View Full Version here: : After 15mm SWA suggestions...

22-10-2006, 11:54 PM
Last night was excellent, my new 27mm Panoptic is a stupendous eyepiece. The wide field, transmission, comfort and contrast are stunning Ė itís just so sharp across the field. Size and weight take bit of getting use to though; itís my first 2" EP. I also gave my LXD75 mount a good test now that I have done a full Hypertuning, itís much smoother and more responsive (although I am starting to find its slewing very NOISYÖ thatís another story).

I am after suggestions for yet another new EP. My main line-up for my Genesis 4" consists of: 6mm Radian, 15 mm TV Wide-field, and 27mm Panoptic (plus a 2x Meade 140 Barlow). I really like the range, it fits the scope perfectly, and I use all three EPís equally. But Iím feeling now that the 15mm Wide-field could do with upgrading Ė I love its field and image size, but it seems not quite up to par with the Radian and Panoptic. So I am thinking something along the lines of 12-15mm with 68-70 deg FOV, ie. basically what I have now but better. I am not keen on 80 deg UWA since I think it will be Ďout of placeí with my current line-up and encroach a little bit into my 27mm Panoptic territory.

What do people think about the 15mm Wide-field generally? - is it that much a generation behind to justify upgrading? I have not read that much about the TV 15mm Panoptic, its been criticised for short eye relief. What other options would you suggest for 12-15mm and 68-70 deg FOV? Thanks, Fox...:whistle:

23-10-2006, 01:00 PM

The world has moved on while the 15mm Panoptic has stood still IMO. There are now better eyepieces available for similar money, due to changes in technology and materials.

I would choose from the 14mm Pentax XW, 13mm Nagler T6, 14mm Denkmeier or the 13mm Vixen LVW with the top two being the 14mm Pentax and the 13mm Nagler T6. The Nagler has a larger AFOV and may be a little flatter than the Pentax. The Pentax has better contrast, sharpness and light transmission, hence it is the best for popping the "faint fuzzies". Some people dislike the slight field curvature of the 14mm Pentax, however IMO it is quite tolerable. I was using it in an F4.5 newtonian recently without issue. It is also worth noting that in your TV Genesis the field curvature will be barely noticeable and significantly reduced compared to what you would see in a fast newtonian. This is because a refractor has an inherently flatter focal plane than a newtonian and also because the Genesis is effectively operating at about F12. Considering those facts I would go with the 14mm Pentax XW but the 13mm Nagler T6 is also a fine eyepiece.

CS-John B

23-10-2006, 03:21 PM
70 degree 15mm is my main EP used on DSOs but its only a GSO SV, not inthe class of your pentax and televue EPs. still i fing 15mm very comfortable. this is in a f6 8" newt. so while i cant vouch for huge performance EPs i can say that a 15mm wide angle EP is very useable and great for DSOs in my scope :)

hope it helps just a little.
what scope do you have?

23-10-2006, 05:13 PM
Thanks Ving, yeah agreed, 15mm is also probably my most used EP, it's just a real sweet spot. I have TV Genesis 4".

Thanks John B. Agreed, I thought that 15mm Panoptic looks rather dated nowÖ indeed, what does that make my Wide-field look likeÖ ancient! Your suggestion of the Pentax sounds great, are they 70 deg FOV, do you think itís a big step up from my Wide-field? Where are they available, I donít think Iíve seen them at Bintel, and I donít go around to Astro Optical that much at all. How much would the 14mm be, roughly? Thanks, Fox...

23-10-2006, 05:45 PM
John pretty much covered it. Star Optics sell XWs and I have found them great to deal with exceptional after sales service. If you're quick you might still get one of the XW-14s on special at $399 (see Sept/Oct AS&T). Pentax increased their EP prices worldwide recently.

03-11-2006, 04:17 PM
Well, I bit the bullet. I just ordered a Pentax XW 14mm from Star Optics. After researching, it came down to the Vixen LVW 13mm or Pentax 14. Although the Pentax is ~ $100 more expensive, I became convinced that the transmission and contrast sound exceptional in the Pentax. In addition, the slightly less magnification/greater AFOV compared the Vixen is something I also wanted at this point.

We'll see about the Pentax field curvature issue at >14mm, but I am sure the XW on all fronts must be steets ahead of my 17 year old TV 15mm WideField it is replacing (and notwithstanding my mediocre observation skills).

Thanks John B, in particular, for all your useful comments about the XW range and suitability for my TV Genesis. Will be waiting next to my letter box... Cheers, Fox.:whistle:

03-11-2006, 04:35 PM
Congratulations...Pentax makes a fine eyepeice...I've got the 7 and 10 XW and like them a bunch...looked through Ausastronomer's 14 XW the other night and found it nice as well...

