During a total lunar eclipse, the moon will pass through the Earth’s penumbra (partial eclipse) and then the Earth’s umbra (totality). At the peak of the eclipse, when the moon is totally within the umbra, no direct sunlight reaches the moon. At this time the moon is only faintly lit by sunlight refracting (bending) through the relatively thin layer of the Earth’s atmosphere. As this refracted light passes through smoke, dust, smog and haze in the atmosphere, it takes on a distinct red tint. Since direct light reaching the moon is whitish-yellow and is many orders of magnitude stronger than the red-tinged refracted light, the red color is only observed at total eclipse when it does not have to compete with direct sunlight. Thus comes the name “blood moon” for such an eclipse. Because of the very low level of light reaching the moon and the speed at which the moon travels through the sky, this is the most difficult part of the eclipse to photograph well. Here are a few tips I have accumulated while photographing past eclipses, and which I plan to use when I try to improve my eclipse photographs this coming week.
1) Use “live view” to focus. Don’t rely on your camera’s autofocus, if you are using a telephoto and trying to render the moon as clearly as possible, make sure the focus is dead on by using the live view mode on your camera. Bump up the ISO (e.g., 800, 1600 if necessary) to make sure the moon is bright enough to focus upon, then restore the ISO after focusing to whatever you plan to use to make your exposures.
2) Focus on the moon before it reaches totality (blood red stage), while there is strong contrast on the edge of the moon to achieve good focus. Once the eclipse reaches totality, very little light is on the moon and focus will be much more difficult, and your blood-red images of the moon may be soft simply due to poor focus.
3) Bracket and Adjust Exposures. Based on my exposures from the August 28, 2007 lunar eclipse, light levels change quickly by more than 5 stops between the point where the moon is approximately half-lit and when the darkest point of totality. So be ready to adjust your exposures quickly as the moon reaches the umbra and begins to take on the red color! Bracketing is helpful here.
4) Avoid camera shake / vibration. You will be struggling for shutter speed when the moon is in the umbra and is red. It is at this time that your technique needs to be at its best or your exposures will be blurry and perhaps ill-exposed. Besides using the obvious sturdy tripod mount, make sure you use mirror lockup and some sort of delay between the point in time the mirror locks up and when the exposure is made to avoid any shake (mirror-induced or photographer-induced) from ruining the image. On my Canon cameras, if I do not have a remote shutter release, I use both mirror lockup (on the first menu screen for 5D3) and 2 second delay (on the frame rate selection control). The combination of these two modes usually results in a very steady images free of any vibration that might be caused by the mirror slapping up. On my Nikon cameras, I use both mirror lockup (selectable as “Mup” on the frame rate control) and 2-second delay (selectable in menu “d4 Exposure delay mode”). For the Sony A7r I would use a wireless remote trigger to avoid touching the camera at the moment the exposure is made.
5) If you are planning to shoot a wide scene containing the entire eclipse, including both penumbra phases and the umbra phase, know that the horizontal (lateral) field of view for this is about 67 degrees, while the lateral field of view for just the umbra phase is about 30 degrees. In other words, the moon will move left to right about 67 degrees during the eclipse. The vertical field of view for the entire eclipse is only about 7 degrees, i.e., it will be moving almost horizontally with a relative small amount of arc. You can use these to figure out what focal length lens you might want to use. I plan to use several lenses in 20mm, 24 and 28mm ranges for my compositions. (These figures are for a point in southern California, use the Photographer’s Ephemeris to figure them out for your location.)
6) Today’s high ISO cameras are the night photographer’s friends. I plan to shoot a lot of my exposures tomorrow night using ISO 3200 and ISO 6400. On my Canon 5DIII and Nikon D800e cameras, these ISOs generally result in surprisingly good images. During totality, when the moon is red, I want to get the shutter speed down as low as possible to avoid motion blur due to the moon hurtling through the sky, and since I do not use a tracking mount and my lenses have a limit to how wide open they can be, the only option available to me to freeze the motion of the moon by jacking up the shutter speed is to increase the ISO.
