Taking the image

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"Well that's all very well" I hear you shout "but how do you actually take these flippin' images? Eh?" And the answer, my friends, is simple: On a wing and a prayer. I point my kit at the sky, set the camera for some random exposure length (sort of) and let it go. Hopefully I'll end up with usable subs that I can stack in DSS, process in CS5 and end up with a decent image. Or I may not.

Now I'm assuming in this post that you're using a DSLR camera, and not a CCD. Probably a reasonable assumption, as if you're using a CCD you're probably not going to be reading this blog!

With terrestrial photography, we can set the camera to auto and it will focus, work out the shutter speed, aperture, iso setting if you want it to, white balance etc. etc. It does all the work for you. Not so with astrophotography. There are no astronomical light meters that will tell you how long your exposure length should be (not as far as I'm aware). There may be mathematical equations you can use, but I'm not that technically advanced! I decide how I'm going to take an image of a particular target using the limited knowledge I've managed to gain in the short time I've been doing this stuff, plus knowledge of how well - or more to the point, how badly - my kit performs. Plus no small amount of guesswork and finger crossing :)

Hopefully you've now got a camera and scope (or just a camera and lens - that's equally fine), a motorised mount of some description to enable you to track the stars, and perhaps a polar scope. You'll probably need some additional kit, which isn't essential, but will make your astro life a whole lot easier:

Camera control software
This will connect your camera to your computer, and will enable you to set the exposure length and how many subs you want to take etc. so that the camera can slave away mindlessly in the cold while you're nice and warm indoors. Some cameras come with this software (like Canons). If you have a Nikon, it's an "optional extra" that isn't cheap. Also bear in mind that some older Nikons will only allow up to 30 second subs using the camera control software - bulb mode requires the IR remote control. There is kit available to overcome this, so have a nose around the internet. Generally, Canons are considered better than Nikons for astro stuff.

A mains adaptor for your camera
There is nothing worse than being mid-way through a session when the camera battery dies, and you don't have a spare charged one. Your camera will eat up batteries like nothing you've ever seen whilst doing this stuff: a mains adaptor will overcome this, and in my opinion is worth its weight in gold.

Dew control
This will stop your telescope/camera lens from misting up, which can happen remarkably quickly during the autumn/winter. A dew band, which is just wrapped around the scope/lens, will raise the temperature of the kit by a degree or so, which is sufficient to keep the thing clear. Or you could keep running in and out with the hair-dryer :) I use Dew-Not, but there are others available. Google "Dew control"

Mains adaptors for all your battery powered kit
You'll find that many of the things you buy, like the dew control, your mount motors and of course your camera, are battery powered. This is so the kit can be used "in the field". Personally, I hate anything battery powered, and as I never go "in the field", all my kit is powered off the mains. When I buy a bit of battery powered kit I run down the local electrical shop (I have a particularly good one here) with the spec, and ask them to sort out the necessary plugs, adaptors and whatever to enable me to operate off the mains. The image below demonstrates how much imagination my local shop had to use to enable me to use the Dew-Nots off the mains, which come with - wait for it - phono plugs!

In my ignorance, I thought phono plugs were only used for audio, but hey, what do I know?! There are probably easier ways to connect a phono to a mains adaptor, but it works and I'm happy :)

Camera Settings
You should have the settings right on your camera before you trundle outside  - fiddling with the camera controls in the dark can be a pain. As regards the settings to use,  that's one for you really, and will largely depend on the quality of your camera. For your initial images, I would suggest you set the iso quite high, so that you at least get something that you can process. Modern cameras go a lot higher than my ancient relic, and are a lot less noisy. I'd suggest at least iso 1600 and see how it goes. If this is too noisy, bring it down a bit - it's a trade off. Turn off your display, as this eats battery power (if you insist on using a battery), and is a little too bright out there in the dark. White balance isn't too important, as you can adjust that in the processing - I set mine to daylight. Obviously the camera should be set to full manual, auto-focus off, and shutter speed set to bulb. If the camera has Long Exposure Noise Reduction, turn it off as it will double the time taken for each exposure - you'll be taking darks anyway, which does the same job (we'll come to that). Image format: RAW. Just RAW - not RAW + jpg. This records as much information as possible.


