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GeoMax ZMP101 Mini Prism

Image of GeoMax ZMP101


The Geomax ZMP100 Mini Prism comes with an Integrated bubble is used in Surveying and Construction as a Target Reflector for measuring distances on the field by Engineers and Contractors.

The ZMP101 is built for durable and stable pole mounting, compatible with the ZPT4 pole. Rugged by design, it consists of a corner cube reflector mounted in a shock resistant plastic with high UV resistance. It is typically used with a stainless steel tip.

A direct equivalent to this prism is the Leica GMP111 Mini Prism.


Height Offset:50.0 mm
Absolute constant: -16.90 mm
Leica constant: +17.50 mm
Weight:170 g
Mount:1/4" Thread


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 ZMP101 FAQ

Below is a list of frequently asked questions about GeoMax ZMP101.

What is the prism constant for the GeoMax ZMP101?

The absolute prism constant (true value) for the GeoMax ZMP101 is -16.9mm. The prism constant as defined for Leica instruments for GeoMax ZMP101 is 17.5mm. For a more detailed explanation on prism constants please see this article.

Can I use the GeoMax ZMP101 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 ZMP101 with a Leica instrument you should use 17.5mm as the prism constant value.

What is the height offset of the GeoMax ZMP101?

The GeoMax ZMP101 height offset is 50.0mm. This is measured from the mounting point to the centre of the prism.