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iPhone Astrophotography: ‘magnifi’ iPhone case.

January 26, 2013 3 comments

This is a guest post by Andy Hewitt @andyuk71

I received a 6” reflecting telescope for Christmas – a Jessops’ TA900-114EQ. Blessed with clear skies and a glorious full moon, I focused the 20mm eyepiece and brought the moon in to sharp relief. Memories from my childhood came flooding back of a Prinz Astral ‘scope my father had bought my brothers and I, many Christmases ago, and I was thrilled to feel the same excitement I had had as a child. Naturally in today’s digital age, I wondered if it was possible to capture these wonderful pictures on my iPhone. I soon discovered that the iPhone is not naturally disposed to taking these kind of images, but a quick search on the net revealed that there’s quite a number of amateur astronomers out there obtaining passable results with them. The light-metering of the phone means that unless the phone is clamped in some way to the lens, unwanted light will leak in and decent results will be hard to get. Some kind of clamp arrangement would also possibly guarantee correct alignment between the phone’s lens and the eyepiece’s aperture. The image below was obtained by holding my phone to the telescope’s eyepiece.

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HR12.5mm lens.

A reasonable result after cropping and some tweaks in iPhoto, but the difficulty of aligning the lens with the eyepiece, coupled with the promise of even better results made my mind up to research if there was a better solution out there.

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Searching online, I found a couple of different options available in the form of cases, and decided to plump for the ‘magnifi’ (seen above), a Kickstarter project from the States that received enough backing to launch it into production. Not currently available direct from the UK, purchasing is easy enough via PayPal, though the mooted Custom’s charge was a suck it and see event… The device isn’t exactly cheap at £61.53, though I was prepared to take a risk, hoping the results would justify the expense. With international postage charges of £9.83, and an £8 Royal Mail handling charge, the grand total came to £79.36. It arrived in just under two weeks, as promised, and on opening, included everything listed on the website. The package comes with 4 rubber ring adapters to attach to your lenses to ensure a snug fit – in practice, this works without a hitch – and they fit very tightly to the lenses themselves; some people may find them a bit fiddly to put on, but no more than that. The case and lens attachment aren’t fitted together in transit, but again, this is really simple to do.

I took the first opportunity that came along to use the magnifi case, with the moon as my target object. It was at this point that certain realities became apparent. Firstly that the lenses supplied with my Jessops 6” reflector, are probably, erm, not the best thing about the telescope.

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As you can see in the picture, the barrels are short and the higher-powered the lens is, the less black plastic there is to clamp the magnifi to. Fortunately, the HR20mm is sufficient in this area and a good lens to view the moon with. The old moon in the new moon’s arms promised a lot with a terminator giving good contrast and cutting down the glare, but ultimately results were disappointing, and for a number of reasons.

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With the phone slotted into the magnifi case and the case clamped to the lens, a relatively large mass is added to your scope – at this point you get the measure of your mount. With the phone turned on to the camera app, it’s possible to view the moon via the phone’s screen and even bring in into focus. However, the fun starts when, after carefully aligning and framing your (moving) object, you press the button to take the picture and hey presto, you’ve introduced camera-shake. I tried numerous different strategies to overcome this issue with varying degrees of success. Undaunted, I moved my sights onto Jupiter and was rewarded through my telescope’s lens, by seeing the familiar bands of Jupiter with my own eyes – my first time – and rather unbelievably, the four visible-from-Earth moons (I think). I badly wanted to capture these images digitally, and did, but there was too big a gap in quality between what I was viewing through the eyepiece and what was being displayed on my phone, and ultimately being recorded.

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A frustrating interval of several cloudy night skies ensued then, but I was far more successful at my next attempt. Steve had pointed me in the direction of an iPhone app called SlowShutter and this proved to be a revelation. With a full moon to aim at on this occasion, I was determined to justify the expense I’d laid out. SlowShutter enables you to set the exposure time and also factor in a delay for shutter release. I set a 0.5 second exposure and a 5 second delay. After a bit of trial and error, dividends were soon in abundance and the gap between the eyepiece and iPhone was metaphorically narrowed.

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Full moon, HR20mm lens, some tweaks in iPhoto.

Some pros and cons. SlowShutter is a great app but, unlike the iPhone’s camera app, it doesn’t permit a digital zoom of the image in view – sometimes this is necessary to overcome the black circle effect that occurs with some lenses when using magnifi, dependent on their viewing aperture diameter. Depending on lens aperture size, the black circle can manifest in two ways, one you can zoom-in past, or one you can’t. I need to test this further though with some different/better eyepieces. Frustratingly, the barrels on my lenses are just physically too short to clamp magnifi to satisfactorily. I’m still very new to astronomy and astrophotography. I know barrels can be replaced or extended but I’m not entirely certain on how this affects the focal length of the lens.

Unless you have a rock-solid mount, pressing the button to take the picture will inevitably introduce blur to your image, which of course is the last thing you want, even the smallest movement is of course, magnified greatly: shutter delay overcomes this. Another problem is exposure. Images like the moon are very bright and play havoc with the light meter of the iPhone’s camera. However, I experimented with tapping on the screen in the light and dark areas, allowing the phone to re-meter and give a better exposure – SlowShutter has this facility too and even has an exposure lock feature, which aids between shots as normally the app would re-expose for the next shot.