So, you're equipped and you're out there, eager to get cracking. You've decided on your target, you're POLAR ALIGNED, and ready to go. Did I mention polar alignment? Yes? Oh OK. So now what happens? Well, the first thing I generally do is look up and find that the clouds have rolled in. This generally results in "Oh blast and bother!" (or words to that effect) whilst I drag all my kit back indoors. I'd suggest that whilst you're setting up you keep one eye on the heavens, as conditions can change remarkably rapidly - at least they can here in the UK. The second thing I do is grab a cup of coffee, but that's optional.

Focus
If your focus isn't sharp, you'll be disappointed with the final result, and if you do several hours of subs they'll all be wasted. If you're using a scope, consider a Bahtinov Mask, which you can either make (plenty of resources on the internet relating to this) or buy on ebay. When using a Bahtinov, focus on the brightest star you can see (don't wait until you're pointing at your target) - you'll find it a lot easier to focus on a bright star. If you're using a camera and lens, you can't rely on the infinity setting - generally the focus will be out. You can make a small Bahtinov (I made a tiny one for my 52mm filter size zooms) or you can take multiple test exposures, zooming right in each time and making very tiny adjustments to the focus until you get the stars as small and tight as possible - it gets quicker with practice. And when I say tiny adjustments, I mean really tiny - you barely have to move it to make a difference to the focus. Once you've achieved focus, make sure you lock it down tight - you don't want it shifting mid-way through a session. Not so easy with a lens - you may have to resort to a bit of blu-tac over the focus ring to stop it shifting if there's no locking mechanism. Be aware though that blu-tac does leave a residue, so don't do this if you want your lenses to stay pristine :)

Find Your Target
You'll need to have some knowledge of the sky if you're going to find stuff up there, even if you're lucky enough to have a goto mount. I'm not going to teach you that - you'll have to teach yourself! Stellarium is as good a package as anything else, and the price is right! And it will tell you what's in the sky above your head right now at your location.

Don't try anything too adventurous in the early stages, you'll probably be disappointed. M42 in the winter is a cracker, and Cygnus during the summer and autumn (this assumes you're in the northern hemisphere!). You should really have already decided on your target before you ventured outside, so let's assume you have. If you have a goto, I'm going to also assume that you know how to use it. If you don't, and you're struggling (it can be tough sometimes looking for something that can't be seen) I've done a video on YouTube that might help.

Taking your lights
OK - you're on your target. Take a quick test shot to make sure you can see what you're expecting to see and that your focus is OK. Then set your control software to rattle off a few subs of whatever sub length you've decided upon. If you're using a scope and a tracking mount (with motors), but not guiding, the exposure length you can get without pear shaped stars will depend on how good your polar alignment is (very much so), the focal length of your scope, the accuracy of your motors and where in the sky your target is (things appear to move quicker on the celestial equator). When I was using a 200p (eight inch reflector) @ 1000mm, I could get 30 seconds comfortably, 60 on a good day. Using just a lens, say 200mm, a few minutes is possible. For now, take a one minute sub and see how the stars look. If there's evidence of star trails (pear shaped stars), go for 30 seconds. If they look good at one minute, try 90 seconds. You get the idea. You'd be surprised how much data you can pick up with one minute subs. For the image below I took 84 one minute subs, giving a total of 1 hour 24 minutes. I took additional subs for the core, but we won't go into that here :)

M42 in Orion. 84 one minute subs

As you can see, there's a fair bit of detail there. If you're just starting out in this stuff, I'd suggest restricting yourself to one minute initially. Take at least 40 of them, more if you have the time. The more subs you take, the better the final image will be - fact. For some of my images, I've taken hundreds.

Done that? Taken your lights (or subs, whatever you want to call them)? Good!

Darks
After your subs come the darks. The darks are taken with exactly the same settings as the lights, but with the scope (or lens) cap on. That's why they're called darks, because they are - dark. The camera also has to be as near as dammit at the same temperature as it was for the lights, so immediately after your lights, whack the cap on and set the camera to take at least 30 darks of the same exposure length.That's the darks done, which, by the way, take out all the dead pixels you will have in your image, and will take out any amp glow if you're unfortunate enough to have the same camera as me :)

Flats
Very important are flats. I've just put up a post on my facebook page about how to take flats, so I'll let you have a look at that. :) Take 30.

