转发两篇对我有很大帮助的城市银河拍摄教程

非常感谢有那么多人喜欢我的角楼银河，先转发两篇对我帮助很大的城市银河拍摄教程，希望也对大家有帮助。我自己的拍摄和后期体会等我慢慢地整理出来。

图虫不能发图文，图文请移步 http://blog.sina.com.cn/s/blog_e99ca4390102vwjy.html

第一篇：How I Photograph the Milky Way from Light-Polluted Skies of Singapore （作者 Justin Ng）

原文链接：http://www.justinngphoto.com/2014/05/16/how-i-photograph-the-milky-way-from-light-polluted-skies-of-singapore/ （不翻墙比较慢）

第二篇：在家也能拍银河 (作者吴彦祖)（名字是不是亮了）

原文链接：http://fotomen.cn/2015/04/bababa/

How I Photograph the Milky Way from Light-Polluted Skies of Singapore

Just came back from my Mount Bromo trip and I finally found time to complete this tutorial, after I wrote my first article for SLR Lounge last week, before I have to fly again soon. I will update this tutorial along the way but meanwhile, I hope this will get you started.

A recent study suggests that Singapore was ranked as second safest out of 99 countries and this may also imply that the heavy light pollution here could have helped maintain the city’s low crime rate. So, light pollution will continue to be an ever-growing problem in major cities that threaten human sleep patterns, animal migrations, natural habitats, heritage of appreciation for our night sky and more. Of course, I am not implying that we should compromise on safety in order for us to admire heavens, but there are smarter ways to light up a city by pointing down the street lights and using very focused LEDs. Check out the video below by International Dark-Sky Association to understand the ecological message behind our efforts to unveil the elusive Milky Way galaxy that’s obscured by the heavy light pollution, apart from proving the popular belief wrong.

So you too can do your part to promote public awareness of astronomy and the importance of preserving the beauty of our night skies through your images. And I am going to show you how you can do just that using photography equipment that you may already have and a workflow that probably works in most versions of Photoshop. In this tutorial, I will assume you have some basic photography and post-processing knowledge, and I will use an image that I’ve taken in Sentosa, Singapore on 06 March 2014 to show you how I did it.

[ SEE ALSO: Rising Milky Way galaxy above Marina Bay Sands Singapore ]

Basic knowledge of the Milky Way galaxy

The Milky Way is the galaxy that contains our solar system and it appears to look like a faint band of cloud, that our eyes can’t resolve into individual stars, arching across the night sky when you try to see it with your naked eye from a very dark location. The brightest part of the Milky Way, which is also known as the Galactic Center, is near the constellation Sagittarius and since we are unable to see the Milky Way with our naked eye in Singapore, we will point our camera toward the constellation Sagittarius to capture the Galactic Center.

Source: Wikipedia

Constellation Sagittarius in this annotated image.

Equipment I am using to photograph the Milky Way in Singapore

Unmodified full-frame DSLR camera (Canon 5D2)

Wide angle lens (16-35mm F2.8)

Tripod (Gitzo) with Manfrotto ball head

Intervalometer (TC-80N3)

Memory cards and batteries

Lee 0.9 soft GND filters

How do I locate the Milky Way?

If you are picking up astrophotography for the first time, you may use smartphone apps like Star Walk or SkySafari to navigate around and learn more about the night sky. But I’ve always like to know how things work and how these apps are able to tell us when the Milky Way will appear before our eyes. So I spent two months, from May 2013 to July 2013, understanding the principles of astronomy before I develop my astronomy tool which calculates the position of all celestial objects in the night sky for an observer at a specific time and location on Earth. You may also read more about the tool by clicking here.

Screenshot from Justin Ng’s web-based astronomy tool

You may skip this part and proceed to the next paragraph if you’re not keen to read more about the tool, but I’ll just explain a little bit more for the sake of those who might be interested. Before you use the tool, be sure to turn on your Location service on your mobile device and set the correct time zone (by default it’s GMT +8 since I’m based in Singapore) so it will automatically show you the information you need to locate the Milky Way. Based on the above screenshot, 113.87° represents the azimuth and 5.93° represents the altitude of the Milky Way. So you just need to point your camera toward 113.87° (with the help of your compass) and you will probably still not be able to see anything yet. That’s because the altitude of the Milky Way is just 5.93° above the horizon which is still too low and it will be obscured by the heavy light pollution. The recommended altitude to photograph the Milky Way in most parts of Singapore will be at least 30° above the horizon. It also shows the Milky Way is visible from approximately 2139hrs to 0541hrs (next day morning) and you probably have around 8 hours and 2 minutes or less to shoot it. By saying it’s visible, I don’t mean you get to see it with your naked eyes in Singapore since it doesn’t take the level of light pollution into account and it also doesn’t take the illumination of the moon into account as well. It’s just showing you the approximate time you have to photograph the Milky Way assuming you’re at a very dark and open location.

[ DOWNLOAD JUSTIN NG PHOTO APP FROM APP STORE AND GOOGLE PLAY! ]

How I shot the Milky Way in Sentosa, Singapore?

