Eyepiece query???

[azrabella]

I need a heads-up on a Circle T Japan k.40mm eyepiece? I guess it's a Kellner, but anyone using them nowadays and if so, are they any good?

 

[John]

They work OK in slow scopes, eg: F/10, F/12 etc. The field of view is limited to around 40 degrees maybe a little less. This assumes that it is a 1.25" fitting eyepiece. You are right that the K means a Kellner design. The Circle-T ones were well made. Not worth a great deal today - just a few £'s really.