Richard Hill & Gordon Garcia
(copyright 1998)

1) Use a black and white film. The grain size for black and white film of a given film speed is roughly one third the size of color or, in other words, you'll get 3 times more resolution from the same speed. Going to black and white film will also increase contrast which is a must for H-alpha photography. You will probably get frustrated with the quality at commercial labs and should do your own developing and printing if you can. If not, take an example of what your photo should look like in with you so the processor knows roughtly what to expect. A good film/developer to use is Tech. Pan 2415 and D19. D19 is especially good for H-alpha images but for white light you may wish to use Tech. Pan developer, HC110 or Rodinal.

2) Keep in mind that daytime seeing seldom better than 1" so you gain very little by using more than an aperture of 4 to 6". Use an off-axis aperture which will give you an f/ratio like f/20-f/30. For the compound telescope designs, like Schmidt/Maksutov-Cassegrainians, there is significant curvature to the focal plane. Stopping down will help you achieve a more uniform focus across the Sun's disk (e.g. across the field).

3) For visual observations use a solar filter that covers the front of the telescope and is rated at neutral density (ND) 5. For photography this is acceptable for photographing the entire solar disk. For high resolution photography of active regions, and even better images of the whole disk, you will need a solar filter that is ND 4 or faster. The goal is to use shutter speeds as close to 1/1000 sec. as possible. This will freeze seeing and telescope vibration. If you feel nervous about this don't do it. Cameras and equipment can be replaced but NEVER TAKE A CHANCE WITH YOUR EYES! Several companies sell filters for photographic use. I prefer the company:JMB Inc.,20762 Richard,Trenton, MI 48183 for glass filters, and Tuthill and Baader for mylar-type filters. Roger Tuthill will, on request, provide a filter that is several layers of the material so one can be removed for photography. Baader makes a 3.8 ND for photography. Their filters are of excellent quality. Baader AstroSolar film is sold by Astro-Physics, Adirondack Video Astronomy. Southern hemisphere observers can contact Phil Barker in Christchurch New Zealand that sells it in nice wooden cells. Celestron now cells it in cells to fit their scopes.


Be sure to protect the eyes from filters of photographic densities. One method is to use a thin piece of Tuthill Solar Skreen (about ND1.5) or Baader film between eye and camera. When it developed any pinholes, replace it right away. The ultimate goal is to achieve shutter speeds of 1/1000 sec. to not only freeze seeing but wind induced vibrations. This is a little risky for a novice so exercise A LOT of caution. Never use your eye to test filtration but rather a photographic light meter, or a shadded white card held to the eyepiece or viewfinder of the camera. If you can see any light on the shaded card, then don't put your eye there! IF YOU FEEL UNSURE OF YOURSELF, DON'T DO THIS. Always better safe than sorry with solar observing.

4) In the Solar Section we know the daytime seeing to be best early in the morning, 9-11 a.m. with the Sun about 20 - 30 degees above the eastern horizon, sometimes it pays to get out earlier. It is strongly site dependent due to pavement, buildings etc., so you will have to determine this for your site. Some observers find their best seeing when the sun is highest and several later in the day. But in every case one of the primary causes for deterioration to our images (after bad "seeing") comes from atmospheric refraction. Using a filter with your black and white film will help you beat this problem by only letting light in a small region of the spectrum (i.e. a specific color) get the most out of your telescope.A red or orange filter is best as this will also help to reduce rayleigh scattering in the atmosphere.

5) A good rule for the novice is to take a lot of images. Keep a log or journal with good notes (you can never write too much down) so you see what works and what doesn't. Mark down the date, time, exposure length, film, filters, telescope and conditions for each image. You will not remember these later! A large majority of observers fail to do this simple task and as a result their observations lose value. Only practice and taking more than 1 or 2 shots will bag you that good one.

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