NIKON NAV SW eyepieces

[25585]

Anybody own or tried these. The 17.5mm has 26mm eye relief and beats any TV.

 

[YKSE]

I have 7mm, 14mm and 17.5mm SW

26mm ER is too long even for glass wearers, therefor the 17.5mm's eyeguard is raised to 20mm as default (can be raised more if needed) as shown in this picture:

The biggest advantage of SW over Delos or Pentax XWs are the weight, and most of all quite smaller footprint, as in the following and first pictures:

[Louis D]

YKSE, how do they compare to the XW and Delos offerings optically?

[YKSE]

I don't have XW nor Delos, so no comparison done by me. The last three pictures were borrowed from CN:er Tammy and Starcam, both have very extensive collection of fine eyepieces. My impression of their comments are optically equal to XW and Delos, Nikon rated their SW to f4. BillP mentioned that he prefered SW's sharper tone than XW, his choice of XW was that XW offerer a complete lineup from 40mm down to 3.5mm.

From the comments in this thread, I'd guess that SW generally has less lateral colors than XW and Delos.

https://www.cloudynights.com/topic/467800-nikon-nav-5sw-eyepiece/page-2

[John]

I have no experience of them myself but there is some discussion of them on the Cloudynights forum from time to time:

ttps://www.cloudynights.com/topic/407409-nikon-nav-10sw-vs-pentax-10-xw/

https://www.cloudynights.com/topic/368496-delos-173-vs-nikon-nav-sw-175/

They are interesting eyepieces. As far as I can see the cost of the Nikon NAV SW's is £340-£380 from APM in Germany (is there a UK source ?) compared with around £330 apiece for the Delos and £249 for the Pentax XW.

[25585]

Weight with a dob is a consideration. I could use a 2x Barlow/Power mate with my Panoptic 35mm but that with a Paracorr also would be too much. All my mounts are alt azi.

Lack of kidney beaning and other black out areas is a factor in deciding. The Nikon does well there. Big expense, I wish there was a UK dealer to visit for a test. Perhaps a main Nikon dealer?

[YKSE]

Nice links, John I believed I read both before I bought mine SWs.

Yes, price for SW has been quite high (550€?) in APM a few years ago, nowadays its the same as XW at APM(as other EU countries), quite higher than XW in UK though. I was lucky to get mine in more affordable prices when Swedish Crowns were more than 20% higher.

[John]

2 hours ago, 25585 said:

Lack of kidney beaning and other black out areas is a factor in deciding...

As long as the eyecup is in the correct position, these issues don't occur with the XW's or Delos as far as I can see.

[25585]

My 10mm XW is an excellent optic. I have read that the longer fl ones have more distortion however, less bean effect generally. Nikon SW eps are well corrected for RD, but not so good for AMD the CN posts indicate.

HW wide fields are the gold standard, but no eye relief published for them to compare with SW. OTT pricing, but it would be interesting to know. Ethos beating wide field, bean free and big eye relief - is it possible?!

[Louis D]

2 hours ago, 25585 said:

HW wide fields are the gold standard, but no eye relief published for them to compare with SW.

From what I've read on CN, the NAV-HW have about 1mm more eye relief than the Ethos line, so 16mm vs 15mm.  It makes sense because the HW eye lens is a little bit wider than the Ethos'.  I'll stick with the ES-92 line which gives up 10 degrees against the HAV-HW, but views like a Delos on steroids.  No finickiness in the exit pupil, a relaxed picture window view, and astigmatism free to the field stop with no lateral color at f/6.

[John]

2 hours ago, 25585 said:

My 10mm XW is an excellent optic. I have read that the longer fl ones have more distortion however, less bean effect generally. Nikon SW eps are well corrected for RD, but not so good for AMD the CN posts indicate.

HW wide fields are the gold standard, but no eye relief published for them to compare with SW. OTT pricing, but it would be interesting to know. Ethos beating wide field, bean free and big eye relief - is it possible?!

