Lumicon · 1.25" → 2" Step-Up Adapter
Lets you use a 2" eyepiece in a 1.25" focuser or diagonal — the opposite of a step-down reducer.
The Lumicon 1.25" to 2" Adapter drops into any 1.25" focuser or diagonal and presents a 2" holder on top, so you can use a 2" eyepiece or accessory on a scope that only has a 1.25" focuser. It carries 1.25" filter threads on the barrel and locks the 2" eyepiece with a brass thumbscrew. This is the reverse of the common 2"-to-1.25" reducer: instead of fitting a small eyepiece into a big focuser, it fits a big eyepiece onto a small one.
Specifications
Telescope side
1.25" male barrel — drops into any 1.25" focuser or diagonal
Eyepiece side
2" female holder — accepts 2" eyepieces & accessories
Filter threads
1.25" — on the barrel
Locking
Brass thumbscrew
How it connects
1.25" focuser / diagonal → 1.25"→ 2" adapter → 2" eyepiece or accessory
Worth knowing: because the light path still passes through the 1.25" barrel below, that barrel acts as an aperture stop. With wide-field 2" eyepieces you may see some vignetting (darkening at the field edge). It works best for longer-focal-length 2" eyepieces and for simply mounting a 2" accessory on a 1.25" scope.
Frequently Asked Questions
Can I really use a 2" eyepiece in a 1.25" focuser?
Yes — this adapter’s 1.25" barrel drops into the focuser and its 2" holder accepts the eyepiece. Keep in mind the 1.25" barrel limits the light path, so very wide-field 2" eyepieces may show some edge vignetting. It works best with longer-focal-length 2" eyepieces.
How is this different from a 2"-to-1.25" reducer?
It works in the opposite direction. A reducer has a 2" barrel and a 1.25" holder, letting a 1.25" eyepiece fit a 2" focuser. This adapter has a 1.25" barrel and a 2" holder, letting a 2" eyepiece fit a 1.25" focuser.
Does it have filter threads?
Yes — 1.25" filter threads on the barrel, so you can thread a 1.25" filter below the 2" eyepiece.
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