Which cameras is the SBIG STX 7 x 50mm Filter Wheel directly compatible with?
The SBIG FW7-STX is designed for direct, bolt-on compatibility with all STX series cameras, as well as the Aluma AC4040 and Aluma AC2020 models. It is explicitly not compatible with the Aluma AC455.
Can I use filters thicker than 2mm in the SBIG STX 7 Filter Wheel?
Yes, you can install filters up to 3mm thick. However, to accommodate the extra thickness, you must not fully tighten the carousel's filter retainer screws. The wheel is optimized for the recommended 2mm thickness. Thin 1mm filters are not recommended and will require shims, which Diffraction Limited does not supply.
How does the SBIG STX 7 Filter Wheel connect to my camera for power and control?
The filter wheel is controlled and powered through a single connection to your camera. It uses an I2C interface with a DB9 pigtail that plugs directly into the camera's AUX port. This simplifies cable management by eliminating the need for a separate power supply or USB cable for the filter wheel.
What is the benefit of placing the guider in front of the filters with the SBIG STX 7 wheel?
Placing an off-axis guider like the StarChaser SC-4 before the filters means your guide camera sees the full, unfiltered light from a guide star. This is a significant advantage for narrowband imaging. It allows for reliable guiding even when you are imaging for hours through a very dark H-alpha or OIII filter that would otherwise make finding and tracking a guide star much harder.
Will the SBIG STX 7 Filter Wheel work for narrowband imaging of the Cygnus Loop (NGC 6960) with an off-axis guider?
Yes. When paired with an STX Guider or StarChaser SC-4, the guider picks off light in front of the filter wheel, so you can guide on unfiltered starlight while the main camera images through your Ha, OIII, or SII filters. This helps keep a usable guide star for long exposures of faint targets like the Cygnus Loop.
I have an SBIG STL camera. Can I use the SBIG STX 7 Filter Wheel with it?
Yes, while it is not a direct-mount fit, the SBIG STX 7 Filter Wheel can be used with an older STL series camera by using the ACC10 Adapter (sold separately). This allows you to take advantage of the 7-position capacity with your STL setup.
What type and size of filters should I buy for the SBIG STX 7 Filter Wheel?
You should purchase 50mm x 50mm square, unmounted filters. The recommended thickness is 2mm for the most secure fit. These are standard sizes for large-format CCD imaging and are available from multiple manufacturers for LRGB, narrowband (Ha, OIII, SII), and photometric (B, V, R) applications.
When imaging the Ring Nebula (M57) with my STX camera, will I have trouble finding a guide star?
It should be easier. With an STX Guider or StarChaser SC-4, the guider picks off a star from the edge of the field before the light goes through the filters, so a narrowband filter used for M57 does not dim the guide stars. You still need a suitable star within the guider's field.
