Hi. I've seen tons of discussion about 1.25" vs 2" eyepieces. But I haven't been able to find anything about dual sized barrels.
The reason I'm asking is that I finally have a decent grab 'n go fast refractor that's been telling me it would be happy with an eyepiece midway between 5mm & 8mm for planetary.
Among the offerings in this range that I've been considering are the Morpheus 6.5mm and Russell 6.7mm Koenig. I do like wide. Both have dual 1.25/2" barrels.
Are there any practical benefits or caveats regarding this barrel design other than the convenience of not having to bother with adapters?
In reality, the Russell choice may be moot. I've been happy with the Koenigs I've bought from Gary but he seems to have a vendetta against his own design, declining to sell the 6.7 - 1.25/2", even though it's been listed as in stock on his web site for years. He said a customer told him it had damaged their diagonal.
Careful. 1.25" eyepieces with 2" skirts are still 1.25" eyepieces.
And in a refractor, if used as 2", the 1.25" section can hit the diagonal mirror.
Specifically, Morpheus eyepieces (except the 17.5mm) have their focal planes at the shoulder of the 1.25" section.
The 2" outer is more a convenience for newtonian users, and, even then, the eyepieces will require a LOT of out focus if used as 2".
I use the Morpheus eyepieces exclusively as 1.25" eyepieces in my newtonian so the focal points are not dramatically different than other eyepieces.
Of course, Brian's solution is a good one if you don't want to use a 1.25" adapter--simply convert them all to 2" by attaching adapters to each eyepiece.
It's what I ended up doing with the 17.5 Morpheus to make it parfocal with the others.