S = to fit 160mm - 250mm tube dia., L = to fit 250mm to 580mm tube dia. 

"I want to make the secondary obstruction of my Newtonian as small as possible by reducing the backfocus out of the telescope tube", "I want to get as long backfocus as possible for prime focus photography", "I want my Newtonian to reach the focus with my binoviewer, by using a lower-possible power focal extender to get lower-possible magnifications", etc. ..... recently the demands for low-profile focusers are increasing among amateur astronomers. However, concerning ordinary single-drawtube focusers, the lower the focuser's profile is, the shorter the focus travel becomes, and additional extension tubes are inevitably required when switching a camera or a binoviewer to an eyepiece. Now, Kasai Trading is offering the very best solution for such problems.

Dual Drawtubes

Kasai Low-Profile Micro Focuser is equipped with dual drawtubes. In spite of the total height (from the bottom surface of the base plate to the 2" adapter end) of whole the focuser is only 47mm, the total focus travel is such long as 70mm: 26mm travel by the outer tube + 44mm by the inner. While, the drawtube's maximum inner height (sticking-out inside the telescope tube when the drawtube is most shortened) is only 15mm or shorter, so it will not interfere the incoming light path. The outer tube is operated with the feather-touch dual-speed crayford focusing mechanism (see below), and the inner tube is to be pushed-and-pulled so smoothly. The 2" eyepiece adapter and the joint part of the tubes employ compression ring stopper system. As a standard accessory, 1.5mm-height extra low-profile 1.25" eyepiece adapter (M48 filter threaded) is included.

1:10 MIcro Focusing Mechanism

Luxury-looking focusing unit with mat-silver & mat-gold finished knobs includes 1:10 micro focusing mechanism. The focusing feel of this crayford system is truly "feather-touch", causing no vibration to the telescope. The tension adjusting function and the focus stopper are fully equipped.

Housing & Finish

Most consisting components are CNC-machined and glossy black anodized, offering top-quality atmosphere. The inner surfaces of the drawtubes are thoroughly mat-blackened to eliminate the incoming stray lights.

Base Plate

The base plate is a universal type, fitting various diameter telescope tubes. Besides, so that it can keep low-enough profile regardless of the tube diameters, we offer two different models: "S" is to fit 160mm to 250mm tube diameter, while "L" is to fit 250mm to 580mm. (Please specify either type when ordering.) In addition to the normal fixing holes for four M4 or M5 screws, two oblong holes are furnished so that it can be fixed with two screws and the whole focuser can be slid left and right. This function will be useful when adjusting the focuser position against the secondary mirror, or extending the backfocus combined with the collimation screws of the secondary mirror, or else.