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On the topic of Barlows, what do people do to really figure out the effective EP focal length, or Barlow factor, in case it matters to them? Other than timing the passing of a star through the field of view.
I find that there is a *huge* difference in the position of the focal points of eyepieces in relation to their barrels, for example between any TV eyepiece and any ortho I've owned. The variation here is 2-3cm, which must make a big difference in the effective Barlow multiplier.
Cheers
Steffen.
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