DSLR Astrophotography: What settings to use for each type of target?

Updated: Dec 28, 2019

A DSLR camera is the easiest way to get into Astrophotography. We started out with a very cheap Canon t3i from Ebay, and upgraded to a Canon 7D Mark II about a year and a half later. We have gotten great images with these, but we also had to trash lots of files over time because the settings we used weren't great for the type of target.

We often get questions on how we choose our DSLR camera settings depending on what we image, and decided to make a tutorial explaining our reasoning.


You can view all the settings we use for each target in our online gallery if you'd like to know what we used for a very specific object.

In this tutorial, we will be talking about the Moon, the Milky Way, Star Clusters, Nebulae, and Galaxies. Woo!




I - THE MOON

Aperture:

11-16

Shutter speed:

1/125 - 1/250

ISO:

100-200

Other:

Crispness level to the Max

Spot Metering



For this target, we need to tighten our aperture so that our big, bright satellite doesn't look all white and washed out in the photo. An F-number between 11 and 16 usually works pretty well. The shutter speed needs to be fast, because you are, in general, just using a tripod and not tracking the Moon on a motorized mount. We like to do either 1/125 or 1/250 depending on the phase of the moon during the night. Both usually work great.


As for the ISO, the lower it is, the less noise you'll have so 100 is the best you can choose, although there is almost no noticeable difference between 100 and 200.


We also like to tweak some other settings, such as the crispness, which we put to the max so that the craters are as visible and defined as possible. We also use Spot Metering to focus as precisely as we can.



Now, let's answer the question of what ISO is best for the next targets in this list.


The ISO number will mostly depend 2 things: your camera and the temperature where you will be taking images. Our basic go-to number for ISO is 400 during the hot summer nights, and 1600 when the temperature outside is chilly. You can go higher if you'd like, but we would not recommend going above 3200 unless you have a very good camera and it is really cold outside.


As a rule of thumb, know that the higher the ISO is, the more you will pick up in your image… including noise.

Temperature has an effect on this, as seen in our 11th Episode of Galactic Hunter.


II - THE MILKY WAY

Aperture:

f/4 or wider

Shutter speed:

Depends on the lens - Use the 500 rule

ISO:

800, 1600 or 3200 depending on the temperature and your camera

Other:

N/A, we keep all the other settings as default.

You may want to play with the temperature slider depending on your personal taste.

For example, a lower temperature (3400 Kelvin) will give you a more blue-ish Milky Way like on the image to the right.






The settings for the Milky Way mostly depend on what lens you are using. If you'd like to know our pick for the 3 best affordable lenses to photograph the Milky Way, check out our video and blog post about it!


The Aperture you'll want to choose is often the widest possible one, so that you can capture as much light as possible in the shortest amount of time before seeing star trails appear on your images.

There is a trick though, we learned it the hard way, but even if you have a camera lens that allows for, let's say, an aperture number of f/1.8, we recommend not going below f/4. The reason for this is that if your aperture is too wide, you will see some slight chromatic aberration around the edges. This is often not noticeable on daytime images, but very visible in Astrophotography as the stars won't look round and sharp.

You can see the comparison between Barnard's Loop at f/1.8 and Barnard's Loop at f/4 HERE.


In short, pick the lowest possible aperture your camera lens allows, but we often avoid going below f/4 and end up happy with the results.


For the shutter speed, do the 500 rule (unless you are using a star tracker):

500 divided by the focal length of your lens equals the longest exposure time you can do without getting star trails.

Example with a 10mm lens: 500/10=50 seconds.

Example with a 24mm lens: 500/24=20.8333, rounded up to 20 seconds.

Note that this is for full frame cameras. If you are using a crop sensor, you'll need to do slightly shorter exposures.



For the last three types of targets, recall that the ISO may vary with temperature, but the F-number will stay the same for all of them…

Well… actually the F-number won't apply if you are using a telescope, since it will serve as your lens. However, if you are NOT using a telescope to photograph deep sky objects with a camera lens, you will need to repeat what we advised for the Milky Way:

The lower the better, but f/4 is a great number to ensure you don't have coma on the edges.


III - STAR CLUSTERS

Aperture:

N/A (your telescope)

Shutter speed:

BULB - 30 sec

ISO:

400, 800 or 1600 depending on temperature and camera

Other:

N/A, we keep all the other settings as default.

Star clusters can be tricky to photograph. We choose to do 30 seconds for our exposures. We actually started with 3 minutes, but quickly realized that this was not necessary. Doing more than 30 seconds for clusters (that do not have any nebulosity, so the Pleaides don't count), will make the stars too bright and their glow can often hide other stars if it is a globular cluster. This is why we now do 30 second exposures for pretty much every star cluster we image.




IV - GALAXIES

Aperture:

N/A (your telescope)

Shutter speed:

BULB - 3 minutes

ISO:

400, 800 or 1600 depending on temperature and camera

Other:

N/A, we keep all the other settings as default.



Although we used to always do 6 minute exposures for galaxies (ex: M101, the Pinwheel galaxy from the first episode of Galactic Hunter), we now find it better to do 3 minutes.


Cutting the exposure time for each shot does not make much of a difference in the quality of the stacked image. Most importantly, it cuts the chances that we'll have to trash some files due to wind gusts or cars passing by with their lights on… by half!




V - NEBULAE

Aperture:

N/A (your telescope)

Shutter speed:

BULB - 3 minutes - 6 minutes

ISO:

400, 800 or 1600 depending on temperature and camera

Other:

N/A, we keep all the other settings as default.




Lastly, nebulae! We prefer to take 6 minute exposures for nebulae, unless they are very, very bright like the Orion nebula where we would do 3 minutes instead.


We also choose to do 3 minutes instead of 6 if we feel there might be a few gusts of winds, or if we are imaging from a location during the weekend where we know cars will pass by often. During a very quiet, week night, we definitely prefer to do 6 minutes as we think it gives us more of the very faint gases.


We hope this helped you out a little bit. Let us know if you how you feel about our settings.

If have your own advice on ISO and F number settings, comment below and tell us why!


Take a look at the video below if you would like to watch this tutorial!


We'll see you next time!


Make sure to follow us on Facebook, Instagram, and YouTube to stay up to date with our work!


Clear Skies,

Galactic Hunter








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