Equipment



This page takes stock of main materials I use for astrophotography.

Mount & Opticals


I use an ORION Sirius EQ-G mount that allows astrophotography in good conditions for payloads about 10 Kg max with the help of a tracking refractor for a precised traking because the mechanical games are too important.

However, I had the original gears replaced by a set of pulleys / belts (Rowan kit) which allows to remove high frequencies on the periodic error and thus improves the autoguiding quality (smoothing the periodic error).




For small objects snapshots (globular clusters, galaxies and planetary nebulae essentially), I use an ORION 203/1000 Newton telescope (F/D=4.9) for which I replaced the original eyepiece by a shorter one in order to have the focal point for my camera.





































I use a 400/80 mm tracking refractor mounted in parallel for autoguiding that has the merit of being light and whose field is not too small in order to easily find a guide star.






































For large field snapshots (essentially large nebulae), I use a Sky Watcher 600/80 mm refractor (F/D=7.5) apochromatic doublet (model 80ED black diamond) which provides a good sharpness for a very good cost ratio.




























As for the telescope, I mounted in parallel another 400/80 mm tracking refractor for autoguiding in order not to have to disassemble the one fixed on the telescope and that is well adjusted.

























For photos while roaming, I use a travel mount "Star Adventurer Mini" from Sky Watcher that put on a photo tripod and allows sidereal tracking on the Right Ascension axis with a max payload of 3 kg (ideal for a camera + lens).

The advantages of this mount are mainly in the ability to perform the station setting using a polar viewfinder and in direct WiFi control from the smartphone.

It also makes it possible to control the triggering of the snapshots via a dedicated plug towards the camera. In addition, a rotation of the horizontal plane is provided for the realization of timelaps.
















For huge field snapshots (Milky Way essentially), I use a Samyang 14mm lens (F/D=2.8), which offers good quality. This objective does not have an autofocus mode, but it has the great merit of being able to switch over a "EOS CLIP" filter due to the weak length of the interlocking system.















For huge field visual observation, I use a binoculars 15x70mm mounted on camera tripod that can see in "3D".














Sensors








In order to photograph deep sky objects, I use an EOS Canon (model 450D) with a filter removed + new one replaced which it is less restrictive (Astrodon filter installed by the company "Astro for EOS") to better see nebulae that emit in the hydrogen emission spectrale line (red). This sensor has a Bayer matrix for color that is less sensitive than a B & W sensor but is much easier to implement when we start astrophotography (no filter wheel, no cooling problem and less expensive to compare to astronomical CCD cameras) I also can use it for photo by day with a modified white balance (autofocus is still working with astrondon filter).










In order to gain in sensitivity especially for images taken with narrow band filters, I opted for the ZWO ASI 1600 MM Pro monochrome camera with a large sensor and cooled (-45 ° C max) to limit noise. I added the kit "Anti-dew heater strip" which is a small heating resistor that attaches to the top of the sensor and avoids condensation due to the very cold temperature of the sensor and the protective glass that is at air temperature.

This camera that uses the USB3 connection also allows to make planetary snapshots due to its high speed.









To capture planets, and in addition to the ASI 1600MM Pro camera, I use 2 cameras :

The first one is a color camera (The Imaging Source, model DFK41) that gives good pictures and is easy to implement. Its disadvantage is not being able to deliver higher than 15 pictures/s instead of double for a model with a smaller but large enough sensor (I therefore advocate the DFK31 / DMK31 model of the same brand if you want a color or B & W sensor).

The second is a B & W camera (iNova, model PLB-Mx) which requires the use of a filter wheel if you want to achieve color images but have the advantage of being much more detailed than a color camera.










For tracking, I use a B & W camera (iNova, model M-PL1) which work well at lower cost and which allows the binning x2 mode for very faint stars.












Correctors






To improve the optical defects, I use 2 field correctors lens :

A coma corrector from Baader (MPCC model) for the Newton telescope with 51mm diameter.

