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My Best Image of the Andromeda Galaxy Yet

|Equipment|7 Comments

My latest photo of the Andromeda Galaxy is my best effort yet. I have been taking deep-sky astrophotography images for over 10 years now, and this might be my favorite photo of space I’ve ever taken.

This detailed image was captured using a small refractor telescope, with a mirrorless camera attached. The image reveals the incredible, dusty spiral arms of Andromeda, in incredible detail. 

On October 17th, 2020, I rented a one-bedroom Airbnb to photograph the Andromeda Galaxy under dark skies. I spent the entire night outside collecting images of this galaxy with my camera and telescope. 

Andromeda Galaxy by Trevor Jones

The Andromeda Galaxy. Trevor Jones (Click to enlarge)

I’ll never take an image of Andromeda that can compete with NASA, but I can certainly continue to improve upon my previous efforts and capture the best shot I possibly can.

I believe that the planning that went into the shot, and my always-evolving image processing techniques are the reason this shot was so successful. If you have questions about how I captured and processed the image, please feel free to leave a comment. 

The Andromeda Galaxy

Messier 31 is classified as a spiral galaxy, but it looks elliptical because it is tilted at an angle from our vantage point on Earth.

The galaxy lies 2.5 million light-years away from us, and it is similar to our own Milky Way Galaxy. On a clear night under the right conditions, the Andromeda Galaxy can be seen with the naked eye.

Through a telescope or a pair of binoculars, the galaxy will appear as a noticeable “smudge”, which is the bright central core of Andromeda. Only through astrophotography, can we reveal the faint out spiral arms of the galaxy.

Although the sky was clear and beautiful the night this image was taken, stargazing was low on my priority list.

I had to make sure all of my astrophotography equipment was running properly to maximize the amount of exposure time collected on M31 in a single night. 

stargazing at night

Setting up my telescope at a dark sky location to photograph Andromeda.

About The Image

Over the past 10 years, I have photographed the Andromeda Galaxy many times, and I am proud to say that my images of M31 are improving each year. The key to this image was planning and the right approach. 

This time around, I traveled to a dark sky location to capture Andromeda in all its glory. The site was a Bortle Scale Class 4, which has much less light pollution than my backyard in the city (Bortle 7).

Many astrophotographers struggle with the negative effects of light pollution, and escaping to darker skies means packing up your gear and heading away from the city. 

light pollution map

The Bortle Scale Class 4 rural location where the photo was taken.

The dark, rural skies allowed me to capture longer exposures of my target, with better contrast. This reduced the amount of skyglow and unwanted artificial light collected in each long exposure photo I took.

To effectively photograph broadband (or broad spectrum) true-color objects in space, shooting from a dark sky site will provide the biggest advantage.

Narrowband filters can help you collect great data from the city, but galaxies and reflection nebulae do not benefit from this type of filtering. This is what makes photographing galaxies so challenging. 

In total, I collected 60 image exposures that were 180-seconds long each. 


The individual 3-minute sub-exposures (light frames) of my image.

This sub-exposure length was selected to find a balance between dynamic range, noise, and tracking accuracy. The Canon EOS Ra camera used for this image handles noise at higher ISO’s exceptionally well. 

The “best” exposure length to use for deep-sky astrophotography will be debated for eternity, but the camera settings used for my Andromeda Galaxy photo may be a useful benchmark for you to use during your next astrophotography project.

Canon EOS Ra Camera

The camera used for my photo (Canon EOS Ra full-frame mirrorless camera).

Recommended Camera Settings

  • File Format: RAW
  • Mode: Bulb
  • Focus: Manual
  • Exposure: 3-minutes
  • ISO: 1600
  • White Balance: Daytime
  • Number of Exposures: 60

The settings above assume you are using an equatorial telescope mount or star tracker to match the apparent rotation of the night sky. These settings will vary widely depending on the aperture of your telescope/lens, your shooting conditions, and the camera used.

Use the histogram to help you determine an appropriate exposure length that does not clip the shadows or highlights of the data. Through image stacking, it is possible to integrate several hours’ worth of exposures into a single image with reduced noise, and plenty of signal (light). 

The Equipment Used

The deep-sky astrophotography equipment used for this photo was specifically selected for this project. The telescope (Radian 61 APO) shoots at an incredibly wide focal length of 250mm, at a focal ratio of F/4.5.

This refractor is capable of capturing stunning, flat-field images of deep-sky objects in space with impressive color correction. When using a full-frame camera like the Canon EOS Ra, the backspacing and tilt of the imaging sensor must be perfect for edge-to-edge performance.

astrophotography equipment

The equipment used for my latest photo of Andromeda.