Bias
These subtract all the electronic noise and stuff that is a characteristic of your camera. Easily done - just put the cap on and set the fastest shutter speed (1/8000 for my Nikon). Everything else the same as your lights, although bias are not temperature dependent, so can be re-used for several sessions (providing all the other settings are the same across the sessions). Again, take 30.

There you go - sorted. Throw all this lot into DSS, and out comes your image - I hope.

This was a long one guys (but nowhere near as long as that DSS video up there!). Hope it helps :)

As always, may your skies be forever cloudless :)

Doug

Tracking the stars

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OK - the next exciting instalment. Sorry this stuff takes me a while but I have a decreasing amount of time I can devote to this. I'm doing my best :)

 If you want to take images of the heavens that are longer than just a few seconds duration, you'll need to track the stars. You may have noticed that the stars move across the sky, which is a bit of a nuisance really when you're trying to take pictures of them. The stars themselves don't move (well, they do, and pretty damn quick, but they're so far away we don't notice). The apparent movement of the stars is due to the Earth's rotation (which you probably already know) and in order to do long exposures, we need to match that rotation so that the stars remain in a constant position on the camera sensor. Easier said than done :)

There are some options available to the budding astrophotographer, but in my limited experience, the EQ (Equatorial) mount is probably the way to go. If you're heavily into DIY, you may want to have a crack at a Barn Door Tracker (I personally would rather stick needles in my eyes). A Barn Door Tracker is for use with your camera only (not with a scope). If this is something that interests you, here's a couple of links to get you started:

Wiki

Dave Trott 

Equatorial Mount
You're unlikely to be able to make one of these, so you'll have to buy one, which is a bit of a pain, but hey ho :). To give the Wiki definition:

An equatorial mount is a mount for instruments that follows the rotation of the sky (celestial sphere) by having one rotational axis parallel to the Earth's axis of rotation.

There you go - that just about says it all. :) You're probably already aware that the Earth is leaning over, and if it wasn't for this we could all track the stars in one axis using an Alt-Az mount (specifically using the Azimuth axis - left, right). But unfortunately the Earth is leaning over and we have to get around this by aligning our mount with the Earth's axis of rotation - this enables us to track the stars using one axis. The axes in an EQ mount are called DEC (short for Declination) and RA (Right Ascension). DEC and RA are used to specify the coordinates of stuff up there, so that we can find what we're looking for. Think of DEC as the equivalent of Latitude and RA as the equivalent of Longitude - if you don't know what they are, google them :) We track the stars in RA only (east to west as they "move" across the sky). Happy with all that? Good :)

How much does an EQ mount cost? I hear you ask. How long is a piece of string? A top of the range mount will cost you an arm and several legs. An old EQ5 - probably between £100 - £200, depending on whether it comes with a scope. That's used by the way - new ones are a bit more. When I started this stuff, I bought a Skywatcher 200p 8 inch reflector with a Skywatcher EQ5 mount for £200 on ebay. I had to add motors (about £100), a polar scope (about £40) and a few other bits and pieces, but on the whole, not hugely expensive. So you can find this stuff if you look around.

Polar Alignment
This is by far the most important thing you will have to do if you want to end up with decent images. That bears repeating:  Polar Alignment is by far the most important thing you will have to do if you want to end up with decent images. Got that? I kid you not guys - without a good polar alignment you WILL get star trails - sausage shaped stars - and probably field rotation. The better your polar alignment, the longer the exposures you will be able to take (up to a point) without star trails. I say up to a point because the chances are your motors won't be precision made and will cause errors in the tracking (called Periodic Error or PE). All motors have PE to an extent. Some mounts are equipped with Periodic Error Correction (PEC) - they memorise the errors and make allowances for them - clever stuff. Probably not within our price range though - certainly not within mine! :)

There are some excellent resources on the internet on Polar Alignment, so I'm not going to cover it here in any detail. I've put a link in below to point you in the right direction, but you really need to get to grips with this stuff if you're serious about taking decent images.

Polar Aligning the HEQ5 for Idiots by Astro Baby

Astro Baby's article on Polar Alignment is excellent, and is a must read, but it contains a broken link. She refers to a program called PolarFinder, but the link provided doesn't work. Have no fear, you can download the thing here :)

Who said this stuff was easy?

