Introduction: Advanced Astro

Advanced Astrophotography Imaging

Astrophotography has been captivating stargazers for centuries, but recent advancements in technology have ushered in a new era of advanced astrophotography imaging. With cutting-edge equipment and techniques, photographers can now capture awe-inspiring images of celestial objects and bring the wonders of the cosmos closer to Earth-all from the comfort of their own backyard.

High-resolution Sensors and Enhanced Sensitivity

One of the key factors driving advanced astrophotography imaging is the availability of high-resolution sensors. Modern digital cameras equipped with larger sensors and increased pixel counts and /or pixel size allow astrophotographers to capture intricate details and finer nuances of celestial objects. These sensors are more light-sensitive, enabling better low-light performance and reducing noise levels in the final images.

Deep-Sky Imaging: Narrowband Filters & Dithering

To explore the depth of the universe, astrophotographers are employing narrowband filters. These filters isolate specific wavelengths emitted by various elements present in space, such as hydrogen-alpha, oxygen-III, and sulphur-II. By capturing these wavelengths separately and combining them during post-processing, photographers can produce stunning, colorful images that reveal hidden structures and phenomena.

Additionally, advanced techniques like dithering have revolutionized deep-sky imaging. Dithering involves minutely shifting the telescope's pointing between exposures. This randomizes noise patterns, leading to better image quality and enabling the extraction of faint details from the data.

Equipment

Deep sky astrophotography is a captivating art form that allows photographers to capture stunning images of celestial objects. To embark on this journey and achieve superb results, it is essential to have the right equipment. Here's a breakdown of the key gear you'll need to pursue advanced deep sky astrophotography:

1. Camera

Investing in a quality monochrome or color camera specifically designed for astrophotography is crucial. Unlike traditional DSLR cameras, astronomy monochrome and OSC (one shot color) cameras provide enhanced sensitivity and detail. Look for a camera with a high-resolution sensor, low readout noise, and a broad dynamic range to capture the intricacies of celestial objects efficiently. Also make sure the camera has a TEC Cooler (thermoelectric cooler) on it, allowing the sensor to run at up to -35 degrees below ambient temps. This will provide the sensor with better performance, lower noise, and heightened sensitivity due to the cold. A good example of a camera is the ZWO ASI 2600.

2. Telescope

A good telescope is the backbone of your astrophotography setup. Opt for a telescope that suits your specific needs and budget. Refractors or reflectors are popular choices. Ensure that your telescope has the necessary focal length and aperture for capturing celestial objects. Consider factors such as portability, ease of use, and compatibility with your camera. There are a lot of resources online that will help you to attach your astronomy camera to your scope. The ASI 2600 camera + Skywatcher Esprit 100ED refractor is a great pair for a setup.

3. Mount

To capture sharp and steady images, a stable and accurate tracking mount is essential. Invest in a motorized equatorial mount capable of accurately compensating for Earth's rotation. This will facilitate the long-exposures you need. Ensure the mount can handle the weight of your camera and telescope combination. Some good mounts are the SkyWatcher EQ6-R Pro, iOptron CEM 40, and a few strainwaves like the iOptron HAE29 or HAE43-depending on your budget. Strainwaves are more expensive, and you need to consider a steady tripod if you go the strainwave route, as they can function with no counterweights so you’ll need to make sure it will not tip over.

4. Filters

Filters play a crucial role in astrophotography. Narrow-band filters, such as hydrogen-alpha (Ha), oxygen III (OIII), and sulfur II (SII), are commonly used with monochrome cameras. These are meant to isolate specific wavelengths of light emitted by celestial objects. These filters help enhance details and create striking contrast in your images. One thing to note is that you wont necessarily need filters for OSC cameras, only one you may need is a light pollution filter. These can be beneficial to reduce the impact of artificial light, especially if you are shooting from urban areas and with a OSC.

5. Focal Reducer/Field Flattener

A focal reducer or field flattener is often required to correct optical aberrations and enhance the flatness of the field in astrophotography. These optical accessories help reduce distortions and vignetting, ensuring crisp and evenly illuminated images across the entire frame. Make sure to choose a focal reducer/field flattener compatible with your telescope's specific focal length and back-focus requirements. Some scopes may come with a flatter, which you must use.

6. Guiding System

A comprehensive guiding system consists of several components, each playing a crucial role in refining the accuracy of astrophotography images. These components include:

• Guiding Camera: A compact camera, typically mounted on a smaller auxiliary telescope, analyzes images of a guide star to measure its position. This information is then sent to the control software for real-time adjustments. A good guide camera is the ZWO ASI 220 Mini.

• Guide Scope: This secondary telescope provides a high-resolution field of view dedicated solely to guiding. It allows the guiding camera to focus on a relatively bright and stable star, ensuring precise tracking of celestial objects. A example of a good guidescope is the AstroTech 60mm scope.

7. Computer System

To control all of this, you can use an ASI Air if you are new to astrophotography automation, OR you can use a windows mini pc with NINA if you are up for a creative challenge.

I will let you decide :) If you need help, shoot me an email.

Processing

Before you continue, I have a useful resource for some great PixInsight workflows. See here.

Below will be a very general overview of some of the most useful processes.

