Optaxis
Optaxis
Coming soon · iOS / Android / HarmonyOS (native)
37 photography calculators. Film development, filter compensation, reciprocity failure, hyperfocal distance, the Scheimpflug principle — every constant is labelled with its source and the date it was checked.
Coming soon on three platforms
Release expected between late December 2026 and early January 2027 · once live, search for “光轴” (Optaxis) in your app store
Films missing from the list can be added yourself — fill in the reciprocity parameters and they show up in Zone Exposure, the shooting diary and film development. Development time is calculated automatically, while every other step’s duration and agitation rhythm can be changed, and you can insert steps of your own. Gear from your default kit carries into Compose, focal length, astro and other tools, and a calculated exposure goes to the timer or the diary in one tap.
Manufacturer datasheets, standard textbooks and industry consensus — every value checked against at least two independent sources. Where sources disagree, the official datasheet wins and the tool notes the difference (e.g. Ilford MG IV and MG V use different compensation for grade 4).
Calculators don’t need a network — there’s no signal in a darkroom, or up a mountain.
Your gear, shooting logs and roll records live in your own account, sync across devices when you sign in, can be exported at any time, and are deleted when you close your account.
Tap a tool name for details
Logging & extras
Log every shoot across three tabs — Today, Planned and History — linked to the location, gear and settings you used, so you can review what worked.
In the app: Tools tab → Diary
Full details →During the shoot · Framing & metering
Meter while you frame: spot, centre-weighted and average metering — tap the picture to read the EV and a suggested shutter speed — plus Zone mapping, false colour and a two-point highlight/shadow reading; composition guides (rule of thirds, golden spiral, centre cross) are overlaid on the viewfinder at the same time, so you can judge the frame while you shoot.
In the app: Tools tab → Compose
Full details →During the shoot · Framing & metering
A Scheimpflug calculator: enter the focal length to get the tilt / swing angle and the resulting plane of focus — for getting near and far sharp in one frame.
In the app: Tools tab → Tilt/Swing
Full details →During the shoot · Framing & metering
Equivalent focal length conversion, depth-of-field calculation and a macro mode — work out equivalent angle of view and DOF across formats.
In the app: Tools tab → Focal
Full details →During the shoot · Framing & metering
An exposure calculator: ND filter stops × shutter speed conversion, long exposures, linked to reciprocity failure compensation.
In the app: Tools tab → Exposure
Full details →Before the shoot · Planning
Weather and light: live conditions, sunrise and sunset, golden and blue hour, cloud cover and precipitation.
In the app: Tools tab → Weather
Full details →Before the shoot · Planning
Aurora forecast: live geomagnetic Kp index, visibility probability for your location, and trip planning around aurora windows.
In the app: Tools tab → Aurora
Full details →Logging & extras
Five astrophotography modes: pinpoint stars (500 / NPF rules against trailing), star trails, Milky Way (core altitude, seasonal window, best nights), light pollution, sun and moon paths, and time-lapse.
In the app: Tools tab → Astro
Full details →Logging & extras
AR overlay: projects the paths of the sun, moon, Milky Way, planets and constellations straight onto the live view, with compass guidance and a time slider to preview any moment.
In the app: Tools tab → AR (or Astro → AR overlay)
Full details →Logging & extras
Print size calculator plus paper recommendations and a wall-mount preview — work out how big your pixels will print, then pick paper and frame.
In the app: Tools tab → Print
Full details →During the shoot · Framing & metering
Live shift simulation: preview pure rise / fall and lateral shift perspective correction (no tilt), with a warning when you shift far enough to vignette.
In the app: Tools tab → Live Shift
Full details →Before the shoot · Planning
A shoot planning checklist with the date, location, time window and gear kit pre-filled before you head out. The Clients entry in the header (Pro) groups your client list by most recent work — clients attach to shoot plans rather than adding a separate booking layer.
In the app: Tools tab → Plan (client management via the Clients entry in the header, Pro)
Full details →After the shoot · Developing & darkroom
Film developing log: track times, temperatures and recipes for E6, C41 and black & white.
In the app: Tools tab → Dev
Full details →After the shoot · Developing & darkroom
Personal EI calibration: record the exposure index each film actually gives you, and calibrate your metering to it.
In the app: Tools tab → EI
Full details →After the shoot · Developing & darkroom
Darkroom enlarging timer plus burn & dodge tracking and a Zone System reference.
In the app: Tools tab → Darkroom
Full details →After the shoot · Developing & darkroom
Reciprocity failure compensation calculator: adjust long exposures per film stock, with 28 film curves built in.
