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joerg

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  1. Thanks
    joerg got a reaction from LiveShots in Suitability of the Sony SEL200600G Lens for Astrophotography   
    In the second section I would like to discuss the possibility of photographing deep sky objects.
    To achieve exposure times of a few seconds the earth's rotation has to be compensated, in my case by the equatorial mount CEM25P from iOptron. With the possibility of autoguiding, here by the MGEN3 from Lacerta in combination with a 50mm finder scope, exposure times of several minutes can be achieved. Seemingly small things are also important in my opinion, like a heating tape to avoid humidity condensation and the use of a dummy battery adapter to be able to run the camera constantly for several hours.

     
    Emission and reflection nebulae
    With the possibility to select the focal length almost arbitrarily between 200 and 1800mm, very many objects can be photographed with the SEL200600G. For emission nebulae with a primary emission at hydrogen-alpha and 656nm the use of an astromodified camera is recommended (replacement of the IR cut filter by clear glass). In my case I took a Sony A7R bought used at E-Bay and let it astromodify.

    Orion nebula M42 Composit 10x10s and 30x180s ISO-800 F6.3 600mm 7xDarks 15xFlats 15xBias Optolong L-Pro Filter

    Plejades M45 28x120s ISO-800 F6.3 600mm 5xDarks 26xFlats 20xBias
     
    Galaxies
    The same applies analogously to galaxies as to planetary photography. It is possible to photograph single galaxies. However, the optic is not fast and not long-wavelength enough for very detailed images.

    Markajan chain 102x240s ISO-800 600mm F6.3 6xDarks 15xFlats 15xBias

    M51 110x120s ISO-1600 1200mm F13 7xDarks 15xFlats 15xBias
  2. Thanks
    joerg got a reaction from Pieter in Suitability of the Sony SEL200600G Lens for Astrophotography   
    In the second section I would like to discuss the possibility of photographing deep sky objects.
    To achieve exposure times of a few seconds the earth's rotation has to be compensated, in my case by the equatorial mount CEM25P from iOptron. With the possibility of autoguiding, here by the MGEN3 from Lacerta in combination with a 50mm finder scope, exposure times of several minutes can be achieved. Seemingly small things are also important in my opinion, like a heating tape to avoid humidity condensation and the use of a dummy battery adapter to be able to run the camera constantly for several hours.

     
    Emission and reflection nebulae
    With the possibility to select the focal length almost arbitrarily between 200 and 1800mm, very many objects can be photographed with the SEL200600G. For emission nebulae with a primary emission at hydrogen-alpha and 656nm the use of an astromodified camera is recommended (replacement of the IR cut filter by clear glass). In my case I took a Sony A7R bought used at E-Bay and let it astromodify.

    Orion nebula M42 Composit 10x10s and 30x180s ISO-800 F6.3 600mm 7xDarks 15xFlats 15xBias Optolong L-Pro Filter

    Plejades M45 28x120s ISO-800 F6.3 600mm 5xDarks 26xFlats 20xBias
     
    Galaxies
    The same applies analogously to galaxies as to planetary photography. It is possible to photograph single galaxies. However, the optic is not fast and not long-wavelength enough for very detailed images.

    Markajan chain 102x240s ISO-800 600mm F6.3 6xDarks 15xFlats 15xBias

    M51 110x120s ISO-1600 1200mm F13 7xDarks 15xFlats 15xBias
  3. Like
    joerg got a reaction from Pieter in Sony 200-600 mm Lens for Astrophotography?   
    To be clear: all the effort with the equatorial mount and elaborate post-processing, which caused me a learning cycle of more than half a year and a financial expenditure comparable to the purchase of a SEL200600G lens and a SEL20TC teleconverter, which are not cheap either, is only needed to photograph faint deep sky objects!
    All the lunar images I posted here in the forum almost a year ago were taken exclusively with the following equipment: Sony A6000 camera, SEL200600G lens, SEL20TC teleconverter on a wobbly aluminium tripod! Partly I used a remote release RMT-DSLR2.
    I used the following procedure for this:
    1. Frame up the moon in the picture, filling about approx. 80% of the horizontal image area.
    2. With the help of the focus magnifier, focus on a crater on the terminator as well as possible (today I would use the Bahtinov mask and a bright star!).
    3. Use an exposure time of well under 1/10s (see below) and ensure a vibration-free release with the built-in timer or a remote control. Take 5-10 shots to catch one moment with little air turbulence, until the moon has finally run out of the frame.
    Because I was unsure whether the focus was perfect, I went through this whole process 4-5 times in one evening and got a really beautiful moon image every night. I have to admit that in the beginning I even shot pure JPG and only did moderate post-processing (exposure and maybe a little sharpening). Of course, all the individual images with embedded meta data still exist and have not been deleted...
    In this way, not only the moon can be photographed, but also various double stars and the bright planets (Venus, Jupiter, Saturn). However, the planetary images (my best Jupiter image is attached) are by no means comparable with those taken with fast and long focal length telescopes and special planetary cameras (webcams), which film thousands of pictures and do not take photos...
    According to the "500 rule", you can use 500/1800 = approx. 1/3s exposure time with a fixed camera and an 1800mm lens on a tripot. In my experience, however, 1/6s is just about possible, 1/8 to 1/10s is better and anything shorter causes no problems at all.
    With an equatorial mount, single exposure times of 15-30s are possible at such long focal lengths (1200-1800mm).
    Only with an autoguider you can you achieve such good tracking that several minutes of exposure time can be achieved, which is very helpful for dark deep sky objects!

  4. Thanks
    joerg got a reaction from Pieter in Sony 200-600 mm Lens for Astrophotography?   
    The plejades (M45), reflexion and no emission nebulae, but I like them (Sony SEL200600G on A6000 28x120s ISO-800 F6.3 @900mm 35mm equivalent 5xDarks 26xFlats 20x Bias):

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