Drift Alignment
A black art. The work of the devil. And stuff like that. Most beginners would rather stick a wasp's nest up their backside than attempt this. It ain't that bad guys - it just takes a bit of practice and perseverance. When you crack it, you'll have about the most accurate polar alignment it's possible to have, which makes you feel good, even if it doesn't improve the snaps :)

When I was trying to improve my polar alignment, I spent ages on the internet reading up about drift alignment. Most of the stuff I read was confusing to say the least, and then I found Peter Kennett's website. It's a great website, but it's no longer maintained due to Peter's work commitments, and most of the links don't work. Plus it's concerned mainly with film astrophotography, which isn't as popular as it used to be. Concerned that his unique explanation of drift alignment would be eventually lost, I sought his permission to reproduce his pages here, and he very kindly agreed. If you click on the new tab labelled "Drift Alignment" at the top of this page, and I strongly recommend that you do, all will be revealed. :)

Now there is a way, apparently, to drift align with just a camera i.e. no scope, which would be very useful for you guys intending to do widefield. The article is here, but I must admit I haven't tried it, although I will soon hopefully. If anyone gives it a go, I'd be extremely interested to hear how you get on :)

OK guys. I was going to add all about actually taking the images, calibration frames etc. here, but this blog would then be a bit too lengthy, so that will have to wait until the next one. I'll try my hardest to get it done a bit quicker though :)

As always, may your skies be forever cloudless

Doug

Astrophotography with a DSLR and Tripod (Part Two)

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I meant to get this up a bit sooner than this, but we've had about four clear nights on the bounce here, so I've been otherwise engaged, as you can imagine (if you live in the UK). You have to take advantage of every clear night you get here, 'cos you don't know if you're ever going to see another one :) You'll find Part One of this blog here by the way.

OK. The last blog covered simple astro shots using a camera and tripod. This one covers a slightly different technique known as "stacking", which many of you will know about. You'll probably also know why we do it, but I'll go into a little detail about that just to be sure. To demonstrate, I'll be using an image that was taken using longer exposures than you can achieve with just a camera and tripod, but as it's just for demonstration purposes hopefully you'll forgive me for this :)

 
The above image is a comparison of a single sub-frame - "sub" or "light" using the jargon (which means a single exposure) - on the left, and a stacked image on the right. The single sub is a 60 second exposure and the stacked image is a stack of 88 sixty second subs. This is obviously zoomed right in to reveal the individual pixels. The difference is kinda obvious! :) Let's clear up one thing right away: the difference in background colour is not a direct result of stacking as such - there is an option in Deep Sky Stacker (the software I use to stack) to use "RGB Channels Background Calibration". That means turn the background a neutral grey, a process that the software performs before spitting out the final result. I select this option by default, so the background is always a neutral grey - hence the difference in the colour of the background in the two images above.

Now what you can see in the image on the left is a star (obviously), and an awful lot of noise, which accounts for the blotchy background. Noise is caused by the electrical circuitry in the camera (among other things) and is affected by the iso setting (higher settings create more noise - much like film), and the exposure length. As we generally use high iso and long exposures in astrophotography, we can't win! The one useful thing about noise is that it is randomly generated i.e. a pixel that appears dark in one sub may appear lighter (or darker) in the next sub (the "tonal value" varies). We can use that characteristic to our advantage: If we stack multiple images eventually the noise will disappear (almost), simply because the tonal value of the noise pixels vary in each image. Imagine six columns of 100 randomly generated numbers between 0 and 255. If we average each column of 100 numbers we should find that the averages will be much the same, as the numbers were randomly generated. The more numbers we use, the closer the match will be when the columns are averaged. The same goes for the tonal values of the noise pixels - the more subs we stack, the closer the tonal values of the noise pixels will become, and the noise will lessen.  I hope that's clear :). As regards the "signal" (jargon for the bit of the image that we want to keep), in this case the star, the value of each pixel will be more or less the same in each sub, so the signal will remain in the final image. It's important to understand that stacking doesn't "boost" the signal as such, it just makes the signal clearer - less swamped by the noise.

The reason we want to remove the noise (apart from the fact that it looks horrendous), is that, in most cases, we need to "stretch" the image (improve the contrast) to bring out faint detail. If we stretch the image, we also stretch the noise, which is bad!

