This FAQ answers a common question which is “What adaptors and spacers do I need to adjust the correct distance between field flattener / reducer and the camera sensor when using the Magnetic Filter Filter Holder?”

The spacing depends on which camera you have, Fan Cooled or TEC Cooled.

Hypercam Fan Cooled Cameras have a front T2 (M42x0.75mm) thread, and 12.5mm sensor-to-flange spacing. The Altair Magnetic Filter Holder has a 17mm optical path depth. (12.5 + 17) = 29.5mm space taken up so far. If you subtract 29.5 from 55 you get 25.5mm. So you need to add 25.5mm of adaptors between the filter holder and the rear shoulder of the reducer/flattener to make up the ideal 55mm optical path to the sensor. The diagrams below illustrates where the measurements are calculated from, and in this case you need the following parts:

If you have a reducer/flattener requiring 55mm and a rear M48 Male thread:

1. Altair 15.5mm M48 Spacer Ring
2. Altair 10mm M48 Spacer Ring
3. Altair Magnetic filter holder M48 to T2 version to connect to the camera T2 flange.

Hypercam TEC Cooled Cameras have a front T2 (M42x0.75mm) thread, and 17.5mm sensor-to-flange spacing. The Altair Magnetic Filter Holder has a 17mm optical path depth. (17.5 + 17) = 34.5mm space taken up so far. If you subtract 34.5 from 55 you get 20.5mm. So you need to add 20.5mm of adaptors between the filter holder and the rear shoulder of the reducer/flattener to make up the ideal 55mm optical path to the sensor. The diagrams below illustrates where the measurements are calculated from, and in this case you need the following parts:

If you have a reducer/flattener requiring 55mm and a rear M48 Male thread:

1. Altair 15.5mm M48 Spacer Ring
2. Altair 5mm M48 Spacer Ring
3. Altair Magnetic filter holder M48 to T2 version to connect to the camera T2 flange.