Getting Started in Astrophotography

This page will be completed with the help and advice of Gareth Jackson.

(Pictures, except Palomar photos, on this page ©Gareth Jackson, 2023)

Gareth is a Wales based astro-photographer who has much more experience in this field, using DSLR equipment than I. Unbelievably he has only been taking photos of the night sky for a few years. Gareth started his journey into astro-photography in 2020. He has kindly agreed to help me devise this page to give would-be astrophotographers a good start in the interesting specialist sideline of our hobby.

Rather than a step by step approach, Gareth will outline his own path and give ponters for you to follow:

Above: Gareth's first picture of The Horsehead Nebula and the Flame Nebula in Orion.

I'm sure you will agree that anything Gareth has to say about photography through the telescope (or just with a DSLR!) will be worth listening to. I can't wait to bring you this page in full.

SuperCooper Says: Years ago, when I started out in this hobby, astro-photography was done with film and a lot of trial and error. The images produced were an average of the seeing conditions and although some good results were to be had, it wasn't until the advent of digital photography and stacking programs that amateur astro-photography really took off.

These days you can shoot video and then pick the best shots from that video before stacking them into one image that shows the most detail. You can thus avoid the moments of bad seeing and the slightly smudged images to produce not an average of all the shots taken, but just of the best shots.

For information on taking Moon shots with your mobile phone (a good start into AP) there is a page dedicated to the process: Click Here.

Pic: Gareth's latest pic of the Dumbbell Nebula, M27 in Vulpecula (Dec 2022). This is a much better quality image than even the best shots of the 1970s, when I was bitten by the bug of astronomy, better even than those from the legendary 200" Palomar telescope!

This was the quality of the photographs that inspired us in the 1970s! This was considered 'cutting edge' quality and detail in those days. Thank goodness for the advent of digital image processing!

Compare the two: The obvious difference is the colour in gareth's image. Then there's detail in the areas that Palomar has overexposed, to get detail in the fainter parts. gareth's image shows the detail, the fainter parts and the stars within the nebula. There is no 'grain' in Gareth's image from use of fast film. From a scientific, and an aesthetic point of view, Gareth's image is far superior to the Palomar image.

Pic: The 200" Palomar Monochrome film image of M27, The Dumbbell Nebula

A similar process can be done using 'long exposure' single shot images. Once again, with the advent of digital imaging this process has changed a lot since the days of film. A long exposure astro-photo of a subject doesn't have to be done all at once. It can be split even over several nights or weeks! Then each session (which might have been ten to fifteen minutes) can be stacked to produce one image with a total exposure time of maybe three hours!

Because of this, and the detail available to modern photo chip technologhy equipment, you can achieve pictures from quite small telescopes that would have been impossible using equipment five times bigger in the past. This is a revolution in imaging that is welcomed by all.

Pic: Gareth's December 2022 pic of the Pleaides.

Beginnings:

by Gareth Jackson

I started my astrophotography (AP) journey, during UK lockdown 1. I have owned a telescope for many years. It was a Tasco Galaxsee on an equatorial mount, and it served me well for many years. (It had a 114mm diameter spherically figured mirror with a focal length of 500mm f4.4)

Although certainly not a great telescope, especially for the price I paid almost 20 years ago (around £240 as I recall), it allowed me my first views of Saturn (I still remember the excitement), Jupiter and some of the brighter Messier objects like M42 Orion, M13 Hercules and M31 Andromeda. For this telescope however, the Moon was probably the best object to look at.

I was browsing the internet one day, I was actually looking for a new finderscope for the Tasco as it had been misplaced (possibly thrown away during the annual shed clearance) and stumbled across some cheapish Plossl eyepieces on Amazon. I thought that would be a good upgrade, and it really was!

During my searches I also came across a very cheap mobile phone holder for the telescope, and I thought what a great idea! Little did I realise then that the rabbit hole went much deeper than I thought possible.

So, my initial attempts at the moon were okay, but then I tried on M42. And what a an awful result! Trailed stars and a blurry image.

Pic: Tasco image of M42 in Orion with Mobile phone.

So then I decided to do some further research on taking photos through a telescope with a mobile phone. I downloaded an App called Nightcap, which allowed a bit more flexibility in terms of exposure time, ISO etc. But still I was frustrated with the setup and imaging results for faint objects using a mobile phone.

