24mm or 27mm Panoptic, or Meade SWA's ...?

Fox · #1 17-09-2006, 10:10 PM

G'day, Fox here.

I am thinking about getting a Panoptic for my TV Genesis, and I am tossing between the 24mm Pano (1.25 inch) or the 27mm Pano (2 inch) - the 24mm retail is ~$485 whilst the 27mm is really getting up there at ~$540.

1) Do people have advice about which is 'better'? Both EPs seem to get great reviews. I guess the 27mm has more FOV with a larger field stop, it has 20mm eye relief compared to 15mm for the 24mm (although I mostly take off my glasses for observing), and in person the 27mm is certainly one serious optical 'grenade'.

2) I am unsure about the significance of a 2inch barrel versus a 1.25inch barrel - keeping in mind my TV Genesis does have a 2inch focuser and diagonal. Does 2inch inherently mean brighter and 'better' images/performance?

3) One thing about 'convenience' that comes to mind is that a 2inch EP means I would have to start removing my 1.25/2.00inch adapter (all my current EP's are 1.25inch) - is this inconvenient or just something one gets used to?

4) Finally, I am also thinking of the 24mm or 28mm Meade 5000 SWA series EP's as well. Bintel reckons they are 'not quite as good' as the TV's, but they are a good $100 less than the TV's - and I suspect that I would not be madly 'offended' by the Meades. From what I gather, the Meades are ever so slightly less sharp at the extreme FOV edge, whilst the Panoptics are sharper but have slight pincushion as a consequence.

Your astro-advice will be most appreciated (my leaning is towards the 24mm Panoptic or Meade SWA's). Cheers, Fox

janoskiss (Steve H) · #2 17-09-2006, 10:27 PM

The more I use my two Panoptics, the 19 and 27mm, the more dissatisfied I get about the off-axis astigmatism I see them display in my f/5 Dob. The 24mm has an unconfirmed reputation for being the odd one out from the otherwise scaled design Panoptic series, and having better edge correction than the rest. I have no idea if this is true. I would not buy another Panoptic unless one came up for a good price 2nd hand. In f/6 and f/5 Newts I much preferred the 22mm LVW to the 19 and 22mm Panoptics I compared it with.

gaa_ian (Ian) · #3 17-09-2006, 10:38 PM

Thats interesting Steve

So you think the 27mm panoptic is not the ultimate low power EP in an F4.5 scope ?
Is there another widefield EP for a F4.5 scope that is as good or better ?

janoskiss (Steve H) · #4 17-09-2006, 10:49 PM

Quote:

Originally Posted by gaa_ian

So you think the 27mm panoptic is not the ultimate low power EP in an F4.5 scope ?
Is there another widefield EP for a F4.5 scope that is as good or better ?

Nagler T5 26mm?

iceman (Mike) · #5 18-09-2006, 05:50 AM

I can confirm that I find the 24mm pano much sharper at EOF than any others I've tried. It's also such a great eyepiece cause it's small and light (being still 1.25").

wavelandscott (Scott) · #6 18-09-2006, 10:47 AM

I can not comment on those specific comparisons but I am really fond of my 24 Pan...small relative size/weight and sharpness make it a winner for me...It is my most used eyepeice...

gbeal · #7 18-09-2006, 02:59 PM

Quote:

Originally Posted by gaa_ian

Thats interesting Steve

So you think the 27mm panoptic is not the ultimate low power EP in an F4.5 scope ?
Is there another widefield EP for a F4.5 scope that is as good or better ?

My 10" newt is f5, so not greatly different.
If you after an alternative, I have no hesitation in recommending the 22mm Nagler type 4. It replaced my 27 Panoptic. It IS big and heavy, not to mention expensive, and it is a 2" barrel. Maybe try each first, if that is possible.

