I just got up from some much needed rest!
Here are my reports and findings from Last night using the 17mm Ultima LX and some other eyepieces.
When I got to the site, conditions were very good with minor haze because fog was due to roll in later that night.
Limiting mag was about 5.0 to 5.5 maybe. The double cluster was just visible using naked eye, so that should be a good base to go on. I let the scope cool with my large computer fan on medium speed on the back of my mirror for about 45 minutes before I started any serious observations. No Paracorr was used at all tonight, as I don't have one anyways.
I grabbed my 17mm Ultima LX and I put it in the focuser. I then immediately looked at the double cluster. From what I could see, and two of my other observing buddies, 80% of the view is sharp in my 10" reflector @ F/4.72.
Not too shabby if you ask me! The outer 20% definitely showed mild field curvature because I could re-focus it to a sharp point on stars. This eyepiece is a lot better then the 17mm Baader Hyperion I used to own, The 17mm Hyperion was good for about 65-70% of the view with the rest turning to a mess.
I had my eye on a 20mm Pentax XW before I picked this eyepiece up, so I wanted to compare. A friend who was observing that night was there with the rest of us, (there were 4 of us in total), and he lent me his 20mm Pentax XW to compare to my 17mm Ultima LX for FC, transmission and overall difference when looking at The Double Cluster. The FL is NOT the same, so a real head-to-head is not rightfully comparable ~ I only wanted to compare FC and transmission because I was going to buy a 20mm XW. The 17mm Ultima LX magnifies at roughly 71x, and the 20mm XW @ 60x.
In going back and forth with these two, the views were extremely similar FC wise. The 20mm XW seemed to show MORE stars transmission wise, but it maybe because of less power? I am not sure.....or because the XW is a superior EP? It could be one, or both, I am not sure why.
The eye relief on the 17m Ultima LX is very generous. I had my balaclava on and I could still see the entire field of view with ease. I left the screw up eyecup all of the way down because I like to leave mine all that way ~ Even on my Pentax XW's and XL's. I just find I can use it with ease that way, others may need to use the eyecup up on them, YMMV in that regard.
I also took a bright star in the 20mm XW and 17mm Ultima LX and centered it, then moved the bright star towards the edges. To me FC was close to identical in both eyepieces, with a tad less on the 20mm Pentax XW. Personally, after trying BOTH of these eyepieces, I would recommend getting the 17mm Ultima LX over the 20mm XW if you want to save some cash because the differences from what I could see were hardly noticeable at all. You'd literally have to find a faint galaxy to see the difference in transmission and see which was better in that regard. I did NOT try that, so I can't say. Sharpness wise on axis and overall was nice in the 17mm Ultima LX, but the nod goes to the XW's I'd have to say. Stars in the XW's are nice tiny "pin points". The difference is not hugely noticeable, but it is there.
I was also lucky enough to try a 16mm Nagler Type 5 and a Baader 8-24mm Click stop Zoom, (Mark II version). The 16mm Nagler T5 was extremely sharp right out to the edges w/o a Paracorr, but I was not a fan of the very short eye relief ~ it felt like the field was getting cut off because I had to really jam my eye in there to see the edges. YMMV there too. The Baader 8-24mm click stop Zoom was nice at the 8mm setting, but at 24mm setting felt very restricted.
I also got to try out a Pentax 8-24mm XL Zoom and I really liked that one. http://www.scopecity...m?ProductID=357
Getting back to the 17mm Celestron Ultima LX eyepiece, I would recommend it for fast scopes for sure! To me, it worked excellent out to 80% of the field like I said w/o a Paracorr, so that's a good thing. Adding a Paracorr to this EP would clean things up perfectly I would imagine, and this is something I really need to look into in the future ~ A PARACORR !!!! If I could still focus all of my eyepieces w/o any problems, I'd be all over a Paracorr in seconds. One more thing: The top cap was too tight and when packing up after everything was really cold, I could barely get it to go on, so I'll be looking for a replacement top cap. Another thing I noticed was that the 2" portion of the barrel was machined too much and when inserting it into the focuser there was slop & play which needed to be tightened up about 1mm more than my eyepieces using the Antares twist lock adapters. It was a bit of a pain because when I did switch to my Pentax XW's and Pentax XL, the 2" adapters had to be jammed in there realizing I needed to loosen my compression rings more. I should also mention that handling the eyepiece is easy ~ it does look a big ugly, but in the dark, handling & performance is all that matters!
I also saw M-42 in all it's glory with this eyepiece and my 2" Orion Ultrablock and it framed the nebula perfectly with excellent contrast.
I forgot to mention that I also compared the 17mm Ultima LX with the 17mm Orion LVW. Performance was almost identical with slightly tighter stars in the LVW. Coma in the 17mm LVW was also ever-so-slightly less apparent than the 17mm Celestron Ultima LX as well. Cost-wise & FOV-wise, it is a no brainer here, with the 17mm Ultima LX winning over.
I could also see the difference in FOV with these two eyepieces against each other with the 17mm Ultima LX having more of that "immersion" factor ~ You could see the difference for sure here.
Overall, The 17mm Celestron Ultima LX is HIGHLY RECOMMENDED.
Ratings: (1-10) 1 being bad and 10 being excellent:
Eye relief = 10
ease of use = 8
how the caps fit = (top cap: 2)
Weight = 10 (It's perfect weight wise for me)
Optics = 8
ergonomics = 9