Astrophotography 

    For camera attached to the telescope photography, not only a 'B' setting is needed, also the camera must fit a 'T' ring. Different cameras adapt different 'T' rings.

    I recommend a camera that is light and has a smooth shutter, in the sense that the camera does not jerk violently on opening the shutter.

    In Singapore, when we read the astronomy books, we see a number of recommended films but we can never find them around. True, these type of films are not available in Singapore. Allow me to recommend films that can be found in Singapore.

Films mentioned are available in : Ang Mo Kio Central, MS Photo, near S-11 hawker centre.

    Some terms:
    ISO 100, ISO 400....... - ISO means the speed of the film or the speed of response of the film. The bigger the number, the faster the film.
    Reciprocal failure - the response of the film with respect to the exposure time. The higher the reciprocal failure, the weaker is the response of the film over a period of exposure.

    ISO 400 film is the minimum requirement for astrophotography. Max speed for solar photography.
    ISO 800 film (Fuji) required for recording planets and constellations, not for meteors.
    Good for prime focus photography
    ISO 1000 minimum for meteors.
    ISO 1600 Best film for prime focus and fixed tripod photography but high reciprocal failure.
    Colour Slide film is good for all purposes but very expensive to use.

    Obviously, a steady tripod is needed, which is also heavy. The option is now to have a motorised tripod or not.
 
    Motorised tripod allows tracking of the object so that the exposure can be much longer (20 mins), rather than 45 secs, so fainter objects can be captured. The greatest disadvantage is that the motorised tripod can cost 100 times more expensive than the conventional camera tripod.

    To test the stability of a tripod, extend the legs fully. Press your palm on the top of the tripod and move your hands a little, like trembling. Watch the response of the tripod. If the tripod vibrates a lot, then discard it as a choice. If it resists vibration, then it is steady enough for astrophotography.

    This type of photography is the cheapest, easiest and the "fastest" type of astrophotography. The other mentioned types of photography needs a telescope and other complex equipment.

    Equipment needed: SLR camera
                                  tripod (not motorised)
                                  Film, ISO 400 at least.
                                  Cable release.

    Method: Point the camera at any desired part of the sky and take a shot for an interval that is dependent on the elevation of the camera.(Refer to table in Astrophotography Manual.) Remember to open the aperature to its biggest, i.e., the f/ratio must be smallest. Go to a dark site, as your exposures cover a big part of the sky, so sky fog must be seriously considered.

    This method allows capture of shapes of constellations, paths of meteors and positions of planets. The deep sky objects captured are limited and very fuzzy. Take note that the zoom of the camera is very important. The bigger the zoom, the bigger the aperture, the more stars captured, but the shorter the exposure. The smaller the zoom, the bigger the area captured, the longer the exposure but more sky fog is also included in the exposure. You judge for yourself on how to find a balance between these factors.

    Zoom examples:

35mm can just cover the area of the summer triangle
28mm can cover from the head of Canis Major to the bottom of Carina.
50mm can cover tail of Scorpio and the teapot of Sagittarius nicely.
70mm can cover the area slightly larger than the False Cross.

    My recommendations:

Constellations shapes: ISO 400, 35mm-50mm zoom, 45-60 seconds exposure, 30 sec for overhead.

Planet positions: ISO 400, 50mm, 30 sec as 60 sec will burn the film.

Meteor photography: at least ISO 1000, exposure not more than 10 minutes, 50mm or 35mm if your camera can have f/1.5. Take the meteors away from the radiant and on a night with showers.

    You need a telescope, Schmidt Cassegrain, refractor or Maksutov Cassegrain but NOT Newtonians. You need a tripod for the telescope, only equatorial mounts, for equatorial regions and fork mounts for high latitude regions. The tripod must be motorised.

    Align the equatorial mounts to the north with a compass and adjust the elevation of the mount to that of your latitude.

    Align the fork mount to the north with a compass (Front lens, facing south), so that the U shape of the mount is east-west. Next is the wedge of the mount. The angle of the wedge is 90⁰ - your latitude

    Other equipment: T-ring and cable release.

    Method: Attach the camera body to the T-ring to the back of the telescope. The exposure must be taken with the motor on. This type is for taking Moon photos and Jupiter's moons or Saturn's rings and the sunspots (of course with a solar filter).

My Recommendations:

    Moon photos: 2320mm 8-inch Schmidt Cassegrain, ISO 400 or ISO 800, 1/15, 1/30,1/60 seconds. Do bracketing of exposures, meaning, take exposures over a range of shutter speeds.

    Jupiter' moons: 2320mm, ISO 800, 4-6 seconds (note: jupiter will be overexposed but no choice)

    Saturn's Rings: 2320mm, ISO 800, 12-15 seconds.

    This type of photography is the most difficult to set up and only for moon close-ups and planets close-ups.

    This method is bacially using the camera as the eye to "see"  through the telescope. The motor is redundant as the camera is not attached to the telescope. Depending on the magnification, the exposure is from 1/1000 to 1/250 to 1/60 seconds.

    My experience;

    I am using a 7 x 50 bino as the optical part and it took me 30 mintues to get both camera and the bino to be in line, then another 15 minutes for the focussing part. The picture, is blurred but Maria on the moon can be seen, not bad but tedious.

    Moon closeups and planet closeups are better done with Eyepiece Projection Photography .

    Extension of the Prime Focus method.

    (For the 8-inch Schmidt Cassegrain).
    Equipment: Telextender with eyepiece screwed in it. Visual Back without lens. T-ring.

    Method: connect the visual back to the back of the telescope tube and connect the telextender to the visual back. Connect the T-ring to the telextender. The exposures must not exceed 1/8 second even with the motor on. Thus, use a very fast film, ISO 1600. Magnification can reach about 150x with 18mm eyepiece.

    This is the most expensive type of photography.

    Equipment: 8-inch Schmidt-Cassegrain
                      Off-axis guider or radial guider
                      Illuminated eyepiece with cross-hairs, get 12mm
                      Motorised tripod with dual axis control and correction with 2x control for guiding.

    The connection is complex, refer to the Celestron site  for more information.

    Method: Choose a guide star in the illuminated eyepiece and use the controls to keep the guide star on the cross hairs while taking the exposure.

    Recommendations: ISO 1000--ISO 1600 and exposure of 15mins- 30 mins, depending on the darkness of site and brightness of object.

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