Plan preferences

The settings for the whole plan, including camera, exposure model, guiding, refocus and cues. Open them with Plan preferences... in the planner.

Preferences are grouped into sections: Solar filter policy, the central-phase capture group, Atmospheric model, System configuration, Imaging base, the SharpCap camera settings, Guiding, Files, Focusing and Audio cues. This page walks through the ones that matter most; individual phase recipes live in the Phase editor.

Solar filter policy (eclipse mode)

Total eclipses only This group appears only on a total eclipse plan. Annular and partial eclipses have no filter-off window to schedule, so there is no policy to choose: the filter stays on from start to finish.

In the Solar filter policy group, choose the eclipse mode: Safe (the default) or Diamond ring (Classical). This changes the filter removal and replacement timing, the C2/C3 exposure brackets and the cues. Choose the mode whose filter procedure you understand and have rehearsed. Full explanation on the Safety & eclipse modes page. A standing safety warning is shown here, and a second amber caution appears if your guiding would run through the unfiltered phases.

Solar filter policy choices and the warning displayed for
Diamond ring Classical mode. — Solar filter policy changes both the filter cues and the derived imaging plan. Safe is the default; select the mode whose procedure you have chosen and rehearsed.

Atmospheric model

The Atmospheric model group contains one setting: Apply standard atmospheric refraction. It is enabled by default. When selected, HelioMaker includes atmospheric refraction in the calculated contact times using fixed standard conditions of 10 °C and 1010 hPa. When cleared, the contact times are geometric and do not include atmospheric refraction.

There are no separate temperature or pressure controls. The effect is usually negligible while the Sun is well above the horizon, but it can become significant for an eclipse close to the horizon. Changing the checkbox recalculates the contact times and the plan windows derived from them, so make this choice before final approval and repeat the rehearsal after changing it.

Refraction belongs to the saved plan Preflight does not edit the atmospheric model. It shows the plan's current value as the read-only text Refraction: enabled or Refraction: disabled. Return to Plan preferences... if it needs to change.

System configuration

The System configuration group selects the imaging device. SharpCap uses the camera currently open in SharpCap Pro. The group also contains the important Guiding camera: choice:

Shared camera (simple full solar disk setup): one scope and one camera do both imaging and guiding (PHD2 uses the Virtual Planetary Camera fed by HelioMaker). Simplest rig, one filter to manage. The entire solar disk must fit comfortably inside the main camera frame because eclipse automation uses the Sun detector in crescent and full solar disk modes. HelioMaker guides through the ordinary partial phases and pauses guiding through the C2 and C3 contact windows and totality. As the photospheric limb becomes bright enough for reliable detection after C3, it automatically recenters the Sun to its locked position. The mount tracks without guide corrections for those few minutes.
Physical guiding camera: a separate guide scope with its own camera, selected in PHD2. Choose this when you need guiding to run through totality or when the main camera shows only part of the solar disk at high magnification. It needs its own solar filter, removed and replaced with the main one if guiding continues through totality. See Gear & rig requirements.

SharpCap camera settings

If SharpCap isn't connected you'll see "SharpCap not connected. Camera settings can't be read or applied." and settings can't be read.

Capture format: FITS, PNG or TIFF. FITS preserves the raw data for later processing.
Binning / Capture resolution: The Capture resolution: (capture area) is important because it fixes the frame size the run will use, which in turn drives the data rate for each frame and the disk estimate. Choose it deliberately; the preflight checklist and the system benchmark test measure against it.

The System benchmark test... measures live-view capture overhead automatically and uses it when HelioMaker calculates safe shot spacing. There is no manual overhead setting to estimate or tune.

The saved plan controls the eclipse sequence Complete these settings before opening preflight. HelioMaker applies the plan's sequence controlled camera settings to SharpCap during preflight and again when the run is armed. Do not treat manual SharpCap changes as edits to the eclipse plan; they can be detected as a mismatch and replaced by the saved values.

The selected SharpCap camera is part of the saved plan. Preflight and final arming block if the camera configured in HelioMaker, the plan camera and the camera currently open in SharpCap do not agree. This camera identity check cannot be bypassed with an ignore-warnings choice.

If physical testing requires a change, enter it here or in the Phase editor, save the revised plan, repeat the System benchmark test when the camera format, colour space, binning or capture area changed, and rehearse again. Avoid last minute tuning after preflight begins.

Capture file naming and location

The Files group is separate from the SharpCap camera settings. Set Base filename: and choose whether Filename timestamp: uses Observer local time or UTC (prefix with utc).

Files group with Base filename and Filename timestamp settings. — The Files group controls the names written within an eclipse run folder.