Preparation is critical if you want to take a good shot of the Milky Way in Singapore due to its heavy light pollution which will wash out most of the faint details, and it will be worse if the atmospheric conditions (transparency, sky illumination and seeing) are unfavorable. It’s also wrong to assume that the atmospheric conditions are favorable if you don’t see any clouds in the night sky and if you attempt to shoot under poor atmospheric conditions, your image will become very noisy (along with other image artifacts) when you try to bring out the details of the Milky Way later in Photoshop. Anyway without further ado, here’s how I usually do it.

1. I will check the weather forecast and atmospheric conditions with my astronomy tool to determine the best time to shoot and the amount of time I have to photograph the Milky Way before the atmospheric conditions take a turn for the worse.

2. If atmospheric conditions are favorable, I will look for constellation Sagittarius and plan my shoot once I’ve reach the location.

3. Switch to bulb mode and set the aperture to 2.8, ISO to 6400, focal length to 16mm and remember to remove the lens cap.

4. Attach the intervalometer to the camera and take a few test shots to check the level of light pollution and to ensure both the foreground and stars are sharp using hyperfocal distance. Then use 500-rule to determine the maximum exposure time you can use before the stars start to trail. If the level of light pollution is 20 degrees from the horizon, you might want to wait until the altitude of the galactic center to reach above 35 to 40 degrees before you hit the shutter.

500-rule: 500 divided by the effective focal length = Maximum exposure time you can use in seconds before the stars start to trail.

So if I’m using 16mm on a full frame camera, then the maximum exposure time I can use will be 500/16 = 31.25 seconds. I usually use between 25 to 30 seconds, as I do not wish to shoot at its limit.

And if I’m using 16mm on a crop sensor (crop factor 1.6 for Canon), then the maximum exposure time I can use will be 500/(16 x 1.6) = 19.53 seconds.

[ UPDATE: 29 MAY 2014 ] – There is no need to apply the crop sensor factor in the 500-rule. Refer to comments by Eddie Agha for further explanation. Thank you Eddie!

But when I am shooting in Singapore, I hardly need to worry about maximum exposure time because based on 16mm @ F2.8 @ ISO6400, the maximum exposure time I can use in most parts of Singapore will be between 1 to 6 seconds, a far cry from 30 seconds. I’m using ISO6400 in this tutorial to give you an idea of how bright Singapore is and for best result, try not to use beyond the base ISO of your camera.

5. Once everything is in focus, take at least 2 exposures (one expose correctly for the bright foreground and one expose correctly for the light-polluted sky without moving your camera) and find out the number of stops difference between the two exposures. The result is usually 3 stops difference in most parts of Singapore so most of the time I will be using Lee 0.9 soft GND filter. But for the case of the image taken in Sentosa, I did not use any filter.

6. I usually shoot in RAW mode and in order to collect the maximum amount of light, I use a technique called Expose To The Right (ETTR), but any method that improves the signal-to-noise ratio will work as well. ETTR image can be produced by increasing the exposure time to push the histogram to as far right as you can without clipping the highlights. This technique, however, has its limitations and further processing is required to bring out the best of what’s recorded in the RAW file.

7. For the case of Sentosa image, the settings I used were 9 seconds at F2.8 @ ISO6400 at 16mm. Notice how the peak of the histogram was pushed to the far right in the screenshot below.

ETTR image taken with settings : 16mm / F2.8 / 9s / ISO6400

8. Now I am ready to process (normalize) the ETTR image to unveil the Milky Way galaxy that’s obscured by the extreme light pollution!

How I post-processed my ETTR image in Photoshop to unveil the Milky Way galaxy taken in Singapore?

There are definitely many ways of post-processing an image but I will show you how you can do this without purchasing additional plugins and this workflow should work in most versions of Photoshop.

1. Guess what you’re going to see after you normalized the ETTR image? The elusive Milky Way!

Faint Milky Way visible after ETTR image was normalized.

2. Adjust the white balance.

Adjust white balance

3. I cropped the ETTR image due to vignetting and I de-noisedthe image as well. If you are shooting at a much darker location where you can expose your camera for 30 seconds with the same settings (16mm @ F2.8 @ ISO6400), then you probably can get away with a good Milky Way shot after adjusting its contrast level or using Levels and Curves. Unfortunately, we need to do more when we’re shooting the Milky Way from Singapore to make the image pop. The post processing workflow will become much more complex if we can only expose our camera for 5 seconds or less.

Cropped the ETTR image due to vignetting and denoised it.

4. Click on Image -> Adjustments -> HDR Toning. Then play around with the Detail slider along with the rest to achieve the look you want.

Use HDR Toning to achieve bring out the details of the Milky Way

5. Mask out the overexposed foreground.

Mask out the overexposed foreground.

6. Play around with Levels and Curves to bring out the details of the Milky Way and create a mask to keep the details of the Milky Way.

Play around with Levels and Curves to bring out the details of the Milky Way.

