Super-Slim Off-Axis guide head add-on! This useful filter wheel accessory makes accurate, flexure-free guiding easy to achieve. The extremely slim assembly screws directly to the wheel face and adds only 13mm to the back focal distance of the wheel.
The USB filter wheel was first introduced in 2009 and adds many new features to a useful imaging accessory. It is unique in that it does not require a separate power supply when used with USB control - the high performance DC gearmotor runs entirely from the USB supply and consumes less than 100mA. It is also capable of operation from a serial input, or from a switched hand controller, both of which power the wheel from a small dry battery.
The wheel is light and slim, with an easy change system of thumbscrews to swap filter disks without tools. A wide variety of threaded adaptors is available - T thread and SCT thread are commonly used, but you can see the full set at the foot of this page. The adaptors can be swapped by using a small screwdriver to release three stainless screws and lifting off the adaptor flange. Each flange can be rotated to any angle before locking down, so that you can orient the wheel and camera into the optimum position.
The wheel is quiet in operation and the Hall-Effect 3 bit encoded positioning gives absolute filter locations (not serially sequential) so you can easily swap between any filters without accidentally losing the wheel position.
The 10 x 8mm prism fully illuminates a Lodestar or EX guider CCD and the pick-off axis may be adjusted to optimise the guide image quality.
An alternative filter wheel face plate for direct attachment of our H18 and M26 cameras is also available (not suitable for other SX cameras as the OAG cannot achieve focus for these, without the camera adaptor in place)
A general view of the filter wheel, fitted with T thread adaptors and a 48mm filter disk
An internal view with the cover removed, showing the 5 x 48mm filter disk with one filter in place. The USB connector is visible at lower left and the Serial/Manual connector is at the lower right.
The 7 x 32.5mm filter disk.
36mm and 50mm unmounted filter carousels
NEW - the original 50mm version has now been adjusted to allow 50.8mm (2 inch) unmounted filters to be fitted.
Cross-sectional dimensioned views of the wheel when fitted with T thread and SCT adaptors
Here are most of the adaptor rings currently available.