Because of lockdown, I was saving quite a bit of money, and so decided to upgrade my telescope. (I was lucky to still be working)

I purchased a nice Helios 90mm f11 refractor from 'SuperCooper' through eBay, but whilst waiting for the auction to end, an 8” SkyWatcher 200P Newtonian on a Dobson type mount came up for sale very close to my home. I bought that too!

The Helios 90mm EQ refractor turned up and I was very pleased with this new bit of kit. I also collected the 200P Dob and tried them both out on the next clear night.

What a difference to the Tasco these two telescopes were! I would recommend the 8" telescope to any beginner. It came with an adaptor for attaching a DSLR, and so I also bought a second hand Canon 600D. But still, I was not having much success except for some moon photography.

(Afetr using the 8" almost exclusively, I sent the refractor back to SuperCooper who sold it for me, for a profit, on eBay!)

Pic: The Moon: An initial, single shot, effort through the 200P with the Canon 600D

At this point, the AP bug had gotten to me. So, I purchased a second-hand EQ5 equatorial mount and also a motor for the RA axis. Now I was cooking and getting some longer exposures without too much star trailing.

I also purchased a SkyWatcher 72ED telescope (Short focal length refractors are great for AP beginners).

I think the biggest jump came when I hooked up my laptop to the system to allow greater control over image acquisition and learned the benefit of using a guide camera to prevent trailing stars. This also allowed me to learn about stacking images, using calibration frames and the dark art of post processing for the final image.

And so, over the last two years, I have steadily built up an imaging rig, learning the process slowly, upgrading some things and adding a few extras, and I am, for now, happy with the images I am producing.

Pic: A compilation of Gareth's images of Mars, Saturn and Jupiter (with two moons and moon shadow) taken as he improved along the way.

Gareth's current equipment set-up is as follows:

HEQ5 mount with either 72ED or 150PDS telescope attached.

50mm guide scope with ASI120mm guide camera.

Canon 600D or Canon 1100D (Astro-modified).

ASIAIR Plus for controlling everything.

Gareth says: "My knowledge of telescopes and eyepieces etc comes from this website."

But, I learned nearly everything else, regarding astro-photography (AP) from watching many informative and interesting YouTube videos (such as Nico Carver’s "Nebula Photos" and Trevor Jones’ "Astrobackyard". I have also visited so many websites and watched so many videos, that there would be far too many to list here. (Search YouTube for yourself - There's a lot out there that will guide you well.)

DSLR Astrophotography

So, you want to take photos of space?

Astrophotography is a great way to share the wonders of the night sky.

So, how do we do it?

Well, let’s first determine what we mean by astrophotography (AP).

Pic: DSLR attached to driven EQ mount on tripod

It’s such a broad term and can be a simple handheld shot of the night sky with a mobile phone camera, or you could hold (or fix) the phone to the eyepiece of a telescope. At the other extreme it could be a long exposure photo of a deep sky object using a monochrome camera with different filters to isolate particular gases in nebulae.

So, let’s start at the beginning (or close to it) and explore the basics and how we can create great photos with modest equipment.

Basic DSLR and tripod

First of all, we need to remember that the stars move (well actually the earth rotates!) and the more we magnify our view, the faster those stars move!

We also need to consider that when taking photos of stars etc, they are very dim and so we need to be able to collect as much light on the camera sensor as possible.

And this, inevitably, leads us to the first issue we need to consider:

Exposure time:

We want to have as long an exposure as possible to be able to catch those precious photons (light particles). Seems straightforward, but consider that the longer the exposure time the stars will begin to trail and look elongated.

This, in itself, is not a bad thing if you want to create those stunning star trail photos. But aside from this style of AP, what we want are pinpoint stars in our photos.

So, how long can we expose for before we begin to see star trails? Luckily there is a well known guide to exposure called ‘the 500 rule’ which states that if you divide your focal length of camera (or telescope) into 500, this will give you a guide to how long an exposure can be.

In reality, this does not work too well, as it depends on what part of the sky you are looking at e.g. pointing your camera at Polaris, this rule will probably be sufficient as the stars are moving slower around the celestial pole. However if you point your camera south, then you may want to adjust the 500 rule to more like a 300 'rule'.

Example of 500 rule: 50mm lens. 500/50=10. Therefore, you have a maximum 10 second exposure before obvious star trailing in the image!

