In astrophotography, the sensor size (format and aspect ratio) directly impacts the field of view, resolution, signal-to-noise ratio, and post-processing workflow, making it a crucial factor when selecting a camera. Below is a detailed analysis of how sensor size affects astrophotography and its significance.

 

Field of View (FOV)

Sensor size determines FOV:

Larger sensors capture wider areas of the night sky.

• Full-frame (e.g., IMX455): Ideal for wide-field targets (e.g., Milky Way, large nebulae like M31, North America Nebula).
• Smaller sensors (e.g., IMX533): Better for high-resolution close-ups (e.g., planets, small galaxies like M51).

Aspect ratio affects composition:

• Square (1:1): Best for symmetrical targets (e.g., Ring Nebula M57).
• Rectangular (4:3 or 3:2): Ideal for elongated targets (e.g., Orion Nebula).

Image Credit:  studiobinder.com

 

Resolution & Pixel Density

1. Pixel sizes & sampling rate:

• Small pixels (e.g., 3.76μm IMX533): Great for planetary imaging or short-focus telescopes but require matching optical resolution.
• Large pixels (e.g., 4.63μm IMX571): Better for long-exposure deep-sky imaging due to higher light-gathering ability.

2. Balancing sensor size & pixel count:

High-resolution, large sensors (e.g., 61MP IMX455) offer wide-field and detailed shots but demand precise tracking and generate massive data.

Signal-to-Noise Ratio & Sensitivity

1. Light-gathering advantage of large sensors:

Larger sensors capture more signal per exposure but may require longer exposures to compensate for edge vignetting. Small sensors (e.g., IMX533): Improve pixel efficiency by cropping, reducing noise in unused areas.

2. Cooling requirements:

Larger sensors generate more heat, requiring stronger cooling to suppress thermal noise.

 

System Compatibility

1. Telescope image circle matching:

The sensor must fit within the telescope’s corrected field (e.g., APS-C needs a coma corrector; full-frame requires premium flatteners).

2. Mount strain:

Larger/heavier sensors may affect equatorial mount balance and tracking accuracy.

 

Post-Processing Complexity

1. Mosaic stitching:Smaller sensors may require multiple frames for large targets, increasing calibration and alignment work.

2. Edge aberration correction:

Large sensors show more distortion, chromatic aberration, and vignetting at the edges, demanding rigorous flat-field calibration.

 

Special Astrophotography Applications

1. Planetary imaging:

Small sensors (e.g., IMX533) excel with high frame rates and global shutter.

2. Narrowband imaging:

Square/small sensors reduce filter costs (e.g., 7nm H-alpha filters)

3. Scientific measurements:

Sensor size must match the calibrated FOV for precise astrometry

 

Common Sensor Sizes Comparison

Format	Example Sensor	Sensor Size	Camera
APS-C	IMX571	1.8"(23.48x15.67)	ATR2600M ATR2600C
Full-frame	IMX455	2.7"(35.98x23.99)	SkyEye62AM SkyEye62AC
Square	IMX533	1"(11.28x11.28)	ATR533M ATR533C
Small	IMX585	1/1.2"(11.2x6.3)	ATR585M ATR585C

 

ATR 2600M/C

SkyEye62AM/AC

ATR533M/C

ATR585M/C

Selection Tips

1.Deep-sky Imaging: Prioritize larger sensors (e.g., IMX571); full-frame if budget and system allow

2. Planetary Imaging: Small sensors + high-speed readout (e.g., IMX533/IMX585).

3. Hybrid Use: APS-C (IMX571) or square sensors (IMX533) offer flexibility.

 

Conclusion

Sensor size critically affects FOV, resolution, noise performance, and system compatibility in astrophotography. Consider:

• Target type (wide-field vs. close-up)
• Telescope focal length (long focal lengths favor small sensors)
• Post-processing capacity (larger sensors = bigger data)
• Budget & hardware limits (full-frame systems cost significantly more).

The IMX533’s square format is optimized for astrophotography, while IMX571/IMX455 push boundaries for different scenarios.

ToupTek Astro now offers the ATR585M bundle and ATR533 bundle, including LRGBSHO filters and a filter wheel - purchase as a kit for a complete astrophotography setup at a discount!