Fox · #8 18-09-2006, 03:53 PM

Sounds like the 24mm Panoptic has an edge over the 27mm? Anyone experienced the Meade SWA's? Thank you for the reponses, please keep em' coming. Fox

ausastronomer (John Bambury) · #9 18-09-2006, 06:28 PM

Quote:

Originally Posted by Fox

Sounds like the 24mm Panoptic has an edge over the 27mm? Anyone experienced the Meade SWA's? Thank you for the reponses, please keep em' coming. Fox

Fox,

Thats not quite correct IMO.

I own a 27mm TV Panoptic which I use regularly in my 10"/F5 dob and have also used in many other scopes including Murell's 20"/F5. Whilst I don't own it, I have certainly also used the 24mm TV Panoptic quite a lot.

Of the two I prefer the 27mm. The 27mm Pano is not perfect but geez it's a dayyam good eyepiece. The 27mm is a very sharp eyepiece, many consider it the sharpest of all the Panoptic series, me included. The astigmatism in the 27mm is minimal as is the rectilinear distortion. Both of these aberrations are worse in other focal lengths of the Panoptic line. One big advantage for me of the 27mm, being a 2" eyepiece, is that it has considerably more eye-relief than the 24mm and provides a more submersive view. I cannot use the 24mm with my glasses on, whereas I can easily use the 27mm with my glasses on. This is a necessity for me at these longer focal lengths and larger exit pupils.

The only way I would rate the 24mm Panoptic ahead of the 27mm Pano is if you can't afford the extra $$$$ of the 27mm, or you subsequently intend to use the 24mm as a pair in a binoviewer. They are both very good eyepieces IMO and a step ahead of the 22mm Panoptic (older design)for use in a fast newtonian.

In terms of better options? There aren't a lot at these focal lengths and price range. The 26mm Nagler T5 is a better eyepiece than the 27mm Panoptic but it's a lot more money, as is the 31mm NT5. From reliable sources that I respect, the 30mm Pentax XW is also a very good eyepiece, but again well over $600. I own 5 Pentax XW's but have not yet tried the 30mm. I may actually buy the 30mm Pentax XW in the very near future.

In a fast newtonian the Meade SWA's are not in the same class as the 24mm or the 27mm Panoptics IMO.

CS-John B

janoskiss (Steve H) · #10 18-09-2006, 07:35 PM

There you go Fox. Listen to the Man (John B) carefully! He knows what he is talking about!

btw. re the 2" vs 1.25" question. You need the 2" barrel once the focal length exceeds 24mm to accommodate the full FOV. It's just a matter of geometry:

With a fixed 68-degree FOV, you are effectively fitting a particular shaped triangle into a rectangular box. Past the 24mm focal length the triangle gets too big for the 1.25" box. For the 27mm you would need a 1.4" box but the next standard size up is 2". So the 27mm must have a 2" barrel while the 24mm can make do with 1.25". That is all. So 2" does not at all "mean brighter and 'better' images/performance". I hope that makes sense.

ausastronomer (John Bambury) · #11 18-09-2006, 10:23 PM

Fox,

One question ? Do you ever use that TV Genesis in the daytime for terrestrial viewing and are you ever likely to use this eyepiece in the daytime for terrestrial viewing ? It changes things somewhat if you do.

BTW, your Genesis is the older F5 version is it not ?

CS-John B

Fox · #12 18-09-2006, 10:34 PM

Ausastro and Janos, many thanks for your experience and insight, I really appreciate your time and thoughts. I am really wondering now if I could wing a 'try before you buy' with Bintel, although I respect it may be asking too much for any retailer.

As for the 1.25 inch vs. 2 inch barrel issue, thanks Janos, it makes sense now. But then again, why do some Naglers have BOTH 1.25 and 2 inch barrels on them? I assume from your answer, that the light cone geometry/performance is exactly the same irrespective of whether you use it in 1.25 inch mode or 2 inch mode, except the 'dual barrels' thing means you can use the eyepiece in either a 1.25 inch or 2 inch focuser, depending on your equipment.

Cheers, Fox

Fox · #13 18-09-2006, 10:48 PM

Quote:

Originally Posted by ausastronomer

Fox,

One question ? Do you ever use that TV Genesis in the daytime for terrestrial viewing and are you ever likely to use this eyepiece in the daytime for terrestrial viewing ? It changes things somewhat if you do.

