"Canst thou bind the sweet influences of Pleiades, or loose the bands of Orion?"

Job 38:31 KJV

So back in July of 2022, I wrote an article here in Focal Points called "Letting the Light In: The Importance of Being Still..." with the focus being on the importance of light when it comes to getting detail in images you photograph and contrasting that with the Spiritual application of how The Lord Jesus works in our lives.

Now I'm going to go into a field of photography that is very dear to me; one that is very rewarding yet very challenging to get right.  It requires a sincere interest in the field because of the time and patience that goes into it, and I will say for some, it will not be their "cup of tea." It's not for everyone. I am talking about Astrophotography, also known as "Deep-Sky Photography," or "DSP" for short.

Many photographers love the idea of taking pictures of the night sky, particularly celestial objects like planets and the moon and the Milky Way Galaxy bands. They probably however may not care for the idea of spending hours and hours in very cold temperatures in a very dark and secluded location taking the same picture over and over and over (and over) again 'till either:

a. Their camera battery (or batteries) are all gone.

b. Their fingers are all gone from the cold.

c. The object they are photographing is no longer visible in the sky or behind some hill or mountain or something.

d. The sun starts to come up and they realize they haven't gone - to sleep yet..... Hey wait a minute!

Ok. So let me take a moment to pause, and kind of reframe the concept... How about this: I would like to share my journey discovering and learning perhaps the most amazing and breathtaking experience in photography that I have had - Witnessing and capturing some of the amazing Works The Creator God Has Placed in the heavens above. It is challenging... but extremely rewarding. Most of all, it humbles me to the core of my person as I realize how GREAT God Is. How Great His Power. How Great His Majesty. How Great His Love. And how very very small, I really am...

There is perhaps no more extreme example in photography of "letting the light in" than Deep-Sky Photography (DSP). For starters, depending on your setup, you will have your camera shutter wide open for anywhere from a few seconds at a time to literally hours on end, depending on what you intend to photograph. I say this because this type of photography usually goes one of two ways. Either you want the object(s) to stay in focus or you want to gather the star trails that spiral through the night sky.

Either way, DSP's strength is in the long exposure. Because Deep-Sky objects like the Pleiades Star Cluster or the Andromeda Galaxy are so far away (especially the latter) and are hard to see in any detail with the naked eye, the example I used back in the 2022 article I mentioned of the camera sensor being like a "sponge" to soak in the light is taken to a whole new level here. Unlike that topic at the time, noise or "static" on the image is going to be unavoidable to some degree this time, no matter how long you keep the shutter open. In the case of DSP however, there is a workaround to that, and that is in the process called "Photo Stacking." (It may also be referred to as "Focus Stacking." Though similar, there are some differences.)

Because Deep Sky Objects are so faint when it comes to their brightness, or luminosity, there is only so much the camera can do in a single shot, even if it is a long exposure. You may be able to see some of it, but it will either be dull or lackluster to how it really is out there.

What if you could take more than one of the same image, and basically mash them together to bring out its strong points. Not a few images though. More like say... 50 or 100 or even 200-300 of the same shots, and cram them together. By doing so, even the faintest light is multiplied exponentially to the point where what was once a dim little fuzzy light is now - brilliant... Think of it like taking a piece of tracing paper, and adding 20 sheets on top of it with the same paper. What was barely solid is now very bright. Or another example, taking a 50 watt light bulb, and increasing the wattage several times over. You get the idea. That is what the process of Photo Stacking does.

Using special programs/apps like Siril or DeepSkyStacker, the Astrophotographer can take hundreds of the same images, and use specialized programs to condense all those pictures to one usable image. And the difference is astounding.

To start, preparation is key. There are various apps like Sky Guide from Fifth Star Labs that allow me to view the night sky and the objects I would consider to photograph ahead of time, so I know what time of the night as well as the area of the sky I should be positioning my camera for shooting. Also, the camera type is also important, as you will want something that has manual control over your exposure, focal length, ISO, etc. A Digital SLR (Single Lens Reflex) or Mirrorless camera would be the way to go. (As far as which is better between the two formats, that's a whole other discussion that has been going on for years that I won't get into here.) When the time is right for the shoot, and I am on location, I start my process.

After praying for God's Help with everything, I go ahead and start a series of multiple exposure shots that fall into four sequences. They are all important and will make a huge difference in the final quality of the image. The order you do these are not too important, but to streamline the workflow this is what I would recommend. Oh, and very important - you'll want to shoot these images in RAW format, not jpeg. Don't forget that.

1. The first sequence of images I would recommend are called light frames. What are light frames? They are actually the very images of the deep sky object you are photographing. So if it's a galaxy, a nebula, etc. - those are going to be your light frames. You'll want to optimize your settings so that your exposure, ISO, and focal length are where you want them to be, and where you have the sharpest and best quality images of this object. I've often found that you'll want to open your aperture as wide as you can to let as much light in, although I will tell you that all the images you will see on this page were actually taken at an F8.0.

On a side-note, if you are shooting with a star-tracker on your camera that follows the rotation of the earth to eliminate trailing star lines, then you can leave your shutter open quite long, even for several minutes at a time per shot. If you don't use a star tracker, I recommend an app called PhotoPills as it will give you an accurate exposure duration depending on your focal length and camera lens, but essentially it follows what has been called the rule of 300 (it used to be 500, but because not all digital SLR cameras have full frame sensors, 300 is safer) and what it is is this: take 300 and divide it by your focal length. Easy example: I took the Andromeda Galaxy image in this article at 300 mm. and if I divide that by 300, that means I would leave the shutter open no more than - one second. If it was 30 mm, then the shutter can stay open for up to 10 seconds... You get the idea. For the light frames, take as many shots as you can; the more the better. At a minimum though, 20 at least. 50 to 100 or more, even better!