sinwp rss feed for PI Articles

articles/Astronomy/a-p-s-w

A look at Astronomical photography - Never Seen Star Wars? (or the Milky Way)

by Mike McNamee

The title is from the Marcus Brigstocke radio series which introduces people to things that they have never experienced before. The relevance of that to this feature is that your editor has never seen the Milky Way! This is in common with many others - 85% of the population have never experienced a truly dark sky and only 2% have seen the Milky Way with their own eyes. For McNamee, then this is a bucket-list item - it is a perverse thing that as a scientist I have blown things up to 21 million times their size on microscopes but never looked the other way at the stars and reduced them down.

Discussions on the stars and the universe are an ever-present on our TV screens and there is no doubt that the output from the Hubble Space telescope has provided some hauntingly beautiful images from deep space. Orbiting above all the rubbish in our atmosphere, Hubble has been able to pull in the light and radiation from stars and galaxies which moved away from their start position not too long after the Big Bang and are now so faint that even Hubble had to use exposure times of 10.5 hours between July 2002 and September 2005 to gather in the light sufficiently to create a Tiff file! The conclusion of the scientists examining the data is that the number of galaxies in the universe is 10 times larger than originally thought and that 90% of them are invisible with the presently available technology - they are simply too faint and too far away. The previous estimate was that there were 200 billion galaxies so the number raises to an equally ungraspable 2,000 billion. Each galaxy averages about 100 billion stars (there are 100-400 billion in our own Milky Way) so when you multiply up the number we are getting short of space to type in all the noughts! We need other ways to contemplate these numbers so how about the number being 100 stars for every grain of sand on Earth? This is what the new number suggests. Do you need another mind-blowing number? The Andromeda Galaxy is the closest to us here on Earth but when you look up at it (probably with at least a pair of binoculars) then the light hitting your eyes set off before man had evolved on our planet.

Astronomy and photography are linked, and have been right from the start of photography (astronomy started well ahead of us), but the latest digital technologies are bringing more information right into the hands of the amateur astronomer even if they can never aspire to creating images such as those that Hubble can create. You might not be able to imagine what a trillion stars looks like but you can see the beauty in a star trail or a deep space image.

This is the backdrop to this feature; it is a simple journey to making the first steps in looking at the skies - really 'looking' not just glancing up from the polluted street in your average city. Your editor is uniquely unqualified for the task but with this ignorance comes the novice's wondering of what it all means. The Milky Way is illusive even if there are 2,000 billion of them hanging around out there!

For the backdrop image printed here, among other data, scientists used the galaxies visible in the Great Observatories Origins Deep Survey (GOODS) to recalculate the total number of galaxies in the observable Universe. The image was taken by the NASA/ESA Hubble Space Telescope and covers a portion of the southern field of GOODS. This is a large galaxy census, a deep-sky study by several observatories to trace the formation and evolution of galaxies.

One of the most fundamental questions in astronomy is that of just how many galaxies the Universe contains. The Hubble Deep Field images, captured in the mid 1990s, gave the first real insight into this. Myriad faint galaxies were revealed, and it was estimated that the observable Universe contains between 100 to 200 billion galaxies. Now, an international team, led by Christopher Conselice from the University of Nottingham, UK, has shown that this figure is at least 10 times too low.

Image Credit NASA/ESA

The first and most important thing you need is a truly dark sky. In all of our cities and conurbations the light pollution level is such that only a few stars can be seen. Step away from the city lights and you get to see hundreds or even thousands of stars. The Milky Way, though is more elusive than this; you need somewhere truly dark and in terms of photography around this part of the world this means about three stops darker than even the unlit beaches of the Wirral.

The dark skies are defined (and to a smaller extent regulated) by the International Dark Sky Association which maps and reports on light pollution and can offer advice where needed or requested on achieving and maintaining a dark environment. They have designated spaces where light pollution is low and the night sky may be seen in all its glory.

Of 11 Dark Sky Reserves in the world, the UK has four: Brecon Beacons, Exmoor, Snowdonia and South Downs. Other sites in the UK carry recognised status such as: Cairngorm, Northumberland, North York Moors and the Lake District (by way of example). More information may be found by following the URL: http://www.darkskydiscovery.org.uk/dark-sky-discovery-sites/map.html where more than 100 sites are listed.

The Northumberland International Dark Sky Park is one of the popular centres in the UK and star-watching events are run from the Kielder Observatory just north of Hadrian's Wall. They also publish the map shown. The courses seem very popular and so booking is essential www.kielderobservatory.org. The vulnerability of an expedition there (especially if you travel from the south of England) is that it might be clouded over, but who says star gazing does not need dedication?