I did not use a light pollution filter inside of the built-in filter vault, opting to deal with any unwanted skyglow during the image processing stage. Collecting 60 sub-exposures was enough to produce a clean image without any serious noise issues.

The camera and telescope accurately tracked the apparent rotation of the night on an equatorial telescope mount, the Sky-Watcher EQ6-R Pro. A small guide scope and guide camera were used to provide better tracking (autoguiding) and utilize dithering.

My Deep-Sky Setup

astrophotography gear

Image Processing Tips

To process the image, I used many of the techniques I’ve described in detail in my premium image processing guide, as well as a few new tricks. The exposures were stacked in DeepSkyStacker using dark frames for calibration, which produced an intermediate file with a healthy signal-to-noise ratio.

For my tastes, I believe the key to a pleasing image of the Andromeda Galaxy is to reveal the gorgeous cool colors in the spiral arms of the galaxy, and really accentuate them. This creates a beautiful play of warm and cool colors that help to show the contrasting values of light from the galaxy core to the outer rim.

For many amateur astrophotographers, one of the more difficult challenges of photographing the Andromeda Galaxy is fitting the entire disc of the galaxy in a single image frame. For this reason, a wide field imaging refractor or a telephoto lens of no more than 400mm is ideal. 

Reducing star size, using layer masks to protect the bright core, and a saturation boost to taste were all applied several times over to create the final image. Several hours of processing (over many days) were involved in the creation of this image. I hope you enjoy it!

I regularly share my astrophotography adventures on YouTube. You can also see my latest images on Instagram, Twitter, and Facebook

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Andromeda Galaxy Astrophotography Tutorial

|Galaxies|16 Comments

In this post, I’ll walk you through the image processing steps I used to create the image of the Andromeda Galaxy shown below. This astrophotography tutorial uses Adobe Photoshop to bring out the intense colors and detail of a galaxy that was photographed using a DSLR camera and a small telescope. 

You can follow along and process the exact same data I did (download here), or you can try these techniques on your version of the Andromeda Galaxy taken using your own equipment. If you choose to download my data and process it, you can skip straight to the Photoshop portion of this tutorial. 

This tutorial uses DeepSkyStacker and Adobe Photoshop. If you are new to this process, you may find the following DeepSkyStacker tutorial useful. The images used in this tutorial were captured using a Canon EOS 60Da DSLR camera with the RAW image type selected.

Messier 31 – The Andromeda Galaxy.

The equipment used for this shot:

telescope equipment

The camera and telescope equipment used for the photo on this page.

About the Image

This image was captured on a clear night under Bortle Scale Class 4 skies. A William Optics Zenithstar 73 telescope was used like a telephoto lens on my Canon DSLR camera. The telescope tracked the apparent movement of the night sky thanks to Sky-Watcher HEQ5 equatorial telescope mount. 

You can watch the complete journey leading up to this image in the following video: Photographing the Andromeda Galaxy. The images were collected while we camped under the stars on a beautiful August night. 

The final stacked image includes 67 x 2-minute exposures (2 Hours, 14 Minutes Total) at ISO 800. Calibration frames were used (15 x darks, flats, and bias) to help calibrate the final integration.

Wide-Field Version 

Roughly a month after capturing the original version of the Andromeda Galaxy shared on this page, I photographed this amazing object again from even darker skies. This time around, I used an ultra-wide-field refractor telescope, the William Optics RedCat 51.

The 250mm field of view at F/4.9 created the widest, deep image of the Andromeda Galaxy I’ve ever taken. Using the same image processing techniques shared on this page, I created the following image using 100 x 2-minute exposures with my Canon DSLR.

Andromeda Galaxy RedCat 51

The Andromeda Galaxy captured using the William Optics RedCat 51. 

I blended in my previous version of M31 using the Zenithstar 73, but only at about 25% opacity. I believe this helped to showcase a bit more of the outer structure details. 

Andromeda Galaxy Image Processing Tutorial

The goal of this image processing tutorial is not for you to follow my process step-by-step to achieve the same result, but to get a better understanding of the tools and techniques I use to edit my astrophotography images. No matter what level of experience you have, I am confident that you will find a number of helpful tricks you can use while processing your own image of the Andromeda Galaxy. 

before and after photo

Assessing your Data

After collecting your images of the Andromeda galaxy with your camera, you need to organize all of the files on your computer so that you can easily find them. I like to sort all of the picture files and calibration frames into separate folders.

Create a folder for your light frames, dark frames, bias frames, and everyone’s favorite, flat frames. The root folder should include the date the images were taken so you have all of the information you need to reference later including the moon phase and location.

