Re: [APML]: Focusing a Takahashi Epsilon astrograph (was: New photos)

[Gene Horr <genehorr@swbell.net>]

The Astro-Photography Mailing List
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Wil Milan wrote:

> I have the rack-and-pinion focuser, and yes it is a challenging
> instrument to focus.

My hat is off to you!  I have the helical which has two 
advantages:  Calibration numbers on the side and an extremely
fine thread (not quite 1000tpi, but it sure seems like it!)
The biggest negative is having to spin the camera forever
for minor focus adjustments.

I have the 6X magnifier and it is very helpful for rough 
focus.  Instead of a knife-edge I use the Tak FM-60.  This
is an extremely handy device for just about any film camera.
It consists of a focusing screen about the size of a microscope
slide with a miniature microscope.  Once you get rough focus
you open the camera back and lay the screen across the film
plane.  You then use the microscope to examine the star
image when fine focusing.  It works GREAT!  The street
price is ~US$200.

> I've uploaded a larger version of the North American - Pelican
> image. See

http://www.airdigital.com/NGC7000_and_Pelican_Nebula_Tak_E130_Pro100_30m_Sunglow_Jun98_larger.jpg

VERY NICE!!!  I like how you were able to get a black background
while still keeping fine detail in the nebulae.

Gene Horr
genehorr@swbell.net