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Old 20-02-2020, 10:33 PM
ausastronomer (John Bambury)
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Join Date: Mar 2005
Location: Shoalhaven Heads, NSW
Posts: 2,513
Hi Mel and Don,

Don raises a very good point. "The 17mm Nikon can't quite reach focus due to insufficient "in travel" when used with the SIPS at its optimum setting."

This is worth mentioning, particularly for those not familiar with adjusting a Paracorr or SIPS and who wonder why the eyepiece won't reach focus, the first time they go to use.

In reality and in the field this isn't any cause for concern. As Don said it gets pretty close. To compensate, you just adjust the SIPS / Paracorr slightly off the "optimal" setting and then the eyepiece will reach focus.

In the field under real sky conditions you can't detect that the Paracorr / SIPS is set slightly off the optimal setting. Observers have been doing this for at least 20 years with the 31mm Nagler and the T1 Paracorr. I also have to do it to reach focus with my 31mm Nagler T5 and my Pentax XW's when used in both my Paracorr T1 and my Paracorr PV2008. Under the stars you don't even notice it.

Worth mentioning for sure. Not a reason not to buy the eyepiece!

Cheers
John B
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