Tag Archives: Astrophotography

20 October 2022 (Paul Money: Astrophotography)

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This week was another joint Zoom talk hosted by Beeslack Penicuik Camera Club. Paul Money, an astronomer and ‘Reviews’ editor of the BBC ‘Sky at Night’ magazine, connected from Lincolnshire to give us a guide to astrophotography. Paul has written a book on astrophotography called “Nightscenes: Guide to Simple Astrophotography” and mentioned that a new version of that book is about to be published.

Paul began by describing his early forays into astrophotography, using a Zenit film camera and high ISO slide film. Those were difficult days for astrophotography because the relatively low ISOs meant you needed long exposures, and you couldn’t see what you were getting until the film was developed. Paul was enthused by the latest developments in digital photography. His latest Canon camera can go up to 120000 ISO, and even modern mobile phones can now capture hand-held images of the night sky! Canon and Nikon cameras seem to be equally good at capturing good images of the night sky. We were given the following hints and tips for good astrophotography:

  • Turn off the noise reduction in your camera settings. Faint stars look like noise and will be removed.
  • Set your camera to manual exposure and manual focus. Most night shots are too dark for your camera’s autofocus to work properly. You can focus on a bright street light at least a mile away or use the “live view” option on your camera to adjust the focus to make the stars look as small as possible.
  • Most exposures will need a high ISO setting, but Paul recommends going no higher than ISO 1600 to get the best quality. Shots of the Moon or bright planets can be done at lower ISO settings.
  • Use a wide aperture, ideally a stop down from the widest setting of your lens. Paul tends to use f/5 but recommends stopping down to f/11 for scenes which include the full Moon or bright lights.
  • Use a decent tripod so you can take long exposures without camera shake. You can fit the tripod with a ball and socket bracket that allows you to point the camera upwards at any angle.
  • Also use a remote shutter release; preferably one that can make a timed exposure or take several exposures at regular intervals.
  • Don’t use a filter. You need to get as much light into your camera as possible through as few glass surfaces as possible.
  • Use a red light to help you see without spoiling your night vision. You can buy a special red torch or just cover an ordinary torch with a red wrapper.

Paul then gave us a quick introduction to the night sky. The stars rise in the east and set in the west and appear to rotate around the north celestial pole. If you point a camera north and take a long exposure you will see star trails revolving around the pole. The stars tend to move more slowly in the sky around this point, so you can get away with longer exposures before they start to trail. If you point your camera away from the pole the stars will move across the sky more quickly and you’ll need a shorter exposure. The exposure also depends on the kind of lens you are using, with telephoto lenses requiring the shortest exposure. Paul gave us the following guide to maximum exposure time before the stars start to trail:

  • Wide angle lens (18mm): Near the pole (60 seconds), Away from the pole (40 seconds)
  • Standard lens (50mm): Near the pole (30 seconds), Away from the pole (20 seconds)
  • Telephoto lens (135-300mm): Near the pole (20 seconds), Away from the pole (10 seconds)
  • Super telephoto (500mm): Near the pole (2 seconds), Away from the pole (1 second)

Paul took us on a quick-fire, enthusiastic and fascinating tour of various types of astrophotography, ranging from wide-angle shots of the constellations, star trails with foreground objects, telephoto views of the planets, a lunar eclipse, Earthshine on the Moon, noctilucent clouds and shots of the aurora borealis. Paul mentioned that, although most photographers like Adobe Photoshop, he prefers PaintShop Pro. He also recommended StarStax software for combining multiple images of the night sky.

If you would like more information here are some of our previous talks on astrophotography:

Ford Renton: Practical Astro-photography

Andy Bennetts: Astrophotography & Action Photography

Next week we have a Digital Photo Feedback session. This session replaces our old “Photo Advice Night”, which was based on prints. Please bring along up to 6 digital images (or email them to me) to get feedback and advice from other members. See you on Thursday.

Steven

18 February 2021 (Astrophotography & Action Photography)

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This week the club had a virtual visit from Andy Bennetts of Haddington Camera Club, who gave us two talks on very different photographic subjects: “Astrophotography” and “Action Photography“. 

