The flattener is a lens that evens out the field, as this is slightly curved by the primary optics. This curvature causes stars that are imaged at the edge of the field of view to be less sharp. The flattener, also called a field flattener, corrects this effect. Astrophotographers can then enjoy images where the stars remain sharp right out to the edge of the exposure. The flattener is installed between the telescope and the camera.
Full-format corrector for refractors with apertures from 80 to 155 millimetres
An essential component of the corrector is an integrated fine adjustment mechanism. By turning the knurled ring on the corrector, you can adjust the distance to the sensor to fractions of a millimetre. Once you have reached the desired distance, fix it with the clamping screw. This allows you to determine the optimum distance with the camera connected by taking test shots without additional adaptors and adjustment rings. The camera does not rotate during fine adjustment.
The following settings from the innermost position of the adjustment to the sensor are recommended:
- Aperture 80 mm / aperture ratio f/6 - 81.2 mm
- Aperture 80 mm / aperture ratio f/7 - 80.2 mm
- Aperture 102 mm / aperture ratio f/7 - 75.3 mm
- Aperture 115 mm / aperture ratio f/7 - 73.0 mm
- Opening 130 mm / opening ratio f/7 - 69.7 mm
- Opening 140 mm / Aperture ratio f/6.5 - 68.0 mm
- Opening 155 mm / Aperture ratio f/8 - 57.0 mm
Calculation example for setting the distance:
- Telescope: Refractor with 130 mm aperture f/7, i.e. 910 mm focal length.
- Camera: SLR camera with 55 mm distance from the M48 thread to the sensor.
The working distance is 69.7 mm according to the table. Simply subtract the 55 mm (distance between the thread and the sensor) from this measurement. This leaves 14.7 mm. Simply turn the variable adjustment 14.7 mm outwards; this can be easily adjusted using the distance mark. You are now at the optimum distance and can start taking photos.
TS Optics is a brand of Teleskop-Service.
