Wide field EP for a C9.25

The_bluester (Paul) · #1 12-01-2012, 10:17 AM

OK, I have posted a similar thread a while back but did not ask this question explicitly.

As per the thread title, I have a C 9.25 based scope (CPC 925 GPS) and I may be in the market for a premium widefield EP in the next couple of months. I posted up recently asking about what sort of field stop diameter I would get away with in that scope (Which has 2" threads for the visual back and about a 46mm ID baffle tube) Suffice to say that it should be able to stand up to roughly a 40mm field stop without vignetting away the wider field the EP would be capable of. I got a 2" SCT quartz dielectric digonal for Christmas so now I can use the bigger format EPs.

What I am looking for is any direct experience of widefield 2" EPs from users of the C 9.25. What works well in the F10 scope? Is a Nagler 31 a stunning thing or is it an expensive waste as it does not suit the scope well, is not as sharp as another design in the scope, not well corrected at the edge etc. I have a handful of Televue EPs and am quite happy with them but if there is another option I should look at I would certainly do that rather than slvishly following a brand, no matter how well known.

What have people got in these things in the 2" format with field stop diameters that are not possible in a 1.25" EP? I would like to stick to a larger AFOV, something approaching the 82 degrees of a Nagler.

As an aside, I do have one gripe against one of my TV EPs, an 11mm Nagler T6. The blackouts and kidney beaning I can live with, once you get used to that it is reasonably straightforward to keep the eye in the right spot, but is is very prone to fogging internally and the only option once it does is to take it inside and carefully unscrew it into the three main assemblies (So as not to have any glass fall out) and let it clear up. It sometimes fogs before the SCT corrector plate does. I know that a corrector plate heater with an EP heater incorporated would fix that but that is money I don't have to spend right now.

Poita (Peter) · #2 12-01-2012, 10:26 AM

The explore scientific 30mm is a beautiful thing to behold, and is sealed, so no fogging.
http://www.explorescientific.com/eye...ee_series.html

The only other 2" eyepiece I have tried is an LV50, but that is a bit too wide for your scope I think!

The_bluester (Paul) · #3 12-01-2012, 10:57 AM

I wondered if someone would bring the ES ones up, but did not want to lead anyone by the hand.

Do you know what the field stop diameter is? I can not find it on the website, if it is something in the region of the Nagler 31 at 42mm it would have to be a startlingly larger TFOV than I have now, . The lowerst power EP I currently have is the 40mm E-Lux that came with the scope so about the biggest field stop it could have would be 30mm if it was simply the inside of the barrel! I think it is more like 27mm.

I love the sight of objects like M42 and Eta Carina, but the 40mm leaves me panning around to take it in where a larger stop would get me moew to look at at once.

Poita (Peter) · #4 12-01-2012, 04:43 PM

The 82 degrees 30mm has an effective field stop of 42.5mm.

Merlin66 (Ken) · #5 12-01-2012, 05:00 PM

Paul,
I use a 32mm TV plossl on my C9.25 - gives about the max FOV.
(I have a 40mm, but it doesn't give any better actual FOV)

AG Hybrid (Adrian) · #6 12-01-2012, 08:06 PM

I have the 30 mm ES. It is a magnificent eyepiece to behold. But, if its a little too rich for you. Look into the ES 68 degree line as alternative to Panoptics. They are in the longer focal lengths 20mm>. Looks like they are tailor made for SCTs since the 82 degree and 100 degree lines suit the refractors and faster newts really well.

casstony · #7 12-01-2012, 08:14 PM

For about $80 used the Andrews 30mm UWA does a good job in Schmidt cassegrains.

Wavytone · #8 12-01-2012, 09:57 PM

A vixen LV50 will be superb. It has a modest field stop and will give pinpoint stars - the 'diamonds on velvet' effect.

Better still will be a TMB Paragon 40mm, a tad larger field (it has no field stop, just the barrel) and the apparent field of view is sigificantly wider than the LV50, and its flat and sharp.

The TMB 30 and 40mm are superb eyepieces, very underrated IMHO.

But the LV50 has a 'wow' factor missing from many eyepieces...

The_bluester (Paul) · #9 13-01-2012, 11:21 AM

Thanks all, some good ideas for me there.

Looks though that the Vixen would be tough to get a new one though?

Hopefully I can get out to a viewing night soon where I may be able to borrow the use of someones EP's with a large field stop to get a real idea of how they might perform in my scope.

Wavytone · #10 18-01-2012, 07:33 PM

Paul,

I'm travelling from Sydney to Bright next week (for a holiday, with scope). Weather permitting I'll be at the observing night on Mt Buffalo... if you can make it you're welcome to see what some big eyepieces can do on your scope. PM me if you want to meet up.

If you decide you want an LV50 or a Paragon, try placing an ad on Astromart - they do appear occasionally, though rarely which implies most who have one keep them. There was an LV50 for sale here recently, pity you missed it.

Poita (Peter) · #11 19-01-2012, 01:30 AM

I can post you my LV50 for a loan if you want to see if they are suitable.

The_bluester (Paul) · #12 19-01-2012, 10:25 AM

If it was on Friday I would be there with bells on although it is quite a trip from me! I just can not get away on the Wednesday night next week as I have a propr commitment on Thursday. It is however a bit of a hike for me, Google maps call it about 270KM one way, which sounds about right.

Peter, sounds lovely, but my question would be, how much would you need for it if it got broken or Aust Post lost it? I really love how the community here pitches in like this to help each other out, I just worry about borrowing someone elses glass via post instead of at a viewing night!