Experts area

Experst! You chose to visit this part of our site since you want to know more and operate our sundial with the highest precision and accuracy. Please find below a short summary of potential causes impacting the accuracy of your sundial reading:

Latitude setting error (+/-1 degree): +/-0.5 minutes

As you can see in the summary above this point is not too sensitive. Based on our calculations we are seeing a time reading error of around 30 seconds per degree setting error. Make sure to use our latitude search tool and set the latitude accurately as described in Step 1 of our instruction manual.

Date setting error (+/-1 day): +/-2 minutes

Our sundial will be about 2 minutes fast for every additional day of setting error (or the other way around). An example: If the sundial shows correct time on May 5, it will be about 10 minutes fast if temporarily set to May 10 and it will be about 10 minutes late if temporarily set to April 30. Carefully follow the instructions at step 2 of our instruction manual to avoid this error source. Tipp: You will see on the middle bridge of your sundial that we divided each months in three boxes representing the beginning, the middle and the end of each month. Use these boxes to increase the precision of your date setting.

Reading error (offset from index line): +/-8 minutes

It also matters how accurately you read the time of our sundial. When doing so make sure that the light-beam falls exactly on the index line of the inner ring. In case the light point is above or below the index line you can experience a reading error of around +/-8 minutes.

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Sun’s annual variation (-15 to +16 minutes): +/-1 minute

The proper time correction to add or subtract is often taken from an Analemma diagram and varies between -15 to +16 minutes. Failing to account for this phenomenon, can contribute the greatest error in your time reading! To make things easier for you please find a simple time correction table below:

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Production variations (within margin): +/-5 minutes

Although we build our sundials with the greatest care and love possible some production variations can occur. We estimate them to be not more than +/-5 minutes and are thriving avoid them all together with every new sundial we produce!

Since there is little chance that all errors add up simultaneously - all positive or all negative - we estimate the regular accuracy of our pocket sundial to be better than +/- 10-15 minutes.

Big thanks to Kenneth, a sundials lover from Sweden, who helped us with this summary.