Magnifi does allow you to take pretty decent images of what you’re seeing through your telescope, and as far as iPhone astrophotography contraptions go, it certainly offers a professional looking and well-made, thought-out practical option. It’s still early days for me and my use of magnifi. I live in a busy city with depressingly high levels of light pollution, so I’m limited to possible objects to capture. However, I envisage that with more experience, better lenses and of course, dark skies, the magnifi will prove to be an invaluable piece of equipment for me and other amateur astrophotgraphers.

Image below captured with HR12.5mm lens.Image

iPhone Astrophotography: Night Modes

January 8, 2013 5 comments

As a follow-up to my previous post about astrophotography with an iPhone, I spent a few minutes tonight playing around with a new app called Night Modes, which claims to allow you to have real (hardware) shutter speeds of up to one second, a substantial improvement on previous apps which have used software tricks to try and mimic long exposures. These are next to useless for capturing star-scapes, photos of the night sky overhead. Even one second exposure is rather short, and will only let you catch the very brightest stars, but still more than enough to make out the constellation patterns.

Night modes allows you to set the exposure to 1/15, 1/8, 1/4, 1/2 or 1s, lets you deactivate the autofocus (which you’ll have to do – autofocus gets confused when you try and snap a picture of the night sky). The app also allows you to set a timer delay, to avoid hand-shake blurring your image as you push the button.

Another essential item to avoid camera shake is something you put your iPhone on when the exposure is being taken – ideally a tripod, but you can rest it on anything that won’t wobble too much. In the absence of a tripod adaptor for my iPhone I simply placed it on the table in my garden, propped against a book, pointing roughly towards Jupiter.

After setting a 5s delay (enough time, I reckoned, for me to place my iPhone gently on the table, and for any wobbles to die down), disabling auto-focus and auto-exposure, and setting the exposure to the maximum 1s, I sat the iPhone down and waited. And this is what I got:

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Orion, Taurus and Jupiter, taken with an iPhone 5 using Night Modes app, 1s, 3200 ISO

Not the best image ever, but you can make out Orion with those phone lines running in front, and in the top right corner you can see the bright (and slightly over-exposed) Jupiter above the V-shape of the head of Taurus. The next step will be to take some images out of the city, somewhere with less light pollution, so I don’t get that horrible orange glow to the sky.

New Telescope for Christmas?

December 25, 2012 Leave a comment

Are you lucky enough to have been given a shiny new telescope for Christmas? If so you have joined the ranks of thousands of other stargazers around the world, and you’re no doubt eager to get outside and use your new toy.

But a new telescope can be quite a complicated and daunting piece of hardware, so let’s go through the basics, to help you on your way.

1. Read the instructions!
Like most complicated pieces of equipment your telescope should have a user manual or a set of instructions. If not, try looking online. These instructions will help you assemble your telescope, and become familiar with all of the various parts, including the finder scope, eyepieces, focus mechanism, and motion controls.

2. Align the finder scope in the daytime.
The small telescope that sits on the main tube of your telescope is called the finder scope. You can use this to locate an object in the sky, and if the finder- and main telescopes are aligned (facing in exactly the same direction) then that object will be in the centre of the field of view of your main scope too. Aligning the finder scope is a bit fiddly though, so do it in the daytime before you observe. Point your main telescope at a specific distant object, like a far away tree, or chimney pot, or transmitter mast. (WARNING: don’t point it anywhere near the Sun). Once that object’s in the very centre of your main scope field of view, look through your finder scope. The chances are it’s not in the crosshairs here, so adjust the position of your finder scope until it is. This is usually done using small screws that physically move the finder scope around till it’s aligned with the main scope. Now it’s ready to use tonight.

3. Pick the correct eyepieces.
Your scope probably came with a couple of eyepieces. These should be marked with their focal length, in mm. The higher this number the lower the magnification. So a 25mm eyepiece will provide smaller images than a 10mm eyepiece. But magnification isn’t everything. In most cases you should start with your least powerful eyepiece, which gives you the largest field of view. Once you’ve found your target you can substitute a more powerful eyepiece in, to get a larger image. It’ll be larger, but dimmer. After all you’re spreading the same amount of light over a larger image. You’ll also notice any wobbles in the telescope much more when you’re using a higher power eyepiece. So your low-power eyepiece will give you brighter, clearer images, even if they’re much smaller.

4. Learn how to move around the sky.
All telescopes are different, and the way that you move them from one object to the other varies. In general though they will all have hand-screws that you can tighten and loosen to lock the telescope in position, or to move it. There may also be dials or screws to give fine adjustments to a telescope’s positioning. On the other hand, some telescopes – called dobsonians – are just moved by physically nudging the telescope tube. However yours moves, you’ll be doing this in the dark, so practice, practice, practice until it’s second nature to you. Some motorised telescopes find and track the stars and planets for you, but these are a bit trickier to set up properly, so read the instructions.

