What eyepiece is this?

[bendiddley]

Anyone know what type of eyepiece this is? Cheers.

[Ruud]

Apparently a Kellner 20mm

I don't know who made it.

[Ricochet]

Looks like a JOC one as supplied with the cheaper Bresser and National Geographic branded scopes. 

[Louis D]

I have a generic RK (Reversed Kellner) 20mm that is surpisingly sharp over a good portion of its 47 degree field.  I've never had the opportunity to compare it to a 20mm Kellner, though.

[bendiddley]

Cheers guys, I was wondering if it was a Kellner. Richochet, what does JOC mean?

[Ruud]

Lord-Eyepiece-Evolution-Tree.PDF

I thought I'd share this. The Kellner is in the middle at the top.

The numbers around it tell you that the eyepiece has
... theta = field  of view = 45°
... epsilon = eye relief = 0.457 times the focal length
... the eyepiece works well in scopes no faster than f/6
... the name is Kellner, after the inventor
... and it was  first made in 1849

It was a major improvement over other eyepieces in its day!

 

[John]

55 minutes ago, bendiddley said:

Cheers guys, I was wondering if it was a Kellner. Richochet, what does JOC mean?

Jinghua Optical + Electronics Co. Ltd (AKA Jinghua Optical Co.)

They owned Meade for a while. Maybe still do ? They also make stuff which is sold under lots of different brandings and some which is sold unbranded.

[Louis D]

20 minutes ago, John said:

Jinghua Optical + Electronics Co. Ltd (AKA Jinghua Optical Co.)

They owned Meade for a while. Maybe still do ? They also make stuff which is sold under lots of different brandings and some which is sold unbranded.

Most notably, JOC more or less owns Explore Scientific and makes all their eyepieces (and probably telescopes as well).

[John]

10 minutes ago, Louis D said:

Most notably, JOC more or less owns Explore Scientific and makes all their eyepieces (and probably telescopes as well).

Yes, these Chinese manufacturers can make a wide range of equipment from the cheap and cheerful to high quality.

[Louis D]

16 hours ago, John said:

Yes, these Chinese manufacturers can make a wide range of equipment from the cheap and cheerful to high quality.

If indeed JOC did make that Kellner, they're smart not to brand it Explore Scientific as it would probably dilute the brand equity.  Their 70 degree line was probably a bad call on their part to brand as ES.  I think they realized the mistake and rebranded it Bresser later.

[LukeSkywatcher]

 I'm a bit confused with this because there is a member here named JOC.

The EP in question is a Kellner 20mm (with eye cup) rather than the volcano top. 

My 1st scope came with these (10,20mm):

Is this what is called Volano.

 

[John]

Not really. These are what are referred to as "volcano tops". They are made in Japan (these happen to be orthos. You can also get Kellners and Erfles in similar designs):