You may also want to include the telescope, camera, and filter that were used in the folder name, as these details may be hard to remember years later. Here is a look at the folder structure for my data on the Andromeda Galaxy.

folder structure

Make your life easier by taking the time to organize your images and calibration frames into folders.

You may find it useful to go through your light frames in a RAW image preview software such as Adobe Lightroom or Adobe Bridge. Delete any frames that have airplanes, or satellites passing through them, or that are not the full exposure length. If your tracking accuracy and autoguiding were successful, you should not have to delete any frames due to poor tracking. 

With the files organized and easy to find, we can now import the image data into DeepSkyStacker for calibration and integration. This will create an intermediate file that can then be processed extensively in Adobe Photoshop. 

Stacking and Calibration

DeepSkyStacker will allow us to calibrate our data using support frames, and improve the signal-to-noise ratio of the final image through integration. The software will automatically align and register the images on top of one another, to reduce noise and increase the signal (light) in the image.

To start, select all of your light frames (the actual pictures) by clicking the Open picture files button on the top left of the screen. This is where you will choose all of the images on the Andromeda Galaxy you would like to stack. If you have organized your images and folders neatly, and have filtered out any images that should not be in there, this process will be very easy. 


Load all of your light frames (picture files) into DeepSkyStacker.

You will then need to repeat the process, for your calibration frames. Click on the buttons for dark frames, flat frames, and bias frames in the top left-hand menu of DeepSkyStacker. I recommend using at least 15 support frames to properly calibrate the image for further processing. 

You can review the details of your image files in the lower portion of the screen.

This is a great time to check to make sure the following:

  • Your light frames are all the same exposure length and ISO
  • Your dark frames match the exposure length and ISO of your lights
  • Your Bias frames are the fastest exposure length possible
  • You have loaded at least 15 flat frames into DeepSkyStacker

image stacking

Review the details of your image files in the lower half of the DeepSkyStacker dashboard.

If everything looks in order, you can go ahead and click check all, followed by Register checked pictures. From here, we will need to make sure that a few key settings are used so that DeepSkyStacker can properly integrate and calibrate the image data. 

Register and Stacking Settings

Use the Register Settings shown in the image below as a reference. Because we have used all of the recommended calibration frames, and have pre-screened the images, these settings should work well. Feel free to try using the exact settings I have used to stack the image, including the sigma-clipping combination method to stack the light frames. 

deepskystacker settings

Recommended Settings in DeepSkyStacker.

You can change the Star detection threshold in the advanced tab of the Register Settings. The setting you use will depend on the type of data you are stacking. For this image, I suggest using a threshold of 25%, as it will speed up the stacking process significantly, and 456 stars are more than enough to successfully register the image. I have always kept the “Reduce the noise by using a Median Filter” option checked. 

star detection threshold

As for the Stacking Parameters (which can be accessed by clicking the button in the Register Settings box), I suggest leaving the default settings in place under the light, dark, flat, and bias tabs. You can select the Enable 2x Drizzle option if you want, but be warned that your computer will kick into overdrive, and the output file will be massive. (learn more about the benefits of using drizzle). 

stacking parameters

Now, click the OK button and review the final Stacking Steps of your image, and the estimated total exposure time. The total integrated exposure time for my image of the Andromeda Galaxy is 2 hours, and 14 minutes. 

Your stacked image of the Andromeda Galaxy may look very different than mine. Everything from the amount of exposure time invested in the image, to the filter used will affect this. 

The resulting image of the Andromeda Galaxy shown below has a typical look to broadband, color images shot using my DSLR camera. This is our intermediate file, that is now calibrated to reduce much of the noise and artifacts present in a single exposure. 

astrophotography image

The stacked 32-Bit TIF file created by DeepSkyStacker.

The integrated data now has a much better signal-to-noise ratio, which will make the processing and manipulation techniques in Adobe Photoshop much more effective. The final processed image will look much different than the version you see at this stage.

Image Processing in Adobe Photoshop

Adobe Photoshop is a powerful tool for processing astrophotography images. It is a robust graphics software designed primarily for photography and design, but many amateur (and professional) astrophotographers use Photoshop for astrophotography image processing. 

Adobe offers a subscription service for their complete Creative Cloud Suite, or for stand-alone products such as Adobe Lightroom or Photoshop.

Adobe Photoshop CC

Download Photoshop CC (Single App Plan)

Open the Stacked TIF Image

The first thing we need to do is open the file that DeepSkyStacker created using all of our pictures and calibration data. By default, DeepSkyStacker will output the intermediate file as a 32-bit .TIF, in the destination you have selected in the settings.

The default name of this file will be Autosave.TIF. You can change this file location in the output tab of the stacking settings option.

Alternatively, you can save the stacked .TIF file by clicking Save picture to file, at which point it will convert the image to 16-bit mode. We need to convert the 32-bit image to 16-bit to fully process the file in Adobe Photoshop anyway.

