TV 41mm Panoptic vs Pentax 40mm XW
Posted 18 March 2011 - 05:11 PM
Has anyone used both in an f/10 SCT? Thanks for any feedback.
Posted 18 March 2011 - 07:09 PM
It is no longer fresh on my mind, but 3 + years ago I tried them both in a brand new CPC1100. I bought both from a dealer with the understanding I would be returning one of them.
The XW had just a touch more FOV, you would not notice it unless you looked for it.
The XW was lighter and balance was important at the time.
The XW had a more neutral color to my eye.
The XW was just more pleasing to my eye.
The Pan had an ever so slightly darker field in my light polluted sky. I related it to the XW's neutral tone.
Never checked either EP for pincushion or coma, as I probably did not know what it was at the time.
Pretty sure that was the total test I gave them both, in the same scope at the same time.
Returned the Pan and I still have the XW.
Posted 18 March 2011 - 08:08 PM
The SCT has enough field curvature inherently. The last thing it needs is the extra field curvature contributed by the XW. Otherwise, you have a significant portion of the outer field out of focus when the center of the field is in focus, essentially shrinking the putative 70-degree XW to a much smaller usable AFOV (i.e., the focused area of the field).
I really like the 10mm and shorter XWs. I really dislike the longer focal length units due to their field curvature. I would go with Panoptics in longer focal lengths and then XWs or used LVWs in shorter.
Posted 18 March 2011 - 08:13 PM
Posted 18 March 2011 - 09:50 PM
Posted 18 March 2011 - 10:06 PM
The scopes I used were a 12.5" f/6 Newtonian and a 8" f/12 refractor. While I was hopeful of a Pentax upset, the field curvature was excessive for a $500 eyepiece. For the usable field, it might as well have been a $100 WWII Erfle. It went back to Astronomics in short order.
While my eyesight is better than 20/15, I am to the point where I need reading glasses for the close-up stuff (too many birthdays my eye doc says). A few folks have suggested the accommodation was the problem. If you are not in that situation, you may be ok, lots of people like them.
Posted 19 March 2011 - 12:39 AM
Posted 19 March 2011 - 12:49 AM
Posted 19 March 2011 - 01:01 AM
Posted 19 March 2011 - 09:39 AM
Posted 19 March 2011 - 10:14 AM
The Pentax XLs and XWs in longer focal lengths never bothered me much prior to a few years ago when I started having minor problems reading up close. At work (cuz I do a lot of reading up close) I use +1.25 reading glasses, and wish they were +1.50s when reading and editing documents. Eyes losing the ability to accommodate may explain why some are turned off by the curvature and others shrug it off. Ten of so years ago I didn't really notice field curvature in f/10 SCTs. Now it's a detractor for me. The only thing that's changed is my near vision.
Posted 19 March 2011 - 04:12 PM
Posted 19 March 2011 - 07:23 PM
I use the same reading glasses as you do, so I can understand your points there!, Never thought about that factor!
Posted 19 March 2011 - 08:21 PM
Thanks for the responses, especially when observers have actually viewed through both eyepieces. I currently own the 40XW, but the last few times I have used it in my C11, the stars show a lot of coma/curvature effects on the outer 40% or so of the field of view. So I was wondering if the 41 Pan would be better for my visual observing in my 56 year old eyes that have a little astigmatism..moreso in my right eye. But with shorter focal length TV Naglers and Panoptics (9mm Nagler through 24mm Pan and 31mm Baader Aspeheric eyepieces), the stars are very sharp/pin points. It is just the 40mm XW that show these effects. Maybe the 41 Pan would be better in my case? Nice price on the 41 Pan right now with the TV sale going on.
You and I are in similar situations. The 41 Panoptic gave me no problems. However, I sold it and kept the 31 Nagler. The limiting factor is my f/6 Newtonian and 0.5 cylinder of astigmatism, I like to keep the exit pupils under 6 mm. The 31N works very well here, the only drawbacks are weight and expense. With the weak market, expense is better now.
For the f/12 scope (and my new f/8.5) I can still use the 31 Nagler and/or a 48 Brandon. Both eyepieces barlow well in a A-P Barcon (1.7x, or 1.7/2.0 in a refractor). This gives me some interesting and useful combinations.
Posted 19 March 2011 - 08:27 PM
Posted 20 March 2011 - 10:23 AM
Maybe I should try the TV 41 Panoptic to compare the two eyepieces side-by-side at the same time. The views through the 24mm Panoptic are fantastic, great eyepiece.
good idea! I really like the 35mm, 41mm Pans, 31N, and big XW's, they're all awesome compared to what we had to use in the eyepiece "dark ages". I think the preference for one or two out of this set is really personal and depends on your scope, your eyes, what you like to see in the eyepiece.
At f/10 I would probably go with the Pentax 40mm. I find the 41mm Pan and 31N to be enormous and a little unwieldy to handle. I like the contast & color tone delivered by Pentax XW vs. TV. However, the 41mm Panoptic does the best job of producing tight stars at the edge. This looks better to most people, but if you like to do a lot of panning around at low power you'll see rectilinear distortion in the TV's, the Pentax have none.
most of the time I'm using the 40mm XW I'm panning around (using it as a finder) or using a UHC filter. The UHC filter bloats all the stars a little so you don't see any breakdown at the edge. I think viewing habits like this determine why some people prefer one over the other.
Posted 20 March 2011 - 04:19 PM
Yes, the added 8 or 9 ozs of the Pan 41 over the 40 XW is a little concerning for me. I am afraid that this extra 1/2 pound of weight might affect the balance of the C11 on my UA Unistar Deluxe altaz mount. The Pentax 40XW weighs about the same as my 22mm Nagler (24 oz.) Maybe if/when I go to our astro clubs sight down the road, someone there will have a 41 Pan so I can try it out in my C11 and compare it to the 40XW.