Eyepiece Focal Plane Data?
Does anyone have any data on the focal plane positions of any of the following eyepieces? i.e. mm either side of the shoulder of the EP.
Televue 13mm Type 6 Nagler
Celestron 25mm E-Lux Plossl
Celestron 32mm plossl
Celestron 15mm plossl
Celestron 9mm plossl
I've read ways to measure the position of the focal plane using a telescopic focusser but I don't have that type of focusser on either my C8 or my PST. Are there other methods I could use?
I'm interested in starting to play about with EP projection, but I'd like to be able to calculate what magnification I manage to achieve.
Thanks,
Al.
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