7. Then the rest is really all about tweaking the image to your own liking.

Before

After

So there you go! Thanks to Photoshop that we can now enhance the data that were recorded in the RAW file to unveil the beautiful Milky Way galaxy which we can’t see with our naked eyes in Singapore. But does Photoshop make the Sentosa image any less real? I don’t know about you, but I have no desire to capture only stuffs that my eyes can see anytime and I enjoy unveiling real stuffs that people didn’t even know existed.

Give it a try and link us to your works using the comment box below! To learn more about astrophotography, do consider joining one of my workshops here. Have fun exploring and here’s some of my other humble shots taken in Singapore till date. Not all the images below were taken or processed using the techniques in this tutorial.

[ SEE ALSO: MILKY WAY IS STILL VISIBLE TO NAKED EYE IN SINGAPORE! ]

28 Feb 2014 – Rising Milky Way and planet Venus in Singapore

27 Mar 2014 – Moon-Venus Conjunction in Lorong Halus, Singapore (Near Punggol Bridge)

30 Mar 2014 – Rising Milky Way at East Coast Park, Singapore

10 April 2014 – Rising Milky Way above Marina Barrage in Singapore.

10 Apr 2014 – Rising Milky Way above Marina Bay Sands Singapore

8 June 2014 – Rising Milky Way above Rocket Tower at Upper Seletar Reservoir Park

25 June 2014 – Rising Milky Way above the trees in Singapore.

25 June 2014 – Taken from a very dark location in Singapore where we can see the Milky Way with our naked eye!

20 July 2014 – Rising Milky Way at Punggol Singapore

21 July 2014 – Rising Milky Way above Marina Bay Sands Hotel and Spectacular Laser Show

14 April 2015 – Milky Way rising above Singapore Indoor Stadium

Frequently Asked Questions

Q1. Where is the Milky Way now?

A1. The Galactic center of the Milky Way is located between Scorpius and Sagittarius constellations. There are many mobile apps available to help you find out the position of the Milky Way. You may also access my astronomy tool from my app at http://www.justinngphoto.com/app.

Q2. Can we see the Milky Way with our naked eye in Singapore?

A2. You can’t see the Milky Way from most parts of Singapore. But it’s still possible to see the Milky Way from some very dark locations in Singapore.

Q3. Do we need a full frame DSLR camera and F2.8 lens to shoot the Milky Way in Singapore?

A3. No, you can use crop body and any aperture to shoot the Milky Way in Singapore. You only need a full frame DSLR camera and a fast lens when you’re shooting at a dark location.

Q4. Do we need to shoot at ISO6400?

A4. Absolutely not. You might yield much better results using lower ISO with your setup. Try using different ISO to see what works best for you. ISO is irrelevant to executing ETTR technique and if possible, try not to go beyond your base ISO to achieve the best possible result.

Q5. Do we still need to shoot at dark locations when using ETTR technique?

A5. ETTR technique alone won’t work in most parts of Singapore and it’s best executed at locations with low contrast and dynamic range. As Singapore offers varying degrees of light pollution, different workflows and shooting techniques are required to unveil the elusive Milky Way. Using ETTR technique at darker locations will increase your chances of getting a good shot and you don’t need a complex workflow to bring out the details of the Milky Way.

Q6. Is it possible to unveil Milky Way without using ETTR in Singapore?

A6. Absolutely yes. Any method that achieves better signal-to-noise ratio will work as well.

Q7. Are your images real since they need to go through extensive post-processing in Photoshop?

A7. My images present what’s real in reality, but the image will never look real because we’ll never be able to see the Milky Way under extreme light pollution with our naked eye. The same goes for all the beautiful galaxies and nebulae in our universe. But we cannot pretend they don’t exist just because we can’t see them with our eyes. I don’t know about you, but I have no desire to capture only stuffs that my eyes can see anytime and I enjoy unveiling real stuffs that people didn’t even know existed.

Q8. I have tried your tutorial on shooting Milky Way under light-polluted skies but it’s not working for me.

A8. The workflow presented in the tutorial only works for locations as dark as Sentosa or darker. If you’re shooting at a brighter location, then you need a more complex workflow to unveil the Milky Way.

Q9. How long should I expose my camera for before I get star trails?

A9. This is something you don’t have to worry about when shooting in very bright locations. But you may refer to the 500-rule in this tutorial to calculate the exposure time.

Q10. Why is the color of your Milky Way images white or blue?

A10. Milky Way images that were taken under extremely light-polluted skies are the most difficult to color-correct as it’s overwhelmed by the skyglow and the color cast caused by the strong light sources in all directions didn’t help much either. So the colors of the Milky Way were lost when I attempted to remove the color cast during post-processing. Here’s how our own galaxy looks like when it’s captured under a dark sky.

03 May 2014 – Milky Way Galaxy from Mount Bromo.

Q11. What advice do you have for beginners like us?

A11. Believe in nothing is impossible.

[ SEE ALSO: Tips & Tricks to Shoot Milky Way Under Extreme Light Pollution in Singapore ]

This tutorial was also published in Universe Today, SLR Lounge, The Creators Project, PetaPixel.