astro viewing.
I then moved to a couple of open clusters (NGC3532 below ETA Carinae, and the Southern Pleiades)
On axis stars were equally sharp in both eyepieces. Focusing on the XF was also a pleasure as the stars seemed to “snap” into focus. On the Delites i tend to hunt for the focus a bit more. Its hard to describe and ultimately a very tactile experience.
Off axis was a bit different. The XF showed some mild FC in outer 10-15%. When stars were sharp in the centre of the field, the edge softened. If i brought the edge of field into focus, the centre would soften marginally. In the Delites the field remains sharp to the edge. I have read varying reports about this characteristic in the XF 12’s so really wanted to see for myself. Given my experience last night, it wasn’t as bad as I had imagined it to be. Given i view on-axis, its something I can live with.
I’m on break for a few days from tomorrow so should have access to dark skies. I plan on taking the Lunt 100’s and these eyepieces so will test some more, however prima facie if my experience continues to be as per my comments above, I’ll be adding the XF 12’s to the collection and moving the Delite’s on.
This gives me a set of Denks in 21mm and 14mm and the XF’s in 12mm and 8.5mm.
I have the APM 120’s on order so most likely I’ll keep the Denk 21’s in the Lunt 100’s to give those wide 2.5* views at 26x mag.
I’m think of leaving either the XF 12’s or Denk 14’s in the APM 120’s - the XF12’s will give me 55x or the Denk 14’s will give me 43x.
The 8.5's will be used once every now and then to push the magnification higher if the need is there..