In the app: Tools tab → Reciprocity
Full details →Before the shoot · Planning
A location scouting bench: overlay the azimuth and altitude grids for sun, moon and Milky Way on the map to pick your spot.
In the app: Tools tab → Scout
Full details →During the shoot · Framing & metering
Long exposure and interval countdown timer, for bulb exposures and time-lapse sequences.
In the app: Tools tab → Timer
Full details →During the shoot · Framing & metering
A unified exposure workflow: reciprocity, bellows factor, filters and manual compensation on one screen, so the total exposure comes out in a single pass.
In the app: Tools tab → Session
Full details →During the shoot · Framing & metering
A bearing compass (azimuth) for working out which way you are facing and where the sun and moon rise and set.
In the app: Tools tab → Compass
Full details →Before the shoot · Planning
Burning sky forecast: a multi-day probability index for whether the morning or evening sky will actually light up.
In the app: Tools tab → Burn Sky
Full details →Before the shoot · Planning
Tide data: high and low water times, so you can read the shooting window as the sea goes out or comes in.
In the app: Tools tab → Tide
Full details →Before the shoot · Planning
Probability forecasts for the landscape conditions that make a trip worth it: sea of clouds, rime ice and alpenglow on snow peaks.
In the app: Tools tab → Specialty
Full details →Before the shoot · Planning
A calendar of keeper-shot windows: six forecast engines (weather, astro and other dimensions) scored per day, so you can see at a glance which days are worth going out for.
In the app: Tools tab → Almanac
Full details →After the shoot · Developing & darkroom
Negative inversion: copy negatives with your camera or import them from your photos (DNG and other RAW included), invert black & white and colour negatives into positives, and handle slide film too; with automatic frame detection, consistent colour across a whole roll, lightbox flat-field calibration, a live positive in the viewfinder, cropping and straightening, and dust and scratch removal.
In the app: Tools tab → Negative
Full details →After the shoot · Developing & darkroom
Film catalogue: browse stocks by name, ISO, type, format, latitude and character notes, see sample looks, and add one to your film shelf or run its reciprocity numbers in a tap.
In the app: Tools tab → Film Catalog
Full details →Logging & extras
Gear comparison: line up digital backs, bodies and lenses side by side and compare their specs.
In the app: Tools tab → Compare
Full details →Logging & extras
Photo contests from home and abroad in one place, grouped by closing date, with reminders, bookmarks and a link straight to the entry page.
In the app: Tools tab → Contests
Full details →During the shoot · Framing & metering
Measure ambient colour temperature (K) and green–magenta tint live with the camera. Aiming at a grey card gives the most accurate reading; you can lock a reading and export it as a result card. Includes K↔Mired conversion, a colour-correction filter table (82A, 85B and so on) and an X-Rite 24-patch reference.
In the app: Tools tab → Color Meter
Full details →After the shoot · Developing & darkroom
A workbook for alternative and historic printing processes (platinum-palladium, cyanotype, salt, Van Dyke, albumen, gum bichromate): pick a process, fill in the recipe parameters step by step (sensitiser ratio, coating, UV exposure, development, toning, washing), attach process and final prints, and get a step-by-step run sheet. Repeatable, duplicable and saveable as "my process". The built-in templates carry the fields and the step skeleton only — no chemistry values, you fill those in. Free once signed in. Also reachable from the Developing stage of the Film Zone.
In the app: Tools tab → Alt Process (or Film Zone → Developing → Alternative processes)
Full details →Logging & extras
Roll album: keep the film photos you shoot organised by the roll — open a new roll (stock, format, size, frame count, start and end dates, place, notes, optionally linked to a batch in your film stock so one roll is deducted automatically), shoot it, mark it as waiting for the lab, then import the scans back in and archive it. The roll list is a grid of film-box cards with a cover, a format badge, a status dot (shooting / at the lab / archived) and a 12/36 counter; rolls loaded sheet by sheet in large format show no denominator. On first open, existing users get rolls built automatically from diary entries that already carry a roll number. Free once signed in — batch EXIF writing, contact sheet export and cloud-drive import will come later as Pro.
In the app: Tools tab → Roll Album (or Film Zone → Shooting → Roll Album)
Full details →During the shoot · Framing & metering
Film viewfinder: see live how this scene would look on film. It opens straight into the live view; swipe the advance dial along the bottom to pick a stock and the picture takes on that stock’s colour at once, and long-press a stock to read about its character. Pull open the drawer above the dial to adjust filter strength and grain on the spot (only for this session — leaving resets it). The shutter bakes the colour and grain into the photo and saves it to the system album: as with film, there is no second chance and no unfiltered original kept. It needs no understanding of exposure at all — no metering, no Zone, no false colour. Every stock is an original Optaxis grade made after the look of the corresponding film; it is not affiliated with those brands and is not a precise measurement. Free.
