Eclipse Photography

This page contains tips on taking pictures of eclipses,
derived from my experiences over the years.

EQUIPMENT

• Camera

  This will generally be digital these days of course but do not overlook the possibility of using a 35mm SLR film camera if you have one. Digital cameras that allow you to change the lens body can cost a lot more than those having a fixed lens so an old SLR might well be the answer if you want to use a "long" lens. The downside is that you won't get to see what you captured until some time after the event, and unless you ask for transfer to CD when the film is processed (which isn't always very effective, by the way) you'll have to scan the resultant images before you can use them on a website etc. It's best to use slide film to get the best resolution but this is getting progressively harder to obtain so we might all have to go over to digital in the end!
  
  If you are hoping to capture details of the eclipse rather than just a general view of the scene you will need a camera which can have its aperture (f-number), exposure and focus set manually - this should be possible with all but the simplest cameras though. It would also be helpful to be able to connect a remote-control.
  
  If you only have a video camera this is best used either to record a continuous image of the sun during totality or to show the changes in the landscape as the moon's shadow passes over. I would not recommend using frames from video footage instead of actual still pictures as the quality will not be as good (due to the image compression applied to generate a movie); the exposure is unlikely to be correct, and the frames themselves will usually have many fewer pixels so the amount of detail will be reduced. Thus if you have a camera that can take both movies and stills don't be tempted to set it to movie mode, point it at the sun and sit back thinking the problem is solved - you'll most likely be disappointed. Make the extra effort and take a series of well-considered still shots "by hand".
  
  A counsel of perfection would be to take four cameras - a stills camera with a long lens for detailed shots, another with a moderate zoom lens for landscape and sky pictures, a video for the eclipse sequence and another video for the landscape. Just about possible, even with a 20kg luggage allowance, but obviously easier if there is more than one person in your party. Also easier to organise things if you don't have to control all the cameras yourself!
  
  

• Lens

  While the sun appears to be an impressive object in the sky, in photographic terms it is actually very small. This means that to get a good view of the various elements of an eclipse (Baily's Beads, prominences etc.) it is necessary to use a very "long" lens i.e. one with several hundred mm of focal length. Even a 1000mm lens only produces an image 9mm across on a standard 35mm slide (or digital sensor), which equates to around 850pixels if scanned at 2400dpi (and about the same number of pixels on an 8Mpixel sensor). Given the small size of prominences, capturing much detail with a small lens is thus going to be difficult. All is not lost, however, it's just that you will have to take a different sort of picture if your lens is no greater than, say, 200mm.
  
  Because of the cost of very long lenses, the usual way of achieving a large focal length is by the use of "doubler" attachments. These sit between the camera body and the lens and multiply the focal length of the lens by some fixed amount - often x2. The lens itself may well be a mirror lens (constructed like a little reflector telescope), as these can provide a large focal length while being physically small. Note that it may not be a good idea to use a high digital magnification on a digital camera to achieve "long lens" numbers, as this simply uses interpolation to increase the size of the image without actually capturing any more detail.
  
  

• Filter

  It goes without saying that the sun is very bright! It remains so even very near to totality so some way of reducing the brightness is required to allow images to be captured at sensible camera settings. The usual recommendation is to use a filter made of Mylar (a type of aluminised plastic sheet, as used in eclipse viewing glasses) but this actually cuts down the light so much that observing becomes very difficult. I thus use two types of filter - one made from darkened photographic filmstock and one from Mylar. During the partial phase, the filmstock filter is used when taking a picture while the Mylar one is used when just tracking the sun. No filter is required during totality itself, of course, so whatever type of filter you use it must be removable. Don't just stick it over the lens aperture with tape, however, as this is rarely satisfactory - indulge your DIY modelling skills and construct a fitment that will slide comfortably over the front of the lens barrel.
  
  CAUTION! The above tip flies in the face of the usual statement that darkened filmstock should never be used. The prohibition is because while filmstock will block most of the light, it will not stop the infra-red (heat) radiation which could damage your eyes or your camera. This is the reason for using the Mylar filter most of the time - when using the filmstock filter while taking a picture, limit yourself to a quick glimpse to ensure the image is centred and all should be well. Also, stand in front of the camera assembly when changing filters to ensure you are shading the lens aperture when no filter is in place.
  
