Early this week, the Dublin weather forecast for this evening’s lunar eclipse on 27 July 2018 looked promising and I was looking forward to doing a time-lapse from the East Pier in Dun Laoghaire as the blood moon rose out of the Irish Sea near the Muglins light and then arced over Dalkey and Killiney Hills. Sadly, however, the forecast changed, and this celestial spectacle was clouded out in Ireland. At least, it's not long until the next one – on 21 January 2019 just as you finish clubbing in Dublin at 3.33am!

As part of my preparations though, I went back and looked at my shots for the last lunar eclipse in Dublin – an effort that I never got around to blogging about until now.  Both timeanddate.com and space.com provide excellent information on celestial events and they told me that the partial phase of the eclipse began at 2.07am and the total phase was between 3.11am and 4.23am with the maximum at 3.47am. There was an additional penumbral phase at the start and end when the moon was in the edges of the earth’s shadow but during this stage, the shading is so light that it is hard to see any difference in the brightness of the Moon. Unfortunately, I slept it out on the night in question, so my sequence starts just after the maximum at 3.54am and I finished around the end of the partial phase at 5.34am – still in a totally dark sky (for Dublin) because astronomical twilight did not start until 5.22am. At the time I had little idea on how to do an eclipse time lapse and I made several mistakes on the night, hence my title on how NOT to do this!

For the 2018 eclipse, I also read up from several sources that give lots of tips and ideas for different kinds of eclipse shots as follows: -

1. A handy introduction from Wikihow.
2. A good overview from Photography Life.
3. An interesting article from Dahlia Ambrose at Lightstalking.
4. 22 tips from B&H.
5. And old article dealing with film from Weatherscapes - with useful exposure tables.
6. Another old one going back to film days from Fred Espenak at Mr Eclipse - and a variant of this published by Nikon.
7. A spectacular one minute video time-lapse over several hours by Jean-Luc Dauvergne.

The first step in photographing any eclipse is finding a good location to shoot it from.  The Photographers Ephemeris told me that the from the North Bull Wall, the moon would be over the Poolbeg chimneys – one of my favourite locations for moonshots in Dublin.

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Once I finally got there, my camera settings for totality, or blood moon phase when its much darker, were 8 seconds at f8 and ISO 1600 at 37mm on a Canon EFS 18-55mm lens mounted on Canon 7D Mark II. Here’s a shot of my setup on what was a very clear calm night – note the camera in vertical mode on the tripod, my cable release to make sure there was no vibration when doing the exposures, and my camera bag hanging off the tripod further dampen vibration. 

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During totality, I used the 500 rule, as explained by David Kingham on Petapixel,  to make sure the moon’s motion did not cause it to blur. In my case, the exposure length multiplied by the focal length and the 1.6 crop factor came to 473 – i.e. just little less than 500. As always for night shots, I level up everything before I start, and I focus at 10x in live view with both image stabilisation and autofocus off. Here's a single exposure from the sequence.

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During the partial eclipse phase, I kept the aperture at f8 and started at 2 seconds at f8 and ISO 200 dropping to 0.25 second at ISO 100 by the end. My goal was to get both the bright and dark part of the moon but this precluded getting detail in the bright part. I decided this wasn’t that important given how small the moon was in the frame anyway. Nowadays, I have two cameras and a tripod for each, so next time I might try dual exposures with settings for both the light and dark parts of the moon, although this would further complicate the stacking.

Once I had the shots in Lightroom, it was quickly clear that a shot during totality when the exposure of the moon was approximately balanced with the nightscape should form the base shot. As in many of my moonshots, I adjusted the white balance toward the blue end, in this case around 2250 Kelvin to get a blue-orange balance between the sky and floodlit areas that I like. I also added a graduated filter in Lightroom over the bottom to tone done the floodlit buildings and to open up the shadows – as well as adding some clarity and sharpness. Sharpening was set to about 100 and masking to about 50 with noise reduction to about 60. Back then, I tended to use the Camera Landscape calibration but nowadays I prefer to start from Adobe Standard because I find the Camera landscape option a bit garish. These develop settings were copied to the remaining 24 shots in the sequence. Subsequently, I changed the white balance setting to auto for the partial phase shots because I thought the settings from the total phase made the moon a bit too blue.

