Archive

Archive for the ‘Astrophotography’ Category

Nacreous Clouds

February 2, 2016 Leave a comment

Twitter was a-buzz yesterday evening (1 Feb 2016) and this morning, as users took snaps of a very rare display of Nacreous Clouds over the UK.

These clouds, also known as Polar Stratospheric Clouds, form high up in our atmosphere (in the stratosphere) between 15 and 25 km in altitude. Normally this part of our atmosphere is very dry but in polar winter temperatures can plunge and conditions can become right for certain clouds to form.

The following pictures were just some of those re-tweeted by @Virtualastro last night; give him a follow to keep up to date.

Nacreous Clouds (named that after the word “nacre”, for mother-of-pearl, due to their iridescent colours) appear when sunlight is scattered through the cloud, and particles within the cloud then produce colours through diffraction processes, making for a beautiful display.

To see a display of Nacreous Clouds you have to head out when the Sun is below the horizon – but only just – during Civil Twilight –  when the Sun is between 0 and 6° below the horizon. Look towards the direction of sunset or sunrise (depending on whether you’re out in the evening or morning), you may see these beautiful clouds for yourself.

Find out your civil twilight times at timeanddate.com. For central Scotland (where I am) the best time to see these clouds is between 0730-0810 and 1650-1730. Remember, these clouds are incredibly rare – you can go years without seeing such a display – and there’s no way to predict whether you’ll see them on any given night, but as they happened last night there’s a good chance they might happen again tonight or the following night, 2 or 3 Feb 2016. Get outside and look up!

 

Advertisements

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.

Image

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.

Image

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.

Image

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.

Image

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.

Image

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.

Image

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:

IMG_6876

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.

Mont Megantic Dark Sky Reserve

August 29, 2011 3 comments

Dark Sky Places Traveling Fellowship Part 1

Thanks to the Winston Churchill Memorial Trust, I have received a traveling fellowship to visit all of the International Dark Sky Places in North America between 22 August and 03 October 2011. This series of blog posts will detail my visit to each of these  very dark places.

Mont Megantic International Dark Sky Reserve

The Galactic Centre from the summit of Mont Megantic

Situated a few hours east of Montreal in the Quebec province of eastern Canada, Mont Megantic National Park is home to a research observatory, a public observatory, and the ASTROlab science centre. In 2007 it was named by the International Dark-skies Association (IDA) as the world’s first International Dark Sky Park (IDSR).

This designation differs from the similarly named International Dark Sky Park (IDSP) designation in that the IDSR was introduced to allow parks that did not fit in to the US national park model to still aspire towards IDA status; that is, the IDSPs were created to apply to large parks under federal control with no population within the park boundary; the IDSR status is intended for parks who want to work with their surrounding communities towards darker skies for all.

And this is exactly what Mont Megantic National Park did, and in 2007 it was announced as the world’s first (and as yet only) International Dark Sky Reserve.

Astronomy Tourism at Mont Megantic IDSR

Mont Megantic IDSR has a range of incredible resources for astronomy tourism, including the ASTROlab science centre, a public observatory, and a professional observatory with a 1.6m scope which is sometimes opened to the public to use.

The ASTROlab runs astronomy events every Friday night over the summer, including a visit to the ASTROlab, observing at the public observatory (weather permitting) and a tour of the professional observatory.

Mont Megantic Observatory 1.6m scope

Each of these resources existed long before the IDSR status was conferred: the professional observatory was built in 1979; the ASTROlab and the public observatory in the 1980s. It was in part to protect the dark skies which these facilities rely on that the IDSR status was granted.

However there are two main difference between Mont Megantic IDSR and any dark sky places in the UK. They are: there is already a well-established winter tourism sector in the area, based around snow sports, and so astronomy tourism isn’t offering to fill an otherwise empty season, as it does in the UK; and it is possible to run astronomy events at Mont Megantic during summer months, unlike the UK, due to Mont Megantic being around 5-10° further south that the UK.

These factors mean that tourism seems to have been far less of a driver in creating the IDSR at Mont Megantic that it is in the UK, where it is really the sole reason, and the driving force in persuading the community around any dark sky place that there are larger benefits than those that accrue to astronomers.

During my visit to Mont Megantic IDSR I stayed at the incredible Haut Bois Dormant in Notre Dam des Bois, just a few miles from the park, run by the delightful Julie Demers. The entire length of the road running through Notre Dam des Bois was festooned with flags advertising the IDSR, and inside the guest house the IDSR was similarly promoted. However speaking to Julie it seems like the astronomy tourism sector is still to grow to its full potential. One limiting factor seems to be the fact that organised astronomy events are only run on Friday nights, and for the rest of the week you’re on your own.

Flag promoting the IDSR in Notre Dam Des Bois

During my visit I met with four people involved in a variety of ways in astronomy tourism at the park. My visit was arranged by Pierre Brosseau, the communications manager at the ASTROlab, who explained a little of the philosophy behind the creation of the IDSR, which he suggested – as did others – was more to do with fact that it was the “right thing to do” and not as much about generating money for the local economy through tourism.

I was also given a guided tour of the professional observatory by Robert Lamontange, the executive director of the observatory, and later that night by Bernard Malenfant, chairman of the board, and founder of the Astronomy Super Festival, who had been there as long as the observatory (legend has it he came in the box with the primary mirror).

The next day I met with Tania Pinard, the Megantic area tourism officer who took me on a tour of businesses that use astronomy to attract visitors in innovative ways, including the Spa Le Montagnais, which offers stargazing from outdoors hot tubs during the Perseid Meteor Shower!

Later that afternoon I met with Sebastien Giguere, the head of education at ASTROlab, who gave me a wealth of information about the public programme within the IDSR.

Dark Sky Survey of Mont Megantic IDSR

On my final night at the park I went to the top of the mountain and took some SQM-L readings of the sky, as well as some astrophotos to gauge just how dark the sky is. The SQM reading average of six readings was 21.4, very similar to Galloway Forest Dark Sky Park and Sark Dark Sky Island. I repeated this reading in the back garden of the Haut Bois Dormant in Notre Dam Des Bois town, and the reading was 21.3, not appreciably different! The Milky Way stood out prominently in both locations, and could be seen all the way to the horizon.

All-sky image showing Milky Way and galactic centre from Mont Megantic IDSR

 

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.

%d bloggers like this: