82deg FOV wasted on smaller SCTs?

[Dunkster]

So folks, I have a birthday coming up soon and want to scheme/plot/conspire to get a shiny new EP.... I've been on the fence about what to do with my low/mid EP situation for a while, and have been torn about getting the shorter FL BSTs - been happy with my 15mm - but given the occasion, open to excusing myself into something a little wider. My current scopes are in my sig.

Almost everyone seems to rave about the TV, and I'm sure for good reason... but I've never had the experience - any volunteers?

The ES and the SW both get good write-ups, not without compromises, but they cost less than the Nagler. The ES are on sale in the US ($119!), and I could almost get all 3 for the same price as 1 Nagler. On the flip side, the TV seem to hold their value on the used market and maybe present a lower risk choice... or higher risk choice if I love what I see

1. Televue Nagler - 8, 11mm (227g) other sizes? - £230+
   
2. Explore Scientific 82 - 8.8, 11, 14mm (374g/334g/374g) - £80ish
   
3. SW Nirvana - 16mm (200g) - £145
   

The ES seem to be a fair bit heavier than the other two options. Should I be concerned about this with the 6SE? My BST is currently my heaviest EP.

If I manage to keep viewing through the rest of the season, I would be considering a bigger scope for the autumn... maybe a C9.25 or a manageable push-to Dob... so I'm looking at future-proofing.

Any thoughts, comments, suggestions in any direction always welcomed

[John]

In slow scopes like yours (F/11.9 and F/10) any of the eyepieces you list would work excellently. In the focal lengths you have listed the 82 degree field of view would be fully useable.

The choice is yours really. I've tried the Nirvanas directly alongside their Nagler equivalents and there is very little difference in performance even with my relatively fast scopes to be honest - the Nirvanas deliver 95% as much, probably close to equal with an F/10. I've not had the pleasure of trying any ES eyepieces as yet but I hear good things about them.

[E621Keith]

Don't forget about import tax and VAT when you buy from the States.

Telescope House is selling the shorter Meade 5000 UWA (5.5, 8.8 14) and ES 82deg for about £140.

Remember the C6 has a 1.25" baffle tube, so you won't get the full field if you get the larger 2" models. As for mounting, I used a 2" visual back, 2" diagonal and a rather heavy Pentax 8-24 zoom (550g) on my C6 SE without problem, you should be fine with the eyepieces you listed. I'd recommend a 2" visual back and diagonal for mechanical reasons.

[Dunkster]

Thanks John, Keith - that's encouraging.

Looks like I'll need the 2" visual back after all. Any feelings on whether the TV one is worth the coin?

I'll be in the US on business soon, likely at short notice, so should only have domestic carriage to pay on top but will need to pick one for maximum savings.

[John]

You might as well get any 2" visual back or just a SCT fitting 2" diagonal. Remember that prices of 2" 82 degree eyepieces jump up somewhat from 1.25" ones and, as Keith says, you won't get the full benefit of those that have a field stop size that is greater than the size of the aperture at the rear of the scope. The field stop is the aperture ring within the eyepiece that defines the edge of the field of view.

[michael.h.f.wilkinson]

If the Meade series 5000 14mm UWA is going cheap somewhere, snap it up, unless you want eye relief above 14mm (as I prefer somewhat). I tried mine in many scopes, ranging from the my C8 (at F/10) and 80mm APM at F/6, to Olly's TEC 140 at F/7 and 20" Dob at F/4.1. Tack sharp images across the field in all scopes. The sharpness is quite comparable to the Nagler 17T4 which I have. My only slight gripe is the eye relief of 14mm. It is just about manageable with my glasses, but a Nagler 12T4 with its 17mm eye relief would be nicer.

I bought a set of top performers for my F/10 mainly because I was looking at some wide-field scopes in the F/5 - F/6 range. I might also get a fast dob some day. Naglers are pretty future proof, but so are ES and Meade UWA. I was planning to get the 30mm 82 deg ES, and only opted for the Nagler 31T5 when one popped up secondhand. On a C8 (and certainly the C9.25) you get the full benefit of the massive FOV of both the 31T5 (1.25 deg true FOV) and 40mm Paragon (1.34 deg true FOV). On you C6 some vignetting could well occur.