Now it’s time to open the TIF file you created in Adobe Photoshop. If you are opening the Autosave.TIF file that DeepSkyStacker created on it’s own, you first need to convert the image to 16-bit, by clicking Image > Mode > 16-Bits/Channel.

You will now have complete access to all of Photoshop’s tools to manipulate the data.

Crop and Initial Curve Stretch

I like to start by cropping the image slightly, just enough to remove any stacking artifacts around the edges of the image. This can create an inaccurate histogram reading, and you wouldn’t want to include these edges in your final image. You can use the Crop tool, or simply select the area you would like to keep (98% of the image), and click Image > Crop from the main menu. 

The first change we will make to the data is a simple curves stretch. Using the Curves tool (Image > Adjustments > Curves), perform a basic curve stretch using the image below as a reference. Now, the data is non-linear, and has been manipulated to help us better see the dynamic range of this object. All of the amazing deep-sky astrophotography images you have ever seen were “stretched” like this. 

curves stretch

My initial curves adjustment.

For this object, it is important that we do not over-stretch the core of the Andromeda Galaxy. It is the brightest area of the object, and details surrounding it could easily be lost. To avoid this, you can either blend in shorter exposure images of the core using a layer mask, or isolate this area (again, using a mask) so that you do not stretch this data as far as the surrounding details.

In the next step, I’ll show you an easy way to selectively stretch all of the areas of the image except the bright core. 

Selective Curve Stretch

To start, we’ll select the brightest area of the image using a mask. Click on Select > Color Range > Sampled Colors. Now, use the eyedropper tool within the Color Range dialog box to select the nucleus of the Andromeda Galaxy. 

Feel free to use settings similar to the ones below on your image. This will create a rough mask that we now need to refine.

color range

Now, navigate over to the Select and Mask tool (Select > Select and Mask) to soften the edges around the selection. This is an important step because we need to create a smooth transition between the areas at the edges of the mask. 

Once you are happy with the amount of feathering around the mask (using the Feather slider in the Select and Mask dialog box), you can click OK, and the selection mask will activate. Now that we have defined the area we want to leave untouched, we need to click Select > Inverse to apply our curves adjustment to. 

Perform a modest curves stretch as you did in the last step, and notice that the areas we have masked off (the nucleus of the Andromeda Galaxy) remain unchanged. You may want to make several iterations of this process, making small curves stretches each time. 


Before and after making a selective curves adjustment. 

If you were too aggressive in your selective curve stretch, you will create an unnatural looking transition between the core of the galaxy and the mid-tone areas. To avoid this, find a balance between the amount of feathering at the edges of your mask and the amount of curve adjustments you make. 

The same process of masking the bright core of the galaxy can be used on the surrounding stars in the image. This technique is a great way to pull your data forward without bloating the stars. 

Color Balance the Image 

At this stage, we will balance the color of the image by setting the black point, and the white balance. Start by creating a Threshold Adjustment Layer (Layer > New Adjustment Layer > Threshold). This creates an exaggerated view of the image showcasing the brightest and darkest areas of the image.

Threshold Adjustment Layer

A threshold adjustment layer used for setting the black and white points. 

We’ll use this layer to plot our black and white prints of the image. The black point is used to balance the background night sky to a neutral grey, while the white point is used to set a natural white color as we know it on Earth from the Sun. 

Using the slider in the properties tab of the threshold adjustment layer, choose an area of the sky that contains no stars, and is not touching the galaxy. Use the Color Sample Tool (found in the main toolbar) to plot 2 points on the image where there is nothing but dark sky.

Make sure that the Sample Size (found at the top left of the screen) is set to 5 by 5 average for the best results. 

Setting the Black and White Points

Now, plot a point on the image that is the brightest “white” area of the picture. In most cases, this is a star, but this time I have chosen to use the center of the galaxy core to set the white balance. For the most accurate rendition of colors, you will want to use a star that is the same type (G2V class) as our Sun.

These plotted points will now give us a reading of the pixel information and the current balance of colors in the image. To see this information, turn off (or delete) the threshold adjustment layer, and open the Info window (Window > Info).  

At this stage, we just need to balance the colors out a bit. If your image is like mine, it is very brown and ugly at the moment. We can balance the colors by adjusting each color channel independently and matching the values of our plotted points.

With the Info window open, click on Image > Adjustments > Levels. From the levels window, select each color channel from the drop-down menu and adjust the sliders. For my first levels adjustment, I have set the black point to read 20, 20, 20 across the RGB channels. These values will increase shortly, as we will pull the data forward even more. 

color balance

This is a good time to save the image. For all further edits, it is wise to create new layers on top of the original. This way, you can save the file with each adjustment made on its own layer. Label each layer with the adjustment you have made, and then you can save the complete .PSD file with the ability to go back and edit at any stage later. 

