Astrophotography toolkit
Calculators
Quick, focused tools for planning sessions, checking gear compatibility, and answering the math questions that come up at every stage of astrophotography. Everything runs in your browser — no accounts, no tracking, shareable URLs.
27 calculators Client-side only Shareable URLs All formulas verified by automated tests
Field of View See how much sky your telescope and camera can capture in a single frame.
Image Scale Check if your arcseconds per pixel match the seeing — oversampled, undersampled, or just right.
Gear Match Get the full picture: focal ratio, FOV, sampling, and which targets suit your rig.
Filter Size Find out if your filters are large enough to avoid vignetting with your sensor.
Guiding Ratio Compare your main and guide image scales to see if your guiding can keep up.
Integration Time Plan sessions by frame count, target hours, or multi-channel (LRGB/narrowband) with weather and progress tracking.
Storage Estimate disk space for lights, darks, flats, and bias frames.
Print Size Find your image's max print size at various DPI levels with quality ratings.
Dew Point Check the condensation risk tonight so you know whether to run a dew heater.
Exposure Equivalent Compare two sites by SQM and see how much more time a bright sky costs you.
Sub-exposure Length Estimate how long each sub should be for your sky, filter, and camera read noise.
Narrowband Ratios Get relative exposure times for HOO, SHO, LRGB, or RGB channel plans.
Target Fit Check whether a deep-sky target fills your frame well with your current gear.
Moon Impact See if moonlight will hurt your target tonight — aligned with planner moon buckets.
Flat Exposure Find the right flat frame exposure to hit 30–50% of full well.
Meridian Flip Find when your target transits and when to flip for maximum east-side time.
Battery Runtime Estimate how long your field battery will last with mount, camera, and dew heaters.
Back-focus Spacing Calculate how much spacer you need to hit required back-focus distance.
Focus Shift Estimate how much temperature change will move your focus.
Crop FOV See how cropping in processing changes your field of view and image scale.
Star Trail Limit Find the longest untracked exposure before stars trail on your sensor.
Finish Target Track progress toward a target integration goal with weather-adjusted nights.
Filter Benefit Compare OSC, broadband, and narrowband time cost at your local SQM.
Guiding Exposure Get min and max guide sub lengths for your mount period and guide scale.
Pier Height Estimate pier height needed to clear a roofline or horizon obstruction.
Comet Trailing Find max sub length before a comet smears across pixels.
Print Viewing Find the ideal viewing distance for a print at a given DPI.
These calculators use standard optical formulas and rules of thumb from years of imaging. They're meant for quick field estimates — not observatory-grade precision. If your setup is loaded with "Use my gear," the values come from my own equipment list. Every calculator shows its work — expand "Show the math" beneath any result to see the formula with your values substituted in.