6mm spherical singlet lens

[regandon]

I was just sent this 6mm Ball eyepiece (spherical singlet lens) and a 2x Barlow from Siebert Optics. The baffling in the 6mm Ball eyepiece looks very good. The fov is 30* and the sharpness and contrast are very good. This is a planetary viewing eyepiece only, and I'm going to keep this as the sharpness is that good. I still need to test this eyepiece in my 152mm MCT, but when use with the 152mm Refractor, the sharpness and contrast was very good. This is not an eyepiece that will be for everyone as the 30* fov will be a problem for most observers. If anyone is interested I will do a full review. Siebert Optics only anodize their large 2.5" to 4" eyepieces, I just wish they would for all their 11/4" and 2" ones. Sorry for the bad cell phone photo's.

[Lady Fraktor]

The fov is 30*

5- 10° useable?
I have a set that I have used for years (as well as some SS3/ SS4) and they are amazing planetary eyepieces though few like the very small FOV.
The ball eyepieces make my TMB Supermonos seem expansive in contrast

Enjoy the views, I love all mine.

A review is always good as many observers today likely do not know these exist and are amazing planetary eyepieces.

[regandon]

I do like the SS3 and SS4 and their 70* Ultra series. I'm looking into their 3" eyepieces next for my 9" refractor project. I'm going to be using a 4" focuser

[Lady Fraktor]

BV pairs? I have a few different pairs from other manufacturers though most of my viewing is in mono.
I have not tried the Ultras though I have a 11 mm Performance+ that equals mt TV 11 mm Plossl.
Do you do your own mill work?

[regandon]

My team and I at the observatory are building the refractor. The photo of the eyepieces are the ones I use the most for binoviewing.

[Bigzmey]

Interesting EP. What is eye relief on it, 2mm?

[regandon]

ER is not much lol, not good for people with eyeglasses, but the sharpness and contrast are very good.

[Lady Fraktor]

The 6 mm ball has about 1.8 mm eye relief, comparable to the Pentax 3.8 mm XP.
If it is a Siebert BK7 ball the focal length is approximately 4.5
Ball lenses are incredibly crisp and contrasty in the central 10° (give or take a bit) and on axis compare favourably with a 4 mm ZOA-II.
Outside the central zone about as clear as a cola bottle