Targeted Curves Adjustment 

A powerful way to make a targeted curves adjustment in Adobe Photoshop is to hold down CTRL on your keyboard and plot a temporary reference point. With the Curves window open, hold down CTRL and click an area of the background sky. Now, holding down CTRL once more, click an area of the Andromeda Galaxy that you would like to brighten (the mid-tones at the edges of the galaxy),

If you noticed, the histogram on the Curves window now has two points plotted on the graph. You can now “pull” at the data with a targeted approach, as you now know where specific pixel data lies in the graph. The goal is to bring out the mid-tones, without bringing up the dark sky, or disturbing the bright core of the galaxy.

Curves Photoshop

Making a curves adjustment with plotted points on the histogram. 

At this stage, we can now see a lot more of the galaxy structure. The image is far from done, but it’s nice to see all of the interesting details of our deep sky object. This is another great time to save the image. I also like to use the History state feature of Adobe Photoshop (Window > History) if I ever need to go back and make small changes during my process.

Saturation Boost

You may want to increase the saturation of the colors in your image (watch my video tutorial on boosting colors). I find the best way to accomplish this is to create a Hue/Saturation Adjustment Layer. We need to define specific areas of the image to apply this effect to, and the Color Range Tool is a convenient option. 

Go to Select > Color Range > Highlights, and adjust the slider to define the areas of light we would like to increase the color of. In my case, I have chosen the bulk of the highlights, as I would like to increase the saturation of the galaxy as a whole, and the brightest stars in the field.

To refine the selection, you can use the Select and Mask Tool, or simply Select > Modify > Feather using a value of 1 or 2. 

With the selection active, go to Layer > New Adjustment Layer > Hue Saturation. Now you can adjust the Saturation slider to taste, boosting the intensity of the colors in your image. This is where your personal taste dictates the direction of the image. I would suggest not going overboard with your saturation boost adjustment. 

At this point, I recommend creating a visual merge (Shift + Ctrl + Alt + N + Eon the keyboard), and naming this layer “SATURATION”. If you have followed a similar path to me, your image and layers will look a little something like this:

Andromeda Galaxy Photoshop Tutorial

The Andromeda Galaxy with a selective boost in saturation. 

If you want to dive deeper into this process, you can read my full tutorial on selective color boosting for a complete breakdown of the technique.

Minimize Stars

Minimizing the size of the stars in your image is a great way to draw more attention to your deep-sky object. I find it to be one of the most dramatic differences between a good astrophotography image, and a great one. 

Reducing the size of the stars in your image is easy, but you will need to monitor a few things along the way. First, create a new layer, and name it STAR MINIMIZE. That way, we can turn the layer on and off to see the difference it made. 

Start by using the Color Range Tool again, selecting Highlights from the drop-down menu. Adjust the slider so that most of the stars are selected, but not the entire disc of the galaxy.

The goal is to select only the stars, so we can apply a minimizing effect on them. We will need to refine this selection and remove the bright areas of the galaxy, as we want these areas to remain unchanged. 

Using the Lasso Tool (found in the main toolbar), hold down the ALT key, and draw around the areas of the Andromeda Galaxy that you do not want to apply a star minimizing effect to. Holding ALT will ensure that this action de-selects area of the selection. 

star minimize

Settings for minimizing stars with the minimum filter in Adobe Photoshop. 

Now, go to Select > Modify > Expand, and expand the selection by 1 pixel. You should notice that the “marching ant” selection has changed and that there is now more room around the star selected. You may want to expand the selection by 1 more pixel, depending on the aggressiveness of the original selection made.

Next, go to Select > Modify > Feather, and use a Feather Radius of 1 pixel. This has softened up the selection around the edges, which is important for blending purposes. 

With our selection carefully refined, we can apply the star minimizing effect to the stars. Go to Filter > Other > Minimum, and use a radius of 1.0 pixels. Make sure that the Preserve option is set to Roundness and click OK. Click anywhere on the selection using the Lasso Tool to deselect it. 

Here is what my image of the Andromeda Galaxy now looks like with smaller stars.

Smaller Stars

Noise Reduction and Artifact Removal

If your stacked image includes 3+ hours worth of exposure time, chances are the noise is minimal. For my data, there is still quite a but of camera noise in the images, even using 67 light frames and calibration data. There is also an unnatural glow coming from the bottom of the image.

