ToupTek Launches AFW-Mini: A Compact 5-Position Filter Wheel

A filter wheel makes a monochrome astrophotography setup much easier to operate. Once several filters are loaded, the camera can move from one wavelength to another without anyone having to remove the camera or open the optical train. There is a trade-off, though. It adds weight and can make a compact imaging train noticeably larger.

ToupTek Astro has introduced the AFW-Mini with this problem in mind. The new electronic filter wheel takes five 1.25-inch filters and weighs 340g. Its body is 20mm thick. The compact filter wheel targets planetary cameras, AstroEye series cameras, and compact deep-sky cameras with smaller sensors.

Five filter coverage and a small size

The AFW-Mini has five slots for 1.25-inch filters. Take LRGB imaging as an example. A monochrome camera needs luminance, red, green, and blue filters to produce a color image. The four filters occupy four positions in the wheel. The fifth slot remains available for another filter.

Narrowband imagers can use the wheel in much the same way. They can load several emission-line filters like Ha, Sii, Oiii and change between them during a sequence.

ToupTek targets planetary, lunar, and solar imaging with this setup. These types of astrophotography require smaller sensors. The 1.25-inch filter wheel seems perfectly suited for such use cases.

The most significant numbers on the AFW-Mini are probably its weight and thickness. At 340g and 20mm thick, it adds relatively little hardware to the space between the telescope and camera.

AFW-Mini uses a stepper motor and two bearings

The AFW-Mini uses a stepper motor to move its filter carousel. That lets the astrophotographer change filters without touching the camera or opening the optical path. For automated imaging, the wheel can move between filters as the capture sequence progresses.

ToupTek gives the wheel two rotation speeds. The standard setting takes about six seconds per revolution, while the slower setting takes 12 seconds. The company says the slower mode increases load capacity and improves operating stability at low temperatures.

The filter carousel also uses two bearings. A thrust bearing handles the axial load, while a deep-groove ball bearing supports the rotating assembly. This arrangement is supposed to keep the carousel stable and reduce filter tilt or wobble as it moves.

Several connection options

ToupTek has included several ways to connect the AFW-Mini to an imaging system. The main holder uses an M42-to-1.25-inch T-mount arrangement and includes an insertion stop. That stop prevents an inserted accessory from reaching far enough into the wheel to interfere with the rotating filter carousel.

The package also includes a 1.25-inch nosepiece. There is an M48 female-to-M42 male adapter as well, and ToupTek lists the adapter at 16.5mm in thickness. The company says these parts allow the wheel to work with telescope systems using 1.25-inch, 2-inch, or M48 connections.

ToupTek also includes dust caps with the AFW-Mini. They protect the open connections when the wheel is not attached to the telescope and help keep dust away from the optical system.

Price and availability

The ToupTek AFW-Mini is priced at $189, and it is available for ordering via ToupTek’s official website.

The AFW-Mini gives astrophotographers an added option alongside the AFW-M. Priced at $229, the larger AFW-M gives users more filter positions and supports larger formats. It can hold eight 1.25-inch filters, five 2-inch filters, or seven 36mm filters.

Clear skies!

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