7) Timing. In the Pacific time zone, these are the notable times for the eclipse (times are Pacific Daylight Time the evening of April 14-15, 2014):
- Partial umbral eclipse begins: 10:58 p.m. PDT on April 14
- Total eclipse begins: 12:07 a.m. PDT on April 15
- Greatest eclipse: 12:46 a.m. PDT
- Total eclipse ends: 1:25 a.m. PDT
- Partial eclipse ends: 2:33 a.m. PDT
Above: partial eclipse. This is the easy phase to photograph, just use the blinkies to get your exposure close to, but not clipping, the brights. Try to keep the shutter speed as short as possible if you are shooting a telephoto. Typical exposures I used for the above partial eclipse photo, rendered at 1000mm on a full frame camera, were approximately ISO 200, f/8, 1/125 second. I will definitely use a higher ISO next time, now that today’s digital cameras produce clean images up to ISO 1000 and more!
Above: there will be a point in time when the moon is entering the umbra of the Earth and is lit only by dim refracted light, rather than strong direct sunlight. During this transition exposure settings will change relatively quickly. Consider bracketing to ensure you get good exposures. I plan to bracket at least 1.5 stops on each side of what I think is the optimal exposure, to ensure that I have something good to work with when I get back to the computer. During exposures such as the one above, which has about 10% of the moon receiving direct sunlight and the other 90% of the moon lit by reddish refracted sunlight, my exposures have been about ISO 800, f/8, 1/2 second. Note this is eight stops darker than the first image, and totality (below) will be darker still.
Above: eclipse totality, the beautiful blood red full moon. My experience in the past show exposures about ISO 1600, f/8 and 1 second work well. Note that this is another two stops darker than the transition (edge of umbra) second photo, for a difference of at least six stops from partial eclipse to the darkest point of totality — it could be even more depending on the strength of the refracted red light illuminating the moon during totality. In the future (such as the lunar eclipse of April 14/15 2014) I won’t hesitate to use considerably higher ISO settings (e.g., 3200 or 6400) and a wider aperture (e.g., f/4 or f/5.6) in order to get the shutter speed down as short as possible. A little bit of motion blur does affect the above image, and that’s what I want to improve upon in my next set of eclipse photos.
Exposure Settings. Some informal personal notes to keep me in the right ballpark tonight vis-a-vis exposures (I’ll be shooting several cameras and don’t want to mixed up without notes):
- 10:58pm begin partial eclipse, entering umbra
- Try ISO 400, f/8, 1/250
- 11:30pm moon is halfway into umbra (drop one stop)
- Try ISO 400, f/8, 1/125
- 12:06am moon completely eclipsed, wholly within umbra (drop about 7 more stops)
- Try ISO 800, f/8, ½
- Try ISO 1600, f/5.6, 1/8
- Try ISO 3200, f/4, 1/30
- 12:45am deepest part of umbra
- This part is hard to predict because the amount of refracted light reaching the moon varies considerably from one lunar eclipse to another. I will start with about ISO 3200, f/5.6, 1/2 second and increase exposure a stop or two as necessary. I have seen some recommendations of up to 10 seconds for this period of the eclipse but in my experience the moon blurs during such lengthy exposures on moderate to long telephotos (70mm to 1000mm) although it works fine for wide angle views (e.g., 24mm, 28mm).
- 1:24am leaving umbra (increase about 7 stops)
- Try ISO 400, f/8, 1/125
- 2:00am moon halfway out of umbra (increase another stop)
- Try ISO 400, f/8, 1/250
- 2:33am leaving umbra, eclipse done, go home
Lens Choices for a Wide View. Typical rectilinear lens field of view measurements, in degrees, based on a full frame 35mm camera. H=horizontal, V=vertical, assuming orientation is landscape.
- 16mm: 95 degrees (H) x 74 degrees (V)
- 20mm: 82 degrees (H) x 62 degrees (V)
- 24mm: 74 degrees (H) x 53 degrees (V)
- 28mm: 65 degrees (H) x 46 degrees (V)
- 35mm: 54 degrees (H) x 37 degrees (V)
The full eclipse will occupy 67 degrees laterally (left to right) in the southern sky, almost due south at mid-eclipse. It will be about 39 degrees above the horizon at start and end, and about 45 degrees off the horizon at mid-eclipse. (45 degrees above the horizon means “halfway” between the horizon and straight up.) The path will be approximately horizontal, with only about 7 degrees of arc (vertical variation) as it travels through the sky. These measurements are based on a point in Southern California.