If we ever get together you are welcome to try my Ethos's and see what you think of them

 

[25585]

42 minutes ago, John said:

If we ever get together you are welcome to try my Ethos's and see what you think of them

 

Be great to meet up! From next month I am hoping to try SSAS meetings in Taunton. Used to go back in the 80s then had to stop for domestic reasons. 

HWs have eye relief of 16mm, so the SW 17.5 still tops the eye relief chart https://www.astronomyalive.com.au/nikon-nav-hw-series-eyepieces.html

[John]

Is really long eye relief the primary factor for you ?

I assume that you wear glasses while observing - is that correct ?

[GavStar]

I never wear glasses when observing and find the 15mm relief of the ethos ok. However, the Pentax xw and Es 92 are  noticeably more comfy and relaxing for me. If Es eventually release more focal lengths in the 92 range I can see my ethos being sold (despite the 92s being rather large and heavy)

[25585]

On 18/09/2017 at 16:43, John said:

Is really long eye relief the primary factor for you ?

I assume that you wear glasses while observing - is that correct ?

It is. I need glasses as much for astigmatism as being short sighted. 

Some older eps I have, are never used now, such as my 13mm Nagler 1. Using charts and atlas, glasses on, look thru ep glasses off, was neccessary once, but now no more. The one thing I miss about using an equatorial mount!

APM have an ebay UK shop!

[YKSE]

The specified ER is measured from the center of the eye lens, so the actually useful ER can vary a lot, even if the specified ER is precise, depending on if the eye lens shape (concave=less, convex=more), how much  the eye lens is recessed, the physiology of individuals', etc, and the AFOV of the an eyepiece too! when our pupils open wider than the exit pupil, a narrower AFOV eyepiecehas longer useful ER than wider AFOV eyepiece (all the other factors remain the same), this picture from other site by Ernest illustrate it well

[25585]

I always go for higher ER than I need. Say the SW was for me wearing glasses advertised as 20mm, might be OK - my TV Radians are, just. 

35mm Panoptic 55mm Plossl - fine. The Nikon is in their class for ER. 

My glasses new lenses cost more than any of those & I need to wear them. 

(With bins the only disappointment is my pair of Fujinon 16x70s, which have an eye relief too small for whole field - 4 degrees - viewing through glasses. Superb otherwise!)

[John]

Hard to get a "true" 20mm of useable eye relief with shorter focal length eyepieces I reckon. Many modern designs use a concave eye lens and some recess the eye lens as well so quite a few mm are shaved off the ER

[Louis D]

1 hour ago, John said:

Hard to get a "true" 20mm of useable eye relief with shorter focal length eyepieces I reckon. Many modern designs use a concave eye lens and some recess the eye lens as well so quite a few mm are shaved off the ER

The Pentax XWs recess the eye lens a few millimeters for no particular reason.  The older XLs were nearly flush mounted and are more comfortable.  The Delos are almost flush mounted as well.  As a result, since both eye lenses are 35mm/36mm wide (XW and Delos), I find the Delos more comfortable with eyeglasses.

The extreme case of concave eye lens for me would be the 27mm Panoptic.  Even though the eye lens is basically flush mounted to the top, it is so deeply concave that it robs about 3mm of eye relief, making it fairly tight to use with eyeglasses.

[25585]

Having recently bought a XW 10mm, it will be interesting to compare with same Fl TV Radian & Vixen LV. 

[John]

2 hours ago, 25585 said:

Having recently bought a XW 10mm, it will be interesting to compare with same Fl TV Radian & Vixen LV. 

Having a loan of a 10mm XW eventually moved me away from my lovely Nagler T6's because the XW was just so nice

I've not yet used a wide angle eyepiece that is better than an XW, at least in the focal lengths of 10mm down.

[25585]

And so it came to pass, that I passed up on renewing my mobile phone for another year...

[John]

Congratulations ! - it looks great

I'll look forward to hearing what you think of it.

[25585]

Just need a clear patch of sky for say 30mins. I will try it with the Genesis first as it's a grab & go scope & mount. Mag x29. 

[John]

My guess is that it will do great in those circumstances. I've found that it takes quite a few sessions to find out what an eyepiece is really like.