Lunar-Eclipse-November-8-2022

WAITING FOR THE SHADOW

Astronomical Observing and Photography - Joseph Cali

Total Lunar Eclipse - November 8th 2022 - Event Information

On November 8th, 2022, a total eclipse of the Moon is visible in this region (NSW, Australia) From eastern, Australia, all of the partial phases before and after totality and totality are visible starting 38 minutes after Moonrise/Sunset. The partial eclipse post totality is finished by 23:49. The penumbral eclipse phase, difficult to detect with the naked eye continues to 1am.

Description:

The penumbral eclipse begins a bit before moonrise. Penumbral eclipses are barely visible to the naked eye so you won't miss much.
Moonrise and sunset are at 19:30.
The partial eclipse begins 40 minutes later at 20:09 with the Moon 6^o above the horizon and 20^o north of east. At this stage, twilight is transitioning from Civil twilight (light blue) to Nautical twilight (dark blue). The partial phases will be seen to progress throughout the deep blue of nautical twilight. This display is a particularly beautiful colour combination and my favourite type of eclipse.
Totality begins at 21:17, one minute after Astronomical twilight(dark of night) with the Moon in the northeast and 18^o up in the sky. Totality lasts 1hr 25m ending at 22:42. This is a relatively deep totality, but nowhere near a record. The total eclipse of July 16, 2000 was distinguished by the fact that it was the longest eclipse of the 20th century. The geometry was almost perfect. The Moon was very close to perigee. The centre of the Moon traversed almost through the axis of the Earth's shadow cone. It all added up to making this a very long deep eclipse with about 1hr 50m of totality;
After totality, the partial eclipse lasts from 22:42 to 23:49 followed by a final near undetectable penumbral phase from 23:49 to 01:00.
You will have all noticed the amazing sunsets we have experienced over the past 9 months. This is due to volcanic dust and aerosols, suspended high in the atmoosphere, courtesy of the Hunga-Tonga-Hunga-Ha'apai volcano eruption in Tonga last January. This dust will have spread right around the Earth and could potentially make this a very interesting, very very dark, lunar eclipse. After the cataclysmic Mt Pinatubo eruption in June 1991, I observed a lunar eclipse in June 1993. The dust which had by then spread all around the Earth, absorbed light and led to a very dark eclipse. It was so dark that at the time, we could barely see the eclipsed Moon at totality. Using film and the rudimentary equipment I had at the time, I didn't record it properly and the Moon was only barely visible in the sky. Neighbours came over during totality and I had to really carefully point out where the Moon was before they could make it out. Years later, I made an illustration of my impression of how it appeared visually against the sky. It's hard to see as was the original event. I've put a box frame around it in the box below.

Above: Drawing of the June 1993 lunar eclipse
Yes, it's there. View it in a dark room.

Contrast to the appearance of a more normal total lunar eclipse

Lunar Eclipse Photography

How big will the Moon be in the frame with my lens?
The exact size of the lunar disc on your sensor is easily calculated. It is the focal length ÷ 114. So a 200mm lens will produce a 1.8mm lunar disc on the sensor but what will that look like. It is often easier to see the size of the lunar image reprsented relative to the camera frame. This illustration shows the size of the frame at different focal lengths relative to a full frame sensor(outer box) and APSc sensor(inner box).

Exposure Guidance
The difficulty photographing total lunar eclipses is that they vary in brightness. As mentioned above, light absortion by the Earth's atmosphere is one reason for this, the other factor is umbral depth or how deep inside the Earth's shadow does the Moon travel?
If this eclipse, turns out to be a dark eclipse like the 1993 event, then it will be very difficult to record. The exposure recommendations below are for a bright coppery red eclipse. However if mid-eclipse is very dark, don't despair because totality will be brighter just after the beginning of totality (21:17) and just before end of totality 22:42.

There is no single "correct" exposure for the partial eclipse phases because as you will see in the examples below, you can expose for either the shadow side or for the sunlit side.

Moon at first contact

ISO 400 f5.6 ¹/₂₅₀s

Moon: Half immersed, exposed for sunlit side ISO 400 f5.6 ¹/₂₅₀s	Moon: Half immersed, exposed for umbral shadow ISO 400 f5.6 ¹/₁₅s
Moon ³/_⁴ immersed, exposed for sunlit side, processed for umbral shadow ISO 400 1200mm f5.6 ¹/₃₀s Raw processed with shadow boost and highlight suppression	Moon ³/_⁴ immersed, exposed for umbral shadow ISO 400 1200mm f5.6 ¹/₆s Raw processed with shadow boost and highlight suppression for sunlit part
Moon ⁹/_¹⁰ immersed, exposed for sunlit crescent ISO 400 f5.6 ¹/₂₀s	Moon ⁹/_¹⁰ immersed, exposed for umbral shadow ISO 400 f5.6 2s Equivalent to ISO 1600 1200mm f5.6 ¹/₂s Raw processed with shadow boost and highlight suppression

Moon at totality
ISO 1600 f5.6 4s
Equivalent to ISO 6400 f5.6 1s
Raw processed with shadow boost
and highlight suppression

How Long Can You Expose without movement?

Some of the exposures shown above are up to 4s long. I used an 8 inch telescope mounted on a high precision mounting to take these images. As the Moon gets deeper and deeper into the shadow, the required exposures get longer and longer. If the eclipse is very dark, much longer exposures may be required. If you use a telephoto lens on a fixed tripod, the Moon's image will eventually begin to move during the longer exposures and show blur.

Using the "Cali's Stationary Stars" formula, you can find the longest recommended exposures you should use for a given focal length to avoid image blur.

The table below is based on the Cali Stationary stars formula, a formula I derived in 2012.

Focal Length mm	Max Exposure(s) No pixel blur	Max exposure(s) 3 pixel blur Suitable for full screen laptop view
12	5s	14s
14	4s	12s
16	3s	10s
24	2.5s	7s
28	2s	6s
35	1.5s	5s
50	1s	3s
70	0.7s	2s
105	1/2s	1.5s
135	1/3s	1s
200	1/4s	0.7s
300	1/6s	1/2s
400	1/10s	1/3s
500	1/10s	1/3s
600	1/10s	1/3s
800	1/15s	1/4s
1000	1/25s	1/8s
1200	1/30s	1/10s

The formula is a very accurate way of determining longest exposures taking pixel size and output size into account compared to crude and inaccurate methods like the "600 rule."

MAXIMUM EXPOSURE(s) = 14 x P x N ÷ F
P - Pixel size (in microns)
N - Number of pixels of blur*
F - Focal length of lens (mm)

The quantity N, number of pixels blur rlates to the final display size. If you want to view the image at 100%, N=1.
Let's say that you have a 24MPx Sensor 6000 pixels wide, and want to view on a full laptop screen 2000 pixels wide.
N=6000÷2000=3 pixel allowable blur (right hand column)

The smaller the display size, the bigger N can be, the longer you can expose.
In the above table, I used a pixel size of 4 microns, a decent average value for many cameras. If your camera is very different to this, use the formula to calculate your own table or a value for your lens focal length.

Read more about this method: https://joe-cali.com/astronomy/articles/tripod_astrophotography_using_DSLR.html

Wide-Angle Photography
If you don't have a long telephoto lens and a tracker, all is not lost. Lot's of good possibilities exist to capture nightscape style photographs without tracking using standard and wide angle lenses.The early part of this eclipse occurs near the horizon and is ideally positioned for this type of imaging.

Here are a couple of examples from eclipses in I've observed in the past.

Good luck!

Joe