Occular Size differences between Brands? (1 Viewer)

[Northman]

I was wondering if people know or could measure their spotting scope occulars to see what difference there is between them.

I bought one with near 48mm diameter occular and it made it difficult to get a good fit and viewing comfortable.

Tried another manufacturer with 40mm which fit better, but smaller lens.

 

[Tringa45]

For what it's worth, here are a couple of measurements:

Kowa TE11WZ (25-60x zoom for 77, 88 & 99 scopes), eyecup dia. 55 mm, eye lens dia. 25 mm.

Swarovski 30x W (for ATM/STM & ATS/STS scopes), eyecup dia. 50 mm, eye lens dia. 29 mm.

There is a relationship between eye relief, eye lens dia. and AFoV and zoom eyepieces may involve larger external diameters because of internal mechanics. The Kowa zoom has an AFoV of 55° to 69° and the fixed focal length Swarovski an AFoV of 65°.

I have a 63 mm IPD and have to incline my head slightly to the right when viewing through the Kowa eyepiece with my right eye, but do not find that particularly uncomfortable.

John