Change of kit brings eyepiece dilemma...

[Mr Spock]

I have up until now been using a 250mm fl1200mm Newt. From Monday I will be using a 235mm fl2350mm SCT. You can see straight away what this does to my eyepiece collection. Each one was purchased for a particular use.

Good news: My stunning Vixen 42mm lanthanum (x56) and 22mm T4 Nagler (x107) are back in the game. These are now my galaxy / cluster crunchers.

Bad news. My TMB 6mm (x391), Radian 5mm (x470) and Vixen 4mm (x588) are all overpowered. I think they will have to go (if I sell the 250).

Nagler 7mm - this was bought for looking at globulars / small planetary nebulae at x171. Now at x336 it will switch to being my high power eyepiece. My 13mm LVW will take over the original use - no complaints there.

My 9mm NLV at x261 will be for planets - no complaints there either.

Apart from the three high powered eyepieces, everything seems to fit. Has anyone got any other suggestions/comments?

[brianb]

I think you'll find 7mm too short. The shortest focal length EP I've ever used with my f/10 SCT is 9mm (BGO) and that is a very rare occurrence; 12.5mm BGO or 14mm Meade series 5000 SuperPlossl are usually as much as the air will stand.

[sixela]

I'm not sure I'd sell all your high powered eyepieces. Personally, I'd keep the TMB (which won't sell for that much) for those nights in which the seeing will cooperate. With Mars smaller but higher up in the sky during the next apparition, I bet you'll be using it from time to time and glad you did't sell it.

[TheThing]

Yes, don't rush into selling anything just yet. Try them first and see.

Sent from my iPhone using Tapatalk

[Andrew*]

I think you would benefit from something in between the 13mm LVW and the 9mm Nagler for high power work on average nights. You could barlow your 22mm Nagler, or get an 11mm something.

Andrew

[Kef9]

Slightly off topic but is the 42mm vixen 72 degree FoV? I know the writing on the barrel says 72 deg but if you go onto websites they state its 65 degrees?

Can I just ask also what edge performance is like. I'm interested because to my knowledge this is the largest FoV possible with a 2" barell. I don't think anything else comes close.

Well done on the new scope by the way

[Andrew*]

Kef9, I've had this conversation with Mr. Spock before and the outcome was that some dealer websites are incorrect and that the 42mm LVW really does have 72° AFOV, which is very intriguing, because as you say nothing else comes close.

I wonder if there is some distortion to allow the extra field...

I almost bought this eyepiece from Mr. Spock but instead got an Aero. I bet it's a superb eyepiece and unique for the largest TFOV anywhere.

Andrew

[Kef9]

Funny how this has 72deg but the rest of the line have 65deg? It does seem strange. I'm interested because it is a large step in fov from a 31mm nagler when compared to the other contenders like the 41mm panoptic which isn't that much of a difference.

I think this is good to have in your armoury just because of the FoV but its no good if its all distorted. Come on Mr Spock. Tell me about edge performance!

[brianb]

Tell me about edge performance!

This is unlikely to mean much unless your scope is the same ... edge performance tends to depend very heavily on the scope design as well as the working focal ratio; sometimes off-axis aberrations, field curvature etc. in the eyepiece partially cancel those in the objective, sometimes they reinforce them.

FWIW I rather like the Aero used in conjunction with a short focus refractor, but it's pretty horrid used with a f/10 SCT which should be a much easier instrument for an eyepiece to cope with.

[Kef9]

Yes I understand that but it would good to have an indication of how it performs on at least 1 scope even if it wasn't the same as mine. A general indication would be very useful and if edge performance is good then its likely to be good on most scopes.

I used to have a skywatcher 26mm panaview and the edge performance on that was shocking on both my F9 C100ED and my F5 Startravel 150. In fact it was similary poor in both scopes. For the money it was great but I just couldn't live with it.

[John]

Funny how this has 72deg but the rest of the line have 65deg? It does seem strange. I'm interested because it is a large step in fov from a 31mm nagler when compared to the other contenders like the 41mm panoptic which isn't that much of a difference...

I've not used a LVW 42mm but I've used a number of the 1.25" LVW's and found them excellent eyepieces - very well corrected across the majority of the FoV even in fast scopes. Like Andrew I have an Aero ED 40mm as my lowest power / widest field eyepiece - it's field stop diameter is 45.7mm so could hardly be much larger within the constraints of the 2" format (the 41mm Panoptic is 46mm). I believe that the LVW would need a 53mm field stop to deliver a 72 degree AFoV so that must be up above the 2" barrel in the body of the eyepiece, in the same way that the Celestron Ultima 35mm (a 1.25" eyepiece) is.

I can't see a company like Vixen claiming something that isn't so TBH. Don't know what the edge correction is like in the 42mm though - I'd love to try one and find out

[Andrew*]

53mm field stop!! If it really is as spec, it must be pretty distorted (barrel distortion??) to "stretch" it to 72°.

Andrew

[Kef9]

Using a fov comparitor website it states the filed stop is 46.6mm

Ummmmmm

[John]

Using a fov comparitor website it states the filed stop is 46.6mm

Ummmmmm

Ummmmm indeed - I've got a 2010 Vixen catalogue in front of me now that quotes the LVW 42mm as giving 65 degrees of AFOV

[Mr Spock]

The 42mm LVW is 72deg and is the sharpest eyepiece I have used (right to the edge) - better than my T4 22mm Nagler. And so easy to look through. No blackouts, no nothing. Can't say I've noticed any distortion.

What a relief I didn't sell it. Now I have a C9.25 it is back in use again. The exit pupil was far too large for a f4.8 Newt.

[Kef9]

Ummmm

I might have to put this on the shopping list.

[Nexus 6]

I have to agree with Mr Spocks comments on Vixen ep's. I have used a Vixen LV 40mm and the views were superb, very well defined, lovely contrast, great er. I have just sold it a close friend who has really enjoyed using it. "the best ep he has" in his own words.

Alan