Cooled Cameras Vs Mirrorless Vs DSLR

When it comes to acknowledge the advantages and downsides of each camera type, it is important to meet your expectations based on the value of your investment (You get what you pay for). 

Since the development of back illuminated CMOS sensors technology in the last years, CMOS sensors achieve higher sensitivity than CCD Sensors because there has been no improvement on CCD Sensors technology since they reached their maximum performance years ago.

Astro-dedicated Cooled Cameras Manufacturers like ZWO/QHY utilize CMOS sensors like Mass produced consumer Digital Mirrorless and DSLR Cameras makers do in several Astro-dedicated cameras with 4/3”, APS-C and Full Frame format Sensors. Some CMOS Back illuminated Sensors reach up to over 90% Quantum Efficiency.

Most Mirrorless Cameras and the newest DSLR carry sensors with the latest technology for maximum low light sensitivity performance for about half the price of cooled color Astro-dedicated cameras.

Mirrorless and DSLR cameras are mass produced and therefore the best bang for the buck in terms of sensor size.

Consider this comparison worth regarding astrophotography. Mirrorless and DSLR cameras features like burst ratio speed, auto-focus points and in-body image stabilization are not accounted for this comparison because are useless for astrophotography.

Every camera design has its own pros and cons. Let us review in depth all of them.

Cooled Cameras (Monochrome and Color)

Pros:

• Thermal noise suppression feature with Thermo-Electric Cooling system
• Monochrome Cooled Cameras have higher sensor sensitivity to low light than DSLR and Mirrorless Cameras
• Monochrome Cooled Cameras produce sharper images than DSLR and Mirrorless Cameras
• Best suited for long exposure astrophotography with telescopes
• Like Mirrorless Cameras, there is no mirror chamber/no mirror shade casted on sensor
• Can reach prime focus with visual newtonian telescopes
• Barrel shape Cooled cameras are suitable for imaging with any Hyperstar/RASA Configurations

• Compared to DSLR, the shorter body flange back focus distance to sensor allows to fit accessories (i.e., filter sliders, OAG, CAA) within the typical 55mm correctors’ back focus

Cons:

• Over twice the price of Astro-converted Mirrorless and DSLR Cameras with the same sensor size
• Computer hook up is mandatory for camera control and focus procedure
• No WIFI Capability
• Cannot change aperture (f-number) or control focus in lenses with electronic-only focusing system
• Less suited to shoot with lenses
• External power source is mandatory. No built-in battery or memory card options

Mirrorless Digital Cameras

Pros:

• An Astro-converted mirrorless camera can cost about half the price of a cooled color camera with the same sensor size. 
• Best portability: smaller, thinner, and Lighter than DSLR cameras
• Being smaller than a DSLR, is suitable for RASA 8/Hyperstar C8 SCT imaging configurations*
• Compared to DSLR, the shorter body flange back focus distance to sensor allows to fit accessories (i.e., filter sliders, OAG, CAA) within the typical 55mm correctors’ back focus
• No mirror chamber/no mirror shade casted on sensor (excellent at f/3 and faster f/ratios)
• Can reach prime focus with visual newtonian telescopes
• The Lighter Weight is more forgiving for your focuser and mount payloads capacity
• Nice eyepiece simulation with the electronic viewfinder pictures display 
• Computer hook up is not mandatory to control the camera (on compatible models with optional Remote shutter release timer)
• Easy focus procedure with digital zoom in Live View through Camera’s LCD Screen
• Built-in WIFI, Wireless Camera full control is doable with manufacturer’s utility free software
• Can change aperture (f-number) and control focus in lenses with electronic-only focusing system
• Like DSLR cameras, are best suited to shoot with all kind of camera lenses for nightscapes, wide field shots of Milky Way and stars fields
• Utilizes rechargeable built-in battery and memory cards

Cons:

• Noticeable Thermal noise builds up with exposures longer than 3 or 4 minutes at warm nights
• Slight sharpness loss compared with monochrome cameras due to the Bayer RGB filters matrix array
• Quantum Efficiency (Photons/Electrons conversion) loss compared with monochrome cameras and therefore less sensitive to low light
• Less suited for long exposure astrophotography with telescopes
• Some models are not compatible with the remote shutter release timer control

*Celestron RASA 8 Astrograph is compatible with some specific Mirrorless cameras models only

DSLR Cameras

Pros:

• An Astro-converted DSLR camera can cost about half the price of a cooled color camera with the same sensor size. 
• Computer hook up is not mandatory to control the camera (With optional Remote timer)
• Easy focus procedure with digital zoom in Live View through Camera’s LCD Screen
• Built-in WIFI, Wireless Camera full control is doable with manufacturer’s utility free software
• Can change aperture (f-number) and control focus in lenses with electronic-only focusing system
• Like mirrorless cameras, are best suited to shoot with all kind of camera lenses for nightscapes, wide field shots of Milky Way and stars fields
• Utilizes rechargeable built-in battery and memory cards

Cons:

• Noticeable Thermal noise builds up with exposures longer than 3 or 4 minutes at warm nights
• Slight sharpness loss compared with monochrome cameras due to the Bayer RGB filters matrix array
• Quantum Efficiency (Photons/Electrons conversion) loss compared with monochrome cameras and therefore less sensitive to low light
• Less suited for long exposure astrophotography with telescopes
• Bigger, bulkier and heavier than Mirrorless Cameras (specially the full frame sensor models)
• Not suitable for RASA 8/Hyperstar C8 SCT imaging configuration due to large light obstruction
• Mirror shade projected on camera sensor at f/3 or faster focal ratios, possible vignetting issues
• Cannot reach prime focus with visual newtonian telescopes
• Compared to mirrorless and cooled cameras, there is no room to accommodate additional accessories within the typical 55mm correctors’ back focus

Conclusion

Cooled astro-dedicated cameras are better suited for long exposure astrophotography with telescopes than DSLR and Mirrorless cameras. 

Mirrorless and DSLR Cameras have a great value. As can be seen, besides the price variance, the main features differences are the thermal noise suppression system on cooled cameras, and the convenient ease of use of DSLR and Mirrorless Cameras on the field with a remote shutter release and full control of all kind of lenses. 

Telescopes typically tend to have slower focal ratios than fast f/stop camera lenses (With the exception of high speed astrographs like Celestron RASA, Hyperstar/SCT setup or Takahashi Epsilon). They are generally between f/4 and f/10. These slower focal ratios require longer exposures to capture the same amount of detail compared with faster focal ratios. Fast camera lenses have focal ratios typically between f/1.4 and f/3.5. 

The longer the exposure, the more thermal noise it will accumulate.

However, thermal noise on non-cooled cameras can be mitigated with proper dark frames subtraction combined with dithering autoguiding.

Despite the pros and cons of each camera type, the most important fact is the complete harness of your camera potential with the right mount/optics combination and proper exposure techniques and imaging software processing techniques.  A quite experienced astrophotographer can produce superior astrophotography images with a DSLR Camera than a newbie with an astrophotography dedicated monochrome cooled camera.

To browse our Astro-Mirrorless Cameras selection click here. 

To browse our Astro-DSLR Cameras selection click here.