Let’s start with the noise. I prefer to use the noise reduction tool found within Adobe Camera Raw. To access this feature, click Filter > Camera Raw Filter. The noise reduction tool is found under the Detail Tab and can be controlled using the Luminance slider under the Noise Reduction heading. 

Zoom into the image to about 200%, and experiment using different levels of noise reduction on the slider. You can also mask and sharpen the image using this tool, but I don’t recommend doing that yet (even though I did in the example). Here are the noise reduction settings I chose to use for my image of Andromeda. 

noise reduction settings

Use the sharpening tool found under the detail tab of Adobe Camera Raw. 

Now that the noise is under control, we can tackle the subtle glow at the bottom of the image. In this situation, I think the easiest way to correct this is by copying the top most layer, and reducing the brightness. Then, I can remove the areas of the image that I do not want to darken using a simple mask and the Eraser Tool

Odd gradients like this are some of the most challenging processing scenarios, and can usually be avoided with proper flat frame calibration. I’m not quite sure what went wrong this time (the horizontal banding indicates it could be something to do with the dark or bias frame signal), but luckily fixing a subtle horizontal gradient like this is not too difficult. 

Gradient Xterminator is a handy third-party plugin for removing gradients and vignetting in your images. This is the method I used on the Andromeda Galaxy image, although I have shared ways to remove gradients without Gradient Xterminator in the past. 

Using Photoshop Actions

I have installed a useful astrophotography image process Action Set to my version of Adobe Photoshop, and I find it exceptionally useful. The Astronomy Tools Action Set contains many time-saving, powerful actions you can apply to your image with the click of a button. You do not need these actions to create amazing images in Photoshop, but I find them to be very handy.

If you are using this action set, I like to run the “Enhance DSO and Reduce Stars” action at this point. It can make a dramatic difference to the image in a single click. It basically pulls the faint details of the galaxy forward and applies another star minimizing effect the image. I prefer to set this layer to 50% opacity once complete.

You can also try running the “Make Stars Smaller” action, which should be used carefully as it can eat away at the stars in your image. 

Here is a look at each layer of the process, to give you a clear idea of when each processing technique took place.

processing steps

Each layer of the image is labeled with the processing step that took place. 

Selective Sharpening

It is wise to only sharpen the areas of your images that you intend to sharpen and to not simply run a sharpen filter over the entire image. For example, you would not want to sharpen empty areas of the background sky or the larger stars with a pleasingly soft glow. 

Again, we’ll use a mask selection to isolate the areas we would like to sharpen. The Select > Color Range > Highlights method works well, and be sure to refine the mask with careful feathering.

The sharpening filter I enjoy most is the one found inside of Adobe Camera Raw. This tool features a number of useful options to apply just the right amount of crispiness to your image. You’ll find it under the Detail Tab of Adobe Camera Raw (Filter > Camera Raw Filter).

Andromeda Galaxy

Finishing Touches

From this point forward, you need to decide the overall story you want to tell with the image. You can apply subtle tweaks to enhance the details of the image you enjoy most, whether that is having tiny stars across the field, cool blues in the galaxy, or a well-defined core. It may take several astrophotography image processing sessions to understand what makes a great image in your eyes. 

You may want to adjust the orientation of the image, too. For the Andromeda Galaxy, I like to see it in portrait orientation so the galaxy is on an angle. To me, this gives the Andromeda Galaxy more depth and better showcases its spiral structure.

One tip I’d like to share is to process two entirely different versions of the image. This means starting from scratch, making subtly different decisions about each action along the way. Then, compare both processes of the image, and decide which one you like best. Often times, I will combine the two processed image together with the top layer at 50%. 

With the selective masking techniques I shared in this tutorial, you’ll have countless ways to process your image of the Andromeda Galaxy in the fashion that you prefer. 


I hope you have enjoyed this image processing tutorial on the Andromeda Galaxy. To keep up with my latest videos, tutorials, and equipment reviews, please subscribe to the AstroBackyard Newsletter

Download My Image Processing Guide

If you would like to learn about every astrophotography image processing technique I use in DeepSkyStacker and Photoshop, you can download my premium guide. The PDF download contains over 100 pages of the specific steps I take to process all of my images. The guide is available here.

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Photographing the Andromeda Galaxy

|Galaxies|20 Comments

With summer coming to a close, I had one last chance for some deep sky astrophotography under dark skies. Choosing an astrophotography target at a dark sky site requires some serious thought. The key is to focus on an object that will benefit from broadband color data without the need for harsh light pollution filters.

After much deliberation, I decided to spend this rare occasion with my sights set on the Andromeda Galaxy. Cataloged as Messier 31, Andromeda is a massive spiral galaxy that demands attention. This month, it’s well placed in the night sky for your next astrophotography project.

