Re: Ecipse Photography
- From: Mark Thomas <markt@_don't_spam_marktphoto.com>
- Date: Mon, 28 Jul 2008 19:27:10 +1000
(used to be) Fat Sam wrote:
Hi,
With the upcoming total solar clipse on August 1st in mind, I was wondering if anyone has any tips or advice on how best to photograph an event like this?
What should I be aware of? Safety considerations both for myself and my camera equipment alike? And any special tricks or techniques to get the best from the experience?
I'm assuming a long lens, small apperture and very fast shutter will be vital?
Presumably no need for a tripod?
But how does one frame up and focus the shot, given that it's ridiculously dangerous to look directly at the sun, especially through a lens that focuses the rays?
I wrote a couple of web articles for one some years back, mostly about film cameras, but the advice still applies. Abridged versions appear below. Sorry about the long post, but you did ask... (O:
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ECLIPSE PHOTOGRAPHY
NOTE - It is dangerous to view the sun at partial stages of the eclipse through some types of camera viewfinders - it is best to avoid viewing the image directly. Also, camera lenses and shutter mechanisms can be damaged by exposure to direct, focused sunlight for more than a very short period. Some cameras could be damaged in as little as ten seconds or so.
A 35mm SLR camera can be used for good results, particularly if you have a reasonably long telephoto lens (300mm or greater).
Do NOT leave the camera pointed into the sun for periods of more than a few seconds, and do not look in the viewfinder to align the camera. Use a solid tripod, pre-focus the camera on infinity (you may need to recheck this depending on the camera). To make sure the camera is properly aligned, use the shadow of the camera, or the projected image from the viewfinder (hold a piece of white paper behind it). Again, the camera type will determine what works best - if you are serious about getting a good image, practice these techniques beforehand. When you practice, try to pick a day where the sun is just visible through light cloud to reduce the risk of camera or eye damage.
Q do I need to protect the camera?
If you are planning to leave the camera pointed at the sun to take photos of the partial phases of the eclipse, yes. You should purchase a solar filter from a reputable camera equipment supplier, and discuss the method of use and exposures with them. Note - you will need to quickly remove this filter to photograph totality, and then replace it, so you should practice the process beforehand.
Q what exposure should I use for the eclipse itself?
If you are using 100 ISO film or equivalent, you can use the following as a rough guide:
Note that exposure times may vary dramatically in a very short time during the eclipse - try to 'bracket' your exposures (i.e. take several exposures at different shutter speeds or aperture settings) when possible to ensure best results.
* Nearing totality, slender crescent sun - f8, 1/500 (through solar filter)
* Diamond Ring effect - f8, 1/125 (no filter, tripod advised for lenses over 100mm)
* Bailey's Beads effect - f8, 1/250 (no filter, tripod for lenses over 200mm)
* Totality, with inner corona detail - f8, 1/60 (no filter, tripod)
* Totality, with outer corona detail - f8, 2 seconds (no filter, tripod)
Many photographers have also used multiple exposures to record all the phases on one frame. Obviously you will need to set the camera so that the movement of the sun does not take it outside the frame of the shot! The camera also needs to be VERY securely mounted. Take images through the solar filter, using the settings above, at 5-10 minute intervals. Keep the solar filter on until totality, then quickly remove it and use about a half second exposure to record the corona effect - this will also record the background sky, clouds, etc. Again it is strongly suggested that this entire technique be practiced beforehand.
REMEMBER - the eclipse may be a once in a lifetime chance, and there are no replays! Practice these techniques beforehand, and if it looks like it will all be too difficult, just forget it and (safely) watch the eclipse. Don't let a stressful photography effort spoil the experience. You can always buy someone else's photos!
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SAFE VIEWING
Yes, it CAN BE dangerous to look at the partial phases of an eclipse. During eclipses in the US, it is common for many people to report damaged eyesight - because they did not heed safety warnings, and follow some simple rules! Thankfully, the number of cases of permanent damage are relatively few, but that is no reason to be careless.
The danger does not come because there is any additional radiation. So what's the problem?
If you look at the sun on a normal sunny day, your eye's pupil rapidly contracts, and within a second or two it feels very uncomfortable. You will automatically tend to look away before any damage can be done, but you will see an 'after-image' which is the first sign of damage. If you were to look at it for several seconds, the area of your retina where the brightest light was falling could be damaged permanently, leaving you with a blind spot. *The damage is not done by the visible light, but by the high energy infrared and ultraviolet light.*
During an eclipse, the level of visible light falls away, so your eye does not 'feel' the discomfort. It will seem as if you can view the partially covered sun comfortably. But the IR and UV light is still just as damaging, even though it impacts a smaller area of your retina. The result can be permanent damage to your retina, and partial loss of eyesight. Note that use of binoculars and telescopes increases these risks dramatically. Some telescopes have 'solar filters' that are totally inadequate - you should seek professional advice. If the 'solar filter' screws into the telescope's eyepiece, DO NOT use it - these filters are particularly dangerous.
While it is quite safe to view the eclipse during totality, you MUST look away or use eye protection as soon as the sun reappears. As the diamond-ring effect returns, the danger does too. It is all too easy to forget that danger in the awe of the moment! You need to use proper eye protection at all times other than totality.
And please, CAREFULLY SUPERVISE CHILDREN!
Q so how can I safely view the eclipse?
IMPORTANT NOTE - If you follow the suggestions below, you should encounter no problems viewing the eclipse, but using these methods must be entirely at your own risk - the author cannot accept responsibility for unforeseen factors that may affect safety.
To safely view the eclipse, it is NOT enough to just reduce the visible light, as this is not what does the damage. So most 'home-built' solutions like exposed photographic film, 'crossed polarisers', etc should be avoided. In fact these methods may *increase* the danger because the user will think they can safely view the event.
The ONLY SAFE VIEWING METHODS ARE:
* approved solar eclipse viewing glasses (if you are not certain if the material is approved, don't risk it!)
* welders glass (of grade 13** or greater)
* projection methods (eg pinhole or binocular, see below)
If you use eclipse viewing glasses or welders glass to view the eclipse directly, it is VERY important you use the device continuously. Your pupil will dilate because little light will reach it, and therefore your eye will be more prone to damage from sunlight if it is accidentally exposed.
** - Grade 14 welders glass is the 'usual' recommendation, as it offers a darker and more 'comfortable' image. Grade 13 should offer ample protection, however, particularly if the eclipse occurs low in the sky. And it's a lot easier to find!
Do not be tempted to use your judgement and just take 'quick looks'. An eclipse is an extraordinarily impressive and emotional event to witness, and caution will invariably be lost in the heat of the moment.
Note that welding glass is not even close to 'optical grade', and is definitely not suitable for photography.
Q how do I make a pinhole or binocular 'projector'?
Pinhole projectors are quite easy to make. You can use a piece of opaque cardboard (any colour), and a smooth white backdrop to use as the 'screen'. Make a small hole, say 1.5mm or 1/16" in diameter in the centre of the card, and then hold it about a meter (3 feet) away from the screen, at right angles to the sun. A small image of the sun should appear in the middle of the card's shadow on the screen. Test this method in advance using ordinary sunlight.
You can also use binoculars to project the image, but do NOT be tempted to look through them! Similar to the pinhole method, hold the binoculars with the large objective lens facing the sun, and carefully angle them until they project an image onto the screen. This method will give a better image than the pinhole method, but it may require some practice to keep the binoculars aligned. Note that there is a slight possibility of damage to the optics of the binoculars if you use this method for long periods while the sun is still bright.
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- References:
- Ecipse Photography
- From: \(used to be\) Fat Sam
- Ecipse Photography
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