Is 28.6 Megapixels the Best Resolution for Astrophotography?

When you are trying to differentiate cameras, one of the first specifications to look at is the megapixel count (MP).

The higher this, the more expensive the camera, and the better most people assume the camera is.

However, in astrophotography, higher megapixels are not always better and can actually result in degrading image quality. And we can back this up with data:

We looked at hundreds of images taken in the world’s leading astrophotography competition and calculated that the average megapixel count in the DSLR and mirrorless cameras used was 28.6MP.

Read on to understand how we got to this figure and to understand more about megapixels and astrophotography.

How Many Megapixels Do The Best Astrophotography Cameras Have?

We looked at three years of shortlisted images from the Astronomy Photographer of the Year competition to ascertain the Best Cameras for Astrophotography.

From 2019 to 2021, there were 376 images shortlisted and, of these, 205 were taken with DSLR or mirrorless cameras. From these 205 images, we did the math and worked out that the average megapixel count from the cameras used in each image was 28.6MP. The median figure was 24.3MP.

You can see here a chart of the top 18 most successful astrophotography cameras from three years in the competition and their megapixel count:

Megapixels astrophotography cameras
(Top DSLR/Mirrorless camera megapixel counts (MP) in order of most successfully used in the Astronomy Photographer of the Year competition (2019-2021))

As you can see, the top camera overall is the Canon EOS 6D with 20.2MP, and that the majority of the models have something in the region of 24MP to 26MP, with only a couple of cameras with 40+ megapixels.

Whilst the average figure should be taken with a pinch of salt, it does provide evidence that a very high megapixel count is not necessarily better for astrophotography.

This also mirrors the advice of some astrophotographers that the ideal DSLR or mirrorless camera for astrophotography will have a full frame sensor with a resolution in the region of 20MP to 30MP. As you can see in this video (around 5 minutes in):

For more on how we worked out the top astrophotography cameras, see the Best Cameras for Astrophotography.

Why More Megapixels Are Not Necessarily Better for Astrophotography

The reason why having a camera with a higher number of megapixels (for instance, 40MP to 60MP) is not always best for astrophotography is because squeezing more pixels onto the sensor means that the pixels are smaller.

Pixel size is also called ‘pixel pitch’ and is measured in microns (µ). The pixels being smaller results in them being less efficient at capturing light, since they are effectively smaller light buckets. With low light photography, like astrophotography, you can understand why this is not ideal.

In addition, having a larger number of megapixels on a sensor results in worse thermal performance and more noise on the images.

High Megapixel Advantages

There are some positives to having a high megapixel count though.

The main advantage of having a high number of megapixels is that you can have improved detail in your images. This is a positive because:

  1. Taking images that capture thousands of stars and other aspects of astronomical objects does require a high level of detail.
  2. You can create images that can be blown up large on screens or printed without losing any sharpness or detail. This can be important if, for example, you wanted to create an image or video that might be shown on a 4K TV, where it would need to be at at least 8MP before showing any degradation.
  3. You can take a full resolution image but then crop into what you want to focus on and still have a large, detailed photo.

High Megapixel Disadvantages

However, there are downsides to having a high megapixel count:

  1. The reduced low light performance (as discussed above),
  2. The increased file size. The RAW photos you create will be significantly bigger in terms of megabytes (MB). This point is significant because it means that your computer or laptop will need to have the specs in terms of processing power and memory, as well as hard drive storage, to be able to handle the bigger files. This is particularly important in astrophotography where you will often be handling multiple large image files to stack them and/or stitch them together in a panorama in post-processing.
  3. The price. High MP cameras tend to cost more.

Megapixels and Dedicated Astronomy Cameras

Separate to DSLR and mirrorless cameras are dedicated astronomy cameras, often just called CCD or CMOS cameras.

These cameras were used in the astrophotography competition results we analyzed but we have left them out of the results here to focus on DSLR and mirrorless cameras.

The best dedicated planetary cameras for use with telescopes can often have a low megapixel count of around 2MP. Deep sky imaging cameras do tend to have a higher megapixel and also in-built cooling to reduce noise.

If you want to see more on the top dedicated astronomy cameras (including their megapixel count), then see the Best CCD and CMOS Cameras for Astrophotography.

FAQs: Astrophotography and Megapixels

Are more megapixels better for astrophotography?

More megapixels are not always better for astrophotography. Having a count too high can result in degrading image quality by the smaller pixels capturing less light and by resulting in increased noise.

How many megapixels is good for astrophotography?

We calculated that 28.6MP is the average megapixel count used in the best astrophotography images. We therefore recommend that cameras with between 20 and 30 megapixels are ideal for astrophotography.

Does MP matter in astrophotography?

Having too low MP will mean you cannot produce astrophotography images that are sufficiently detailed. Having too high MP can degrade the image quality.

How do I choose an astrophotography camera?

For landscape astrophotography, we recommend DSLR or mirrorless cameras with 20MP to 30MP full frame sensors.

See the Best Cameras for Astrophotography.

What is more important megapixels or sensor size?

Sensor size is more important for astrophotography and full frame sensors are the best, especially for landscape astrophotography.

See Full Frame vs APS-C: What’s Best for Astrophotography?.

What are megapixels in cameras?

Megapixels are the number of millions pixels on a camera’s sensor.

For example, the Canon EOS R6 has 5472 x 3648 pixels on its sensor. This is 20.1 million pixels, or 20.1MP.

Conclusion: How Many Megapixels Do You Need?

The main point to take away from this is that you don’t need to aim for the highest resolution camera if you want something for astrophotography.

Our calculation points to around 28MP being the best average megapixel count but this isn’t exact and so cameras in the 20MP to 30MP range are ideal.

However, in general, you don’t need to overthink this. Our findings also show that people are taking award-winning astrophotography images with DSLR and mirrorless cameras with anything between 12.2MP and 62MP.

Therefore don’t panic if you already have a 40MP+ camera. Our findings show the Nikon D850 with 45.7MP and the Sony A7R III with 42.4MP are right up there, so high-level astrophotographers are having great results with these cameras.

If you are looking to buy a new camera specifically for astrophotography, then you might as well save some money and get a model in the 20MP to 30MP range, rather than going for the higher megapixel model at more cost.

However, if you’ve got the money and want something for more than just astrophotography (for example, high-definition video), then maybe the higher megapixel count is what you need.

We hope you found that useful. Please let us know below if you have any comments or questions.


Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.