RE: [APML] Suggested Astrophoto Accessories for Vixen VC200L

["Thom Iwancio" <tiwancio@sc.rr.com>]

John, my experience is very similar.  When I got my NEG the t-ring that
came with it for an OM was what Lumicon called a "wide t-ring". The
inner part protruded from the camera adapter part.  When I switched to a
Pentax screw mount system I was able to use this inner part with the
outer part that mated to the Pentax (it was flush).  When I again tried
this with a Pentax-K ring I found the diameters of the inner rings were
different.  Apparently not all brands / models of t-rings have the same
dimensions of the components.  I was able to loosen the 3 set screws
however and pull enough of the inner ring out to barely make purchase on
the NEG. Barely!

This worked ok for my newt since I could rotate the tube so the camera
was usually facing down.  When I converted to an SCT I was a little
concerned about the ring barely being grabbed by the SCT EG and the
camera hanging at some awkward angles.  My solution was to turn down a
piece of aluminum to fit the camera adapter piece and the EG.  Since I
wasn't planning on using filters this also allowed me to increase the
inside diameter of the ring to reduce vignetting.  

FWIW,

Thom Iwancio
Elgin, SC
www.machunter.org

-----Original Message-----
From: astro-photo-bounces@seds.org [mailto:astro-photo-bounces@seds.org]
On Behalf Of John C. Mirtle
Sent: Wednesday, September 03, 2003 9:01 PM
To: Discussion of Film Astrophotography
Subject: Re: [APML] Suggested Astrophoto Accessories for Vixen VC200L

----- Original Message ----- 
From: "Alen Koebel" <alen_koebel@yahoo.ca>
To: "APML" <astro-photo@seds.org>
<- snip ->
matches all the pictures I have seen of these
units. Perhaps Lumicon changed the design? Maybe
someone else with this OAG can weigh in here.
<- snip ->

OK guys,
    Here's what I have. My NEG is old - 1986 vintage. My T-rings are all
at
least 10 years old, so your mileage may vary considerably from my
observations. First, T-rings. Let's say they have a top and bottom. The
top
is the part with the flange parts - the bit that attaches to the camera.
The
bottom part is where the threaded insert goes.
On MY T-rings, the threaded insert is flush with the bottom of the
T-ring.
There is no way to attach this to a NEG. When I purchased my NEG, it
came
with a small "flange" that attached with 3 set screws to the inside of
the
T-ring, in place of the threaded insert. This protrudes from the bottom
of
the T-ring by 3/16ths, and is threaded for 48mm filters. The 3 screws in
the
body of the NEG pull this flange down tight. On the GEG there is also a
flange provided, it sticks out a bit further at 1/4" from the bottom of
the
T-ring. These flanges are not part of any T-ring I bought, they are
Lumicon
parts as far as I can tell.
    When word got out that Lumicon was toast, I picked up a used 1.25"
NEG
for parts - age unknown. It's flanged bit also sticks out of a standard
T-ring by 3/16ths. Maybe newer T-rings are "outies" instead of flush - I
don't know. But I do know that my T-rings are all flush and slide off of
NEG's.

This is what I have, I am not trying to step on toes or change the
destiny
of the universe - YMMV. :-)

John Mirtle
Calgary, Ab. Canada

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