The Gift of Light

Image Critiques Nightscape & Astro Critiques
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Critique Style Requested: Standard

The photographer is looking for generalized feedback about the aesthetic and technical qualities of their image.

Description

This was made over the weekend from along the coast in Big Sur, CA. I am looking southwest out across the Pacific Ocean in a Bortle 2 sky. There were some clouds that got in the way most of the night, and wouldn’t you know as soon as I had all the gear packed away, the clouds started to dissipate. The coolest thing for me was the reflection that you could clearly see in the water from the perch I was on about 400 feet above sea level. I struggled with trying to bring that out in the photo without bringing to much of the noise.

The ancient light that comes from the core of our galaxy has always intrigued me, and its a marvel that has piqued the curiosity of the ancient civilizations so deeply that it prompted them to work out the math to predict its motion, as well as all the other stars, and put humanity on the trajectory to develop the science and technology that we have today that allows people like us photographers to capture that ancient light and share it with others.

Specific Feedback

Any feedback on the photo or processing is most welcome.

Technical Details

I took over thirty frames while I had the camera on an equatorial tracker with 15 second exposures at ISO 3200 on my 24mm f/2 lens MF, held wide open at f2 on a Nikon D850. The lens has bad coma in the corners which does show up in the photo. I am ok with it though.

The problem I had, is that since the camera was on the tracker, I had a very hard time trying to stack all the frames, as the horizon was oriented differently in each frame, not to mention the changing clouds in each frame. In the end, I just used one frame and tried to use the Darks, Flats, and Bias frames (20 of each) to get rid of some of the noise. In the end, only the Flats seemed to produce any effect on the image.

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A wonderful view of our galaxy, seen through the lens of our tiny planet! I think the clouds lend a very mystical feeling, and the nebulous reflection on the sea adds intrigue. Very well done!!

Tracking for single exposures of maybe 1-2 minutes is a good idea to get the ISO down. Using the sea for a FG is a fantastic idea, as the blurring is actually good there and we can pretend the fuzzy horizon is just a bit obscured in the usual distant haze.

I don’t think the idea of stacking a lot of exposures works that well for MW shots. The idea is to reduce noise but I’m pretty sure the current crop of NR software does an equally good job for MW exposures. But not all of them work equally well and some are flat-out awful. I tried some comparisons a while back and Topaz Low Light did the best and LR Enhanced NR was about the same. DXO was awful when you zoomed in, creating tiny worm-like structures. (I have seen that in past years, but don’t remember with what software. Maybe an older DXO. I’ve tried it with 3 trial versions over the years and each time decided it was not up to my standards.)

The idea of using Dark and Bias frames in deep sky astrophotography is to reduce a level of noise that we would never see even in MW exposures – it is a factor only for incredibly dim objects where we need to stretch the histogram to a degree unimaginable in our normal images. LR/ACR corrects hot pixels and most lenses have decent profiles that can be applied.

I need to try the Ministars action in hopes it will correct the distortion in my 2 wide and fast lenses, but haven’t done it yet.

I envy your location. If I go to the coast here I have a lovely view of San Francisco beneath the MW.

1 Like
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Even this time of the year? I was facing slightly NW when this photo was made. Nowhere near SF but definitely not south or southwest.

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comparison
comparison2160×3840 2.37 MB

Firstly a fine photo. The clouds, horizon and sea lift it above the normal, Well done. Your photo and comment prompted me to think about how I handle noise.

My go-to is as per below, but be warned, it is painstaking.

If this note is inappropriate or in the wrong place, I do not mind if it is deleted or moved somewhere else.

All three examples are at 200%

The top photo

Five photographs merged for noise reduction purposes, merged once for the sky and a second time for the ground / sea. Each photo was taken approx 4 seconds apart. Some of the Mangrove trunks have been burnt in to remove the effect of nearby light pollution spots (read street lights behind trees). Traversing aircraft have been removed by means of masks - that piece of sky being replaced from the merge below. Tripod, Hoya starscape light polution filter, remote shutter control. Not sharpened. Each photo has the same basic parameters. Levels and a slight crop to remove the photo alignment edges. Macleay island from Coochiemudlo island in a North Westerly breeze, dry air and in winter. No moon. Removed dust spots. This area used to be Bortle 4, a lot worse now.

crop sensor Canon 90D, 17mm sigma, F2.8, ISO3200

Five photos
Top = 20% opaque
Next = 25% opaque
Next = 33% opaque
Next = 50% opaque
Bottom = 100% opaque
Formula is
N photos.
X is layer number (top is layer 1)
Each layer opacity is
=100/(X*(1-(N-1)*1/X))

This was a fixed tripod so I had to align the sky. I take two prominent stars and level them (all photos) Using the next up layer and the bottom layer, I stretch the corners of the upper photo and move it till the difference mask goes black. Repeat. This does take time. Flatten

The ground is easier as it did not move wrt the camera. Again, the same 5 photos un levelled, but this time I work on the ground based objects. Flatten

Merging them with masks takes patience, particularly trees in the slightest zephyr. If you look carefully at the top photo you can see star streaks between the boughs of the trees. I could have nailed these with a healing brush.

Perhaps aligning the ground and merging the sky would work.

The middle and lower photo are only processed in raw with default values

I must mention thanks to Dianne for her help in improvement of the top photo. The final image of that series is elsewhere on NPN

Rob

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@Youssef_Ismail – Ooops – apparently I’ve been going to bed too early! The galactic center is NW here? I’m off to check Stellarium – I’ve been thinking it was SW or maybe WSW by dark. (Too much light pollution at home to see it directly.) But I guess it crawls along the horizon more than I’ve been thinking. Thanks for the heads-up!

@Rob_Sykes – completely appropriate and very welcome here!! I just saw it as I was responding to Youssef and will have to digest it later – going outside now to get the tracker online with the iPad so I can run it from inside when it gets dark. Trying for a better mosaic of The Elephant’s Trunk tonight. There are so many ways to process night shots, and probably no one is right for every situation.

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Thank you @Rob_Sykes for the suggestions. I will look into that. I had a hard time stacking this composition due to the clouds kept moving from frame to frame. So I just went with one frame and hoped for the best.

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It is always choices and even the best of intentions do not always work. By the way, I forgot one step. After levelling each layer, it needs to be aligned before the corners are stretched. Sometimes this is enough.

Re the clouds, you will find the clouds that are not in all layers will become more transparent as for eg 5 photos, you only get 1/5th the cloud density when the cloud is in one layer.

Keep having a good time - I am
Rob