  

• Tripod

  If you are going to use a long lens a tripod is essential to enable you to keep the image in the viewfinder and to avoid it moving when you are taking the shot. There are basically two types of tripod you can use - a standard photographic tripod and a tripod designed for a telescope. A photographic tripod will usually have a handle with which you adjust the vertical position of the camera, secured with a simple clamp arrangement, and this is often its greatest weakness. Long lenses tend to be heavy, and if the camera+lens assembly can only be attached to the tripod by screwing the fixing directly into the camera base, the weight of the lens can put so much stress on the clamp that it will not work effectively, allowing the assembly to slowly "sag" and make accurate picture-taking very difficult. If there is a mounting point on the lens it should thus be used, to achieve a better balance. A telescope tripod will not have this problem but may need adapting to enable a camera to be fixed to it at all. Many such tripods have some form of removable mounting plate, however, which can often be drilled to accommodate a standard screw-fixing without too much trouble.
  
  The second advantage of a telescope tripod is that (assuming it is of the equatorial type) it will only need adjustment in one axis as the sun moves across to sky, thus making it easier to keep the image centred. Photographic tripods will need adjustment in both altitude and azimuth (left-right) which with their generally less precise construction can be rather a pain. The great disadvantage with telescope tripods is their weight - a good way to clock up excess-baggage charges!
  
  
  

WHAT PICTURES TO TAKE

The elements of a total eclipse that you should aim to capture if you have the equipment to do so are the opening partial phase; the final sliver of light; Baily's Beads; the chromosphere; any prominences; the corona; the Diamond Ring, and the closing partial phase. In addition, if you have another camera you should try for a general view of the sun in the sky, plus any planets that might be in view; the landscape around the horizon (which tends to look yellowish during an eclipse due to light spilling in from areas not "under the shadow") and your fellow travellers enjoying the spectacle.

Due to image-size considerations, with a lens of less than 200mm you will be limited to general views, and much of the detailed imaging will not be possible unless you have a lens of at least 500mm. Above 1000mm the prominences will be well-seen but once you go over 1500mm the image size will be sufficiently large that the corona begins to disappear from the frame [I generally use a 600mm lens together with a x2 doubler, giving an effective size of 1200mm: this seems about right for capturing everything]. It thus follows that the longer your lens the more hectic totality will be!

ORGANISATION ON THE DAY

So, the great day has arrived. Your array of cameras is pointing heavenwards, the sky is clear and the final seconds are counting down. What do you do now? Panic, probably, as you suddenly realise you have no idea of what to look for, the exposures to use and much else besides. The solution, as with so much in life, is preparation!

If you have a long lens and are going for detailed shots, the first thing to realise is that capturing images of the partial phase presents a very different problem compared to imaging totality. While there is still a portion of the sun's disc on view the image brightness will be uniform and very high (hence the need for filters) but this means you can leave most of the decision-making to the camera. So, set it to Program mode (or whatever the automatic exposure mode on your camera is called) and snap away for the first hour or so. There are two things to be careful of though: focus and exposure weighting. Autofocus systems are not too good at locking onto dim subjects with no contrast so it's best to set for manual focus and deal with this aspect yourself. Don't just assume that the correct focus point is at the "infinity" mark though! Look through the viewfinder and adjust for maximum image sharpness. Exposure weighting should be set to centre-weighted rather than any form of multi-segment system because the only thing of interest (the sun) will be in the centre of the frame: multi-segment calculations will take account of the [dark] sky round the sun and thus tend to over-expose.

As the eclipsed crescent steadily reduces, you will eventually need to change to Manual mode and set things up for the first phase of totality. If your camera will remember them, it is advisable to pre-set the initial manual mode settings in advance so you can go into totality with minimum delay. In contrast to the relaxed feeling during the partial phase, the onset of totality is a frantic period as you will need to take several images at different exposures in a very short time - literally just seconds. Different exposures are needed because the image brightness changes drastically as the sun's disc is covered: by a factor of around 8000, in fact! Tables have been drawn up to help with the calculations though, so it's just a question of following the rules (see later). Familiarity with your camera's controls is vital during this phase as you must be able to quickly change exposure without looking at the "dials", so as not to waste time. As mentioned earlier, a remote control is useful here so you can adjust with one hand and take with the other.

Those with more modest equipment should also be taking some shots of the partial phase but probably in a more "artistic" way. Using a relatively wide-angle lens can produce some excellent images of a partially-eclipsed sun against landscape but exposure can be a problem - this is about the only time when a little cloud would be welcome! Pictures of other tour-party members setting up their equipment are always popular after the event as they won't be able to take them themselves. Also try making a pin-hole camera (literally a small hole or holes in cardboard, for example, or use a colander - what do you mean there wasn't room for one in your case!) and project the image(s) onto a white background: this will show the partial phase very well. Taking a time-series of shots of the same scene can be very interesting, showing the gradual darkening as totality approaches.

