Budget astrophotograhy

We took a Nikon D5100 and Sigma 150-500 f5-6.3 to a designated dark spot in the Cotswolds. I’ve imaged Jupiter with this lens from South Manchester, at 5.1AU distance, so I figured I could get photos at least that good from a dark site, with Jupiter at 5AU distance.

Well here is Jupiter, with some motion blur due to my strong and stable tripod:

Just out of curiosity, I also tried to get some shots of Saturn. Saturn is ~10% smaller than Jupiter, and was also almost twice as far away (9AU distance), so I didn’t expect to get any detail – maybe an oval would be the best result I could manage at 500mm with glass optics?


(Click for viewer)
 

In the creative and poetic words of Donald Trump: “Wrong!” – Saturn’s rings are visibly distinct from the planet itself, although no moons were resolved in any of the photos I took.

That’s Saturn and rings at 9AU distance, on a D5100 body and with a Sigma 150-500mm lens, processed with RawTherapee.

Nice. Unfortunately 9AU is the closest Saturn gets so I’m unlikely to get a better photo with the budget equipment although I’ll take some with a 1metre f/5 Skywatcher when I get time. Jupiter’s closest approach is 4.5AU (10% closer than so I’ll also try Jupiter again with the telescope when it’s at closest approach – the Skywatcher should be able to resolve the atmospheric bands on Jupiter too.

Jupiter and the Galilean moons

After the 2012 RAF Waddington Air Display, I felt that my Nikkor 55-300mm lens just didn’t have the reach or quality that I needed.  The replacement (Sigma 150-500mm) is an excellent lens and was sharp enough to resolve Jupiter’s larger moons, at a distance of approximately 608,800,000 kilometres (about as close as Jupiter gets to the Earth).

Click on a photo to view it at full-size. Includes some photos of our own moon…

On a long exposure, I noticed some dim streaks running parallel to the bright one that Jupiter had produced
The moon also looks quite nice through the Sigma
The moon also looks quite nice through the Sigma. At full zoom, the contrast is reduced a little.
On a shorter exposure, these streaks resolved as the Galilean moons. The big blob is of course, Jupiter.

I saw a very bright blob in the sky, near the moon, and guessed that it was probably a planet.  I took a few photos of it out of curiosity, wondering how much detail my lens could resolve.  I didn’t manage to get any nice “marble” photos of the planet, but did notice several “streaks” following the planet in my longer exposures.  After taking some short exposures of them, I realised that I was seeing moons!

Budget telescope: A Pentax/Nikon hybrid

Now that Pentax SLR cameras are a dying breed, the lenses for them go for next to nothing on eBay.  £30 later, I have six teleconverters to go with my old Hoya 75-205mm lens, in addition to a Pentax/Nikon adapter.  In short, I have a 20 metre focal length on my Nikon DSLR and while the speed/sharpness are going to be terrible, the cost is small.  While the Hoya lens is pretty good even by today’s standards (here),  this is a set-up that should make any photographer cringe:  7.2–19.7m @ f/256.

I had no problem photographing the moon – but finding the moon was quite difficult, since my tripod wobbled all over the place under the weight of all the glass above it.  Focussing the lens was also quite tricky at that distance, the lack of sharpness in the photos isn’t solely due to the amount of teleconverters that I was using.