Astrophotography: an Introduction

Beginning with visual astronomy, there is a chance you would dive in the rabbit hole of amateur astronomy, be it gears, or reading about recent events and discoveries for hours. Or discovering something on your own – we will talk about this in the next article. Sooner or later you will discover “Astrophotography”, a point of no return. And there is a high chance that you would spend thousands of rupees on astrophotography gears. The most expensive gears in Astronomy comes for the field of astrophotography. A hobby where you can contribute to scientific discoveries. You could take pictures of the heavens above that would be highly detailed and can compete for results from a scientific observatory.

Scientific grade Astronomical gears are commercially available. And in the coming years, they will only get cheaper. So, here’s a little introduction you would need to start your journey…

Beginner setup 

If you just starting into astrophotography and don’t know if you are serious enough, then get a DSLR first. A DSLR with a tripod stand is a great starting point. You can just use lenses that come in the kit. And yes, any DSLR will work, camera with a manual setting is all you need. There two main points you will be considering – sensor size and sensor sensitivity (tilt screen will just be a plus point).

Entry-level DSLR is a good starting point. With a lens, mostly it comes with two lenses, 18-55mm and other 75-300mm. And for a beginner, this will work.

The articulated screen is something you will never think you need one but your neck will thank you during high altitude shots.

Now for some technical talks, Sensor Size –

Source: Wikipedia

Light after getting collected in the lens hits on the sensor – that rectangle thing which you see in front of the camera when the lens is not on. The size of the sensor decides signal/noise that the camera will capture.

The above image shows the various sensor sizes available in the market, 35mm is the largest – they are called full-frame cameras. APS-H Canon is next – they don’t make these anymore. APS-C Nikon is the next best choice and then the last stop should be APS-C Canon. You can see a slight difference in the size of APS-C Canon and Nikon. Here are some DSLRs recommended for astrophotography for a beginner –

  1. Nikon D5300
  2. Nikon D5500
  3. Nikon D5600
  4. Canon T7i / 800D
  5. Canon T6i / 750D
  6. Canon T5i / 700D
  7. Canon T4i / 650D
  8. Canon T3i / 600D

You can opt for getting a used DSLR, they work perfectly fine. Always go for a Canon or Nikon for astrophotography, they have the best sensors (personal opinion).

So, what should You get? Well, full frames are better, you will get bigger pictures and the effective field of view will be larger. But there are two problems with these cameras – Heavy and Expensive. So that’s a no go.

One thing with APS-Cs is the effective focal length of the lens is increased by a factor of 1.6X or 1.5X (for Nikon or Canon). A 18mm will work like a 28.8mm lens that’s a problem, increasing the focal length will decrease the usable shutter speed for the lens and since smaller the sensor, higher will be the noise it captures in low light conditions. And that’s something you want to reduce in your photos. The best option would be the Nikon APS-C sensor – if you are looking for something in the lower price range. Nikon D5600 is my personal favorites.

Lenses

Fixed focal length lenses tend to give better results as compared to a zoom lens, due to fewer number of internal elements. For untracked astrophotography always go for wider lenses, by an 18-55mm you can shoot milky-way core and constellations. With wide lenses you can try milky-way landscape, star trails (since you will not be using a star tracker). There is plenty of dimensions in which you can hone your skill of astrophotography, before diving into any serious kinds of stuff like DSOs and investing a fortune on gears. You can shoot all these, but no DSOs, for that you would need something around, 200-300mm range telephoto lens. For a telephoto lens, don’t buy them, I would recommend getting a refractor.

Barn door tracker

Once you are pretty experienced in DSLR + Tripod setup you might want to take some long exposure shots – it might become a little frustrating to stack those 5-10 second images. A dedicated star tracker mount starts from around 30,000 INR. There is a cheaper solution for this – Barn Door Tracker. With a precise barn door tracker, you can take as long as 1-minute shots. Here is a quick introduction –

barn door tracker, also known as a Haig or Scotch mount, is a device used to cancel out the rotation of the Earth for the photography of astronomical objects. It is a simple alternative to attaching a camera to a motorized equatorial mount – which is pretty expensive. A simple single-arm barn door tracker can be made by attaching two pieces of wood with a hinge. A camera is mounted on the top board, usually with a ball head to allow the camera to be pointed in any direction. The hinge is aligned with a celestial pole and the boards are then driven apart (or together) at a constant rate, usually by turning a threaded rod or bolt.

A simple barn door tracker. Source: Wiki

Although this design looks simple but will increase your limiting shutter speed drastically – means you will capture less noise and you can track your targets.

DSLR, Tripod, and a barn door tracker is a decent setup for a beginner.

After getting expertise with DSLR astrophotography, you could get your first dedicated refractor telescope – Astrograph. Here’s a quick introduction on Astrographs.

~AK

Published by Anand Krishna

Amateur astronomer and astrophotographer. Interested in astrophoto processing, astrostatistics, comet hunting, visual and radio astronomy.

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