5. Choose the right targets.
Don’t go hunting down very faint elusive objects on your first night out; stick to the brighter ones that are easier to find. On Christmas night and for a couple of days after, the Moon and Jupiter are up in the evening. Even a small telescope will give great views of the Moon (although you’ll get a better view when it’s not quite so full, and you can observe the line between light and dark, called the terminator line) and will let you see Jupiter’s moons, looking like four tiny specks next to the bright planet Jupiter.

Whatever you look at with your new telescope, enjoy it, and remember that patience is a virtue. You’re the proud owner of a great stargazing tool, but you need to practice to get the hang of using it properly.

Let everyone know what you’ve been observing, and how you’ve found your new telescope, in the comments below.

iPhone Astrophotography: My First Attempts

June 24, 2011 6 comments

This evening I decided to try some iPhone astrophotography. This blog post will let you see how I got on, and give you the info you need to get started yourself.

While the iPhone 4 camera is far from ideal for astrophotography (the sensor is small compared with a DSLR; in fact it’s not even as good as most point and shoot cameras) it does have one distinct advantage – it’s usually very much to hand, just in my pocket in fact.

There are two kinds of astrophotography you can do with an iPhone: with and without a telescope. The former is called afocal astrophotography, but it is the latter that I tried out tonight: just using the iPhone camera, some extra hardware, a 59p app, and a clear sky.

Afocal Astrophotography. Simply hold the camera to the eyepiece of a telescope (or binoculars) and snap a picture of whatever is in the field of view. For this you can just use the standard camera app on the phone to snap a picture, and it’ll use software to ensure that the image is exposed correctly (although this might not always work). I’ve tried this once before, using the Moon as my target, with decent enough results:

Pic of the moon taken on my iPhone 3GS held to the eyepiece of my 110mm TAL-1 telescope

You can also buy several apps that claim to allow you to take longer exposures, even letting you use a bulb setting (this isn’t actually possible with the iPhone shutter hardware – each of these apps is actually using a clever software work around, but you’re not getting a true 60 second exposure when you set your “shutter speed’ for 60 seconds).

The apps that I use are:

Slow Shutter Cam: has shutter speeds of 0.5, 1, 2, 4, 8, 15′ and a B (bulb) setting, plus a crucial self timer delay to prevent wobble when pushing the “button” to take the shot (£0.59 on iTunes App Store)

Magic Shutter: has shutter speeds of 1, 2, 4, 8, 15, 30 and 60′ and a B (bulb) setting, but no self timer (£1.79 on iTunes App Store)

Both of these apps have a variety of software setting to allow you to get the best picture; tonight I used Magic Shutter with a 60s shutter speed.

(These apps might allow you to take better images while the camera is mounted to a telescope, but I haven’t tried this yet. Watch this space for test of this later in the year.)

Afocal Astrophotography Hardware

The main obstacle to taking long exposure shots with the iPhone (apart from the fact that the hardware won’t actually let you!) is that you need to make sure that the iPhone doesn’t move at all during the duration of the exposure, so holding it in place with your hand isn’t an option. Luckily there’s a great gadget available from a company call Magnilux. The device is called the Magnilux MX-1 Telescope Adaptor, which allows you to attach your iPhone to any telescope eyepiece. It also doubles as a tripod adaptor.

Magnilux MX-1 Telescope Adaptor

Magnilux MX-1 Telescope Adaptor with iPhone 4 attached (works with any iPhone model)

Magnilux MX-1 Telescope Adaptor configured as a tripod mount

Astrophotography Without a Telescope

Tonight I didn’t connect my iPhone to my telescope since my target, the International Space Station (ISS), moves so quickly and travels across such a large part of the sky that you need as wide a field as possible to catch it.

To capture the ISS you need a long exposure (use Magic Shutter app – see above). The pass tonight lasted 4’19”, and traveled 90° through the sky (from 254° WSW to 164° SSE). The iPhone 4 camera field of view is only 60.8° so I couldn’t capture the whole pass. Instead I decided to try to capture a 60s exposure as the ISS rose to its highest and brightest, at 206° (SSW).

With a 60″ exposure, of course, I had to have my iPhone mounted to a tripod. I could have used the Magnilux MX-1 Adaptor set up for tripod mode (see above) but instead I opted to use my new Kungl iPhone case with built in tripod thread, which I attached directly to my tripod.

Kungl iPhone Case

This held the iPhone still, and using the Magic Shutter app set to 60″ exposure I managed to get this image:

The ISS passing over Glasgow, iPhone 4 Camera, Magic Shutter App set for 60″ exposure, 2344, 23 June 2011

Far from ideal, but not bad given (a) it was my first attempt, (b) I had one chance to take the image before the ISS faded from view, (c) the sky was very bright (this was taken at 2344 on 23 June 2011, just after midsummer, with the sky just out of civil twilight), (d)  cars kept driving past (note the light art in the foreground!).

Once the sky darkens again later in the year I hope to test this set up under a truly dark sky to see whether it can pick up sharp star images. I suspect that might be tricky!

If anyone else has tried iPhone Astrophotography please let me know in the comments.

UPDATE: See my latest attempts at iPhone astrophotography here.

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