Advances in iPhone astrophotography

Now that I gained some experience in astrophotography with a ccd webcam, I gave the iPhone another shot. I used the adapter I made earlier to attach my iPhone 5s to a 9mm eyepiece. This gave a 900/9=100x magnification with the smaller reflector and a 650/9~72x magnification with the larger reflector telescope.

I photographed both jupiter and the orion nebula with both telescopes and I found that the higher magnification refractor gave better images of planetary objects, while the larger aperture reflector gave better images of deep sky objects (objects beyond the boundaries of our solar system).

When trying to capture jupiter (or the moon) with an iPhone, you will find that the background is so dark, that the iphone will automatically turn the exposure to the max (ISO 2500). This results in highly overexposed jupiters and moons since they send boatloads of light towards your iPhone lens. For some reason, Apple won’t let you manually adjust this brightness and you would be stuck with overexposed jupiters if it weren’t for clever app developers.

Camera+ lets you lock the exposure and focus settings. So I aimed the camera at a lamp, saw auto exposure drop to ISO 100, locked it and attached it to the telescope. 😛 When attached to the telescope, camera+ is constantly refocussing and this just doesn’t work. So I locked that as well and used the focusser on the telescope to sharpen the image. After stacking 14 frames and some photoshopping I got this:

Jupiter and moons shot with iphone through a 90mm refractor

Jupiter and moons shot with iphone through a 90mm refractor

Not bad for an iPhone on a small telescope huh? 😛 Note that I had to RGB allign the image. This is beceause the refractor telescope uses a lens and not all wavelengths have the same refracting index through the lens.

As I said, I also shot the Orion Nebula. To capture enough light I used the Slow Shutter Cam app again. This time I severely pre-processed the photos in photoshop to remove most of the noise. Deep Sky Stacker still rendered the images unusable, but I found registax willing to help me out. It stacked 3 of the 2 second exposure frames and after some after processing in photoshop I got:

The Orion Nebula as captured with my iphone through a 130mm reflector

The Orion Nebula as captured with my iphone through a 130mm reflector

This is by far the best shot I got of the Orion Nebula since it is the only one that shows slightly more than just the inner trapezium nebula. Still though, it is highly inferior to the picture I got from MicroObservatories. They use pretty much the same telescope, but have a special astro camera and a guided mount which allow for much longer exposures with a lot less noise. Anyway, I think some serious progress is noticeable if you compare these photos to the photos I took for the first 3 posts. 😀

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