Vixen LVW 42 experiences?

[ollypenrice]

Does anyone know this eyepiece? It would be used in a 14 inch SCT and would open up the view from the 0.6 degrees of the present 26 Nagler to 0.76 degrees. That's not a great deal but works out as a roughly 20% increase and the dropping of the magnification from 137x to 85x might brighten up the fainter targets.  Exit pupils are 2.6 for the Nagler and 4.2 for the Vixen. 

The 41 Panoptic I'd probably have gone for is just too expensive at the moment.

Olly

Edited October 29, 2022 by ollypenrice
Typo

[Stu]

I believe @Mr Spock is a big fan….

[Mr Spock]

Mine was superb in my C9.25. Very sharp. 

It does have the largest field stop you can get, but, magnification and field of view are somewhat dubious. I have a thread on it somewhere, but, the eyepiece suffers from a difference in magnification across the fov. So, it's only 42mm in the centre; an average across the 72° fov is 38mm, so use that to calculate the true field of view (or use the field stop size). You can't see this difference in magnification when looking at stars, but, it is something to be aware of.

[ollypenrice]

23 minutes ago, Mr Spock said:

Mine was superb in my C9.25. Very sharp. 

It does have the largest field stop you can get, but, magnification and field of view are somewhat dubious. I have a thread on it somewhere, but, the eyepiece suffers from a difference in magnification across the fov. So, it's only 42mm in the centre; an average across the 72° fov is 38mm, so use that to calculate the true field of view (or use the field stop size). You can't see this difference in magnification when looking at stars, but, it is something to be aware of.

That's interesting. Thanks.

Olly

[rwilkey]

I have the 35mm Panoptic and find that pretty good with the eyeguard extender and I find that helpful, eye relief about 24mm, though I don't know what the exit pupil is. 

Edited October 29, 2022 by rwilkey

[Pixies]

I think @Franklin has one, too?

[Mr Spock]

 

[Franklin]

3 hours ago, Pixies said:

I think @Franklin has one, too?

I do indeed and it's a cracker.

Mine is the older version that says 72deg on it. 

[Don Pensack]

6 hours ago, Mr Spock said:

Mine was superb in my C9.25. Very sharp. 

It does have the largest field stop you can get, but, magnification and field of view are somewhat dubious. I have a thread on it somewhere, but, the eyepiece suffers from a difference in magnification across the fov. So, it's only 42mm in the centre; an average across the 72° fov is 38mm, so use that to calculate the true field of view (or use the field stop size). You can't see this difference in magnification when looking at stars, but, it is something to be aware of.

If the magnification varies across the field, that will affect the apparent field you see, but will not affect the true field seen by the eyepiece.  What matters there is the field stop diameter.

Two eyepieces of identical field stop diameters will see identical true fields, but the nature and % of distortion will determine the apparent fields seen.

Using the apparent field to calculate true field is very inaccurate in eyepieces with angular magnification distortion.

Your calculation might be decent for average magnification in the eyepiece field in the scope, though I would assume someone would want to know the focal length at the center more than at the edge.

 

[Louis D]

Why not just get the Lacerta ED 40mm for a lot less money?  By all accounts, it's at least as sharp with the same true field of view.  I find it nearly as sharp as the Pentax XW 40mm at f/6 with just 3/4ths the weight.

[Louis D]

From my Lacerta ED 40mm write-up:

Here's my test image at f/12 in my 127mm Mak, which would be similar to your SCT f-ratio wise:

Distortion is quite low across the field as can be seen above and from the center/edge magnification measurements below:

Thus, the measured AFOV is nearly equal to the eAFOV calculated from the measured field stop and central focal length.

[gorann]

I am 98% an imager but I do have a set of eyepieces so I got curious reading this thread. For a wide field eyepiece I have a Williams SWAN 40 mm. How is that rated among you connoisseurs?

Edited October 29, 2022 by gorann

[badhex]

4 hours ago, Louis D said:

Why not just get the Lacerta ED 40mm for a lot less money?  By all accounts, it's at least as sharp with the same true field of view.  I find it nearly as sharp as the Pentax XW 40mm at f/6 with just 3/4ths the weight.

+1 for this. I own both the Lacerta 40mm and a Pan 41mm and I rarely use the Pan - the extra weight and hassle of rebalancing for one EP etc is not worth the optical gain most of the time. I imagine in the C14 it would be excellent. 

Edited October 29, 2022 by badhex

[Louis D]

15 hours ago, gorann said:

I am 98% an imager but I do have a set of eyepieces so I got curious reading this thread. For a wide field eyepiece I have a Williams SWAN 40 mm. How is that rated among you connoisseurs?

Here's a CN review from 17 years ago.  From reading multiple experienced users' reactions to it, it is similar in performance to the 38mm Orion Q70 in performance.  There's astigmatism and field curvature at f/6 starting around 60% out.  By f/8, it improves to 80% out.  By f/10, many folks are completely satisfied with the views.  Thus, it's another notch below the Lacerta ED which gives you about another 10% to 15% corrected field at each level.

Given that the WO's price in Europe is comparable to the Lacerta, I don't really see a reason to go for the WO.  However, in the US, the WO is considerably cheaper than the Lacerta because we have to individually import the Lacerta.

Edited October 30, 2022 by Louis D

[Stephenstargazer]

On 29/10/2022 at 09:05, ollypenrice said:

The 41 Panoptic I'd probably have gone for is just too expensive at the moment.

I have an older one for sale on here if that would interest you. No longer having the larger scope to use it with.

https://stargazerslounge.com/topic/399440-televue-eyepieces-41mm-panoptic/