So this 'rule' is okay if you are using fairly wide angle lenses found on a DSLR (28-50mm). However, when we start to increase the focal length, even to 600mm, we are suddenly down to maybe less than a 1 second exposure and this is not going to show any detail in those faint fuzzies! Luckily, there is a process called ‘stacking’ where we take multiple images of the same shot and stack them together to increase the effective exposure time. Another way to avoid trails is to use an EQ mount that allows tracking of the sky, so you can track your object to negate the trails altogether.

There are some other considerations regarding the exposure 'rule' for unguided shots, which we will come on to later in this exploration, but which may not apply once you add tracking and stacking into the process - Read on!

Getting started:

Anyone with a smartphone or DSLR with a basic kit lens can take great images of the night sky, but to do so requires some knowledge of how to use the camera effectively i.e. have a basic understanding of manual camera adjustments such as exposure time, ISO settings and aperture control. There are also some extra bits of equipment which you will probably need such as a tripod, lens warmer and intervalometer (or a way to program the camera to take multiple shots with a long exposure time).

Let's start with camera settings.

Exposure time: As discussed earlier, exposure time will depend on the focal length that you are shooting at. Use the 500 or 300 rule to get a starting point. Take some test photos and increase exposure until obvious star trails are evident (Note, for Milky Way shots, a bit of star trailing may not be noticeable unless zooming right into the image (pixel peeping!). Try to get a balance between max exposure and how much star trailing is acceptable (to you!!).

ISO: ISO amplifies the signal that each pixel in the sensor receives. Each camera will have a sweet spot where the increase in signal is not overwhelmed with the noise generated. An ISO setting of 800-1600 would be a good place to start.

Aperture: Telescopes have a fixed aperture (link to your section), whereas camera lenses' allow the aperture to be adjusted. For astrophotography we want as much light (or signal) hitting the sensor during each shot and therefore we want the lowest F number possible. For a basic 18-55mm lens this would be around F3.5. However, it may be advisable to 'stop' the aperture down by 1 or 2 stops, as this will sharpen the image and reduce aberrations (especially star shape) caused by a fully open setting. Again, this will vary with different lenses, and there is a compromise to be made between maximum light and funky looking stars! Try different settings and decide what is acceptable for YOU!

Other settings:

File Type: RAW. Although JPEG is acceptable for one shot images, especially when starting out, for multiple image stacking it is best to use RAW files as there is little data loss in the images. All of the software I use is compatible with RAW (canon) files.

Manual Focus: Turn off any autofocus or auto stability setting on the lens.

White balance: Use sunlight white balance. Let's face it, we are taking pictures of other 'suns' and so we want the camera to match the 'sun' light!

Focusing:

Focusing can be tricky, especially at night. Trying to focus on a dim star can be very frustrating, especially using the small screen on the back of the camera. To make things easier, try focusing during the day on a distant object. This will get you in the right area for nighttime focusing. At night, if the moon is out, try to focus on this, if not, use a bright star such as Sirius or one of the planets. Basically find the brightest object in the sky. Now, use the zoom function on the back of the screen and try to focus until sharp. For the moon, use the craters along the terminator. On stars, try to get the star as small as possible. Once you are happy with the focus, you can carefully use a piece of electrical tape to 'lock' the focus in.

So, let's say we want to photograph a nice shot of the Milky Way.

For a typical 18-55mm kit lens, we want the following (as a start):

Camera set to manual

ISO 1600

F 3.5

Exposure (at 18mm focal length) = 15-30 seconds

The important thing to remember here is that your particular camera/lens may work better at slightly different settings to the above. Try ISO3200 or higher. Modern cameras can go higher. Try the next F number if the stars look too distorted. Experimenting is the key.

Once you are happy with the images, take a few for stacking. Make a note of the settings you used.

If you are planning to spend some time outside taking photos, remember your dew heater (or carry a USB portable hair dryer with you!).

The next step - tracking:

Remember how the earth rotates and so the stars seem to be moving across the sky? Well, by utilising a tracking mount, we can match the rotation of the earth and therefore we can 'track' the stars as they move. This allows us much more freedom with the exposure length. Exposure times of 60-120 seconds are now achievable, which allows much more light to hit the sensor. This also means we can be less aggressive with the ISO settings and reduce the aperture (camera lens, not telescope) to sharpen up the stars.

