What do you need for astrophotography?

If you’re wondering what you need for astrophotography, then this is going to answer your question. In particular, I’ll explain the different equipment that will enable you to get started and what you’ll need for the different types of astrophotography, be it Night Scape Photography with the Milky Way, Deep Sky Photography, or Planetary astrophotography.

For astrophotography, depending on your target, you will need a camera, a lens (or telescope which acts as a lens), a tripod or mount, and a computer to stack and process the images. For longer exposures, you may also need a guide scope and camera to keep your target from moving.

You will find information about different types of equipment elsewhere on this website, such as on this page about how to get started on a tight budget. Here I want to focus on what camera you might need to get better results from your astrophotography and how to decide what is best for you.

Do you need to get your DSLR camera modified?

If you are using a DSLR camera for astrophotography then one thing you could consider is having it astro-modified to make it more sensitive to Hydrogen Alpha light which normally registers as red. This kind of modification involves removing the filter in front of the camera sensor and therefore the camera will need to be dismantled and then put back together.

You can do this job yourself if you want, but I wouldn’t recommend it as you could damage your camera. I didn’t risk it and asked a friend who owns a photography shop to get it done for me. What were the results of an unmodified vs a modified DSLR? Nothing short of amazing!

Here is a detailed article looking at how to do this modification and what kind of difference it makes to your astrophotography.

Test: unmodified Canon 600D v Modified Canon 600D

To show the difference modification can make to a DSLR camera, I performed the following test:

I asked a friend who owns a Photography Business to remove the filters in front of my canon 600D, also known as astro modification. The filters in Canon DSLRs block much of the hydrogen alpha and IR wavelengths and when removed should improve astro images captured by the camera because of the added signal received in these wavelengths. This should be an improvement, especially for emission nebulae.

I took 10 photos of the Orion Nebula before I got my DSLR camera astro modified in October 2020, (Image A). I then took another 10 photos of the Orion Nebula after the astro modification was done, (Image B). Both images were processed in the same way to create a direct comparison between modified and unmodified image:

  • the 10 lights were stacked in Sequator and darks were used to reduce the noise.
  • sub exposure length was 10 seconds
  • An Astronomik clip-in CLS filter was used
  • Canon 600D was attached at prime focus to Celestron 130SLT telescope and mount.
  • Stacked images were processed in Photoshop
Orion Nebula taken with Canon 600D unmodified
Image A – taken with an unmodified Canon 600D
Orion Nebula taken with astro modified camera
Image B – taken with astro modified Canon 600D

Image B shows clearly how much more hydrogen alpha was captured as a result of the astro modification. Just look at the added detail! I have since gone on to create even better pictures of the Orion Nebula with my DSLR, so be sure to check those out!

Conclusions of the Test:

My test confirmed that It is worth having a DSLR astro modified because the camera will become significantly more sensitive in the Hydrogen Alpha wavelength and therefore more details will be captured in the same amount of time. It is possible, of course, to image without getting this modification done but you’ll need much longer integration times to capture as much detail as with a modified camera. For this reason, I can recommend you go ahead and get the modification, it is worth the money.

As a modified camera is more sensitive to Hydrogen Alpha, a signal that is strong in most emission nebulae, the signal-to-noise ratio will be increased and the quality of the image should also improve.

Suggested Resource

I include this excellent video by Cuiv the Lazy Geek in which he goes through the different pieces of equipment you need for a setup that will allow you to start imaging deep sky objects (DSOs):

I hope you find this video as interesting and informative as I did!

Do I need a cooled camera for astrophotography?

A simple answer to this question is no, you don’t, …but should you?

I have bought a new cooled camera because I thought it was necessary and would enable me to get even better pictures of deep sky objects. The main reason I decided to switch to a dedicated astronomy camera with cooling is that I wanted to reduce the noise in my images.

I bought a ZWO ASI533 MC PRO camera and have used it with my existing setup rather than the Canon 600D DSLR that I was using for almost two years. It has definitely made a huge difference!

In the summer of 2022, I found that the amount of noise in my images taken with my modified Canon 600D was very high. I tried to take many images and for some targets, I managed up to 7 hours or so of 2-5 minute exposures but still, the noise was so bad that some targets were too difficult to get a good result and one I did manage, the Wizard Nebula, was not spectacular.

In summer, the sensor was reaching, on average, 7 degrees C higher than ambient temperature and I regularly observed that through the night my camera sensor was showing 34 C according to APT (Astrophotography Tool software). Even with stacking the remaining noise was extremely hard to deal with and my images were either unusable or quite bad and lacking detail.

Now, with my new ZWO cooled camera, I am cooling the sensor down to 0C any darks I use to subtract noise are also calibrated at 0C. Before with the DSLR, it was impossible to match darks taken at the same temperature as the lights. Even now, when summer has gone using my DSLR would result in a sensor temperature of roughly 20C given an ambient temperature of 13C. The noise reduction from 20 degrees plus down to 0 should reduce the noise substantially. For every 6-7 degrees that the camera sensor temperature drops the noise is halved (Photometrics.com), and so this equates to the following:

Noise Reduction with Camera Sensor Cooling

Sensor Cooled Below Ambient (°C)% Noise level
0100
-750
-1425
-2112.5
-286.3
-353.1
Change in noise level of image with sensor cooling (original research)

Remember also that if your images are each reduced in noise then they will also be further reduced by your stacking sequence and this makes the difference even greater than above. So, for my camera and my current situation, if my ambient temperature is 13 then I would be reducing my sensor temperature by 20 degrees with my new camera compared to my DSLR and this would reduce noise in each image by almost 88% according to the above.

