Re: [APML] 9mm or 12mm guiding eyepiece

[Cees Bassa <c.g.bassa@phys.uu.nl>]

Hoi Marios,

I suppose you are going to do piggybacking but you are waiting for a 
guiding eyepiece.

First, for wide-field piggybacking you can do without a guiding reticle. 
Just use the eyepiece
with the shortest focallength and turn your guiding star a little out of 
focus to make it a disk.
Check in which direction the RA and Dec. are with respect to the eyepiece 
and center the
star in the eyepiece in declination and put it at one of the edges of the 
field. To guide just
keep a part of the stars disk obscured by the edge of the eyepiece. This 
way you can easily see
if you need to adjust the RA. It is very hard to see declination drift, but 
with short exposures and
wide-angle lenses you don't need to adjust the Dec. with proper polar 
alignment. I've used this
method numerous times succesfully with a 200 mm lens on 35 mm film.

Second, you can make your own guiding eyepiece! With a long hair and some 
tape you can easily create your own eyepiece. Try to make a double reticle 
so you get a box in the middle. Human hairs are thick and you magnify them 
when you are looking through the eyepiece so it will be difficult to guide 
with a single reticle. With a double reticle you can make the box as small 
or large as you want.

Recently I made my own guiding eyepiece as described above. I use a Barlow 
lens to get a high magnification and turn the star a bit out of focus so I 
can see where the box is. This works very good.

Success!
	Cees Bassa

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