From Leuven to Spain: how our collaboration with TotalControl began
In June 2025 we found ourselves in Leuven, Belgium, for the Solar Eclipse Conference hosted in Leuven Home | Vereniging Voor Sterrenkunde: two days bringing together people who study, calculate, and chase eclipses around the world. Eclipse photography featured heavily in the programme, and it was there, in the margins of the conference, that we first crossed paths with Maciej Szupiluk — a Polish developer and veteran of seven total eclipses, already deep into building his own automation software for Sony cameras.
That conversation grew, over the following months, into a genuine collaboration. Maciej joined the beta testers of our Eclipse Countdown App and, in parallel, his own project kept advancing: TotalControl, an open-source Windows application built to plan and automate Sony Alpha series cameras for the entire sequence of a solar eclipse, from the partial phases through third contact.
TotalControl isn’t the only automation tool eclipse photographers can turn to, and Maciej built it after running into the limits of the existing options in the field: Solar Eclipse Maestro, still widely used, depends on an old version of macOS and offers only limited Sony support with noticeable shutter lag; Solar Eclipse Workbench doesn’t run natively on Windows and relies on gPhoto2, which adds roughly 250 ms of latency on Sony cameras, too slow for a tightly timed bracketing sequence during totality. TotalControl was built around Sony’s own Camera Remote SDK instead, cutting that latency to about 80 ms, and around precise contact times computed directly for the observer’s exact site
Why a tenth of a second actually matters
During the seconds around second and third contact, the sky’s brightness changes fast and that’s the moment the solar filter has to come off (or go back on) . A bracketing sequence built for eclipse photography has to track this shift second by second: filtered, short exposures during the partial phases; unfiltered and comparatively long ones for the faint outer corona; short again near Baily’s beads and the diamond ring, where the exposed sliver of photosphere is still blindingly bright. If the contact times feeding that sequence are off by even a couple of seconds, the camera fires the wrong exposure, filter setting included, at the wrong moment, and there’s no second chance during totality.
This is where our IQP calculation method comes in: a fully three-dimensional approach that accounts for the real topography of the lunar limb, the observer’s exact location, an up to date solar radius and all smaller effects, going beyond the simplifications of classical Besselian models. We expose IQP through a dedicated API, and TotalControl queries it directly to obtain local contact times (C1-C4) to within a tenth of a second, which it then uses to drive the automatically generated exposure sequence for each connected camera.
Under the hood
TotalControl controls up to four Sony cameras independently via Sony’s Camera Remote SDK. Each shot in the timeline is one of three block types (single frame, burst, or bracketing sequence) with shutter speed, ISO, and aperture set in advance and fired at its scheduled time. Baseline sequences are generated automatically from the contact times (for example, a one-frame-per-minute time-lapse for the partial phases, or a full bracketing run concentrated around second and third contact) and can then be edited or extended by hand.
A separate long-exposure shot is timed to the exact midpoint of totality, when the corona is roughly symmetric, while the surrounding bracketing sequence is weighted toward third contact to maximise the number of frames captured during Baily’s beads and the diamond ring. The software also generates an optional spoken audio cue track for the totality sequence, and its built-in sky simulator overlays each camera’s live feed onto the simulated position of the Sun, matching focal length, pointing angle, and tracking target, so framing and alignment can be checked on site before totality begins.
TotalControl is open source (GPLv3) and free to download. Maciej is now calling on the community: anyone with a compatible Sony Alpha camera is invited to test the software before August 1, 2026, the deadline for bug reports ahead of final preparations for the Spanish eclipse.
A conversation started on the sidelines of a conference, now helping photographers around the world make the most of the few, precious seconds of totality.
Learn more about TotalControl and get involved in beta testing: github.com – Presentation video: TotalControl Overview
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