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GeoMax ZPR100 Prism

Image of GeoMax ZRP100


The GeoMax ZPR100 Circular Surveying Prism is used in Surveying as a Target Reflector for measuring long distances in the field. It consists of a corner cube reflector, inside a red plastic holder. Commonly used with the GeoMax ZTP100 target plate for precise aiming over long distances.

A direct equivalent to the ZRP100 is the Leica GPR113 Surveying Prism.


Height Offset:86.0 mm
Absolute constant: -34.40 mm
Leica constant: +0.00 mm
Centring accuracy:±2.0 mm
Mount:12mm (Leica) Spigot


Below is a table with approximate prism ranges, based on atmospheric conditions.

Surveying Prism PoorGoodBest
ZPR100 Standard Prism 1800m3000m3700m
3x ZPR100 Prisms2300m4500m5400m
ZRP1 & GRZ122 360° Prisms800m1500m2100m
Leica GRZ101 360° Mini Prisms500m800m1000m
ZMP100 & ZMP101 Mini Prisms800m1200m2100m
ZTM100 Reflective Tape200m200m200m

Atmospheric conditions are defined as:

  • Poor – Strong haze & 5km visibility or strong sunlight with severe heat shimmer
  • Good – Light haze & visibility about 20 km or moderate sunlight with slight heat shimmer
  • Best – Overcast, no haze, visibility about 40 km & no heat shimmer.

GeoMax ZRP100 FAQ

Below is a list of frequently asked questions about GeoMax ZRP100.

What is the prism constant for the GeoMax ZRP100?

The absolute prism constant (true value) for the GeoMax ZRP100 is -34.4mm. The prism constant as defined for Leica instruments for GeoMax ZRP100 is 0.0mm. For a more detailed explanation on prism constants please see this article.

Can I use the GeoMax ZRP100 with a Leica instrument?

Yes, you can use the prism with a Leica instrument as long as you set up the correct prism constant in the instrument settings.

What is the prism constant value that I need to use with a Leica instrument?

In order to use the GeoMax ZRP100 with a Leica instrument you should use 0.0mm as the prism constant value.

What is the height offset of the GeoMax ZRP100?

The GeoMax ZRP100 height offset is 86.0mm. This is measured from the mounting point to the centre of the prism.