The good news is, the Andromeda Galaxy can be appreciated using nothing more than a stock DSLR camera, a telescope, and a tracking mount. Finding the ideal field of view is the tricky part.

The Andromeda Galaxy is primed for imaging this month

Whether you are new to this hobby or have been capturing the night sky for years, I hope that you were able to get out and enjoy astrophotography this season.

Despite the almost record-setting rainfall in my area this summer, the season included its fair share of clear nights as well.  The warm nights create challenges for DSLR astrophotographers, making thermal noise a real pain.  Needless to say, I welcome the cooler nights of September and October with open arms.

Photographing the Andromeda Galaxy

The William Optics Zenithstar 61 ready to capture Andromeda

Camping Under Dark Skies

Way back in April, I booked a camping trip one of my favorite dark sky sites in Ontario, Rock Point Provincial Park.  I was overjoyed to find out that the Saturday night of the trip had clear skies in the forecast. I’ve lucked out with my astronomy camping trips this year, both to Long Point PP and Cherry Springs.

My campsite had all the elements of a great astrophotography site.  I scouted out the campsites at the park on a previous visit, to find a site with large open areas of the sky.  Campsite 140 included a power supply station, wide open views in all directions and privacy from surrounding campsites.

Deep Sky Astrophotography

Ready for a night of deep sky astrophotography

As always, Rudy provided great company as he is quite used to hanging around me as I fiddle with telescopes and cameras.  He even performed his usual backyard ritual of cozying up on the rug I place underneath my deep sky astrophotography equipment.

He was a big hit with the other campers, as many people approached him to say hello. Rock Point has an incredible beach, and Rudy enjoyed some long walks along the shoreline during the day.

William Optics Zenithstar 61 APO

I am delighted to announce that a brand new William Optics Zenithstar 61 APO arrived in the mail on Friday.  I have always been a fan of William Optics equipment, having previously used the 72 Megrez doublet, and the WO Field Flat III 0.8X Flattener/Reducer for many years.

With the Z61 arriving on Friday, it gave me one night to get things in order for a dry run, and then an opportunity to test the optics under some dark skies the following night.  I am just starting to get my feet wet using the new Z61, so I’ll save my review for a little later.  However, my early experiences say a lot about the ease of use and build quality of this refractor from William Optics.

DSLR astrophotography

Connecting a DSLR camera to the Zenithstar 61 telescope

The package included a William Optics Flat 61 Field Flattener, complete with a Canon DSLR T-Mount adapter.  The first challenge I faced was learning that the flattener actually threads directly into the 2″ focuser drawtube, as opposed to clamping the barrel into a compression ring.

The build quality and attention to details in the Z61 are evident in the Z61

The camera locks into place securely, ready for fine focusing on a bright star using the buttery smooth dual speed focuser.  The temperature gauge is a nice touch and can indicate a need for an adjustment later as the temperature drops throughout the night.

I have stated many times how much I love apochromatic refractors.  The forgiving wide fields of view, sharp stars, color correction, and reliability are among my favorite features.  The Z61 happens to be a doublet with a focal ratio of F/5.9. This affordable imaging refractor has proven to be a real performer.


Zenithstar 61mm Apochromatic Telescope

The Zenithstar 61mm Apo


  • Aperture: 61mm
  • Focal Ratio: F/5.9
  • Focal Length: 360mm
  • Design: Air-Spaced Doublet


  • Extremely Portable & Lightweight
  • 1:10 Dual Speed Micro Focuser
  • Synthetic Flourite (FPL-53) Glass
  • Optional Anodized 200mm Dovetail

iOptron SkyGuider Pro Mount

Next up was mounting the Doublet for deep sky imaging on a tracking mount.  The Sky-Watcher HEQ5 Pro that carries my Explore Scientific ED102 seemed overkill.  If only I had something a little more portable and lightweight?  Oh right, the iOptron SkyGuider Pro (On loan from Ontario Telescope and Accessories)

The iOptron mount can handle the Z61 telescope with ease, utilizing the included counter weight for balance.  The Zenithstar weighs a mere 3 lbs, meaning the SkyGuider Pro is well suited for this instrument.  Perhaps I could have even got away without the counterweight.

iOptron SkyGuider Pro Accessories

iOptron SkyGuider Pro Mount – Camera Tracking Device

The image of the Andromeda Galaxy below is proof that you do not need a bulky motorized equatorial mount for deep sky astrophotography.  The iOptron SkyGuider Pro continues to impress me with its reliability and performance.

Deep Sky Astrophotography with a DSLR

Photographing the Andromeda Galaxy

As dusk set in, I did my best to capture the emotions and anticipation felt on nights like this.  For a full recap of the trip including my final image, have a look at the video:

The deep sky target I chose on this magical night was the massive Andromeda Galaxy.  The focal length of the Z61 (360mm) was a great fit for this object.  The skies were so dark, I was able to use the viewfinder in my Canon T3i to locate and frame M31.