Set the capture root on the HelioMaker main screen The plan preferences do not choose the base capture folder. Set Capture Folder: in the Sequence area of HelioMaker's main screen. HelioMaker creates the eclipse run folder beneath that root. Confirm the location and its free space before the run; preflight shows the resolved capture folder and lets you verify it again.

Central-phase capture: Still versus Live This group chooses how the central phase's HDR brackets are captured, using Still mode (exact exposures) or Live view. On a total eclipse it governs the C2/C3 brackets. The choice is offered for every eclipse type, and it depends on your camera. See Capture mode: Still versus Live.

This dialog defines the imaging plan Choose Safe or Diamond ring (Classical) under Solar filter policy. This changes the filter removal and replacement timing and the affected phase recipes. Then choose Still mode (exact exposures) or Live view under the capture group named for the eclipse type (Totality capture, Annularity capture or Central phase capture); that choice changes how the bracket is captured and how many sets can fit. Read Safety and eclipse modes and Capture mode: Still versus Live before deciding. Apply these choices before tuning individual phases.

Imaging base: the exposure model

HelioMaker anchors the whole exposure plan to one filtered reference exposure and gain, together with the solar filter density. It combines these physical inputs with Fred Espenak's eclipse exposure recommendations to derive the starting recipe for every phase. These are the most important imaging parameters in the plan. Set:

Imaging base settings for full solar disk exposure, camera
gain, solar filter density, partial phase interval and totality filter margin. — Measure the full solar disk exposure and gain with the filtered physical rig, then select the matching effective density of the complete filter stack before HelioMaker derives the phase recipes. Totality filter margin is disabled in this Diamond ring mode example because it applies only to Safe mode; on an annular or partial plan that slot carries Central interval instead.

Full solar disk exposure (ms): & Full solar disk camera gain:

Your correct exposure and gain for the filtered full solar disk with the physical eclipse rig. Adjust them in SharpCap until the photosphere is bright and detailed without clipping, then record the pair and enter it here. Do this on an ordinary sunny day before the eclipse, or no later than the initial partial phase before automated imaging starts. HelioMaker applies this reference gain to every phase when it derives the plan.

Solar filter density:

Select the effective optical density of all attenuation in front of the sensor when you measured the full solar disk exposure. The choices are ND 5.9 (visual film + 3 stops), ND 5.6 (visual film + 2 stops), ND 5.3 (visual film + 1 stop), ND 5.0 (visual film), ND 4.0 and ND 3.8 (photo film). HelioMaker combines this value with the filtered full-disk exposure to derive the C2/C3 and totality exposure defaults.

Always use a certified front-mounted solar filter. Ordinary photographic ND filters are not safe solar filters on their own and must never face the Sun directly. If used for additional attenuation, they must sit farther back in the optical train, behind the certified solar filter. Add their optical densities to select the effective total. For example, ND 5.0 plus a one-stop ND 0.3 filter is ND 5.3.

Add attenuation only when the shortest practical camera exposure still overexposes the filtered disk. Going below approximately 1 ms increasingly exposes the result to read noise. Measure and enter the reference exposure using the same complete filter stack that will be used for the eclipse.

Partial phase interval

Fixed interval (a constant time between shots, in seconds) or Uniform coverage (shots spaced to sample the changing crescent evenly, set by Coverage step (% magnitude):). The choice applies to partial ingress and egress, and on Apply it also sets the pre-eclipse and post-eclipse intervals to match, so the whole outer eclipse is paced one way.

Annularity interval (s): / Central interval (s): (annular and partial eclipses)

The time between shots through annularity, or through the central phase of a partial eclipse. Unlike totality, these phases are long and their brightness barely changes, so shooting flat out would fill the disk with thousands of near-identical frames for no gain. Pick a spacing you actually want to keep. It occupies the same slot in the dialog that Totality filter margin uses on a total eclipse, because only one of the two can ever apply. To change how wide the central phase is, rather than how often it shoots, select its row in the Phase editor and use Start before (s): and End after (s): there.

Totality filter margin (s): (total eclipses)

Safe mode only. This parameter creates a deliberate buffer at both ends of totality. HelioMaker sets filter removal to C2 plus the selected margin and filter replacement to C3 minus the same margin. It does not change the calculated C2 or C3 contact times; it shortens the interval during which the telescope is unfiltered. The buffer lets you wait until after the predicted C2 before removing the filter and begin replacing it early enough to finish before the photosphere is predicted to return at C3. Choose a value that allows for uncertainty in the predicted contact timing and for handling the physical filter. A larger value provides more buffer but reduces unfiltered imaging time. The timeline, run monitor and audio cues use these filter change instants. The setting also influences the default Safe mode phase layout: when you accept recipe regeneration, HelioMaker sets the C2 diamond trail and C3 diamond lead to the rounded margin plus two seconds, leaving a small overlap beyond each filter transition. Those phase boundaries remain separately editable in the Phase editor. In Diamond ring (Classical) mode this setting has no effect; the C2 and C3 diamond phase windows determine the filter change points instead.

