Reticule Eyepiece

[centroid]

Is the illuminated Reticule eyepiece that is part of the Skywatcher 9x50 Finder Scope, a standard 1.25" eyepiece, that can be removed, and attached to another scope when needed.

 

Also does it have a 12.5mm focal length as is standard with stand-alone Reticule eyepieces.

[Don Pensack]

The answer to your question is no.  It is a threaded-on eyepiece and not 1.25".

The likely focal length is 22-23mm to yield 9x in a 200mm focal length front lens.

Reticle (note spelling--reticule is a seldom-used variant and usually refers to a small drawstring bag) eyepieces in 1.25" are available quite cheaply on eBay and Amazon.

Stellarvue produces a small finderscope with a 1.25" eyepiece, as does Antares, but they are rare birds.  Most dedicated finder scopes (not 50mm refractors repurposed as a finder) do not use 1.25" eyepieces.

[Mr Spock]

Actually, reticule is more correct, coming from reticulum (Latin for net).

Reticle is a corruption. I note this site's spellchecker underlines it 

Reticule
Graticule

[Don Pensack]

https://www.lifehacker.com.au/2014/08/whats-the-difference-between-a-reticle-and-a-reticule/

https://www.yourdictionary.com/reticule

https://www.collinsdictionary.com/us/dictionary/english/reticule

https://www.merriam-webster.com/dictionary/reticule

https://www.lexico.com/en/definition/reticule

My dictionaries in the house refer to the drawstring bag first and a variant spelling of reticle second.

Spellings are listed as variant, the index states, when they are not as common and are used, usually, only in specific geographical areas.

I at first thought this must be a British spelling, like colour/color or honour/honor, but the dictionaries convinced me otherwise.

It is possible, I speculate, that reticle became the dominant spelling to differentiate it (and avoid confusion for the reference) from the word reticule used commonly to describe a bag.