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Image quality measurement of binoculars


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Image quality measurement of spotting scopes

ImageMaster® Afocal

Image quality testing for telescopes, riflescopes, binoculars and spotting scopes

Afocal optics, such as those used in riflescopes, are often still tested today using purely visual test procedures. The results are therefore based on the subjective assessment of the tester and thus the repeatability of the measurement results is not guaranteed. Due to the multitude of determining factors, subjective quality testing often reaches its limits even among the most experienced professionals.

With the ImageMaster Afocal® optical afocal systems like telescopes, riflescopes and binoculars are tested in terms of functionality and image quality with a variety of specific optical parameters.



The measurement process with the ImageMaster® Afocal is manual or fully automated. The measurement is possible for finite and infinite object distances. A wide range of parameters such as the MTF or magnification are already measured in the standard configuration. Specific measurements such as parallax (free distance) can be easily performed with a focusable collimator. Measurements of other specific parameters, such as the eyerelief of riflescopes and spotting scopes or the subjective and objective field of view, can be performed with upgrades.

  • MTF on-axis and off-axis

  • Magnification

  • Distortion

  • Lateral chromatic aberration

  • Longitudinal chromatic aberration

  • Astigmatism

  • Field curvature

  • Parallax (alignment check of reticle)

  • Field of view, objective and subjective (optional)

  • Eyerelief (with optional autocollimator)

Technical Data

ParameterImageMaster® Afocal
Spectral Range450 … 750 nm
Clear Aperture2 mm … 110 mm (depending on collimator)
Illumination SourcesHalogen light source / LED panel
Max. off-axis object angle±15 °
Max. off-axis image angle± 90°
Magnification0.5x … 60x
(MTF on-axis and off-axis)
± 0.02 MTF on axis / ± 0.03 MTF off axis
(MTF on-axis and off-axis)
± 0.01 MTF
Object distances20 m … ∞ for parallax / 100 m … ∞ for MTF
(h x w x d)
253 mm x 1,782 mm x 627 mm
Weightapprox. 185 kg


MTF-Lab for ImageMaster®Afocal

  • Measurements of MTF, magnification and a range of other parameters using special target patterns and dedicated software routines

  • Functions for easy alignment of the sample under test

  • Conventional MTF measurement using a single slit or a crosshair as a target

  • Automated selection and positioning of the suitable reticle (target) and filter for the current application

  • Configuration files with optimized process parameters and password protected access for operator and supervisor

  • Scripting tools for customer specific programming and analysis

  • Intuitive user interface and time-saving lens test routines

  • External control via TCP/IP

Upgrades & Accessories

In order to meet individual requirements, the test bench is available with various upgrades. The result are flexible configuration options for measurement of different specific parameters of optical afocal systems, for instance the subjective as well as the objective field of view. Another important parameter, especially for riflescopes and spotting scopes is the eyerelief. It rounds up the versatile measurement functionality of the ImageMaster® Afocal. Additional options and sample holders allow the measurement of binoculars and spotting scopes.


Sample mounting of binoculars


Sample mounting of spotting scopes

Knowledge Base

ImageMaster® Afocal

Image quality testing of optical afocal systems

The ImageMaster® Afocal measures at infinite and finite conjugates. A collimator (A) simulates a distant object which may be located at infinity or some closer distance. A motorized video telescope (C) views the image created by the sample (B).

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Measuring principle of the ImageMaster® Afocal

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