Anyone who deals with astrophotography someday and inevitably stumbles over the term: Flatfield . If a photograph is taken by the telescope, artifacts resulting from the different degrees of illumination of the sensor will occur. In order for the image editing software to correct this error, it is necessary to take pictures of a uniformly illuminated area, which are created under the same conditions as the actual pictures. Such an area produces the Aurora Flatfield Illuminated Film.
The advantages of Aurora Flatfield illuminated foils:
- Completely uniform illumination of the lens opening
- Full spectrum, therefore also usable in combination with line filters
- Power supply for 12V or mains voltage available
The Aurora Flatfield foils are supplied pre-assembled in a plastic frame: The frame is made of unbreakable plastic, has rounded corners and is fitted with an edge protection: your Aurora foil is thus perfectly protected on the transport to the observation point, and the milky front panel ensures an even more uniform brightness distribution.
The diameters of the foils are chosen so that the typical instrument sizes are well covered:
- Diameter 100mm for devices up to 4 "opening
- Diameter 160mm for devices up to 6 "opening
- Diameter 220mm for devices up to 8 "opening
- Diameter 315mm for devices up to 12 "opening
- Diameter 420mm for devices up to 16 "opening
- Diameter 590mm
- Diameter 750mm
Choosing the right size:
- To get high-quality flatfield data, the free opening of your instrument must be completely covered. The diameter of the dew cap or similar is not crucial! As an example: For a 6 "(15cm) refractor, the 160mm Aurora is sufficient, regardless of the diameter of the dew cap!
- If you use a Newton, RC, ODK or similar, the Aurora luminescent film must be larger than the free diameter of the optics! The rule of thumb for a Newton is: Free mirror diameter + diagonal of the sensor of your camera. Here's an example: For a 8 "Newton, a 220 Aurora is enough if you're using a camera with a very small chip (<14mm diagonal). If you're using a typical DSLR with APS-C sensor, you'll need to choose a 315mm Aurora.
It is easily possible to use a large Aurora for smaller instruments: For example, if you own a 315mm Aurora, you can use it without restriction for a 4 "refractor or your camera lenses.
The brightness of the slides is ideal for shooting with filters , but for shooting in white light or only with an L-filter, it must be reduced. The brightness of the Aurora Flatfield luminescent films can be controlled within limits by reducing the input voltage (only when using 12V inverters). In addition, the brightness can be easily and inexpensively realized by placing one or two layers of white paper in the frame between the film and the instrument! For use with very high-speed devices or for large cameras with a slow shutter, see "Recommended accessories" for gray film filters in the appropriate sizes. With these films, a very strong reduction in brightness is possible. For use on high-speed astrographs we recommend to order these foils directly!
The power supply : For each size of the Aurora Flatfield light foils, there is the corresponding inverter. A normal power supply is not usable because the light films are operated with high voltage. Due to the low current level there is no danger! Please use the slides only with the recommended inverter: Although they also shine with larger inverters, their lifetime is greatly reduced!
Scope of delivery: Aurora Flatfield luminescent films are supplied as a completely ready-to-use set. This consists of the luminescent film in the frame, the matching inverter, all the necessary cables and a printed operating manual.