Once the shots were processed in Lightroom, I prepared the final shot in Photoshop as follows: - 

1. Export all 24 shots as JPEGs, resizing to 2,400 pixels on the long side. My moderately high spec Dell XPS 8500 desktop with a i7-3770 3.40GHz and 16GB of Ram (well it as fairly high spec when I bought it in 2013!)  would struggle to stack 24 full-resolution JPEGs. To help keep track of the layers in Photoshop, I numbered the filenames in Lightroom’s export module.
2. Export the base shot again as a full resolution JPEG – typically the first one- and label it no. 1. This file needs to be full resolution as it will comprise most of the image whereas the lower resolution of the moon exposures won’t be noticeable because they are so small in the frame.
3. Reimport these files into Lightroom and then do Photo > Edit in > Edit as Layers in Photoshop. If you have numbered your files correctly, your base layer will be on top and the rest of the exposures will be in layers in start to finish order. You can also get these files into Photoshop in layers using Bridge - use Tools > Photoshop > Load Files into Photoshop Layers.
4. Note that the base layer will be in a much bigger canvas because it is full resolution image. Hit Ctrl O to fit this layer in your window.
5. Select the top layer with your base image & decrease its opacity to about 50% so that you can see the next layer.
6. Select Free Transform using Ctrl T and drag the bottom right corner of the top layer until it is the same size as the next layer. Hold the Shift key while doing this to maintain the aspect ration (relative proportions) of the top layer. When you are done, reset the opacity of Layer 1 to 100%. This will align the top layer with the rest of the layers without losing any its pixels.
7. Do a rough crop to the size of layer 2 while holding the Shift key to maintain proportions.
8. Hit Ctrl 1 to maximise the cropped image in your window and fine tune the crop to align the image size in Layer 2.
9. Select all layers and set the Blend mode to Lighten – this simple trick shows the lighter moons from all the layers in the top layer. Note, that my sequence is not properly aligned because I accidentally moved the tripod in the dark due to rushing because I was late. I also did not know the correct shot intervals to space out the moon exposures properly – next time I would do an exposure every five minutes or so. The key thing is to have an alarm on a timer so that you stick to the same interval between shots throughout the eclipse. If your camera has intervalometer you may also be able to set it up to shoot automatically – but it would be best to practice this in advance!
   
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10. Turn layers on and off to identify near duplicates and delete those you don’t want to reduce the final file size.
11. Use Free Transforms (Ctrl T) to move layers around with the arrow keys to line up the moons and position them approximately equidistant from each other - other than layer 1 with the full res version. Again, turn layers on and off to see which exposures you are working with. This step is only necessary of you have not been able to keep your tripod in the one position for the entire eclipse. However, it is important that several shots are shot with the tripod in the same position to keep establish the line of the moon’s travel during the eclipse. Finally, be sure to preserve the relative order of the exposures so that the sequence looks natural.
12. Because of all the Free Transforms, the ground in the shots is now in many different positions so a mask to show only the moons must be applied to all layers other than the top one to deal with this.
    
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13. Zoom in on the moon in a layer other than top layer and select one of the red moons. For this image, Magic Wand settings of Tolerance 30 and Contiguous worked well. Contiguous is important to avoid selecting similar tones on other parts of the image such as the ground. I modified the selection by applying a three-pixel smoothing and expansion and a five-pixel feather – you may need to tweak these selection modifications to ensure that the moons coming through from lower layers blend well with the top layer.
14. Ensure your foreground is set to black an add a layer mask, this will hide all of the layer other than the moon itself. If you want to reduce your file sizes, you can permanently delete the parts of these layers that you don’t want by Applying the masks – but it might be better to wait until the end to do this unless your computer is really struggling.
15. This masking darkened the moons a little – I’m not sure why, but I dealt with that later with Lightroom tweaks of the final image. To get the Moon in the top layer to match these darkened moons, I also selected it and darkened it slightly with a localised Brightness and Contrast adjustment layer.
16. Repeat steps 13 and 14 with all the moon exposures – this is the most tedious part of the procedure. Even if you didn’t have to do the Free Transforms in Step 11, these masks will be necessary as the exposures of the ground will differ as the eclipse progresses. Sometimes saving a selection from a previous layer and moving it with Transform Selection worked and this speeded things up a bit – although I sometimes I had to reapply the feather.
17. As you work on doing these moon selections at high zoom, you may also see that some of your Free Transforms positions from Step 11 need tweaking.
18. When I was working on the masks for the exposures in the partial eclipse phase, it was easier to use the elliptical marquee tool with the Shift key down to make a circular selection based on the bight crescent. 
19. In one case, a moved moon ended up behind a star so the star was cloned out.

Once the image was completed, I brought it back into Lightroom for some final tweaks including boosting the whites to make the partial phase moon exposures a bit brighter. I also added another graduated filter to the bottom to cancel out the effect of this on the buildings. OK, I think I’ll stop the photoshoppery now!

Overall and despite the various issues, I am pleased with this image. Despite arriving late, I got exposures from the peak of the eclipse to the end of the partial phase and I think the composition works well with the Poolbeg chimneys. Because of all the transformations, it not a scientifically accurate record but I’m happy with it as a picture of a special night out for me.

This shot is available to purchase in my new land and seascapes gallery– prices are in the gallery. 

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