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Old 26-08-2021, 03:41 PM
astro744
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Join Date: Apr 2007
Posts: 1,244
Quote:
Originally Posted by Merlin66 View Post
Astro,
The T thread adaptor is for rigid connection to the camera. It also reduces the backfocus overhang. There's no "correct spacing"
I've had a few PM's over the years and still use the x2.5.
My x2.5 is a smooth barrel with a filter thread. I've never seen the stepped barrel.
Ok. Thanks. Maybe I could have worded that better. I was referring to the graph on Tele Vue web site and the first para directly under the graph talking about 0mm position.

See https://www.televue.com/engine/TV3b_...id=53&Tab=_app

See here for image of original Powermate: https://www.bintel.com.au/product/te...v=322b26af01d5

Sometimes when sold used the bottom cap is on in the photo so you don’t know which one you are getting. Both work well, just the newer (at least within 10 maybe 15 years) takes filters.
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