Moravian External Filter Wheel with 7 positions for C1× and C3 Cameras (D=50mm)

Astronomical cameras with monochrome silicon-based sensors are sensitive to a wide range of wavelengths, from near ultraviolet (UV) to near infrared (IR) light. If only part of this spectral range is to be detected, a color filter must be placed in front of the sensor. For this reason, Moravian Instruments cameras are designed to work with a wide range of Moravian Instruments filter wheels.

Like the cameras themselves, the Moravian Instruments filter wheels are computer-controlled so that they can be integrated into complete image processing systems.

This EFW with 7 filter positions is suitable for the Moravian camera series:

• C1+
• Moravian C1x CMOS Cameras (various versions available) and
• Moravian C3 CMOS Cameras (various versions available)

Note:

Since the external filter wheels use the power and control provided by the camera, EFWs do not require additional power and control lines.

External Filter Wheels have several advantages:

• EFWs offer a wide range of filter sizes and filter slot positions.
• EFWs can accommodate very large filters (up to 65 × 65 mm), so they are also available for cameras with large and very large sensors.
• EFWs are compatible with asymmetrical cameras, as well as with corresponding symmetrical models.
• Opening the EFW housing and replacing the filters is easier because there are no mechanical or electronic devices inside the housing, only the motor drive of the wheel.

The diameter of the external filter wheel has design limitations; it is not possible to simply enlarge both the EFW housing and the filter wheel itself. The diameter and weight would be so large that the use of such wheels would not make sense.

The natural solution to this problem is to fit two smaller filter wheels side by side. The total number of filter positions is less than the sum of the positions in both wheels for one obvious reason: one position in each wheel must remain empty (free) and is set as the current position when a filter from the other wheel is to be used so as not to interfere with it. The filter wheel control electronics built into Moravian Instruments cameras cannot control two independent filter wheels simultaneously.