Sampling Calculator
What This Calculator Tells You
Sampling determines whether your imaging setup captures all the detail your seeing allows, or wastes pixels on blur you can't resolve. Enter your image scale and typical seeing to find out if you're optimally sampling your images.
Calculator
Calculate this with the Image Scale Calculator if needed.
Typical seeing at your location. Urban: 3-4", Suburban: 2-3", Dark site: 1-2".
Good match for typical deep-sky imaging; captures seeing-limited detail efficiently.
Recommendation
No change needed.
Should be ≥1.0 for proper sampling
Sweet spot (2.0–2.5 px/FWHM)
Typical DSO range (1.5–3.0 px/FWHM)
Understanding Sampling
Sampling is limited by atmospheric seeing. The atmosphere sets the finest detail you can record, not your telescope alone. For deep-sky imaging, ~2–2.5 pixels per seeing FWHM is a good target. Values outside this range are usable, but involve trade-offs between resolution, noise, and efficiency.
- Nyquist theorem: To fully capture detail, you need at least 2 pixels across your smallest resolvable feature (seeing FWHM).
- Factor 1.5–3x is acceptable: Captures seeing-limited detail efficiently for typical deep-sky imaging.
- Undersampling loses detail: If your pixels are larger than your seeing, you can't capture all the resolution your sky offers.
- Oversampling has trade-offs: Extra pixels can help with processing and rounder stars, but cost SNR and storage.
Typical Seeing Values
| Location | Typical Seeing | Ideal Scale |
|---|---|---|
| City/Urban | 3-5" | 1.0-2.5"/pixel |
| Suburban | 2-3" | 0.7-1.5"/pixel |
| Rural/Dark site | 1.5-2.5" | 0.5-1.2"/pixel |
| Excellent (mountain) | 0.8-1.5" | 0.3-0.8"/pixel |
Related Calculators
- Image Scale Calculator - Calculate your current image scale
- Pixel Scale vs Seeing - Optimize for your conditions
- Field of View (Imaging) - Calculate your camera's field of view