However, to take advantage of this tracking means that we really have to be as accurate as possible when polar aligning the mount. Good enough will not cut it, and so it is recommended to have access to a polar scope with a reticule to allow the mount to be adjusted accurately. It is also a good idea to download a free app, such as @polarscope@ which mimics the reticule in a polar scope and tells you exactly where Polaris should be within the reticule.

Other highly recommended equipment:

Tripod: You may already own one and if so use that. Otherwise, purchase the best you can afford.

Lens warmer: Dew is one of (many) enemies that the astrophotographer has to deal with. Nowadays relatively cheap USB powered dew straps are available on-line and can be powered by a power bank. A simple dew heater will keep the lens warm enough to keep it dew free for several hours.

Intervalometer or remote shutter: An intervalometer allows the camera to be programmed to take multiple shots at varying exposure lengths without having to touch the camera. Some cameras already have this ability in the software, so check your camera's settings. A remote shutter release cable is just a way to press the shutter without touching the camera. You can also set a delay function if you do not have either an intervalometer or shutter cable. Either way, you will need to be able to take a photograph without touching the camera and introducing vibrations.

Astro-Photography on a budget

Astrophotography can become a very expensive hobby. But it doesn't have to. For example, the camera used to take the image of the horsehead nebula was a 10 year old Canon 600D. The same camera can be currently purchased on mpb.com for £169 with a 6 month warranty! A Canon 18-55mm kit lens for around £25. Okay, so you have to limit your expectations, especially when it comes to lenses (and telescopes) but older cameras are actually quite good for astrophotography. Remember, we are using the camera in manual mode, so all the new features that come with the latest DSLRs are generally improvements in the automated settings. CMOS sensors in cameras have obviously improved in the last 10-12 years but in older cameras the pixels are generally bigger, which can help in collecting those valuable photons!

All the software programs I use for image capture, pre and post processing are available as free downloads. YouTube has endless tutorials on how to use this software effectively.

NOTE: As mentioned this page is for guidance:

Gareth has suggested the following headings for future installments to this page: These are considerations that you will need to address as you move along your AP journey.

Importance of polar alignment
Polar Alignment Methods
Attaching a DSLR to a telescope
Motorise the EQ mount
The importance of balance
Exposure and ISO
FOV and focal length
Planetary imaging
Deep Sky imaging
Image processing
The next level: Guiding and automation

Here are some of Gareth's various equipment set-ups.

He has a SkyWatcher 150PDS with all the knobs and whistles

With which he can turn out a photo like The Horsehead Nebula shot at top and the Pleiades pic.

Gareth also has a superb SkyWatcher 72ED

With which he can produce a photo like the Dumbbell Nebula shot!

Gareth has a number of amazing instruments and uses them all regularly. This refractor is being used for visual observation of Jupiter, under yet another superb Welsh sky!

Gareth started out with a modest Tasco Galaxsee telescope and a mobile phone.

Following the advice in this page, and throughout this website, you too can learn to take excellent photographs of the wonders of the night sky.

If you plan to have a go, you could start off today with a visit to the SuperCooper 'Moon Photography' page: HERE

Gareth's astro-photos shown on this page are taken under the darks skies of Wales and represent the best of British sky conditions. With a little patience and perseverance, you could get similar results with your equipment if you carefully follow the guidance on this page.

M101 in Cassiopeia Distance = 21M light years

This galaxy is visible in your telescope as a small fuzzy patch, larger telescopes may show some detail. An excellent target for AP.

In 2023 this galaxy had a supernova erupt in its outer spiral arm (See animation). This is a photo by Gareth. It shows the galaxy before and after the supernova became aparent. The light from a supernova can outshine all the other stars in the galaxy. See how bright it is compared to the brighter stars in the M101 galaxy.

This is the one area where DSOs may change over time. The supernova will subside in the coming months and the galaxy will return to looking very similar to its apearance before the event. Nevertheless, this is an interesting part of observing and photographing DSOs.

Gareth Jackson's M31 - Taken with his SkyWatcher 72ED scope.

I think you'll agree that anything Gareth has to say on this subject will be very well recieved.

Pic: Yet another of Mount Palomar's 1970s efforts - This time in colour!

It's a wonder we ever got inspired!

Moon Photography

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