Learn how you can find the best astrophotography targets for your camera and lens (or telescope)!
By now you may already know that you don’t need a telescope to take deep space astro photos (if not, read: How to do Deep-Sky Astrophotography Without a Telescope).
The essentials are a good tracking mount, some persistence, and a great working knowledge of your DSLR and lens.
But how do you know what targets you should be pointing your camera at? While you might have seen a great image by another photographer, is it the ideal target for you to image?
Use Stellarium to calculate your field of view
Thankfully you don’t have to learn every object in the night sky. The freeware program Stellarium makes it easy to understand and research the sky, and helps you choose targets that are suitable for your setup.
By using the Oculars plugin in Stellarium, you can calculate the approximate field of view (FOV) for you astrophotography setup, by inputting your DSLR sensor information and lens specifications. This gives an accurate depiction of what the target will look like relative to the focal length of your DSLR and lens.
How to customise the Ocular plugin
- Load the configuration window.
- Select the Plugins tab and scroll down to Oculars. Load on startup should be selected, then select configure.
- You can also quickly access the Oculars configuration window on the top right by selecting the square with the circle & tool inside.
In the Oculars configuration settings, you will input your camera(s) and lens(es) or telescope information.
How to add your DSLR / CCD camera and lens
- Select the sensors tab.
- Press Add to add your sensor settings, then proceed to update the settings to the right with your sensor details.
- Name: Add a name for your camera. Normally your model name so that you know which sensor you’re working with if you are loading multiple cameras.
- Proceed by adding the sensor information of Resolution x & y (width and height, in pixels), Chip width & height (in mm), and Pixel width & height (in microns). The easiest way to gather the info is a Google search of your camera make and model. This information should also be available on the manufacturer’s website.
- Next, select the Telescopes tab. Note that there is a lenses tab, but for photographic purposes Stellarium will use the telescope settings to calculate the imaging FOV. In this case lenses refer to Barlow lenses and focal reducers.
- Select Add, to add a lens or telescope, then proceed to update the settings on the right.
- Name: Name your DSLR lens (or telescope lens).
- Add the Focal length and the Diameter (in mm). It is important to note here that you can only add 1 focal length per lens. So if you have a zoom lens, you will have to repeat this step multiple times to input a variety of focal lengths for the same lens. As an example, on my 70-200mm zoom lens I entered 3 focal lengths for the same lens — 70mm, 135mm, and 200mm. Every time I add a new lens or telescope I name the lens and focal length so it’s easy to find. (e.g. Lens 70-200 AT 200mm)
- Leave the other checkboxes as is (Horizontal flip / Vertical flip / Equatorial mount)
Now that you have your sensor and lens added, let’s go about finding and framing your target!
How to find and frame your target
- To ensure you see the target clearly, increase the Milky Way brightness in the Sky and Viewing Options window.
- Using the search window, search for your target and Stellarium will navigate to it on the screen.
- Select the Image Sensor Frame view – located top right of your screen. This will give you the sensor, telescope, and lens options you entered in the Ocular configuration window.
- Select the sensor and lens combination you have added and Stellarium will highlight a red box around your target, which is the field of view you will have when imaging with the chosen lens and sensor combination.
For example, the following image was shot with a Canon 60Da DSLR and a 70-200mm lens at 135mm, as in the example above!
Simple as that!
Explore the sky, try frame some targets and see what works well with your DSLR and lens combination.
Some noteworthy targets to try
- Pleiades (M45)
- Orion Nebula (M42)
- Carina Nebula (shown below)
- North American Nebula
- Heart and Soul Nebula (IC 1805 / IC 1848)
- California Nebula (NGC 1499)
- Running Chicken Nebula (IC 2944)
- Andromeda galaxy (M31)
- Rho Ophiuchi cloud complex (shown above)
- Saggitarius region (M20 / M8)