Include thin-crescent phase

Adds the dedicated thin crescent phases just before and after the central phase.

Keep the camera gain equal across all phases Using the same gain for every phase is recommended. HelioMaker derives the plan this way from the full solar disk reference gain, while exposure time and bracketing provide the exposure changes between phases. Make an individual phase gain change in the Phase editor only when testing with the physical camera supports that deliberate exception. If some phases have drifted away from the reference gain, applying preferences offers to put every phase back on it in one step, so you do not have to reset each row by hand.

Exposure and gain are locked once imaging starts The current eclipse workflow does not support changing exposure or gain during a run. The plan editor locks when automated imaging starts, and the run sets the camera from the planned phase recipes. A change made only in SharpCap will not update the plan and will not persist as a planning correction. Determine the reference pair early with the physical rig, apply it here, let HelioMaker derive the phases again, then use the Phase editor to tune individual recipes before approving and rehearsing the plan.

Guiding

The PHD2 guiding: selector controls guiding. For a total eclipse with a Physical guiding camera (see above), the choices are:

Guiding group for a separate physical guiding camera,
including guide exposures for partial phases and totality and the plan-wide guide interval. — With a separate guide scope and physical guiding camera, set the guide exposures for the filtered partial phases and, when used, the unfiltered totality interval. The guide interval applies in both physical setups.

No guiding: tracking only.
Partial phases only: guides during the ordinary partial phases and pauses through the C2 and C3 contact windows and totality.
Partial phases and totality: available with a physical guiding camera. It guides during the ordinary partial phases and inside totality, but still pauses through the thin crescent and diamond ring phases around C2 and C3.

Guide interval (ms):

The start-to-start time between guide frames: how often PHD2 samples the guide image and can issue a correction. The allowed range is 500 to 6000 ms (0.5 to 6 seconds), and 2000 to 4000 ms (2 to 4 seconds) is the recommended starting range.

The best value depends on the physical mount and the seeing. Some harmonic-drive mounts need a shorter interval toward the lower end of the range so their periodic motion is corrected promptly. In poor seeing, use a longer interval, commonly above 3000 ms, so PHD2 is less likely to chase rapid image motion caused by the atmosphere. Test the value with the actual mount, guide optics and observing conditions.

The interval applies to both shared-camera and physical-guiding-camera plans. When you apply a changed value in Plan preferences, HelioMaker writes it to every phase. You can subsequently tune an individual phase's Interval (ms): in the Phase editor. Keep the interval longer than that phase's guide exposure.

Guiding through totality means an unfiltered guide scope Partial phases and totality only works if the separate guide scope can detect the Sun during totality, which means removing its filter too. HelioMaker warns about this here, in the preflight checklist, and in the live cue (which names both filters). If in doubt, guide in the partials only and let guiding pause through the central phase. (With a Shared camera, guiding always pauses through the contact windows and totality, so this option does not apply.)

Focusing (automatic refocus)

Enable Automatically refocus before totality to run a single guarded refocus a few minutes before C2 (requires a motorized focuser). Set Minutes before totality: and a Refocus timeout (s):.

Annular and partial eclipses This group is available for every eclipse type. The wording follows the eclipse you are planning: the option reads Automatically refocus before the annularity phase or Automatically refocus before the central phase. It names the phase rather than the instant deliberately, because that is what the scan is timed against: the countdown runs back from the moment that phase begins, which includes whatever Start before (s): you gave it in the Phase editor, not from annularity or maximum itself. The purpose is identical everywhere — the temperature has been falling for an hour or more by the time the central phase arrives, and focus drifts with it.

HelioMaker relies on SharpCap Focus Assistant and repeats its last successful solar focus scan. Before enabling this option, use the physical eclipse rig to configure Contrast (Edge) Detection or Fourier Detail Detection, complete at least one successful scan, and manually confirm that SharpCap Refocus returns to sharp focus. Without that saved successful scan, HelioMaker automatic refocus will not work. During the automatic scan, HelioMaker pauses PHD2 guiding corrections to avoid correction-induced jitter and improve focusing accuracy. Planned captures continue, so an image taken while the focuser is moving may be slightly blurred. See Focusing.

Focusing group with automatic refocus enabled, minutes before
the central phase and refocus timeout settings. — These settings schedule one SharpCap refocus before the central phase — totality, annularity or maximum eclipse, depending on the plan. Prepare and prove SharpCap Focus Assistant before enabling the option.

