What is a lunar eclipse?

This astronomical event occurs when the Earth crosses between the Sun and the full Moon, casting a shadow on the Moon.

Why does the Moon turn red (like a “blood Moon”) during a total lunar eclipse?

Usually, the white part of the Moon that you see is lit by sunlight that reflects off of its surface. During a lunar eclipse, some sunlight reaches the Moon, but it first goes through the Earth’s atmosphere. Our atmosphere filters out most of the Sun’s blue light, so the Moon reflects red light back to us. (Source: NASA)

How do I see this lunar eclipse from Canada?

A map showing who will see this lunar eclipse in Canada is available at EclipseWise.com. All eclipse calculations there are by Fred Espenak.

Photographing a total lunar eclipse

Here are some tips on photographing the Moon during a lunar eclipse from those two people who have done it.

The basics

Lunar eclipses are well worth photographing. They are relatively frequent and long lasting, because the Earth’s shadow is much larger than the Moon and takes considerable time to cross it. Often, there are opportunities to capture a lunar eclipse with an interesting foreground. One of the striking effects in lunar eclipse events is the colour change that occurs with the Moon turning to a red or orange colour, depending on the condition of the Earth’s atmosphere at the time.

I like taking eclipse sequences by getting separate pictures at regular intervals and combining them in image software such as Photoshop afterward. All that is needed is a camera with manual settings and a tripod. A cable release is useful to avoid jiggling the camera.

— John McDonald

Use the right mount

Taking shots of the Moon is a relatively easy task even for the beginner, but you have to be ready for longer exposures during the totality, when tracking at the lunar rate is needed due to a much darker scene. For lunar closeups, it is recommended to use a mount capable of tracking at the lunar rate. An altitude-azimuth GoTo mount, equatorial computerized telescope mount or star tracker like Star Adventurer will do the image justice. Just make sure you know how to switch it to “lunar” rate.

You have to keep in mind, though, that more light-weighted mounts (like Star Adventurer) can only be used with cameras equipped with relatively light lenses, and most of them don’t have a focal length large enough for detailed closeups of the Moon. In this case, you may want to consider using a heavier mount and a telescope with T-adapter to connect your camera to it.

— Taras Rabarsky

Manual controls

It may be enough to use your camera in full auto mode for both exposure and focus control, but I would not recommend it. Instead, I would suggest learning your camera controls well before the event and using it in completely manual mode for both focus and exposure. Important thing also is switching off the image stabilization feature, if your lens has such. 

With manual controls, your exposure strategy will be using lowest possible ISO with (if applicable), fully opened iris and exposure time long enough to expose the image well (always check the histograms!), yet not causing the drift of the lunar image itself (please note: at longer exposures there may be, however, some drift in the stars position, as the Moon and the stars don’t move at the same rate). Low ISO will provide for less noisy images. Be ready to change your exposure time and ISO as the Earth shadow moves over the Moon, decreasing its brightness. Check your images regularly to make sure you don’t have clippings in bright areas or an underexposed or noisy image.

— Taras Rabarsky

Exposure

The main challenge is getting the exposure right. When the Moon is full (as it always is for a lunar eclipse), it is about the same brightness as the sky on a clear day. Using auto-exposure at night will drastically overexpose the Moon, so it is important to use manual settings. You can estimate what is needed by using manual exposure to get a well-exposed sky in the daytime, and then start with that setting to capture the full Moon stage.

— John McDonald

Prepare your shots

And the last but not least — think through your imaging strategy ahead of the event. Try to find a nice scenery with open space toward the path of the eclipsed Moon. Anything relevant to the stars, astronomy or lunar legends will be great: an observatory dome, a monument with some stellar or lunar symbolism or maybe a statue of a howling wolf. Think of scenario for your shots. Will you be going to show all the phases of the eclipse of some particular once (like a totality or maximum coverage by the shadow)? Will you be thinking of creating a time-lapse sequence of your shots? In latter case, you would need to make sure that the time intervals between your shots are equal. 

But observing the lunar eclipse event is a quite unique and unforgettable experience by itself. As the lunar surface gets covered by the shadow, full Moon will change its shape to crescent, and will become filled with red hue as the crescent gets thinner, culminating at unnaturally red Moon, majestically floating in the full of stars skies.

— Taras Rabarsky

More about the summer night sky

Take a jaunt through more of the summer night sky in the July/August 2021 edition of SkyNews. In his column, “Beyond Messier,” swim the Cygnus Loop and travel the North America Nebula with Chris Vaughan!

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