Test of the new Optolong L-eXtreme F2 filter: Sadr and the Belly of the Cygnus.

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Test of the new Optolong Astronomy Filter L-eXtreme F2 filter

Sadr and the Belly of the Cygnus.

Image and article Credit: Tommaso Massimo Stella (Italy)


Sadr is a yellow super giant star, 33,000 times more luminous than the Sun and 12 times more massive.
It is identified in the center of this wide-field image which portrays the center of the Northern cross (internal asterism in the constellation Cygnus). At bottom center and to the left, the Crescent nebula and the effects (cyan color, OIII) of the star Wolf-Rayet 134 can be seen.
The filter under test is designed to work with super fast optics centered on a focal ratio of 2. For the occasion, a full aperture Samyang 135mm f/2 lens connected to the Omegon veTec571V4 camera was used.
The result is the stack of 11 exposures of 300 seconds and the processing was limited to the adjustment of the curves and a minimal stellar reduction without the use of AI tools.
The filter was compared with a normal commercial L-Extreme and with an advanced version that has never been marketed (L-Extreme2).
Sky: SQM 19.95


In the following photos you can see the comparison of single 300s lights acquired with the new F2 filter, with commercial L-Extreme and with L-Extreme 2 (an improved version never released).
In the first image the same STF values were used for the 3 lights while in the second the stretch was automatic.

Same STF:



Auto STF:



I've done a lot of tests on L-Extreme and Ultimate and even valuable triplets have shown a few too many haloes, something not found by changing tubes (and sometimes cameras... imagine that).