iPhone Astrophotography: ‘magnifi’ iPhone case.
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.
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.
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.
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.
￼￼￼￼￼￼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.
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.
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.