Does eyepiece size matter?

[StuartT]

I have a bunch of 1.25" eyepieces for my 20cm SCT, but I now have a scope with a 2" focuser. Fortunately I have an adapter so I can use my eyepieces with the new telescope.

But my question is, given that 2" eyepieces are more expensive than 1.25" ones, what size should my next eyepiece purchase be? Obviously if I buy a 1.25" it can be used with either scope, but would there be an actual advantage of buying a 2" one for my new scope (even though I couldn't use it with my SCT) ?

 

Edited August 8, 2021 by StuartT

[Knighty2112]

2” EP’s are really good for widefield, so anything above 25mm should be good. Ive got a Vixen NLVW 30mm which gives nice widefield views in most of my scopes. Also works good in my 8” SCT too, but not as wide a view as in my shorter focal length scopes.

Edited August 8, 2021 by Knighty2112

[John]

The only advantage of the 2 inch eyepiece format is that the apparent field of view for a given focal length can be larger because the 2 inch barrel can accommodate a larger diameter field stop than the 1.25 inch barrel.

So in medium to shorter focal lengths (ie: less than 18mm focal length) eyepieces are generally 1.25 inch format because they don't need to be larger. Some do have a 2 inch barrel option or hybrid design to give the option of holding them in the larger focuser drawtube but optically they are still 1.25 inch eyepieces.

Above around 18mm in focal length, the 2 inch format allows the ultra and hyper-wide fields of view that have become popular with some (like me !).

 

[StuartT]

thanks both. Very helpful. I tend to only use eyepieces for solar system objects in any case so wide field is less of an issue.

[KP82]

35 minutes ago, StuartT said:

thanks both. Very helpful. I tend to only use eyepieces for solar system objects in any case so wide field is less of an issue.

Wide field eyepieces can also be useful for high mag planetary use. On a manual mount it reduces the need to constantly nudge the scope to keep track of the target. As for GOTO mount unless the GOTO is pinpoint accurate, there is a higher chance that the target will land in the field of view of a wider field eyepiece reducing the need for manual correction or swapping for longer FL eyepieces just to locate the target.

Edited August 9, 2021 by KP82

[Space Hopper]

Warning  : big 2" glass can lead you towards a slippery slope !!

 

[StuartT]

6 hours ago, Space Hopper said:

Warning  : big 2" glass can lead you towards a slippery slope !!

 

Yikes!! That's enormous! I think I'll stick with my 1.25s thanks