Based on some comments I had read about the Field Curvature in the 14 XW I was a bit surprised by how little I noticed it...the view was better than I expected.


03-11-2006, 05:19 PM

Just something else to ponder. As Scott Mitchell just mentioned we used my 14mm Pentax XW in my 18"/F4.5, 3RF Obsession telescope last Saturday night. Even in the fast F4.5 newtonian it performed wonderfully well, a little bit of field curvature towards the EOF but superb on axis and across at least 85% of the FOV. As a comparison, we viewed NGC253 in the 18"/F4.5 Obsession with both the 14mm Pentax XW and Andrew's (Rocket Boy) 17mm Nagler T4. The Pentax was better than the Nagler in just about all respects, including it's correction at the EOF.

However, I am firmly of the view that a paracorr would "clean up" the view considerably in the 17mm Nagler T4 and may not necessarily offer an enormous improvement in the 14mm Pentax XW.

I am sure you will really enjoy the 14mm Pentax XW in that 4" APO.

CS-John B

03-11-2006, 07:21 PM
Thanks chaps, can't wait! A 3rd option ofcourse was to do nothing and just see what newer 14-15mm 68deg FOV eyepieces might turn up on the market in the future. But they may be tomorrow, or years away... Fox

18-11-2006, 07:01 PM
I don't think the Pentax XW 14 quite suits my Genesis that well. Images on-axis are stunning, but EOF does not quite do it for me. Oh well, back to the drawing board - its on sale at Buy, Swap, Sell. Cheers, Fox

05-12-2006, 12:55 AM
OK, 15mm 65-70 deg EP suggestions... take Two...

To recap, I sold my Pentax XW 14, and I am glad to report that its new owner is extremely happy using the EP in his Vixen VMC scope. His main EP's up 'til now were $40 GSO's, so the Pentax was giant step up in quality. In my brief experience with the Pentax, its transmission, contrast and sharpness were far above my TV WideField; the whole image just opened up with a very black background. In the Genesis, however, I did find the field curvature distracting enough to bother me, a pity considering its other outstanding qualities.

Having said that, I am now the owner of a new Vixen LVW 13mm! Just had first light tonight, and very happy to report that I love this EP, it has much flatter behaviour in my Genesis compared to the Pentax. I am very impressed at the beautiful finish on this EP, like the Pentax, the LVW is one very serious piece of glass. Coatings on the eye lens seem incredibly deep (to my non-expert eye).

Full moon glow was horrid (!), making Octans through my LXD75 PAS invisible. I had to guess the azimuth position of the SCP, but alignment stars Sirius and Aldebaran were spot on - this LXD75/Autostar is one forgiving system! Under these conditions, I could only really test the LVW using a few bright clusters eg. M41, Pleiades etc. The Vixen performed superbly, very sharp and detailed, much less distortion at the edge compared to the Pentax (in my Genesis). Eye placement in the LVW though, seems a bit more fussy compared with the Pentax XW 14; from what I remember of the Pentax, eye position and the screw eyecup are very comfortable.

The LVW just leaves my old TV 15mm Widefield in the dust, any stars vaguely off-centre in the Widefield really begin to start sprouting wings; the whole image in the the WF has this 'fishbowl' thing happening, with little eye relief (I am brushing my eyelashes up to the eye lens in the Widefield). Not so with the LVW, it's much more comfortable, flatter and well behaved off-axis; Pleiades in my 27mm Pano and 13mm LVW give extraordinary pretty frames. I guess the WF to LVW comparison is rather unfair; a 20 year difference in design and materials...


05-12-2006, 09:23 AM
Good to hear you found an eyepiece you are comfortable with. Not much fun spending a wad of cash on something that's not quite right. I have a LVW 17mm that I find very pleasant to view through.

05-12-2006, 12:58 PM
Hi Casstony, not too worried about the 'expense' of trialing the Pentax 14. It was a calculated risk and worth the experience, I got about 75% of original cost which is a fair return in my view, and the new owner is very satisfied. I definitely could see myself going for a 7mm Pentax XW down the road, I thought the on-axis performance of the Pentax was that good, all that is was raved to be.

Its has crossed my mind that if the Vixen LVW is that much far ahead of my 18 year old TV Widefield, how much better would a current-day TV NP101, TMB or WO Apo be compared to my 18 year old vintage Genesis - does the scope itself require upgrading? And how long is a piece of string...... Fox