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Click for hires
The
Witch Head nebula, in Orion, is a well known subject also for Northern
Hemisphere photographers thanks to the not so negative declination
(-8°). But from my home at +46°N the maximum altitude on the
horizon is 36°, while in Tivoli Farm (lat 23°S) the max alt is
75°! Then add the perfect sky (22 mag/arcsec^2) and the absence of
humidity (27%), and the result is much better respect a longer exposure
I've made with exactly the same instrument from Italy. See here for comparison.
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| Optics | Pentax 75 apo refractor |
| Focal Length | 500 mm |
| Focal Ratio | f/6.7 |
| Exposure Time | 1 h 40 min
(single exp of 10 min) |
| CCD | Canon
EOS 5D with Baader filter |
| Sensitivity | 800 ISO |
| Location | Tivoli Farm
(Namibia) at 1350 m height |
| Date |
2 September 2011 |
| Mount | Kenko NES |
| Tracking | Lodestar with a small refractor (F.L. 100 mm, aperture 23 mm) |
| Temperature and humidity | T= +7°C, RH=27% |
| Sky brightness at zenith (with SQM-L) | 22.0 mag/arcsec^2 |
| Notes | This
image is a collaborative effort of the Namibia 2011 expedition.
Processing: Lorenzo Comolli. Images by: Lorenzo Comolli, Luigi Fontana,
Giosuè Ghioldi, Emmanuele Sordini. |
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