In the app: Tools tab → Film View
Full details →Before the shoot · Planning
Pose library: poses curated by us, filtered by subject × setting × light. Subjects run women / men / any / pairs / groups (deliberately not a binary choice, which also covers couples and group shots); settings run beach / street / café / hills / studio / night; light runs backlit / front-lit / overcast / window / rim / sunset / night. Each pose comes with an official reference photo and three cues — where the hands go, where the eyes go, how high the camera sits. Bookmark the ones you want, or add one to a shoot plan in a tap so it becomes a shot item (photo and cues included) you can shoot from on the day. Browsing and bookmarking are free — guests can see the free part too — and the full library needs Pro.
In the app: Tools tab → Poses (or Plan → shot flow → pick from the pose library)
Full details →Before the shoot · Planning
Lightning scouting and forecast (M1): answers "can I shoot lightning from this spot tonight?". The server grades CAPE (convective available potential energy) and WMO thunderstorm codes (95/96/99) into a 0–100 chance index, with the peak hour and a confidence level. On screen you get a CAPE atmospheric profile (instability drawn as a sounding-style curve, with vertical ticks at the hours the model actually produces storms), an hour-by-hour window for 16:00–23:00 tonight, and a three-day outlook. The chance index and the profile are free to preview; the hourly window and the three-day outlook need Pro. You can subscribe to a location and get a push when the evening window looks promising. Note: this is a weighted heuristic, not a lightning probability forecast — follow your met office warnings when deciding to go out.
In the app: Tools tab → Lightning
Full details →Before the shoot · Planning
Light pollution map: worldwide light pollution from VIIRS night-time satellite data (~500 m, z2–8), with the Bortle class 1–9 estimated automatically for your position or the centre of the map, a class legend and a plain reading of what each class actually lets you shoot. You can cache the current map area locally so it still works up in the hills with no signal. It answers "which way do I drive tonight, and how far, to get dark enough?". It and Astro are two modes of the same screen — entering from here lands you straight on the light pollution map.
In the app: Tools tab → Light Pollution (or Astro → light pollution)
Full details →During the shoot · Framing & metering
Recce (formerly Video Scout; director’s viewfinder — works for stills scouting too): pick a camera body and recording format, type in a focal length and an anamorphic squeeze, and the phone’s live picture gets the frame that cine camera would actually see, worked out from geometry — outside the frame dims, the frame lines are gold. Swipe left/right for exposure compensation and up/down for focus; the axis locks on the first movement, so the two never move together. You can build a recce project per location, record the parameters plus one reference frame for each set-up, and export a self-contained HTML recce report (images embedded, single file, readable offline) to send to the director and producer. A tape measure and a bit of triangulation calibrate your phone lens’s real angle of view, so the frame matches what you shot. The whole screen is locked to landscape — cinema formats are wide. Its split from Composition & Metering is deliberate: that one is a stills camera with a meter (galvanometer, Zone scale, false colour, latitude), this one has no metering at all and answers one question, what this shot frames. Free.
In the app: Tools tab → Recce
Full details →Before the shoot · Planning
Moon photography on one page: phase, age, illuminated fraction, Earth–Moon distance, apparent size, magnitude, libration and relief (how long the crater shadows are along the terminator); today’s moonrise, transit and moonset with direction and altitude, the altitude curve and how fast the Moon drifts, and whether moonrise or moonset falls in golden or blue hour; a suggested shutter for phone, digital, digital back or film (Looney 11 as the base, with extra stops worked out from the phase and from low-altitude extinction) and the longest shutter before the Moon blurs; field of view, how much of the frame the Moon fills and the focal length you need for a given size, by sensor format; hourly cloud, seeing, transparency and dew risk (Pro) plus sky darkness; and what’s coming up — phases, supermoons and micromoons, lunar eclipses and lunar occultations. Lining the Moon up with a peak or a building is done in the Planner, linked from here. Free.
In the app: Tools tab → Moon (or Astro → Sun & Moon → Moon photography)
Full details →Coming to iOS, Android and HarmonyOS (native) at the same time, expected between late December 2026 and early January 2027. Once live, search for “光轴” (Optaxis) in your app store. The calculators work offline.