Solar Eclipse Observing and Photography - Joseph Cali

by Joe Cali

To photograph a solar eclipse, you will ideally need a camera with manual settings and a solar filter (ND5 filter -100000x light reduction). These can be purchased from astronomy shops and suppliers. Camera stores generally don't sell suitable solar filters. You can make your own safe solar filter holder to suit your camera but you must buy and use a safe and certified solar film that you purchase from a reputable supplier.

Detailed instructions for making your own solar filters like this can be found at
https://joe-cali.com/eclipses/EQUIPMENT/solarfilters.html   but you must buy and use certified solar film.

Instructions for safe visual observation of a solar eclipse can be found here https://joe-cali.com/eclipses/Eye_Safety/index.html

The easiest pictures to take are of totality using a wide angle lens with camera set to AUTO and compensation set to -1.5eV. This is covered at the end of the article.

•    Keep it simple and enjoy the experience!
•    Watching a total solar eclipse with your own eyes is a very special experience. Do not forget to look!
•    Any camera or video will give some photographic record of the event. Match the style of image to your equipment.
•    Do not buy new equipment just before the eclipse. Totality is not the time to be reading a camera manual.
•    Bright camera/phone displays will reduce dark adaptation of your eyes & spoil your view and experience of totality.

1.    Attach the ND5 solar filter to the front of your lens or telescope to protect your camera and your eyes from the intense light of the sun during the eclipse. The fitting needs to be very secure so that it can't accidentally blow off, but also easy and quick to remove a few seconds before totality. The type shown in the construction tutorial meets these requirements.

2.    If you plan to photograph the corona, the Sun's outer atmosphere, in detail, you will need to use the longest telephoto lens you have and you may need to increase your ISO to capture the features of the corona. You can capture the total eclipse, corona, lunar shadow on the sky, and some landscape, with a wide-angle lens but the fine details of the corona will be lost. This animation illustrates the changing size of an eclipse image with focal length.

3.    Set your camera to manual mode, and adjust the aperture to about f5.6.

4.    Set your ISO to a low value, around 100-200, to avoid noise in the image.

5.    Set your shutter speed to a relatively fast value, around 1/1000 s, to freeze the motion of the eclipse. Use this setting for most of the partial phases of the eclipse. You can test this long before the eclipse on the uneclipsed Sun to check if the exposure is correct.  However, when the crescent becomes extremely thin, increase the shutter speed to 1/500 s.

6.    Use a tripod or other stable surface to keep your camera steady while taking the photo.

7.    To frame the shot, it is important to have the Sun in the centre of the frame, and to adjust the focus on the Sun before the eclipse begins.

8.    During the eclipse, periodically check your camera's live view or use the camera's LCD to check the focus, composition and exposure of the shot and make any necessary adjustments.

9.    During the total eclipse phase, the light level drops significantly. YOU MUST remove the solar filter about 15-30 s before totality and replace it 15-30 s after totality otherwise your images of totality will just be blank frames. Experienced eclipse photographers take a very wide range of exposures to capture the intensity differences between the very bright inner corona, prominences, and diamond ring, and the outer corona, some 10000-15000 times fainter. Typically using a telephoto lens or small telescope they take a picture at ISO100 f5.6 at every shutter speed from 1/4000s to 1s. This requires a very dedicated and careful technique or computer control of the camera. After the eclipse, the exposures are combined into a HDR image. The sequence below shows you what part of the corona is captured at different shutter speeds. These images were captured with a 300mm lens but the focal length of the lens only affects the overall image size. The extent or spread of the recorded corona relative to the diameter of the Moon is a function of the overall exposure.

Above: Extent of the corona recorded at a variety of exposures. This applies to any camera and lens, be it wide-angle, telephoto, or a telescope. The image size will change with focal length but the extent of corona measured relative to the diameter of the solar/lunar disc will remain approximately the same.