In the above image, both sides have been stretched by an identical amount. On the left, bad. On the right, good - not perfect, but an awful lot better. :) Now a single star is reasonably bright - if we were looking at faint details here, the signal in the image on the left would be lost in the noise. It would be much clearer in the image on the right.

"So how do I stack images?" I hear you ask. I'm glad you asked me that! You could do it manually in whatever software package you use to edit your photos - I use Photoshop. The software needs to support layers (most do I believe) and you need to know how to use them. Unfortunately I can't do a tutorial on each of the software packages out there, so you'll need to do a bit of research on the interent if you don't know about layers. Or you could use software that is dedicated to this stuff, like Deep Sky Stacker (DSS) - other software packages are available!! ;)

Manual Stacking

Pick your best sub and make it the background layer - not sure how important this is, but do it anyway :) Set the opacity of this layer to 100% (research your software if you don't know what this means). Then stack each sub in a new layer, setting the opacity as follows:

2 subs: Background 100%, 2nd sub 50%
3 subs: Background 100%, 2nd sub 50%, 3rd sub 33%
4 subs: Background 100%, 2nd sub 50%, 3rd sub 33%, 4th sub 25%
5 subs: Background 100%, 2nd sub 50%, 3rd sub 33%, 4th sub 25%, 5th sub 20%
and so on.... Get the idea?

The only thing you need to be careful of here is to make sure each of your subs are exactly aligned, otherwise you'll get rather fuzzy results.

Now if that all sounds a bit much, try this:

Stacking in DSS

You'll find Deep Sky Stacker, which is FREE, here:

Deep Sky Stacker

Luckily I've done a video tutorial on DSS, which you'll find on my YouTube channel here:

Deep Sky Stacker Tutorial

I tried embedding this, but it came out a bit small :) This video goes into the intricacies of calibration frames such as darks, flats and bias. Don't worry about that stuff at this stage - just stack your "lights" - I'll explain about calibration frames in a later blog.

You'll also find tutorials on my YouTube channel about processing images, starting with the basics. I use Photoshop in these tutorials, but the principles are the same for most photo editing applications (as far as I'm aware). If you don't know about this stuff, download GIMP (GNU Image Manipulation Program) from here - it's FREE again! :

GIMP

There are plenty of resources on the internet for GIMP. The more comfortable you are with your software, the better you'll be at this stuff - trust me :)

OK guys. Hope this is useful. If you use this process with some success, feel free to post your results on my facebook page :)

Speak again soon no doubt, but in the meantime may your skies be forever cloudless :)

Doug

Astrophotography with a DSLR and Tripod (Part One)

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Most people, on hearing the word "Astrophotography", will immediately form a mental picture of a telescope. That's understandable, as most people tend to think that Astronomy itself revolves around the use of a telescope. The latter is partly true, although you can get a lot of pleasure from the night sky just by using your eyes, and even more so if you have a pair of binoculars.

Astrophotography, however, is not solely the domain of the telescope enthusiast. Very good images of deep sky objects can be obtained with just a camera. You'd be amazed at how much is up there, and how wide an area of the sky some of this stuff covers, but which we can't see purely because it's all too faint. For example, the Andromeda Galaxy, the nearest spiral galaxy to our own, is about six times the width of the full moon in the sky - quite amazing (I wonder if nocturnal animals can see it?). The core of Andromeda, the bright bit in the centre, can actually be seem with the naked eye if the skies are dark enough (some lucky people actually have skies that dark!), and can certainly be seen with binoculars, although it will be nothing more than a faint smudge.

Although the image below was taken with the aid of a tracking mount (not a basic tripod), it gives you an idea of what can be done with just a camera and 200mm kit zoom lens:

M31 The Andromeda Galaxy

This image is actually made up of thirty 4 minute exposures, so it was necessary to use a tracking mount - a mount that follows the apparent movement of the stars across the sky - otherwise the stars would have been long streaks. Andromeda isn't an ideal target for a 200mm lens - 300mm would be better, but I don't own one of those ;)

But - you don't need a tracking mount to get some very nice images of the night sky. If you have a camera and a tripod, you're adequately equipped to take some decent images. A DSLR (Digital Single Lens Reflex) camera is preferable, rather than a compact, as ideally you need full manual control of the camera. If you've never done any form of night sky photography before, and don't know where to start, try this simple exercise:

