Sub-exposure
The camera/sky model asks how long each frame should be before read noise becomes a small part of the background noise, then tempers that against target highlights.
Astro Lab
Target-aware imaging planner
Deep-Sky Exposure Planner
Start with a real target, then combine camera noise, focal ratio, filter and sky brightness to estimate a sensible single-sub exposure and how much total integration is worth planning for.
1. Target & result depth
Choose one of the curated targets, then decide how deep you want the finished stack to go.
2. Camera & gain
The same camera database and read-noise model used by the Sub-exposure Optimizer.
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3. Optical system & filter
Focal ratio sets how quickly extended targets and sky background build signal per pixel.
Advanced capture assumptions
4. Sky quality
Use Bortle as a convenient starting point, or enter a measured/planned SQM value.
Editable — overrides the Bortle preset
What the planner is estimating
Sub-exposure and total integration solve different problems.
Total integration
The target library provides a practical baseline that is adjusted for focal ratio, sky brightness, QE, filter family and the result depth you select.
Dynamic range
Bright cores and star clusters can justify shorter subs even when that is not read-noise optimal. Stacking more short frames is often the better compromise.
Planning guidance, not a guarantee
The total-integration result is intentionally approximate. Target surface brightness, transparency, moonlight, gradients, seeing, sensor spectral response, filter curves, calibration quality and processing skill all matter. The target library gives a useful starting range; your real histogram and first processed stack should decide whether to continue collecting data.