Photography is of great assistance in looking at stars; the digital sensor can gather in more than the eye can see, even when using super-wide-angle lenses. The high ISO and low noise capability of today's chip has revolutionised the pursuit of star images. Photoshop, time lapse and image-stacking software have all brought star trail photography into the grasp of photographers using only the kit that many already possess. A tripod, an f2.8 lens and a DSLR is all you need to start. Even if you do become hooked, telescopes and tracking mechanisms seem quite low cost compared with what we are used to paying for our everyday gear!

Little of this is a commercial proposition unless you can find a relevant, maybe iconic foreground to set off your stars; and even then you might need some luck, a car sweeping its headlights into your field of view could ruin a few hours of work (it is surprising how many clandestine courting couples there are arriving in some remote places - they often panic at the sight of a camera!).

Before you go

You need to establish where you can go to find dark skies and also study both the weather forecast and lunar timetables - you need a moonless night for best star viewing (assuming, of course that the moon is not your quarry!). Photographer's Ephemeris is the weapon of choice for predicting both sun and moon directions but a reconnaissance in daylight might save you driving your car into a ditch in the darkness - never lose sight of safety with this type of photography, by definition you are likely to be in remote places and far from help if you have an accident.

As well as having a thorough understanding of your camera settings you also need to be able to set things up in the dark. Practise the entire shooting workflow before you depart; you might need to consult your camera user guide (you know, the little book still in its cellophane wrapping in a hidden corner of you office). By way of example, we thought we had understood setting up the intervalometer on a Nikon - we had not! The camera kept stopping after a small number of Raw shots or a slightly larger number of JPEG shots because the buffer was filling up; we had totally misunderstood Nikon's instructions and missed the fact that the 'interval was timed from the start of each shot (ie you set 33 seconds if you have a 30 second exposure and this waits three seconds for buffering - we set our interval to 3 seconds which was 'used up' during the exposure). A head torch is also a requirement both for safety getting into position (full white light) and preserving your night vision while working (red light). After a small amount of web searching we took ourselves off to the Cotswold outdoor suppliers and sought their advice. We came away with a Black Diamond Cosmo 120 costing £40 - certainly not the cheapest you can get. However, it has proved to be excellent; it triples up as a dog-walking aid and an assistant when grubbing around under the desk looking for a USB port! It can be operated with gloves on and adjusted to point ahead or downwards, as required.

There are some other practicalities to consider before you start. If you are having a practice session in your garden make sure that the family don't turn on the lights and open the curtains to check you are OK!

Also turn off your security lights; the last thing you want at the end of a long sequence is the local Macavity turning up and triggering the PIR spotlight.

Unless you are very well versed in the stars, you are going to need a star field map or mobile phone application so that you can find your way around. After trying a couple of things, we came across Stellarium which is free for the PC and a couple of pounds for the iPhone. It is superb, works in conjunction with your phone GPS and also has an optional red interface to preserve your night vision. A compass on your phone is also useful if, for some reason, the allimportant North Star (Polaris) is obscured.

Finally don't forget warm clothes; it can get very cold standing around, especially on the preferred frosty nights when things are crystal clear!

Exposure Settings For star trails you can choose a single long exposure or multiple shorter exposures. For the latter you will need a stacking program which can be Lightroom, Photoshop or one of the free utility programs that are available from the web. A sturdy tripod is a must and for single frames the exposure must be limited to prevent the m o v e m e n t of the Earth creating an e l o n g a t e d blur for all your stars except Polaris (which does not move as it is directly above the North Pole). The exposure limit may be calculated using the '500 Rule' which teaches that the exposure in seconds should be less than the number 500 divided by the lens focal length (that equates to 36s for a 14mm lens and 21s for a 24mm lens).

As pro-photographers you might find this a little too long when you pixel peep. The dilemma is to choose between the noise of high ISO settings and the length of time to gather in light from faint stars.

For star trails many photographers choose between 14 and 24mm focal length and the Nikkor 14-24 f2.8 is the weapon of choice for it has a tremendous reputation for its sharpness and accurate drawing (distortion). A good starting exposure is to shoot Raw, set 5,000K for white balance and then 30s at f2.8 for an ISO of 3200. This will be good for a start, although on our maiden outing we found that the light pollution was such that we needed at least two stops less to prevent the light from clouds fogging the entire shot (we were on an island a mile off the coast and not in a recognised dark space).

The number of shots you use to create a star trail and the exposure time per shot will determine the length of the arc that your trail covers. The Earth rotates once every 24 hours or 1,440 minutes so dividing 1,440 by 360° gives a degree every 4 minutes. Hence a 10° arc will be made with a 40-minute exposure. The little gaps created while each exposure is written to your card will be filled in by the stitching software if needed.

