My FS128 is equipped with a Moonlite focuser. Last night on the moon some folks were "egging me on" to jack the power up beyond any reasonable expectation. It was fine at 300x with the 3.5mm XW. There appear to be 4 ways to use the Barcon:
ANYHOW, I gave in to the pressure and (1) put the AP Barcon in "the usual way": Barcon into the top of the diagonal, eyepiece into the Barcon. If I read AP's web site right that's about 1.6x or 480x power. The view was good, and I *could* focus.
Then I tried (still under pressure from three onlookers) for 600x by (2) putting the Barcon into the drawtube and then putting the diagonal into the Barcon and the eyepiece up top. The distance between the Barcon and the eyepiece gets bigger, leading to more magnification.
I couldn't reach focus.
Then I said, well, we can reduce the distance a bit. (3) I screwed the Barcon lens on to the mirror diagonal, inserted the diagonal in the drawtube, stuck an eyepiece in, and could not reach focus.
Then I said well I hear about people needing longer and shorter tubes depending on what they're trying to do so maybe this isn't going to work when it occured to me I had option (4), which was to insert the AP Barcon's lens-less extension tube into the refractor drawtube, and then put the diagonal, to which the Barcon lens was screwed on, into the *top side* of the Barcon extender (it's not screwed on in the usual way here).
That actually worked! I could reach focus, but have no idea of what the effective magnifying ratio of the Barcon lens was in this unusual position. It *definitely* seemed to be higher magnification than the 480x achieved in (1).
Anyhow there's a lot of ways to use a Barcon.
I was wondering what exactly is going on with the positions that "work" and the positions that don't work and what my effective magnification was when I hit paydirt with position (4).
FWIW, the views at 300x and 480x were excellent, and the view in position (4) was pretty good, but beginning to take on that "excess magnification feel". I think the optical limit of the FS128 is really as a practical matter 300x, maybe 400x under some circumstances.
regards
Greg N
ANYHOW, I gave in to the pressure and (1) put the AP Barcon in "the usual way": Barcon into the top of the diagonal, eyepiece into the Barcon. If I read AP's web site right that's about 1.6x or 480x power. The view was good, and I *could* focus.
Then I tried (still under pressure from three onlookers) for 600x by (2) putting the Barcon into the drawtube and then putting the diagonal into the Barcon and the eyepiece up top. The distance between the Barcon and the eyepiece gets bigger, leading to more magnification.
I couldn't reach focus.
Then I said, well, we can reduce the distance a bit. (3) I screwed the Barcon lens on to the mirror diagonal, inserted the diagonal in the drawtube, stuck an eyepiece in, and could not reach focus.
Then I said well I hear about people needing longer and shorter tubes depending on what they're trying to do so maybe this isn't going to work when it occured to me I had option (4), which was to insert the AP Barcon's lens-less extension tube into the refractor drawtube, and then put the diagonal, to which the Barcon lens was screwed on, into the *top side* of the Barcon extender (it's not screwed on in the usual way here).
That actually worked! I could reach focus, but have no idea of what the effective magnifying ratio of the Barcon lens was in this unusual position. It *definitely* seemed to be higher magnification than the 480x achieved in (1).
Anyhow there's a lot of ways to use a Barcon.
I was wondering what exactly is going on with the positions that "work" and the positions that don't work and what my effective magnification was when I hit paydirt with position (4).
FWIW, the views at 300x and 480x were excellent, and the view in position (4) was pretty good, but beginning to take on that "excess magnification feel". I think the optical limit of the FS128 is really as a practical matter 300x, maybe 400x under some circumstances.
regards
Greg N
"Scope will get you through times of no money better than money will get you through times of no scope." --Freewheelin' Franklin