In this section, we will be talking about processing with PixInsight, which is an extremely powerful image processing software platform that is used by astrophotographers to process their raw images and create stunning images of the night sky. However, it is a complex software platform with a steep learning curve. There are many tutorials and resources available to help astrophotographers learn how to use PixInsight. It offers a wide range of tools and techniques for image processing, including calibration, registration, combination, noise reduction, color calibration, contrast enhancement, sharpening, and deconvolution.

• The calibration process in PixInsight involves correcting for the effects of the camera, telescope, and atmosphere. This includes correcting for dark current, bias, and flat field errors. The registration process aligns multiple images so that they can be combined. This is important because it allows PixInsight to combine the images in a way that minimizes noise and maximizes the signal-to-noise ratio.

• The combination process in PixInsight combines multiple images to improve the signal-to-noise ratio. This is done by averaging the images together, which effectively reduces the noise in the image. The noise reduction process in PixInsight reduces the noise in an image without blurring the details. This is done by using a variety of techniques, such as wavelet noise reduction and adaptive noise reduction.

• The color calibration process in PixInsight corrects the color balance of an image. This is important because it allows the colors in the image to be accurately represented. The contrast enhancement process in PixInsight enhances the contrast of an image to bring out the details. This is done by adjusting the brightness and contrast of the image. The sharpening process in PixInsight sharpens an image to improve the definition of the details. This is done by increasing the edges in the image.

• The deconvolution process in PixInsight removes the effects of atmospheric turbulence from an image. This is important because atmospheric turbulence can blur the details in an image. Deconvolution is a complex process, but PixInsight offers a number of tools to help astrophotographers achieve good results.

Here are some additional tips for using PixInsight for astrophotography image processing:

• Start with a good quality raw image.

• Use a variety of processing techniques to achieve the desired results.

• Experiment with different settings to find what works best for your images.

• Save your work regularly.

• Don't be afraid to ask for help from other astrophotographers.

Data Processing Steps

Calibration

The first step in deep sky processing is to calibrate your images. For this example we will be using narrowband data.

Calibration includes correcting for dark current, bias, and flat field errors.

• Dark current: Dark current is the amount of noise that is generated by the camera's sensor even when it is not exposed to light. This noise is caused by the thermal energy of the electrons in the sensor. To correct for dark current, you need to take a dark frame, which is an exposure of the same length as your light frames, but with the shutter closed. The dark frame will contain only the dark current noise, so you can subtract it from your light frames to remove the dark current noise.

• Bias: Bias is a small amount of noise that is present in every image, even if it is perfectly exposed. This noise is caused by the electronics in the camera. To correct for bias, you need to take a bias frame, which is an exposure of a blank screen. The bias frame will contain only the bias noise, so you can subtract it from your light frames to remove the bias noise.

• Flat field: Flat field is a correction that is applied to an image to correct for uneven illumination across the sensor. This is caused by dust on the sensor, uneven illumination from the light source, or vignetting. To create a flat field, you need to take a flat field exposure, which is an exposure of a uniformly illuminated surface. The flat field exposure will contain only the uneven illumination noise, so you can subtract it from your light frames to remove the uneven illumination noise.

Registration

The second step in narrowband processing is to register your images. This aligns multiple images so that they can be combined. This is important because it allows PixInsight to combine the images in a way that minimizes noise and maximizes the signal-to-noise ratio.

There are a number of different ways to register images in PixInsight. One common method is to use the ImageRegistration tool. This tool allows you to align images by matching features in the images. Another method is to use the StarAlignment tool. This tool aligns images by matching stars in the images.

Integration

After registration, integration is next. The ImageIntegration process in PixInsight is used for stacking multiple images to improve signal-to-noise ratio (SNR), reduce noise, and enhance details in astrophotography. It allows for advanced combination methods like averaging, median stacking, and sigma-clipping to reject outliers (such as cosmic rays, satellites, or hot pixels). This will generate your master frames for the next step.

Channel Combination

The third step in narrowband processing is to combine your master images. This is usually done using the LRGBCombination OR ChannelCombination tools. These tools combine the images in a way that preserves the colors of the objects in the image.

Stretching

The fourth step in narrowband processing is to stretch your images. This enhances the contrast of the image to bring out the details. This is done by adjusting the brightness and contrast of the image.

There are a number of different ways to stretch images in PixInsight. One common method is to use the HistogramTransformation tool. This tool allows you to stretch the image by adjusting the brightness and contrast of the histogram. Another method is to use the LocalHistogramEqualization tool. This tool stretches the image by equalizing the histogram in local regions of the image.

Inspection and adjustment

The fifth step in narrowband processing is to inspect your images and adjust the levels as needed. This is where you will make the final adjustments to the image to get the desired look.

This may involve adjusting the brightness, contrast, color balance, and sharpening of the image. You may also want to use masks to protect certain areas of the image from being over-processed.

Saving

Of course, the final step in processing is to save your images! Export them in either .TIFF or .JPG.
TIFF if you want to do any further processing. JPG for posting on social media, and sharing with others.

Thats it!
If you read all the way here to the bottom, thank you! I hope you were able to gain something useful from this massive page. For any further questions, please don’t hesitate to reach out.