Quote:
Originally Posted by erick
By the way, adding a 2x barlow in the focusser often solves the reaching focus problem, but at a price of 2x magnification!
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I struck a similar problem with a Bintel (GSO) 2" SP 40mm eyepiece in my 8" f/6 Dobsonian.
When the SP 40mm was seated normally, I couldn't move the focuser out far enough to get it focus. Lifting it in the focuser tube moved the focus point back within the reach of the focuser, but with the risk that it wasn't "straight". (I suspect the brass compression ring will limit how much it could be out-of-whack compared to a simple locking screw?)
I tried it (and my other eyepieces) with a Bintel (GSO) 2" ED 2x Barlow. The Barlow also needed to be lifted from the seated position to allow the eyepieces to reach focus - I assume this is normal? (The Barlow doesn't have a safety groove like the eyepieces, so there isn't an obvious "home" position.)
I'll try pulling the mirror down as far as possible with the collimation knobs; I don't think any of my eyepieces needed much in-focus, so it shouldn't be a problem.