I want to upgrade the 1.25" focuser on my 8"
Does anyone know the correct minor axis size given the focal length (60" or 1524mm) and the use of a 2-inch eyepiece? My "L" distance (focal plane to diagonal) is 10.25" (260mm)
Thanks,
Looks OK to me but there are are several different criteria. Berry and Dakin say it's a touch small. Efberg and Peters and Pike say it's OK.JayTee wrote: ↑Fri Jul 09, 2021 1:16 am Hi all,
I want to upgrade the 1.25" focuser on my 8" f/7.5 Newtonian to a 2" focuser. My question is, will my current diagonal minor axis size (38mm) be adequate for a 2" eyepiece?
Does anyone know the correct minor axis size given the focal length (60" or 1524mm) and the use of a 2-inch eyepiece? My "L" distance (focal plane to diagonal) is 10.25" (260mm)
Thanks,
You don't make it easy.Looks OK to me but there are are several different criteria. Berry and Dakin say it's a touch small. Efberg and Peters and Pike say it's OK.
Same but different
Here's an online calculator that I've found handy.....
http://www.catseyecollimation.com/designie5.html
That's also a good online calculator.JayTee wrote: ↑Fri Jul 09, 2021 8:08 pm Along with the helpful link that nFA provided (thanks), I have used that in the past but I find the multitude of inputs to be a bit confusing so I found another old bookmark from Stellafane that is a lot easier to use. For now, it seems that the diagonal currently installed should be sufficient. We'll see.
https://stellafane.org/tm/newt-web/newt-web.html
Cheers
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