How did we do?

We have photographed the Milky Way!

In truth it was something of an anticlimax. We worked in very trying conditions on a storm-tossed island replete with flying foam and a furious gale. Salt spray was clouding the lenses over in under 30 minutes and the speed of the clouds was enough for them to pass right through a frame in 30 seconds. It was not a good start. Such was the general fight for survival we only 'discovered' the Milky Way during subsequent Photoshop processing, after we had identified the Summer Triangle and confirmed that the white 'clouding' in the image was in fact our Milky Way. Star trails were completely impossible as there was never more than a couple of minutes of clear sky. Talk about a baptism of file, but we learned an awful lot!

Our first star trails were obtained from the back garden a week later and represent little more than a starting point (and no, we are not going to embarass ourselves by printing them!)

At the outset of this venture we spoke to local photographer (and fellow retired microscopist!) Rob Devenish, having noted his postings of star trail shots on Facebook. Although he modestly proclaims to be a novice, he has made far more progress in the intervening time than we have made at Imagemaker! We therefore asked if we could publish some of his images as examples of what can be done with very 'modest' gear. Rob has been using a Canon EOS 1Dx with a 17mm TS lens and a Sony ILCE-7RM2 with a 50mm f1.8 lens - no telescopes or tracking devices involved. We put his better progress down to superior skill and perseverance for he has certainly put in more hours than us and it is starting to pay off - he has apparently written to Father Christmas requesting some more specialised gear. Not only has he bagged the Milky Way, he also managed to image a spiral galaxy on just a 50mm lens. His tree and lighthouse images here are just the sort of example we were referring to at the outset of the feature and could be used commercially.

Realising that our own ventures to date are at little better than primary school level (although we do not know many youngsters who own a 14-24mm Nikkor!), we investigated the options for going forward. It soon became obvious to us that the images from Hubble, released by the likes of the European Space Agency, have cornered the market in high-quality deep space imaging - no matter how much you spend, your images are never going to better that which is freely available from the web. This has led to the evolution of a subgroup of enthusiasts who spend their time taking Hubble images (or other professionally made large telescope imagery) and then assembling them using Photoshop. One of the leading experts from this creative imaging group is Robert Gendler, whose work may be seen at (www.robgendlerastropics.com). Gendler is a Connecticut physician who has created some iconic images which have gone on to win major awards. As well as being decorated with lots of beautiful images, Gendler's website hosts quite a number of essays on stars, galaxies and nebulae, and tutorials on technique - it is well worth a visit.

The workflows described by Gendler often utilise images created by others, sometimes from a number of observatories and they are thus disqualified from use in our monthly and 16x20 competitions (and in truth most 'photography' competitions). If you want to make eligible images you are going to have to invest both time and money. By photographic standards, a lot of astronomy kit seems modestly priced; if you look at the telescope shown it seems like a lot of hardware for the money. As with all other things in life, the more you pay the better the equipment you can gather. You still need the skills though.

An outflow from this discussion is the notion that you have to take advice to avoid expensive pitfalls. We spoke to Telescope House (www.telescopehouse.com) who dealt very sympathetically with our lack of knowledge and provided a rough guide to the outlay required. It seems that around £2,000 will get you going with a telescope, tripod and an equatorial mount - you will also need a GOTO device to move your telescope into position, especially if your target is faint and undetectable by eye. We assume that you have a camera and Photoshop! One snippet of information we gleaned from Telescope House is that a number of professional photographers have taken up astrophotography as a diversion from their day-to-day work (any Imagemaker readers out there might care to drop us an email!). Depending upon your wallet, £2,000 might or might not sound like a lot of money but when a 400mm f2.8 costs close on £10,000, it seems like value for money.

"In the image the stars of the Milky Way seem to be pouring forth from the open dome of the telescope. The brightest patch close to the telescope is the Carina Nebula (NGC 3372), which contains some of the most massive stars in our galaxy (see for example eso0905 and eso1031). Near the top of the image are the stars of Crux, the Southern Cross. This constellation, and that of Carina, are in the southern sky and are therefore not visible from most northern latitudes.

The telescope in the image is the fourth 1.8-metre Auxiliary Telescope, part of the Very Large Telescope Interferometer (VLTI). The VLTI consists of four 8.2-metre telescopes, and the four smaller Auxiliary Telescopes, which have mirrors 1.8 metres across. Thanks to the size of the telescopes, their cutting-edge technology and the excellent conditions at the site, it is no wonder that Paranal is considered the most advanced visible-light observatory in the world."

Credit: ESO/José Francisco Salgado (josefrancisco.org)



Updated 27/04/2026 16:44:22 Last Modified: Monday, 27 April 2026