During totality, do try to find time to look at the spectacle "by eye" - it's very easy to forget to do this! Now is the time to use your wider-angle stills camera to take pictures of the general scene and capture any planets which have been made visible by the reduced light of the eclipsed sun. You will again need to know the camera well, as totality is surprisingly dark: now is not the time to start hunting round for a torch! The camera can be left to decide the correct exposure for "general landscape" shots (but as this will be considerable a tripod or other steadying device is vital) but for the sun plus planets you will probably need to "bracket" quite widely i.e. take a range of different exposures and assess the results, as the large amount of sky will affect the camera's judgement. Fortunately, you'll generally have some time to do this. While finding a good exposure you'll probably also capture some useable images showing the corona at various distances from the sun, which can be a bonus. By the way, if this camera is a fairly basic one it may insist on firing the flash so do please remember to turn it off beforehand! Use of flash will guarantee you don't capture anything useful (as the exposure will have been reduced to compensate) and will also seriously annoy your fellow photographers.

It is vital to keep a watch on the passage of time, as you don't want to be taken by surprise by the end of totality. Picture-taking here is basically the reverse of that as totality began. Do be careful about the massive surge of light at the end though - it will be very dramatic (and potentially dangerous) as your eyes will have become accustomed to the dark. Duck away from the camera quickly (even as you take the last shot!) and have a filter readily to hand. You'll probably want to give your emotions time to settle at this point but don't forget to then set the camera back to Program mode to take some shots of the closing partial phase.

EXPOSURE and FIELD-OF-VIEW

Exposure

As I said above, to capture the detail of totality you do need to use the correct exposure. This depends on the effective f-number of your lens, the film (or camera) ISO setting and the phase of totality. For a mirror lens the f-number is usually fixed - but make sure by doing a test beforehand that it truly performs at the quoted value: my Sigma f8 behaves as if it were f11, for example. Other types of lens can usually be stopped-down by the camera so give you a bit more choice. Don't forget that if you use a doubler then the f-number must be multiplied by 2. The ISO setting is determined by the film if you are taking slides but can be chosen if you are using a digital camera - on the whole, a lower ISO is preferable as this gives the best image quality. However, it will also require a longer exposure which may give a problem with blur due to image movement (which is magnified with a long lens).

There is a very large number of possible combinations involved, so I shall just detail a typical list of exposures which can then be modified if needs be. It is based on a lens working at f/11 at ISO100 (equivalent to f/16 at ISO200 or f/22 at ISO400) which should be attainable for most cameras and keeps the exposure times within reasonable bounds. For example, my lens plus doubler will be f/22 so if I use 400ASA film I can use the standard values. If I could only get 200ASA film, the exposures would need to be doubled. If your camera won't let you stop down your lens for some reason and you must therefore use it at, let us say, f/5.6 then you should either set the ISO at 50 and use the standard values or leave it at 100 and halve all exposure times. Hope that's clear!

"Last sliver" refers to the moment before totality when the sun is still just visible - the time to remove your filter. A range of exposures is given for the Corona because it extends well outside the sun's disc but gets steadily fainter, so no single exposure will capture all of it. The "Moon" column is there because with a long enough exposure you can actually capture details of the dark and light areas on the moon: the rest of the image will be very over-exposed of course. You will note that successive exposures are simply twice as long - this makes adjusting your camera after each shot quite easy: a good thing when you're taking pictures very quickly!

Field of View

The exact definition of the field of view of a camera is not usually important, as you normally just move the zoom until the desired subject is well framed in the viewfinder. It is useful to know it in the case of an eclipse though, as you may not be able to see some of the objects you wish to capture: planets and stars that are not very bright, for example. Knowing the angle from the sun of these objects, it is then an easy matter to choose an appropriate focal length for the lens so that they are in the frame, though not visible by eye. A long exposure should then reveal them.

The view through a standard camera is wider horizontally than vertically, in a ratio of 3:2. Referring to the horizontal direction, a good rule of thumb is that a 200mm lens has a field of view of 10 degrees. This explains, by the way, why the sun is so small in the frame with moderate lenses: its diameter is about 0.5 deg, which is only 5% of the frame width at 200mm. Doubling the focal length will halve the field of view, and vice versa, so if a planet is 15deg away from the sun you could just capture it by placing the sun at the centre of the frame and setting your zoom to 66mm [which would provide a field of view of 30deg] or placing the sun at the edge and using 132mm [i.e. a field of view of 15deg]. The second option would also result in a bigger image of the sun. In practice, 50mm and 100mm would probably be used to allow some margin of error.