I have photographed the Andromeda Galaxy in the past using a larger refractor (Explore Scientific ED80) with more exposure time, on a Celestron CG-5 Mount.  The difference in detail is evident, but I believe the Z61 + SkyGuider Pro could produce an image just as deep with enough time.

It’s also worth noting that the color balance changed quite significantly from the original image using a stock Canon DSLR.

In the coming weeks, I will share a detailed review of the William Optics Zenithstar 61, complete with multiple example images.  I’ll need to spend some more time with this telescope before giving it an honest review.

The Andromeda Galaxy

The imaging sequence was automated using an inexpensive remote shutter release cable, and fired away at M31, capturing 70 x 2-minute exposures in total. I then shot 40 dark frames and subtracted them in DeepSkyStacker to reduce noise.

Andromeda Galaxy - Deep Sky Atrophotography

The Andromeda Galaxy using a DSLR Camera

The Andromeda Galaxy (Cataloged Messier 31), is a spiral galaxy located about 2.5 million light-years from Earth. It resides in the constellation of the same name and is the largest galaxy in the Local Group.  Other notable galaxies in the Local Group include our own Milky Way Galaxy and the Triangulum Galaxy.

The apparent magnitude of the Andromeda Galaxy is 3.4. This makes it one of the brightest Messier Objects in the night sky and can be easily spotted in binoculars or a small telescope.

Canon DSLR Camera

Equipment Used:

Imaging Telescope: William Optics Zenithstar 61 APO
Camera Adapter/Flattener: William Optics Flat 61 Flattener and T-Mount
DSLR Camera: Canon Rebel T3i/600D (Full Spectrum Mod)
Filter: IDAS LPS Filter (Clip-In)
Mount: iOptron SkyGuider Pro Mount
Camera Control: Polaroid Remote Shutter Release Cable

Photo Details:

Total Exposure: 2 Hours, 18 Minutes
70 x 120s @ ISO 1600

Stacked in DeepSkyStacker with 40 Dark Frames

Image Processing in Adobe Photoshop

Image Processing Workflow:

1. Levels Adjustment
2. Curves Adjustment
3. Set Black Point
4. Increase Contrast (Carboni’s Tools)
5. Increase Star Color (Carboni’s Tools)
6. Star Reduction (Carboni’s Tools)
7. Increase Saturation (Select Color Range)
8. Noise Reduction
9. Smart Sharpen
10. Selective Sharpening


I want to thank everyone for the thoughtful comments on my video, both on YouTube and Facebook.  I am very lucky to be able to share my astrophotography journey with you all. You can stay up to date by subscribing to the AstroBackyard Newsletter.


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Monster Galaxy

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This post showcases one of my first images of the Andromeda Galaxy. The photo was captured using a small refractor telescope on a tracking equatorial mount. I have since photographed Messier 31 several times through a variety of different telescopes.

Have a look at my experiences photographing Andromeda using a William Optics Z61 refractor on an iOptron SkyGuider Pro mount: Let’s Photograph the Andromeda Galaxy. This post includes a video and description of my deep sky astrophotography setup.

M31 Andromeda Galaxy taken with Canon Xsi in July 2012

M31 – The Andromeda Galaxy

On Friday July 21st, I spent another lonely night at the CCCA Observatory in Wellandport Ontario. I started a bit late, and it was complete darkness as I made the 40 minute drive from my house.  I was delighted to see the milky way appearing as I looked out my sunroof on that cool July night.

When I got to the observatory, I instantly noticed how clear and stable the air was.  I took a few 30-second exposures on my tripod while I set up.

Milky way taken with Canon XSi on Tripod

The Milky Way at the CCCA

After setting up all of my equipment, I set my sights on Andromeda.  After a little bit of framing with some 10 second exposures, I let Canon EOS Utilities take over and set it to take (75) 240 Second Exposures at ISO 1600.

My PHD graph was looking great so I knew I was in for some great data.  Because I had almost 3 hours of great frames, and I was under dark skies, processing was very straightforward and a pleasure to perform.

Here are the details for the above photo of M31

51 x 240″ ISO 1600

Stacked with 16 darks

ES ED80 Triplet Apo
Orion Mini Guidescope
Meade DSI II
Canon 450d unmodded
Stacked in DSS

As you may or may not have noticed, I have updated the astrophotography image gallery of this website.  I wanted to include more details of how I shot each object, in hopes to give some direction to aspiring astrophotographers.  It is still a work in progress, but I plan on having it finished by the end of the month.

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