Eclipse composite:
  This composite image is made up from 12 different exposures ranging from 1/1000s to 2s at f4
using a Pentax K5 DSLR, Pentax 300mmf4 EDIF lens at ISO100 combined in Photoshop. Note the blue in the sky is beginning to show up,  and faint coronal streamers extend out to 7 solar radii past the limb of the Moon, and the cratered lunar surface, lit by light reflected off the Earth, is showing faintly. 
Detailed descriptions and video tutorials of this type of eclipse compositing
& processing by Photoshop Guru Russel Brown can be found at:
http://www.russellbrown.com/tips_tech.html and https://vimeo.com/221971705

10.    A single exposure of 1/60s f5.6 ISO100 can be raw processed with highlights low, shadows high. Not quite as good as a full spread of exposures but much easier and gives a respectable result with minimal work processing the image afterwards.

The raw developer settings are shown in the panel on the right in the image above and that below. Exposure, Contrast, Shadows, Blacks, Texture and Clarity all UP; Highlights and Dehaze both DOWN. The exact amount will depend upon your camera. Lens focal length will  only change the size of the solar image however, the expanse of the coronal streamers relative to the solar disc will be similar to this regardless of the focal length used.  The example below is also captured at ISO100 but at 1/125th s f2.8 (the same overall exposure value) with a 50mm lens. Note that with identical exposure values and similar processing the corona extends faintly to approximately 4 x the radius of the solar disc in both images. Both images were captured simultaneously at the same eclipse and different cameras used for each so the processing settings are tweaked for each camera.

Wide angle imagery of totality -  primary recommendations
Equipment: Any camera, video mobile phone + wide angle lens.
Exposure mode: Manual (M)
Aperture Value (Av): ƒ4
Exposure Time Value (Tv):
Support: Tripod or clamp-stand. Not hand held!
Process: Use above recommendations in raw processor

Wide angle imagery of totality with a smart phone camera or any camera set to auto exposure
Equipment: Any camera, video mobile phone + wide angle lens.
Exposure mode: AUTO
Exposure Compensation
-1.5 eV
Support: Tripod or clamp-stand. Not hand held!

11.    Remember! When photographing a solar eclipse, it's never safe to look directly at the sun, even when it's partly covered by the moon. Always use proper filters for eye protection and camera equipment to avoid eye damage and damage to your camera sensor.

Examples of wide angle photography:-

Gansu Province, NW China, August 2008. A 35mm film camera set to auto, with -1.5eV compensation was used to capture this dramatic image of the total eclipse. The sand ridge on the horizon is lined with other eclipse observers and the huge lunar shadow is engulfing the sky.  The trailing edge of the Moon's shadow was just clearing the horizon as the photo was taken seconds before the end of totality and you can see the curve of its oval shape just clearing the horizon. When this edge advances to where the corona is in this shot, the eclipse is over and it erupts into a spectacular diamond ring. 

Partial phase of an annular eclipse, Pilbara, Western Australia, May 2013. After observing a spectacular annular eclipse rising from the horizon, the late Bengt Alfredsson casually observes the partial phases as the eclipse comes to an end.  The solar filter evens out the exposure difference between that blazing sun and the morning desert landscape. Example of image taken with a mirrorless digital camera, low ISO, Auto exposure, compensation -1eV with a standard lens (50mm)

The Sun At Totality With Partial Phases At 3 Min Intervals. 
The two stars in the upper right of the frame are Castor and Pollux while the fainter star at the 10 o'clock position is the 2nd magnitude double star Ahlena and above it to the left is 3,3 magnitude Alzirr and the in the 4:30 position is 3rd magnitude Mebsuta.  In addition to the thirty-three partial eclipse images, five different exposures of totality were radially composited to show the corona from the limb out to approximately 5 solar radii from the limb. Fortunately, the two tiny clouds at bottom left were the only two clouds in the sky.

Partial eclipse image sequence: 

Pentax K1 full frame DSLR.
50mm lens  f 2.8  1/4000 s (equivalent to 1/1000 s @ f5.6)
Baader Astrosolar V5 solar filter.
1 exposure every 3 minutes for 2 hrs using intervalometer.

Total eclipse image sequence:
Solar filter removed 30s before totality
Pentax K1 full frame DSLR camera 50mm lens  f 2.8  ISO 100

HDR composite  combining 5 exposures  ranging from 1/500 s to s
Processing:  Adobe Lightroom & Photoshop

Total Eclipse, March 2015, Longyearbyen, Svalbard, 800km fromthe North pole. Temperature -23oC . Example of photo taken with a mirrorless digital camera, lSO 100,  Auto exposure, compensation -1eV with an ultra-wide-angle lens (12mm)