Optec 19054 - Alnitak Flip-Flat 270+ Flat Field Panel

Optec 19054 - Alnitak Flip-Flat 270+ Flat Field Panel

The flagship product of Alnitak Astrosystems, the Flip-Flat, is a robotic lenscap and flat field illumination source for small to medium size refractors.

The Flip-Flat employs advanced electroluminescent lighting panel technology to provide a uniform source of illumination for the production of high quality flat field frames necessary for serious astroimaging and photometric work. With the Flip-Flat, on-demand flat fields with uniformity errors less than 1% are now possible.

In addition to providing excellent flat fields, the Flip-Flat protects the objective lens of the telescope from dust that typically plagues remote installations where the user cannot manually replace the lenscap after an imaging session.

The Flip-Flat is easily mounted to the front of any telescope tube (or rigid dewshield) with an OTA outside diameter between 6" (150 mm) and 8" (200 mm), but it can be used up to 8-1/8" (206 mm). The Flip-Flat is attached to the telescope OTA with industrial nylon zip straps and easily removable for transport and storage.

New: Optec has partnered with Chris White of Overcast Observatory to re-design the Flip-Flat electroluminescent calibration panel mechanical design. The new Alnitak Flip-Flat 270 design allows a full 270-degree rotation of the flat field panel to rest against the side of the telescope tube.

A simple Windows interface provides the ability to open and close the Flip-Flat and turn on the light source. The intensity of the light can be adjusted to your needs.

How do I get a good flat field image?

A good flat compensates for edge shading (vignetting), but also for darkening caused by dust on the filter, sensor or corrector. The background becomes even, the contrast can be raised further to make finer details visible in faint nebulae. The following basic settings should be noted:

The ISO or gain setting must be the same as for the lights, i.e. the actual astrophotography.

Telescope, camera and accessories, such as filters, off-axis guider etc., must be the same as for the actual exposure, also the position of the focuser should be unchanged.

The exposure time should be so short that nothing is "burned out", i.e. overexposed. Only in this way can the flat unfold its full effect. We recommend an exposure of 30-50%. The flat should not be burned out, but it should also not have any unexposed areas.

How do I find the right exposure time with the shooting software, for example Maxim DL?

The ADU value (Analog Digital Units) helps here. Every capture program shows this value when you move the mouse over the image. In the center of the image, where the illumination is highest, the ADU value is highest. The longer you expose, the higher this value becomes. If the ADU value is higher than the maximum value of the camera, the image is overexposed. A camera with 16 bits has a max. ADU value of 65536, one with 14 bits has 16384, one with 12 bits only 4096.

The exposure time of the flat should be so short that in the middle of the flat the ADU value is at most 50% of the maximum value of the camera. Then the flat looks well exposed. We recommend to take at least 10 flats per exposure and to process them to a "master flat".

If the flatfield box is too bright, that means it always produces overexposed images, then a white paper, which is fixed in the flatfield box, helps. This will dim the light and allow for slightly longer exposure times.

Safety informations: PDF Download