M 51, also known as the Tourbillon galaxy (Whirlpool Galaxy in English) is a couple of galaxies located around 27.4 million light years in the constellation of Hunting dogs.
This famous couple is composed of a regular spiral galaxy massive whose diameter is estimated at 100 000 light years and a small irregular galaxy .
Spring star, it is one of the most famous galaxies of astrophotographers, with very pronounced colors and presenting beautiful nebulae, accentuated here by the joint use of a Halpha Hydrogen filter.
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Passionate about astrophotography since 2016, I practice from my garden in Amiens but also collectively within an association since 2017 (Repères Astro in the Oise).
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This association offers activities and public reception, training courses (Affiliated with the French Association Astronomy). I regularly run "3rd and 4th star" astrophoto courses there (initiation and improvement) and in 2019 we also organized the 1st edition of the Rencontres des Astrophotographes des Hauts de France.
Since 2018, the Merles observatory has been equipped with the 600mm telescope manufactured by Bernard Christophe in the 1990s that we maintain, a very formative and enriching experience.
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As in many passions, forums and social networks (facebook, Astrobin, webastro, astrosurf etc.) greatly contribute to the learning of the different techniques and necessary knowledge, as well as the websites of other passionate amateurs sharing their experiences at through articles or tutorials.
The AIP association in this case was a great help in learning processing techniques with Photoshop and Pixinsight software.
In 2016 and 2017, I was also able to participate in two team stays at the St Véran observatory, located at an altitude of 3000m in the Hautes-Alpes, one of the most suitable places for the practice of astrophotography. in France (exceptional quality of the sky due to the altitude and the isolation of the parasitic lights of the cities).
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The astrophotographer is very often passionate, or quite simply interested in General Astronomy and / or photography, and within this vast discipline he will build his way and will probably develop preferences, in terms of the typology of celestial objects by example, and / or instrumentation.
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Indeed, there are generally several categories within Astrophotography, each requiring a type of equipment, and specific techniques:
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- planetary and lunar imagery (body of the solar system: planets, comets, Moon ...)
- solar imagery (the Sun is the only star close enough to photograph details interesting from its surface and its atmosphere)
- deep sky imagery (stars outside the solar system: star clusters, nebulae ... see outside our galaxy: galaxies, galaxy clusters ...)
- large fields and nocturnal landscapes (Milky Way, constellations, nocturnal landscapes ...)
- visual assisted (rapid imagery aimed at assisting visual observation deep sky objects invisible or too faint to the eyepiece ...)
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For my part, I have more affinities with deep sky imagery (nebulae, galaxies, star clusters, etc.) and my material is therefore more oriented towards this type of imagery although it also happens to me. to practice lunar and solar photography.
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In the following section I present my evolutions of equipment and my progress since 2016:
2016
My 1st equipment: A Skywatcher Newton 250 f / 4 telescope (250mm diameter and 1000mm focal length) on a Skywatcher EQ-6 equatorial mount I found used.
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Knowing that I was probably going to start photographic very quickly, I decided to immediately take this equipment suitable for both visual observation and astrophotography, as well as my very first CCD camera: the Meade DSI Color v2, a model that was already very old at the time but which would make it possible to get started in CCD imaging.
I made the choice to go directly into data acquisitions with an astronomy camera rather than going through the digital camera stage, which would have been much easier to understand at the beginning, but more limiting in the medium term in the idea that I had it. In the end, it is on the contrary the Meade DSI which very quickly turns out to be more limiting than a correct digital camera ...
The very first images with the Meade DSI2 color ...
2017
Purchase in 2017 of the QSI 683WS8 monochrome camera with Astrodon LRVBSHO filters to replace the Meade DSI color.
Investment in an optical divider and an ASI120mm camera which will be used for guidance and the first planetary and lunar images.
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Some examples of images after a 1st year of practice:
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My 1st fixed shelter (a chalet with a tarpaulin roof because there is no room in my 6m2 yard for a rolling roof) will be built in 2017, at the same time as the second-hand purchase of an astronomy camera more serious : the QSI 683WS-8 which will satisfy me during the 4 years of use that I will make of it.
Once I get started, this camera will help me start producing images that liked at the time, after about 6 months of learning to use the mount, the telescope and cameras.
At the end of 2017, I will be purchasing my first apochromatic telescope, the Télévue Genesis SDF 101/540. The idea will be to be able to complete the Newton by having an instrument with a shorter focal length making it possible to image larger objects.
Found used, after a recollimation at Optique Unterlinden this telescope will prove to be very pleasant to use, although it will be limited in the long term by its doublet formula and its non-scalable focuser and not adapted to modern imaging trains.
Some pictures with the Televue 101 Genesis and the QSI683:
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2018
The requirement increases with practice (keeping the mediocre collimation of the newton skywatcher, eyepiece doors of the telescope and the newton flexing under the load of the CCD camera, limiting optics of the two instruments, etc.)
I sold everything after two rich years of learning, and opted for the comfort of use and the quality / price ratio of the following equipment, still second-hand: Triplet Skywatcher 120 Esprit f / 7 (Newton + Televue Genesis replacement) on Skywatcher EQ6-R mount (replacing the EQ6).
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This setup will make me happy for the next two years which will be productive in images.
The EQ6-R mount will prove to be very pleasant to use and above all very precise for a mount of this range.
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At the same time, I will upgrade my shelter by building an opening roof for it (shutter hinges because there is no room in my yard for a sliding roof).
2020
After these two years of comfortably imaging with the telescope in a fixed position, the year 2020 and its confinement was a year of reflections and tests of different setups until opting for:
- CMOS camera QHY163m to replace the CCD camera QSI683
- Avalon Linear mount replacing the EQ6-R
- Ritchey Chretien 200mm f / 8 telescope for galaxies and small objects
- ASKAR Fra400mm f / 5.4 scope for extended objects
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The 120/840 telescope proved to be an excellent compromise in terms of focal length, but the desire for a longer focal length (1600mm for the RC8) for galaxies, and shorter focal lengths (400mm for askar) for extended objects have oriented the new choice of instruments.
The choice of frame is oriented towards the Linear, for its high precision in order to tolerate the very low sampling of the RC8 + QHY163m configuration (0.6 / pix) and its relatively laughable price for a frame of this range.
Construction of the new Summer 2020 observatory: a commercial garden shed placed on stilts with modification of the roof (wheels and gate rails).
At the end of the year, replacement of the QHY163m camera by the brand new ZWO ASI 294 mono, much more sensitive.
2021
One year of imaging with the RC8 and the fra400mm telescope on the Avalon Linear mount, then another change of project for a return to the Newton 250/1000, this time more qualitative with the Lacerta Austria brand, renowned for its astrographs. These are skywatcher newtons sorted optically and then customized so that in the end only the mirrors, the barrel and the spider + secondary support remain.
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Replacing the 294mm UPS with the 2600mm UPS, larger in size and with smaller pixels.
Replacement of the linear avalon by the Ioptron CEM120, with a much higher load capacity, more suited to the size of the Newton than the Linear, and adapted to the possible reception of a larger Newton thereafter.
This choice was guided by the sampling of 0.8 "/ pixel which is sufficient to obtain the finest details accessible under our plain skies (the RC8 with its 1600mm focal length is no longer necessary today. very sensitive small pixels and was also a real waste of time with its f / d ratio of 8 against f / d 4 for the newton).
Also wide field imaging with a short focal length telescope is really fascinating but does not allow the originality of the framing obtained at a longer focal length, and does not give sufficient access to the details of structures of photographed objects to my liking.
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In other words, preference that turns to long focal lengths, with a minimum sampling of 0.6 to 0.8 "/ pixel which guides me therefore towards an instrument with a focal length of approximately 1000 to 1300mm. The Newton is then today the best choice in my eyes because of its very low F / d ratio for this focal length.