Image Acquisition & Capture

The "press the shutter, repeatedly, all night" tier — narrower than Mount & Session Control (which sequences the whole night) and focused on the camera itself: live view, gain/offset/exposure tuning, region-of-interest, frame format (RAW16 / SER / FITS), histogram, focus aids. Most full session managers wrap a capture engine of their own, but specialised solar / lunar / planetary work and EAA (Electronically Assisted Astronomy) live with dedicated capture apps.

For the surrounding session controller see Mount & Session Control; for live stacking see EAA & Live Stacking; for solar/lunar/planetary stacking see Solar / Lunar / Planetary Stacking; for the cameras themselves see Astro Cameras & Sensors; for non-astro DSLR tether see Photo Tethered Shooting; for processing the output see Photo RAW Editors and Image Editing.

Free Windows capture

• ★ ★ SharpCap — Win-only; free tier covers 95% of hobbyist needs, paid Pro (~$15/yr) unlocks polar align, sensor analysis, sequencer, smart histogram, AI denoise live stacking. Default Windows capture for ZWO/QHY/Player One/ToupTek. Direct ASCOM / INDI / Alpaca camera support; live stacking; planetary high-FPS ROI capture; deep-sky single-frame integration into Pro live-stack. The Windows free standard.
  • https://www.sharpcap.co.uk
• ★ FireCapture — free, Win/Linux. The planetary / lunar / solar capture standard; very fast SER recording, automatic histogram tuning, ROI, image stabilisation, ADC (atmospheric dispersion) helpers, derotation hints. Used in tandem with AutoStakkert! / RegiStax.
  • https://www.firecapture.de
• AstroDMx Capture — free Win/Linux/Mac; cross-platform sibling to FireCapture; planetary-leaning.

Free Linux / macOS capture

• ★ ★ KStars Ekos Capture module — GPL, cross-platform; the capture half of Ekos. Talks INDI to any supported camera; full filter sequence (R/G/B/Ha/OIII/SII/L), darks/flats automation. Default Linux/Mac/Pi answer.
• oaCapture — free Linux/Mac/Win. Lightweight; planetary; talks libASI / libQHY / V4L2 / libuvc.
• lin_guider — Linux capture + autoguider in one (older).
• INDI Web Manager + INDI client — headless capture on a Pi from CLI/web for time-lapse / unattended.

Free smart-scope companion apps

These are the ZWO/Vespera/Dwarf companion apps — see Smart Telescopes for the hardware. They're all-in-one capture + processing UIs locked to specific scope ecosystems:

• ZWO Seestar app — free with Seestar S30/S50; iOS/Android.
• Vespera Singularity — free with Vespera; iOS/Android.
• DwarfLab app — free with Dwarf 3 / DwarfII; iOS/Android.
• Unistellar app — free with eVscope; iOS/Android.
• Stellina — Vaonis app, sibling to Singularity.

All closed-source. The deal: you give up extensibility, you gain "tap → image" simplicity.

Paid Windows capture

• ★ N.I.N.A — actually free; included here as a reminder it has a great capture engine even if you don't use the sequencer. See Mount & Session Control.
• APT (AstroPhotography Tool) — paid (~$25). Capture-focused; older; declining share. Free trial.
• MaxIm DL — paid; capture + processing + plate solving in one heavyweight Windows tool.
• Backyard EOS / Backyard Nikon — paid (~$50). DSLR-tethered capture; the easy answer for canon/nikon DSLR astrophotography on Windows. Mac/Linux DSLR users use gphoto2 under Ekos.
• TheSkyX Camera Add-On — paid; only buy if you're already in the TheSkyX ecosystem.

Paid Mac

• AstroDSLR (Cloud Maker) — paid macOS; DSLR-leaning capture. Niche.
• Theli — academic deep-sky pipeline; specialist; free for academic use.

Mobile capture

• DSLR Controller (Android, paid) — Canon DSLR USB tethered capture. Useful field-to-tablet rig.
• SiriCap / NebulaCapture — niche iOS apps; thin clients.
• Most modern mobile workflows are smart-scope companion apps above, or VNC into your laptop / Pi.

Common knobs to know

• Gain / offset for CMOS — set "unity gain" (where one electron = one ADU) for deep-sky; high gain for planetary; check sensor-analysis report (SharpCap Pro / Ekos).
• Exposure binning — bin 1×1 for short focal length; 2×2 only on mono CCDs (CMOS bin is software).
• Cooler set-point — most cooled CMOS run at -10 to -15 °C; matched dark library lives or dies by repeatable temperature.
• File format — FITS for deep-sky (16-bit, header metadata), SER for planetary high-FPS, RAW16 for native sensor.
• Region of interest (ROI) — subset of sensor; doubles or triples the framerate for planetary at the cost of FoV.
• Auto-flip / dithering — the session manager handles these, not the capture app.

Calibration frames

Bias / dark / flat / dark-flat libraries are managed by the sequencer (Ekos has a "Dark Library" tab; N.I.N.A has Flats Wizard). Capture apps just record them — see your stacking pipeline for how they're used.

License / pricing summary

• Free: SharpCap free tier, FireCapture, KStars Ekos, oaCapture, AstroDMx, smart-scope companion apps.
• Paid (~$15–$50): SharpCap Pro, APT, Backyard EOS/Nikon.
• Paid (~$200+): MaxIm DL, TheSkyX Camera Add-On.

Pick this if…

• Free, Windows, deep-sky: SharpCap free + N.I.N.A for sequencing.
• Free, Windows, planetary / lunar / solar: FireCapture.
• Free, Linux/Mac/Pi: KStars Ekos.
• Smart scope: companion app — you don't pick capture software, the scope does.
• DSLR-only, Windows: Backyard EOS / Backyard Nikon.
• Polar align / sensor analysis without buying N.I.N.A's ecosystem: SharpCap Pro ($15/yr is a steal).
• Headless Pi capture: Ekos via INDI Web Manager.