Probably the best small APO refractor all around. Large 90mm aperture in a short and compact package.

Aperture: 90mm
Focal length: 500mm
Photographic speed: f/5.9 in prime focus, f/8 with Extender-Q, f/4.4 with reducer


In prime focus perfect for wide filed observing. For planetary views, the traces of chromatic aberration can be reduced using optional Extender-Q.

For CCD or DSLR / film imaging, the scope has too much field curvature and off-axis astigmatism. However, with the optional f/4.4 reducer, the field is flat and aberration free to the edge of DSLR chip. Perfect astrograph for wide to medium sized objects.