First of all, make sure you are familiar with your camera, not just how to use the thing but the menu settings and options that are available to you. Different makes of camera have different settings but all should have the following options somewhere in the menus:

1. CSM/Setup Menu: Set this to Full, so that all the menu options are visible.
2. White Balance: Set this to Daylight, which seems to work OK. There isn't a setting for Pitch Black in the Middle of the Night!
3. ISO Auto: Off. You need to set the ISO manually.
4. ISO: Set this to at least 1600. If you have a modern camera (modern as at 2012) then you may have ISO settings much higher than this available to you. If you do, you could try 3200, or even higher, but the higher the ISO setting, the noisier the image, so don't overdo it. Try 1600 or 3200 first. 
5. Auto Image Rotation: Off, definitely.
6. Image Quality: Set this to RAW. RAW files hold more information, but the file size is larger. That shouldn't be a problem with a decent sized memory card in your camera.
7. Long Exposure Noise Reduction: If this is available, turn it on. This will double the time it takes the camera to dump the image to the memory card, but that won't be a problem for this exercise.
8. You want to be using remote shutter release, either infra red or cable (or whatever system your camera uses), so set this option, whatever it may be called in your camera. This assumes you are equipped with the necessary bit of kit to remotely control the shutter release - if not, don't worry too much.

Constellation of Orion, 20mm, 15sec, ISO 3200 by Dave DeHetre

Now, a couple of things that you probably already know, but I'm going to mention just in case: A Prime Lens is a fixed focal length lens i.e. not a zoom. A Fast Lens is a lens with a maximum aperture below f4 (some consider f4 to be fast - it's a matter of opinion). Generally speaking, a fast, prime lens is best for astrophotography, but if you don't own one of those (like me), a slow, zoom lens will do just fine (but not too slow!).

OK. Set your camera to full manual mode (this may require a setting on the lens as well). Put your camera on your tripod and go outside, preferably when its dark and moonless, and preferably when there are no clouds in the sky! Make sure you can see some stars - some nights are cloudless but the visibility is terrible. The more stars you can see (and the less they twinkle), the better. Make sure there are no lights on in the house shining at you - you want it as dark as possible. This also apples to neighbour's lights, but I wouldn't suggest you knock on their door and ask them to turn them off! If lights are a problem, at least make sure you can point your camera away from the lights. Use a focal length of about 50mm or less (wider), select the widest aperture (lowest f number), set the focus to infinity, and select a shutter speed of about 10 seconds. Now point your camera at the sky - anywhere will do for this exercise, but stay away from any areas of light pollution if you can (the sky will be orangy where there is light pollution). Make sure the tripod is nice and steady, and release the shutter. Now keep still until the shutter closes - no really, keep still; cameras on tripods are very sensitive to vibration.

Now take a look at the result. You may be surprised at how many stars are in the image compared to how many you can see in the sky - the image should show quite a few more. That is your first astro image (well, it may not be, but I'm assuming you've never done this before!) Zoom in as as far as you can on the LCD screen and examine the stars. If you are using a good quality prime lens, they may be in focus, but the chances are they are slightly out of focus. You'll know this because they will be slightly "blobby" as opposed to nice sharp points of light. If setting the camera to infinity was all that was required to achieve focus, a DSLR astrophotographer's life would be a lot simpler, believe me! Unfortunately, it doesn't work like that - most lenses go slightly past infinity (which doesn't sound possible, does it?) so you need to do a bit of work to get perfect focus. If you have a distant street light visible, you may be able to switch your camera to Auto Focus and focus on that, or the Moon if it's out (best to do this on a moonless night though - the Moon's inclined to be a little bright!). If this isn't an option, you'll need to make a tiny adjustment to your focus ring (and I mean really, really, tiny) and give it another go. Zoom in again - do they look better? If not, keep at it, making very tiny adjustments, until you've got the stars as small as possible. This is very much a trial and error thing, and can be quite frustrating (welcome to the world of astrophotography), but keep at it and, as is the case with most things, with practice you'll get better. If you have an M and A switch on your lens (Manual and Autofocus), or something similar, then after each adjustment set it to A. This will lock the focus and stop it slipping, but remember that if you need to make another adjustment you'll need to switch it back to M, otherwise you won't be able to move the focus ring. If you don't have this switch, and you're having problems with the focus slipping (this can be the case with inexpensive zoom lenses), then a small blob of blu-tack conveniently placed will help to hold the focus ring in position, but be aware that this may leave a residue (there, you can't sue me now!)

