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"We love seeing your work and welcome any and all sketches on this forum, but please note whether your sketch is a through-the-eyepiece sketch or your rendition from an existing image / painting."
Attached is another sketch of Jupiter. On the 18th the seeing was not really good, but that funny chain and two festoons were , together with the transit of IO once again reason to make a little sketch.
Initially, the seeing left much to be desired. Magnification dropped along to 100X. Because you do have a sharp image at that magnification, but miss the finer details ( that chain and the festoons, for example) a bit, I ended up taking 150X. This not only made the image darker and a bit less contrasty ( it's like self-flagellation) but I also had to wait longer for quiet moments to catch details ( chain link counting).
The first sketch I left for a few days, I didn't think it was that special either. The image of Jupiter-disc sketched here is from more than 15 minutes before the transit. Later I thought it would be a nice idea to include the observed transit of IO. As a result, the picture is actually incorrect, since at the time of the beginning of the transit the orb had already turned a little further.... Fortunately, as a sketcher you can ignore that when it comes to a nice enjoyable picture.
While observing, I switched the location of the barlow a few times: before and after the Atmospheric Dispersion Corrector. With an ADC corrector, the smallest possible f-number is actually necessary (f/21), so first the barlow and then the ADC. But this turned out to be too high a magnification in combination with the Leica ASPH zoom. So I reduced it a bit: first the ADC and then the barlow. As a result the light cone will be f/7.5 for the ADC, but f/15 for the eyepiece. According to the manual, the ADC then works less well; this is barely visually perceptible. With a camera you will probably be punished.
Enjoy!
John
Telescopes in frequency of use : *SW Evostar 120ED F/7.5, * Vixen 102ED F/9 on Vixen GPDX. GrabnGo on Alt / AZ : *SW Startravel 102 F/5, *OMC140 Mak F/14.3, *SW 102 Mak F/13, Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5. Commonly used bino's: *Jena 10X50 , *Canon 10X30 IS,*Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40 Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C8, * Meade 14 inch SCT on EQ8, *Lunt. Amateur astronomer since 1970.
Bigzmey wrote: ↑Fri Oct 21, 2022 5:51 pm
Great sketch John! I have not seen details like these in years due to bad seeing.
Thank you.
In that case, I think your SV102 with BBHS diagonal,combined with the XWs and Delites are best suited to beat seeing. As a refractor the SV is the least sensitive to seeing, colorfast images and a lens diameter large enough for details.
I must honestly say that the ADC goes a long way. Without ADC those red and blue images fluttering over each other, with ADC they are neatly laid on top of each other, also makes a huge difference in the calmness and contrast of the image.
A sketch is actually a sum of short good seeing moments. When I have finished all the details of a sketch, sometimes I am surprised by the overall picture too.
Telescopes in frequency of use : *SW Evostar 120ED F/7.5, * Vixen 102ED F/9 on Vixen GPDX. GrabnGo on Alt / AZ : *SW Startravel 102 F/5, *OMC140 Mak F/14.3, *SW 102 Mak F/13, Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5. Commonly used bino's: *Jena 10X50 , *Canon 10X30 IS,*Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40 Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C8, * Meade 14 inch SCT on EQ8, *Lunt. Amateur astronomer since 1970.