A flat field corrector / reducer from Televue (TV-85 model) for the 80ED refractor with 51mm diameter which allows imaging larger objects due to the 0.8x focal reducer.












Filters




















As far as the filters are concerned, there are the four interferential LRGB filters (Astronomik) which make it possible to create color composite images from a monochrome sensor.

In order to be able to create false-color images called "Hubble color", one finds there the 3 narrow-band filters H-Alpha, OIII and SII in 6 Nm (Astronomik) which make it possible to create composite images "SHO".

The narrow-band filters H-alpha, OIII and SII make it possible to recover only the emission lines in the spectral bands corresponding to alpha hydrogen, oxygen 3 and sodium 2 as well as to cut the lines corresponding to the light pollution (mercury, sodium, ...)

All these filters have been voluntarily bought from the same manufacturer with the same diameter in 31.75 mm screwed so that they are parafocal between them, that is to say that the thickness of the filters is the same for all and that the focus made with a filter will be kept with others.

All of these filters are housed in a ZWO motorized filter wheel that connects directly to the USB2 Hub of the ASI 1600MM Pro camera. This filter wheel has the merit of having a very small width so that the filter is closer to the camera to reduce vignetting.






For the Reflex, I also use 3 filters "SHO" type "EOS CLIPS" (Astronomik) respectively named "H-Alpha CCD", "OIII CCD", "SII CCD" in 12 Nm which are clipped directly into the Reflex.

To reduce the light pollution of long exposures, I use the filter "CLS CCD" (the filter "CLS" is recommended compared to the equivalent filter "UHC" because it is less restrictive and allows a color rendering fairer)

In the case of captures without filters with Reflex, I also have a neutral filter that prevents the sensor from recovering all the dust during long exposures.









For solar observation, I use a Baader Astrosolar filter mounted in a cache suitable for the 80ED refractor.


Finally, for visual observation, I use a lunar filter and a light pollution UHC filter with 31mm diameter screwing directly on the eyepiece.
















Focus









This focuser from ZWO manufacturer, linked with a dedicated application, let us to have a fix focus during all the night thanks to an automatic control taking into account the air temperature variation and the brightness of a choosen star (FWHM).

It is useful for remote control of the station.













Eyepieces & Barlow lens









For visual observation, I use 5 eyepieces in 28, 26, 12, 8 and 6 mm with a Baader Hyperion 8mm model (with a 68° field visual comfort) and a Sky Watcher 28mm model in 51mm diameter.
















To increase the focale on global, I use 3 Barlow lenses : a standard model in 2x, an APM lens with good quality in 3x and a very good model from Televue in 5x (the 3x Barlow is specific to Newton telescope because the lens directly corrects the coma abberation)

















Various


Essential to have a precise collimation of the Newton telescope, I use the CATSEYE system in 2" which gives remarkable results:

   1 - Centering of the secondary mirror in the eyepiece holder with the TELETUBE tube adjusted to the F/D ratio of the telescope

   2 - Setting the secondary mirror using the "INFINITY" eyepiece

   3 - Setting the primary mirror using the "BLACKCAT" eyepiece

   3 - Iteration of points 2 and 3 until collimation is impeccable































In addition to the CATSEYE system, I use a HOTECH collimation laser which allows a good centering in the ocular door but which remains less precise than the CATSEYE system because the laser will never be perfectly centered in the ocular holder and it not even precisely tuned to its support.

When adjusting inside the telescope, I use an artificial star (model with green spot in 9um and variable intensity)







In terms of connectivity, I use an USB / RJ45 interface in order to connect the PC directly to the command port of the mount.

In the various material components, I regulary use Bahtinov masks that accomplish best focus on bright stars.

Very comfortable to perform flats and because I am not very handy, I directly bought a dedicated luminescent panel with a max diameter of 250 mm which is convenient to implement.

To prevent the dew comming spoil the snapshots, it is imperative to hang heating resistors to the refractors. As I happened to have the frost inside the Newton tube (the 2 mirrors !) during cold winter nights, I also have two heating resistors for the primary and secondary mirrors of the telescope.





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