Orion again, 50mm, f1.8, 5sec, ISO 3200 by Fred Agustin. Very dark skies I would assume :)

You may also find that the stars are slightly sausage shaped, which is caused by the apparent movement of the stars across the sky - this will depend upon the focal length you used and the shutter speed. There is something called The Rule of 600 which you can use as a guide: just divide 600 by the focal length you are using and this will give you the longest shutter speed you can use without getting star trails e.g. 50mm focal length = 600/50 = 12 seconds. Very useful.

You may want to target a constellation you are familiar with, in which case you'll need to use an appropriate focal length to get it all in the frame. You could end up with a portfolio of images of all the major constellations, or perhaps all those in the Zodiac - the possibilities are endless! Good luck, and don't get frustrated and give up - this hobby takes practice and perseverance.

I've reproduced throughout this blog a few images I've discovered on Flickr that were taken using this method, with appropriate credits. In the next blog, I'll cover the stacking of images to reduce the noise and enhance the signal, which should give you a result you can be even more proud of - so watch this space for Part Two :)

The Plough, or Big Dipper. 20mm, f2.0, 29sec, ISO 400 by Paul Richards

OK guys, have fun out there. Feel free to post any images you take using this technique (or any technique for that matter) to my Facebook page - there's a link at the top of this post. It would be good to see them, and at least then I'll know I'm not talking to myself here. :)

As always, may your skies be forever cloudless :)


Doug

M51 The Whirlpool Galaxy in Canes Venatici

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Messier 51 The Whirlpool Galaxy in Canes Venatici

The Whirlpool Galaxy (also known as Messier 51a, M51a, or NGC 5194) is an interacting grand-design spiral galaxy that is estimated to be 23 ± 4 million light-years from the Milky Way Galaxy in the constellation Canes Venatici. It is one of the most famous galaxies in the sky. The galaxy and its companion (NGC 5195) are easily observed by amateur astronomers, and the two galaxies may even be seen with binoculars. The Whirlpool Galaxy is also a popular target for professional astronomers, who study it to further understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions. Wikipedia

This image was created using data from last year combined with data I captured in April 2012. It consists of 142 individual sub-frames, each of 60 seconds duration (the most I can get out of my EQ5 mount without star trails becoming a problem). The sub-frames - or subs - were stacked in Deep Sky Stacker (DSS), and the resultant tif file was processed in Photoshop CS5. For those of you already familiar with DSS, there's a vid on stacking multiple sessions on my Youtube channel here. For those of you not familiar with DSS, there's a (rather lengthy) vid on how to use it here :)

This is a relatively bright and easy target and is a good one to aim for once you've got the hang of using a scope and camera. Once this blog gets off the ground properly, I'll post a JargonBuster page, to give you an idea of what all the technical stuff means. I also hope to post a blog for each of the more popular targets that us amateurs like to aim at, giving you an idea of where it is and the best way to approach imaging the thing.

Promised blog on DSLR/Tripod imaging will be with you shortly.

May your skies be forever cloudless :)

Doug

So you want to do Astrophotography?

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It is now 19:30 (UK time) on Tuesday 19th June 2012. I say this because if you happen upon this blog tomorrow, you'll know why there is very little content :)

OK. If you want to get into Astrophotography, then apart from kit, like a camera (always useful), some sort of mount (preferably an equatorial mount - more on that later) and a computer with an image processing program installed, you will need:

1. Time, and lots of it
2. The ability to survive on very little sleep
3. Dogged determination
4. Patience of a saint, preferably a little bit more
5. Shed loads of enthusiasm
6. The ability to persevere under the most testing circumstances
7. A sense of humour
8. The ability to not take all this stuff seriously :)

If you've got all that, and you really, really want to do this, then I can offer a few tips and tricks, the benefit of my very limited experience, and a virtual shoulder to cry on when it all falls apart, as it will do - frequently.

