Adjustable Eye Relief?

[tomw28]

I think I saw an advert in the for sale section for a TMB Planetary a few weeks ago. In the description I remember it mentioning "adjustable eye relief". Is this the case, as I spent a good few minutes staring at my own TMB (6mm) and cant for the life of me see how it would work? If it is indeed the case, how to I use it?

Thanks!

[Ad Astra]

I'm guessing they meant "adjustable eye cups", some EP's have eye cups that actually adjust up and down with a twist.

Very nice, but not 'adjustable eye relief' - that's a property of the lenses and as you suspected, not adjustable.

Dan

[NGC 1502]

Hi Tom, Dan is right. I've seen that description too. Zoom eyepieces can have

different eye relief at various focal lengths, but the eye relief of a standard fixed

focal length eyepiece is not adjustable, it's inherent in the design.

Eyepieces with long eye relief often have an adjustable eyecup, screw or click stop

as on the Televue Radian & Nagler Type 4. It's there so your eye is in the best

position. Too far in, and you will be inside the correct eyepoint, and get shadows

intruding. Too far out and you cannot see all of the field of view.

Regards, Ed.

[tomw28]

Thanks, I thought it meant the eyecups but thought it was worth checking on here just incase. Still a nice eyepiece though!