NEXT STEPS in astrophotography
Some of the advanced equipment and techniques used by experienced astro imagers to capture stunning images
The Moon and planets
While imaging the Moon using a DSLR camera at a scope’s prime focus gives good images, slotting a high frame-rate (HFR) camera in at prime focus on a similar setup will deliver WKH EHVW UHVXOWV 7KH OHV FDPHUDV OLNH ZWO’s ASI120MC-S (£151) or the Celestron NexImage Burst Imager d FDSWXUH DUHQ W WKH QLVKHG picture, though: they need to be processed with specialist software.
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Our star is so bright it poses a real danger to eyesight and equipment, VR FDUH PXVW EH WDNHQ WR NHHS WKH ends of any telescope pointed at the Sun covered with either end caps or a specialist VRODU OWHU
There are different W\SHV RI OWHU WKDW FXW out most of the energy of the Sun’s light. White OLJKW OWHUV XQGHU d allow a tiny portion the Sun’s spectrum through and show detail on the Sun’s visible surface. Hydrogen-alpha DQG &DOFLXP . OWHUV RQO\ VKRZ light from those respective parts of the Sun’s full spectrum, but these are expensive (around £2,000). They do, however, enable solar imagers to use large aperture telescopes to capture stunning detail at different levels on the Sun’s chromosphere.
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Galaxies and nebulae
The challenge with galaxies is they are so faint that capturing enough of their photons to produce decent images requires long exposures and LQFUHGLEO\ DFFXUDWH WUDFNLQJ So a sturdy, well-aligned mount and WULSRG DUH NH\ (4 RU (4 W\SH mounts (£550 and £1,250 respectively) are popular choices. Though Go-To isn’t necessary, a motorised RA axis WKDW WUDFNV WKH VN\ GXULQJ ORQJ H[SRVXUHV LV D PXVW ([SHUW LPDJHUV RIWHQ NHHS WKHLU VHWXS RQ WUDFN E\ ‘autoguiding’ it; correcting any drift with a separate scope, FDPHUD DQG WUDFNLQJ software. '6/5 FDPHUDV ZRUN well on galaxies, though their sensors can become hot during long exposures, increasing unsightly noise. To combat this, specialist CCD RU &026 FDPHUDV OLNH WKH ZWO ASI071MC Pro Cooled d RU WKH $WLN +RUL]RQ d have built-in fans to cool their sensors. Processing is important here too: typically many calibration frames are FRPELQHG ZLWK WKH QDO LPDJH WR remove noise and hot pixels using VRIWZDUH VXFK DV 'HHS6N\6WDFNHU
The Atik Horizon is an example of what’s known as a cooled camera – a fan keeps the sensor from overheating during long exposures
A single frame taken by an HFR camera will look like the image on the left, but many such images can be combined, or ‘stacked’, to produce the final image (right)
You can view the Sun with a range of kit, from specialist solar telescopes to filtered instruments