I have a self made, computerized barndoor tracker. The computer controls a stepper motor very precirsely. The tracking unprecisions come from building limitations and orientation precision. I do have a canon 6D and a 70-200 F2.8.

what is decently visible with this lens? I know of Andromeda, pinwheel galaxy and the pleiads. The location is central italy in mid august on a very dark location.

I will be out for my first nightsky shot in 3 weeks and would need to have as much information as possible since I travel 600 km to be there. Thanks!

2 Answers 2


with a 200mm lens you are going to struggle to see anything much, I would highly recommend you get a teleconverter, as at 200mm even the moon will be tiny.

But more importantly, TEST IT BEFORE YOU GO!!!

  • Thanks! Unfortunately extension tubes cost a lot if they have a lens. Without lens you cant focus at infinity anymore.. Jul 13, 2015 at 10:17
  • 2
    Extension tubes are totally useless for astrophotography. Extension tubes move the lens further from the camera body, allowing it to focus more closely than it can otherwise. In short, extension tubes are for macro photograph, near things not distant things. Jul 13, 2015 at 21:02
  • Agreed, I meant teleconverter! Jul 14, 2015 at 7:26

As Digital Lightcraft points out, the 200 mm focal length will prevent you from imaging objects that requires significant magnification, at least the resolution will be rather poor. If I were going to a dark location, I would focus on deep sky objects, many of these don't require much magnification. In fact, at low magnification, faint objects are more easily seen and photographed (with a smaller field of view, the entire object will cover less pixels, so each pixel will gather more light).

What I would be particularly interested in seeing at such a location are the things that can only be seen with the naked eye from there. As pointed out here, there are many such things that are impossible to see even if there is just moderate light pollution:

Class 1: Excellent dark-sky site. The zodiacal light, gegenschein, and zodiacal band (S&T: October 2000, page 116) are all visible — the zodiacal light to a striking degree, and the zodiacal band spanning the entire sky. Even with direct vision, the galaxy M33 is an obvious naked-eye object. The Scorpius and Sagittarius region of the Milky Way casts obvious diffuse shadows on the ground. To the unaided eye the limiting magnitude is 7.6 to 8.0 (with effort); the presence of Jupiter or Venus in the sky seems to degrade dark adaptation. Airglow (a very faint, naturally occurring glow most evident within about 15° of the horizon) is readily apparent. With a 32-centimeter (12½-inch) scope, stars to magnitude 17.5 can be detected with effort, while a 50-cm (20-inch) instrument used with moderate magnification will reach 19th magnitude. If you are observing on a grass-covered field bordered by trees, your telescope, companions, and vehicle are almost totally invisible. This is an observer's Nirvana!

Now taking pictures of airglow, zodiacal light etc. requires using a low focal length lens, so you should consider taking a e.g. 17 mm lens with you in addition to your 200 mm lens.

  • unfortunately i recently upgraded to full frame and my lenses were not compatible.. the only lens i have at the time is the 70-200 f2.8 Jul 13, 2015 at 18:18

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