[Dunkster]

Thanks Michael, John!

For now I'm entertaining myself with planets and some of the classic DSOs, at least those I can see from here. Consequently, longer FL isn't a priority at the moment, so vignetting should be an issue (I hope). I know my location isn't ideal, but time is limited, and I have yet to hunt for a dark striking target.

The Meade 5000 UWA seem to be still available in the US (at around of a few $$s of the ES), so that makes the choice harder in some respects. For the Naglers, the UK pricing doesn't seem to be radically different from the US unless I'm looking in the wrong places! I'm not looking to throw money away, so if they're all fair investments then it reduces the risk element, but the occasion deserves celebrating with glass(es)

Is the 2" visual back/diagonal essential structurally? And do these work out about the same size as the current 1.25" pairing or larger because of the extra diameter barrel? Just thinking about looking up and not running aground

[E621Keith]

Is the 2" visual back/diagonal essential structurally? And do these work out about the same size as the current 1.25" pairing or larger because of the extra diameter barrel? Just thinking about looking up and not running aground

Personally I would say it's a good idea to use 2" if you planned to use heavy eyepiece. I never find the thumb screw on the stock 1.25" visual back very secure. I haven't tried a compression ring type 1.25" visual back, so I can't comment if you use those. I use my C6 on a GEM as well as a SE mount, so using 2" is essential, because the eyepiece can be turned upside down on a GEM.

The 2" system is larger than the 1.25, and there is a small risk it may not clear the base of the SE mount if you view near the zenith. I remember seeing my diagonal driven into the base on two occasions, but I can't remember whether I was using the C6 or the SV80s.

If you go for a 2" system, you get a more choices of quality diagonals in addition to the mechanical advantage. There is no point using high quality Televue eyepieces, if you use it with the rather poor stock 1.25" diagonal. William optics do a dielectric diagonal in 1.25", but I don't think anyone else does.

[Dunkster]

Diagonals steers me into a whole other (unfamiliar) territory

Dielectric... quartz... 1/10th wave

FLO seem to have a nice pairing ... WO 2" WO 2" dielectric diagonal with SCT adapter

Will I notice much difference with this one? It's half the price, but looks like it adapter-less...

Altair Astro 2" diagonal for SCT

[John]

The differences between dielectric diagonals are virtually impossible to detect visually I've found having owned the William Optics, my current Revelation Quartz and the rather pricey Tele Vue Everbright. The SCT compatible diagonals just screw straight onto where the 1.25" visual back screws onto the scope.

[Dunkster]

Thanks John - no other disadvantages other than being scope-specific then? I figure it'll prolly work with the Mak too, but not a dob or frac.

For 70 notes I can probably live with that

[E621Keith]

The differences between dielectric diagonals are virtually impossible to detect visually I've found having owned the William Optics, my current Revelation Quartz and the rather pricey Tele Vue Everbright. The SCT compatible diagonals just screw straight onto where the 1.25" visual back screws onto the scope.

Yes, but the optical difference between a dielectric and the stock diagonal is quite easy to tell. However, I agree it's almost impossible detect the difference between a 98% and a 99% reflective dielectric diagonal.

Thanks John - no other disadvantages other than being scope-specific then? I figure it'll prolly work with the Mak too, but not a dob or frac.

For 70 notes I can probably live with that

If you plan to use it on non SCT, you will be better off getting a 2" SCT visual back and use regular 2" diagonal rather than SCT specific ones.

[John]

Yes, but the optical difference between a dielectric and the stock diagonal is quite easy to tell. However, I agree it's almost impossible detect the difference between a 98% and a 99% reflective dielectric diagonal....

Yep - thats why I worded it as I did

[Dunkster]

Thanks chaps, appreciate it!