[ATM] Crayford focuser protrusion problem

[John Lynch <john_p_lynch2004@yahoo.com>]

To the ATM listserv:

I plan to use a JMI DX2 2" Crayford focuser with my
future 8" f/6.25 reflector telescope, and a telescope
tube with an inside diameter of 9.375".  Based on the
focusers' low profile and 1.25" travel range, and
eyepieces that I plan to use with this telescope, I've
determined that some (longer focal length eyepieces)
will cause the drawtube to protrude into the telescope
tube by approximately 0.4".
This is with a focal plane at 0.8" above the fully
racked in position (1.6" height off of the telescope
tube).  Shorter focal length eyepieces require the
margin I have left beyond this point.  My question 
is:  Will the 0.4" protrusion of the drawtube cause
undesireable effects that I should try to correct?

Thanks for any advice.

John Lynch


	
		
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