2
Congratulations on your purchase of an Orion
®
Premium 190mm f/5.3 Maksutov-Newtonian
Astrograph. Your 190mm Mak-Newt Astrograph is
designed to deliver a flat field across the field of
view of an APS (advanced photo system) size cam-
era sensor, such as the StarShoot
™
Pro or DSLR
imager. Coma is reduced considerably when com-
pared to a Newtonian of equivalent focal length.
The exceptional optical and mechanical quality
of your 190mm Mak-Newt will provide you with a
pleasing telescope experience. The optics are rig-
idly secured in place to reduce image shift; and dif-
fraction is minimal because the secondary mirror is
held by the corrector glass, eliminating the need for
spider vanes.
Parts List
Optical Tube Assembly
Optical tube dust cover
1.25" eyepiece adapter
Camera adapter
2.5mm hex key
Phillips screwdriver
Collimation cap
Getting Started
Your 190mm Mak-Newt arrives fully assembled from the fac-
tory. The optics have been collimated, however you should
check the telescope collimation to ensure the collimation held
after it was shipped to you (see “Collimation”).
We recommend keeping all of the original packaging. In the
unlikely event you should need to ship the telescope back to
Orion for warranty repair service, you should use the original
packaging to ensure the telescope stays intact during shipping.
Take a moment to inspect the telescope and all of its parts.
Using 1.25" and 2" Accessories
Your 190mm Mak-Newt can accommodate both 1.25" and
2" accessories, including just about any eyepiece or camera.
The Crayford focuser has a 2" eyepiece holder with a 1.25"
eyepiece adapter installed. Both the 2" eyepiece holder and
1.25" eyepiece adapter feature a brass compression ring to
hold your accessories in place. The brass compression ring
securely holds the 1.25" or 2" accessory in place without
marking up its metal barrel.
Dual-Speed Crayford Focuser
The 190mm Mak-Newt features a heavy-duty dual speed
Crayford focuser, designed to handle the weight of your
eyepieces and imaging systems. The Crayford design offers
smooth and gradual motion, free of image shift. If the draw-
tube slips under the weight of your equipment, simply increase
the focus tension by tightening the focus tension setscrew
(Figure 2).
Crayford focusers generally perform better than rack-and-pin-
ion models because the design eliminates “focus shift”. Focus
shift is when an image moves position in the eyepiece when
it is being focused. This is very hard to eliminate in rack-and-
pinion focusers due to slight gear and tolerance imperfections
which cause the drawtube to move slightly left or right when
focusing. For the Crayford design, the drawtube is constantly
tensioned (by the focusing shaft and four “roller bearings”)
so the drawtube cannot move perpendicular to the desired
motion.
The focuser provides the most focus range for accessories
that require extra in-travel. With a minimum focus height of
58mm, this focuser is an excellent choice for any astro-imag-
Figure 1.
The Premium 190mm f/5.3 Maksutov-Newtonian Astrograph optical tube assembly.
Corrector
lens
Finder scope
dovetail base
Primary
mirror cell
Dual-Speed
Focuser