The first bit of advice I will offer, and this is pretty boring guys but I make no apology, is to prepare yourself before you even think about pointing a camera at the heavens. By that I mean research the subject on the internet, read books, and then do some more research and read more books. When you think you've done enough, do some more research and read more books. Until I say stop ;) There's a good reason for offering that advice: If you don't know what you're doing and just jump in, you will fail and you'll give up - guaranteed. Astrophotography is an extremely steep learning curve - not just taking the images (the easy bit), but processing them in Photoshop or whatever (the hard bit). If you try doing all this without even the basic knowledge that you need, your results will be very disappointing and you'll think it's just you that can't do it - everybody else seems to be able to. And you'll give up and carry on watching the telly or something.

This is the very first astro image I ever took:

M45 The Pleiades aka The Seven Sisters  in Taurus

and this is the second:

M42 The Great Nebula in Orion

A bit blotchy, and not superb processing, but for first images they're not bad. Now I don't show these images to demonstrate how clever I am - far from it. The point is that by the time I came to take these images I had a reasonable idea of what I had to do and how to do it, because I had spent at least two months reading as much about this stuff as I could. There really are no short cuts guys - IMHO :) These images were taken with a Nikon D40, which I already had, and a second hand Skywatcher 200p and EQ5 mount that I purchased together on ebay for £200. I had to add motors to the mount so that I could do long exposures (these images are about 30 seconds) and that cost about £80. I still use this kit now, although I now use a second hand Nikon D70 (£99) which I modified myself (£0) :) So you don't need to spend a fortune on kit (although you may very well end up doing that) - hence BudgetAstro :)

Now take a gander at this stunning image:

Orion by Rogelio Bernal Andreo - Deep Sky Colors

Not bad eh? When I first saw Deep Sky Colors I was gobsmacked. I didn't know such images were possible, and Rogelio's website was a huge motivating factor in my decision to take up astrophotography - I urge you to pay it a visit (the link is in the caption above). This particular image is a mosaic of 32 individual frames, with a total exposure time of 28 hours, taken over several nights in October 2010. Rogelio will think nothing of driving for ten hours into the desert to find the darkest of dark skies to take his images, and having acquired the data, he will spend countless hours processing it - total dedication to his craft.  Now if I'm brutally honest with myself, I know that I will probably never take an image of such quality. Not because I don't have the ability (although that may very well be true), but because I do not possess that extraordinary level of  dedication. Oh, and he probably doesn't use budget kit - but that's another story ;)  The point here is setting expectations. You'll find plenty of stunning astro images on Flickr and other image sharing sites - I would suggest that you don't try to match them, at least not in the early stages of your astro imaging career, because you probably won't be able to. Use them for inspiration by all means, and for reference, but don't beat yourself up if your images aren't as good. The creators of those images have probably been doing it for years, and have acquired a great deal of knowledge and skill, and probably some decent kit, along the way. Apart from that, no matter how good you are, there will always be someone doing it better (not sure that applies to Rogelio though!)

I know a guy that is forever buying new golf clubs: new complete sets, new and better (and more expensive) drivers, the latest utility club - it goes on forever. He honestly believes that if he buys better and better clubs his game will improve, and it probably would if it wasn't for the fact that he can't play golf. He just isn't very good, and it doesn't matter how good his driver is, it will never go further than 100 yards. The same applies to astrophotography. I promote astrophotography on a budget, because that's what I do, but you may have more funds at your disposal. I would suggest that you don't go rushing out buying the best kit that you can afford at this stage, because you probably don't know what to do with it (I make that assumption because you're reading this blog :) ). As a result your images, taken with your expensive driver - sorry - telescope, probably won't be as good as mine, taken with kit that cost next to nothing (relatively speaking). You need to learn to crawl before you can walk before you can run, and I hope the stuff I put on this blog will go some way towards giving you the required knowledge. Mind you, I'm still very much a learner myself, and I've made many mistakes along the way, but if I can help you avoid the same mistakes, I'll have done my bit :)

One final point before you doze off: Astrophotography has a reputation for being a bottomless pit, and so it is. As you're experience grows, and your images improve, you'll always be able to find a bit of kit that will improve your images further. Unfortunately, they don't give this stuff away for nothing. My advice would be to keep the plastic well and truly hidden and to set yourself an upper limit above which you will not go - you don't want to end up re-mortgaging the house :)

OK, OK enough already! The next post will be about taking images with just a DSLR and a tripod, which you may already have - you won't need to do too much research for that :)

Cheers guys, and may your skies be forever cloudless :)

Doug