Flat field Geoptik (CODE 30B304)
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The Geoptik flat field adapter solves the problem of unevenly illuminated deep-sky images. This effect is often caused by vignetting (inherent to all optical systems, more or less) or prisms of off-axis-guiders inside the optical path.
Problem solution is capturing an evenly lit background. With this "flat field", image processing software is able to remove the vignetting effect from the main picture. Here, we recommend taking several flat fields and combining them to one "master flat". Nearly all astromical image processing softwares (Astro Art, MaxIm DL ...) can handle this.
Advantage of the Geoptik Flatfield Adapter:
At the sky, an evenly lit background is nearly never present. Even if clouds, late dusk or fog appear as absolut evenly illuminated, in fact they aren´t. These errors will then be calculated into the latter picture. The Geoptik flat field adapter provides a true flat field - a first class reference. We recommend taking such flat fields in darkness to prevent stray light from entering the optical system.
Using the Flatfield Adapter:
This is very simple: Direct the telescope or lens roughly to the zenith and put the flatfield adaptor on the top of it. Switch the adaptor on. Now you have an even lighting on the chip, only changed by irregularities in the telescope or on the chip. Make flatfield exposures, we recommend 4. Make them in the darkness to avoid stray light adulterating the results. Now you have a base which can be combined to a "master flat".
The image above shows a typical flat field with obvious and slightly uneven vignetting. This is normal with most telescopes.
♦ Suitable for lenses / telescopes 156 up to 260 mm
♦ 27 mm thick. Locking with three nylon thumbscrews
♦ Powered by an external 12 V DC power source
♦ Weight: 700 Gramms