In summer when my DSLR was at 34C I would be reducing noise in each image by about 97%. All of this is assuming the cameras operate similarly but in reality, the ZWO camera has much lower dark noise than the Canon 600D. So if anything our comparison is underestimating the difference slightly.

So, if you care about noise, and you should, especially for deep-sky objects, you should consider getting a cooled camera. DSLRs are not designed to be cooled although a modification could be designed. The most practical way to do this is with a modern low-noise cooled camera. The results are amazing and have certainly improved my astrophotography!

If you would like to see my latest images as I release them then follow me on Instagram.

What camera for astrophotography: mono vs colour

When considering whether to buy a cooled camera, I saw that some models were mono and some were colour. These colour cameras are also referred to as OSC – one-shot colour cameras. I actually decided to buy an OSC rather than mono, but did I make the right choice?

It’s not easy to answer this one because, on the one hand, it is easier and more familiar to me to use a color camera. You just point and shoot and you have an RGB colour image. With a mono camera, you need to take at least three photos to get an image, one with a red filter, one with a blue, and another with a green filter. After this, you can put the three images together and you’ll have an RGB colour image.

The photographic quality is better for the mono camera because to get the RGB colour image in the OSC camera, the sensor has filters of red, green, and blue already over the pixels of the sensor. The pixels are divided up into the pattern RGGB which means for every four pixels of a color camera sensor, one is red, one blue, and two are green.

The Bayer Matrix filters over pixels on the colour camera’s sensor. Image source: Wikimedia Commons

A mono camera has no filters over the pixels and so 100% of them are available to image the target and one filter is then placed over the whole sensor.

This means that while a mono camera uses all of the sensor’s pixels for an image the OSC divides the image into three channels. However, it will take much longer to get your final image in full colour.

According to Chris Woodhouse (2017), a monochrome camera will have a slightly better resolution than a colour camera. I decided to research this to discover how much better image resolution would be for a monochrome camera compared to an OSC colour camera using data from several sources (see below).

My Research: How much better is image resolution for a monochrome camera vs. a colour camera.

The aim of this research was to determine how much difference there is between the resolution of an image created by a monochrome camera sensor compared to that created by a colour camera or OSC. This should be very helpful for anyone who is considering buying a monochrome camera, and is probably more familiar with colour cameras. This would mean making a change and the natural question here is whether or not it is worth the extra time and effort (and perhaps cost) of using a monochrome camera rather than a colour camera.

The data I used for this research is from the following sources:

Each pixel on a monochrome sensor captures 3 times as many photons of light as that on a colour sensor and the sensitivity is improved 1.5 times, resulting in finer details in the image, (PixelRajeev.com).

The Bayer Matrix in a colour sensor reduces the light captured by each pixel to 33% according to the above source. This is illustrated below:

Incoming light and resulting colours captured by the sensor with a Bayer matrix image from Wikimedia Commons

This seems oversimplified and so taking the data given we can make some calculations to see if this is true and then propose an accurate answer that might help to settle this issue for someone looking at using a monochrome sensor.

Assumptions: the filters in the Bayer Matrix are perfect in that they only transmit the colour it is designed for, in reality, there is some small overlap. Also, it is assumed that pixels are all registered as capturing the light of the filter colour, whereas in reality software demosaics the image, meaning it actually adjusts some of the pixels and may change the colour to get a better picture. Demosaicing only happens in colour cameras.

So here is what I have found from making calculations on the data:

  • It takes three times longer to get an OSC-comparable image with a monochrome camera because we need to image through three filters – red, green, and blue.
  • Light captured by OSC camera captures 25% red and blue light and 50% of green.
  • If you image with an OSC camera for one hour and a monochrome camera for one hour on each filter you will capture 3.33 times as much light and if you image for one hour total divided amongst the three color filters the difference in the light captured is 1.11 times, a slight improvement.

Conclusion: in reality, the actual difference in any resulting OSC image is likely to be even less. Many astrophotographers claim that monochrome cameras provide much better quality images and that only appears to be true if you take the time to image through filters which takes three times as long.

In order to determine the actual difference of resolution between a monochrome camera and a colour version would be to compare the MTF chart or Modulation Transfer Curve of both types of camera. This gives a good comparison such as the one here that compares the MTF curves of a Canon 30D for different colors and shows the effect of the Bayer Matrix filters. There is a sharp fall at higher frequencies for contrast and resolution of the image. MTF charts are usually given to compare lenses but it can be used to compare two cameras that have the same lens and optical setup.

The only valid comparison, therefore, is to compare a full colour and a black-and-white picture and to see which has better resolution. The monochrome image will win. But, we care about colour, don’t we?

Just remember that if you are thinking about whether it is worth buying a mono or colour camera, there is no clear winner. The colour camera is convenient and saves time, the monochrome camera can produce better pictures but takes longer. Perhaps just take more images with an OSC?

Final Words

We have looked at what you need for astrophotography and by now you should have a much better idea of the kind of camera (DSLR, dedicated astronomy camera, cooled camera, monochrome or OSC), whether it should be modified (if a DSLR). We have focused mainly on the camera and on other pages we shall focus on the type of mount, filters, telescope, etc.

Enjoy the equipment you get and have fun imaging!