The System benchmark test

System benchmark test introduction and settings, including bracket
repeats, the extended camera test and totality timing verification. — The benchmark tests the selected camera, current image size, planned HDR bracket and capture drive together. Optional longer checks can expose occasional faults and verify totality timing.

Click System benchmark test... to open the benchmark. It measures your camera's real capture overhead for each frame. Set Bracket repeats in each pass:, then Start. It runs a measure pass, a validate pass, and an extended pass if needed, shows the frame size it measured against, benchmarks your capture drive, and (for a Still mode plan) qualifies still mode on your camera. The summary reports rows such as Camera check, Still capture, Live capture, Capture drive and Plan timing. Two optional deeper checks are worth using before the eclipse: Test the camera for 5 minutes (slower, finds occasional faults), a soak test that surfaces intermittent Still mode failures, and Verify the plan's totality timing (slower). When you're happy, Update & close applies the result to the plan, including the minimum interval for each phase and the disk space estimate.

System benchmark in progress during the first measuring pass. — Let both measurement passes complete without changing the camera, capture resolution or drive.

Run this; it is not optional busywork The benchmark is what lets HelioMaker automate the sequence realistically. Its measured overhead sets the minimum interval for each phase and produces the estimate of how many HDR cycles you can actually capture in the central window (shown as “~N sets in totality / in annularity / in the central phase”, following the eclipse type; on a total eclipse that window is C2 through C3). Without it, the plan is guessing. You could arrive at the central phase with intervals the camera can't sustain, and capture fewer frames than you planned. Run it on your actual eclipse camera and capture configuration, well before the day.

Do this after choosing your capture area The measurement is tied to the frame size. Set your Capture resolution: first, then run the benchmark. Otherwise the preflight checklist will flag that the measurement describes a different frame size than the run will use. For a Still mode plan the qualification can block the run if the camera cannot switch into Still mode reliably. See Capture mode: Still versus Live.

System benchmark summary with camera check, still and live capture
overhead, capture drive speed, camera name and frame size. — Review the camera check, measured Still and Live overhead, drive throughput, camera and frame size, then select Update & close to apply the result to the plan.

Audio cues

Play audio cues during eclipse enables the spoken prompts during a run; Preview audio cues plays them so you know exactly what you'll hear (it toggles to Stop while playing). Preview them until they are familiar. See The run console. What you hear depends on the eclipse type.

Total eclipses

A set of three prompts that adapt to the mode: awareness, preparation to remove the filter, and preparation to replace it. These prompts control the imaging-scope filters; they never change the separate rule that certified eye protection stays on until totality.

Annular and partial eclipses

Exactly one spoken prompt, about a minute and a half before annularity or before maximum eclipse. It tells you the central phase is approaching and restates that the solar filter stays on.

There are no filter prompts, and there never will be On an annular or partial eclipse the filter never comes off, so there is nothing to prompt for. If you have photographed a total eclipse, do not wait for a remove-filter cue here — none is coming, and the absence is deliberate rather than a fault. The one prompt you do hear says so out loud.

Because the prompt names the astronomical instant, it fires relative to that instant and not to the start of the central phase. The central phase is a window several minutes wide centred on annularity or maximum, so the cue normally sounds well after that phase has already begun. That is correct: it is announcing the moment of deepest eclipse, not the start of capture.

Preview audio cues plays the chime and that single prompt, which is the entire cue list for the run — the preview rehearses exactly what eclipse day will sound like.

The same checkbox also enables HelioMaker's critical alarm. It may sound during a physical eclipse run if HM detects an unexpected PHD2 or SharpCap error that may require your attention. In some cases HM will attempt to relaunch the affected application, reconnect and resume eclipse imaging automatically. An alarm still means you should read the red/amber console status and confirm whether recovery succeeded. The Silent shutter button does not mute this alarm; clearing Play audio cues during eclipse does.

Critical alarms and the spoken eclipse safety/filter prompts play on independent audio paths. An alarm can overlap a scheduled spoken instruction without stopping or muting it. Cosmetic shutter feedback may pause briefly so the alarm remains clear.

Preview alarm plays the actual 2.638-second critical sound so you can verify its volume before eclipse day. It is a test control and remains available whether or not run-time audio cues are currently selected.

Audio cues group with the option to play cues, a Preview audio
cues button and a Preview alarm button. — Enable the cues, preview every prompt the plan will actually play, and test the critical alarm at a useful field volume.

After editing preferences Changes made after approving a plan create a draft. When you are happy, approve it again with Save as final so the preflight checklist sees an approved plan. → Planner basics ▸ Draft vs final

Plan settings changed status beside the Apply plan settings
and Cancel buttons. — The changed status appears after an edit. Apply the settings, review the derived phases, and save the completed plan as final again.