Astrophotography

Andy showed us examples of different kinds of astrophotography. The easiest subject to photograph is the Moon, which is best photographed on a clear night with your longest possible telephoto lens. Andy’s examples were photographed with his 400mm lens, with a 2x converter, at ISO 3200, 1/2000sec at f5.6. The tripod and fast shutter speed help remove camera shake at this extreme magnification. You can use the web site https://www.timeanddate.com/ to predict the phases of the Moon and look up the times of moonrise and moonset.  Andy also likes to photograph the Sun at sunrise or sunset. You need to be careful not to look at the Sun through the telephoto lens and use a narrow aperture to protect your camera. The Sun will appear as a featureless disk unless you use a dark solar filter (see https://www.baader-planetarium.com/en/solar-observation.html), so it is best photographed next to a landmark. The web site https://photoephemeris.com/ can be used to predict when and where to photograph the Sun and Moon against local landmarks. There are also smartphone apps called TPE and Sun Surveyor which give you the same information.

Andy then showed us how to photograph more difficult subjects, such as the stars and Milky Way. These are best photographed from a dark site well away from light pollution. The most convenient dark site near East Lothian is the B6355 from Gifford to Duns. The camera should be set to manual focus and manual exposure for best results.  A red headlight is useful for setting up your camera in the dark.  Andy recommends focussing by looking at a magnified “live view” on the back of the camera, rather than just setting your lens to infinity. Photographs to emphasise star trails are best made with a wide angle lens, with the camera on a tripod. Exposure times of up to an hour can be achieved by setting the shutter speed to “bulb” and using a remote shutter release. Images containing some foreground detail, such as trees, lakes and mountains, will have the most impact. Use a wide aperture and an ISO setting below 400 to reduce noise. On the other hand, photographs to emphasise the Milky Way need an exposure time of 20-30 seconds to prevent star trails. These shots require an ISO setting greater than 1600. Andy recommends taking 5 or more shots of the same scene and stacking them in Photoshop to reduce the noise. Layers can be matched together manually using the “difference” blending mode. The Milky Way shows up better on a dark, clear night without the Moon.  Andy showed us some beautiful images he had taken by the Whitadder reservoir.  Finally, Andy showed us some post-processing tips for astrophotography:

  • Darken the shadows to emphasise the blackness of the night sky
  • Increase the contrast to brighten the stars.
  • Increase clarify, vibrance and saturation to emphasis the faint detail and colour.

Action Photography

Andy then showed us the techniques he uses to capture action shots, using different kinds of sporting events as examples. The photographer has control of the aperture, shutter speed, focal length and camera movement.  A wide aperture (such as f2.8) is useful for reducing the depth of field to emphasise the action while blurring the background.  A fast shutter speed (such as 1/500s) will help to freeze the action, while a slower shutter speed (such as 1/50s) can help to emphasise movement. Panning the camera helps to emphasise the movement of fast-moving subjects such as motorbikes, cars and cyclists.  A long focal length lens allows you to zoom in on the action from a distance. You can also eliminate a distracting background (such as ugly buildings behind a sports stadium) by cropping closely on the action, such as a rugby scrum. You can hand-hold a lens up to 200mm, but for longer focal lengths Andy recommends a tripod or monopod. A monopod gives you the best compromise between steadiness and flexibility. If you don’t have a long lens there are also opportunities for capturing action from a closer viewpoint, such as at the Edinburgh Marathon or at road cycling events.

Getting the focus right is one of the most difficult aspects of action photography. Autofocus works better when your subjects are well separated from the background, but even then most of the shots will not be focussed properly. Andy takes lots of shots and selects the ones with the best focus. Some sporting events, such as horse racing, are difficult to get right with autofocus. For those events, Andy recommends manually focussing on a stationary object, such as a fence, and waiting for the riders to jump or pass that fence.

Andy gave us some hints on where to find subjects for action photography. There are usually (when not in lockdown) regular football, rugby and cricket events in Haddington. Horse racing can be photographed at Musselburgh, action water events often take place at Fox Lake Adventures, near Dunbar, golf at Gullane, Canoeing at Grand Tully, wind surfing at Longniddry and Gullane beach (best viewed at high tide) and Motor Cycling at East Fortune.

Thank you to Andy for a very enjoyable and informative double evening.