BTW, your Genesis is the older F5 version is it not ?

CS-John B

John B, I use my Genesis exclusively for astro use. Yeah, it is one of the older non-sdf F5 versions, serial no. 1548, so I guess it's the 548th scope off the manufacturing floor. IMO, it's a real beauty, I love the dark flat field. I had a Meade 2080 SCT before it, and I know we could argue forever about 4inch (semi)-apo vs. 8inch SCT. There is no doubt the SCT gave brighter images, but gee, I found it so much more fussy to use overall. Sometimes I wonder if a current SCT would behave better, the current altazimuth Meade SCTs with full Goto look so enticing. I'd love a 5inch apo, but that would cost so much nowadays... Fox

janoskiss (Steve H) · #14 18-09-2006, 11:43 PM

The 1.25/2" dual barrel on some EPs is only for convenience so you wouldn't need to swap out the adapter when mixing them with 2"-only EPs of longer focal lengths.

You could try the EPs in the shop, or just outside in the street. Not ideal, but better than nothing. (Just beware smaller pupil size for daytime viewing.)

Fox · #15 19-09-2006, 01:14 AM

Quote:

Originally Posted by janoskiss

You could try the EPs in the shop, or just outside in the street. Not ideal, but better than nothing. (Just beware smaller pupil size for daytime viewing.)

Yeah, good idea actually, it certainly would be better than nothing, I am sure Bintel would not mind that. It may well give me some indication of edge sharpness, weight, eye relief etc. Thanks, Fox.

ausastronomer (John Bambury) · #16 19-09-2006, 11:38 AM

Fox,

It won't be quite as good as you think, because it may turn you off a perfectly good night time astronomical eyepiece. Panoptics are not a great choice for daytime use. I alluded to this in my previous post. The Panoptics, some focal lengths moreso than others, suffer pincushion distortion which is a type of rectilinear distortion. This distortion will cause straight lines (like the edge of buildings or the waterline of a ship) to bend. It is not an issue for astronomical viewing and this aberration is left in the eyepiece design to increase the sharpness of stars near the edge of field when used in fast F-Ratio telescopes.

Consequently if you use the eyepiece in the daytime ignore the distortion, because you don't see it at night except when you are panning the sky, which isn't a concern for me as it is not intrusive under these conditions.

CS-John B

Fox · #17 19-09-2006, 01:06 PM

Thanks John, I see your point about being led up the garden path via a terrestial viewing trial. I have decided not to go for a 2 inch barrel now, which narrows the field for me a lot. Cheers, Fox.

Merlin66 (Ken) · #18 19-09-2006, 03:48 PM

Anyone compared these to the Pretoria "corrected" 28mm eyepiece? At long last I'm about to get one.... only taken me about 18 months to find a "seller"

mickoking · #19 19-09-2006, 04:46 PM

My opinion, Pans ROCK

Fox · #20 23-09-2006, 03:05 PM

Well I bit the bullet; I went in today convinced I was going to walk out with a 24mm, either the Pano or Meade SWA. It was only a daytime audition, nonetheless I was really impressed how the Meade compared to the TV, there really wasn't that much between them IMO, and Meade had slightly better eye relief, and the rotating eye guard is an excellent touch. I had all but decided...

But then I also tried the 27mm Panoptic, it really blew me away - I repeat what John B says above, the eye relief, overall view and comfort are streets ahead compared to the 24mm EP's - you can really sense that porthole feeling with this EP, 'immersive' is the definitely the word here. Another thing that swayed me in particular was the much brighter illumination; the 2inch diam and larger field stop make a huge difference here.

There is no doubt just how much the 'eye comfort' factor has influenced my most 2 recent EP purchases; a Radian and now 27mm Panoptic. I did not look at the Meade 28mm which is the 27mm Pano contender - the Meade diam was just getting too big and grenade like.

So end up walking out with the TV 27mm Pano! Thanks John B and others for your helpful info, Fox.