Retrograde hands expressions?

I’ve searched the term retrograde and not a single post comes up. Is there a basic tutorial for rotational expressions for retrograde hands? I’m accustomed to the lua code used in the Watchmaker app, but don’t have a handle on expressions in Facer yet. Most commonly I’ve used retrograde for a date hand, but I’ve used them (and would like to use them in Facer) for Hours, Min, and Seconds too. Any guidance, or an open inspection mode example face would be appreciated!

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In Facer you would simply put a minus sign in front of the relevant tag.

Eg. for an hour hand you would set the rotation to:

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Thanks Mike, but that simply goes backwards. A retrograde hand sweeps or ticks on a fixed arc of less than 360 deg. Say an hour hand where 12 starts at 20 degrees and it sweeps clockwise over 12 hours to 160 degrees, then returns to 20deg.

I know how to do that in fact with a battery indicator in Facer, but when I replace the battery indicator expression with a seconds hand expression to test the hand doesn’t respect the range assigned. …hope that makes sense. :slight_smile:

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for an extreme retrograde example: This watch has retrograde minutes, date, and chrono min/hours.

This will move the second hand from -70 to + 70 degrees:
(-70 + (#DWFSS# / 360 * 140))



I adapted the above for a retrograde date hand. using this:
(-120.5 + (#DMR# / 360 * 233))

The date numbers are precisely laid out from -113 to +113 and this code works perfectly in the creator preview, as well as the preview I see in this post. But on my fossil watch and in the Facer app preview on my phone I’ve just noticed that it’s got the date as about 25 1/2 instead of the 24th which is what it still should be as I write this. Any ideas??

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It looks like the app always bases it’s rotation on a 31day month, while the watch (I have a Fossil as well) bases it on the maximum days in a month. This expression forces it to use 31 days and works on my fossil:
(-120.5 + (#Dd# / 31 * 233))


Ah… That does indeed do the trick, thanks!

Thanks for the explanation. When I saw your question I was not sure what you meant so I looked up “retrograde” to confirm my immediate memory that it meant “go backwards”. This came from my other hobby astronomy, where retrograde motion is used to describe the apparent backwards movement of Mars during part of its orbit. It did not occur to me to look up retrograde in the context of watch design, which as you point out, means something very particular in that context. Still so much to learn :slight_smile: