Lead'Air Inc. has announced innovative new aerial survey multi-focal lenses at the 2019 INTERGEO in Stuttgart, Germany.
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Lead'Air Inc. has announced innovative new aerial survey multi-focal lenses at the 2019 INTERGEO in Stuttgart, Germany.

October 09, 2019 -- The GSD, Ground Sample Distance (or resolution), is the key specification of any digital aerial photo mapping project. For a given camera and focal length, the GSD determines the altitude above ground AGL at which the aircraft must fly. Flying higher or lower changes the GSD and inherently produces images that do not meet the project's specifications. This limitation is now obsolete on all Lead'Air aerial cameras. Lead'Air is developing multi-focal lenses, which allows the planner to choose the mission altitude while preserving the required GSD. When circumstances (weather, ATC, etc.) require an altitude change, the survey aircraft crew can select a new altitude on the fly while maintaining the required GSD.

This system is based on commercially available variable focal lenses.  The lenses are entirely re-engineered in Lead'Air's optical lab and converted to photogrammetric lenses, which are configured with different predetermined focal lengths. A Lead'Air multi-focal lens can have up to 20 preset focal lengths; each setting corresponds to a given altitude and GSD and is calibrated to true photogrammetric standards. The lenses are motorized and precisely controlled by the FMS system. On his screen, the operator chooses at which altitude he intends to fly, and the software automatically amends the flight plan. The lens adjusts itself accurately to the correct focal length, and the focus is fine-tuned to ensure maximum sharpness. Manual input is not necessary.

Example. Your crew is attempting to fly a major city with an extensive air traffic control zone around its main airport. It is not unusual for a hard-working air traffic controller to transmit "unable to comply at 5,000 feet" and to decline the entry into his airspace. A survey aircraft equipped with Lead'Air multi-focal lenses can request another altitude which the delighted controller will be glad to authorize. Alternatively, the aircraft can climb above the controlled airspace and finish the mission instead of landing and waiting for another good weather day. Anyone who has flown aerial surveys in congested controlled airspace will appreciate the operational improvements such lenses will bring to the profession.

Lead'Air is currently manufacturing multi-focal lenses for the 50-megapixel small format digital cameras (Nikon, Canon, etc.) which are re-engineered by Lead'Air and used on the MIDAS oblique cameras. As well, we are assessing Multi-focal lenses for medium format cameras (Hasselblad, etc.). Upgrading older Lead'Air aerial camera systems with multi-focal lenses is possible.

Example; D850 Nikon with Lead'Air multi-focal lens 80mm to 400mm configured to capture 2-inch (5 cm) GSD with a vertical camera and oblique cameras at 45 degrees. The table shows the focal lengths corresponding to each altitude.


Alt. AGL feet











2-inch (5cm)

Vertical mm










Oblique mm










We are discovering other advantages of multi-focal lenses by the day, and there is no doubt that aerial surveyors will find many more beneficial applications.

For example, the above Nikon multi-focal lens would allow the operator to collect resolutions between 2 inch and ½ inch (5 cm – 1 cm) using the 400 mm focal length between 11,000 feet and 2,000 feet. The focusing will automatically adjust for the selected altitude, and the lens will have a calibration report for each possible altitude.



5 cm

4 cm

3 cm

2 cm

1 cm

Alt. AGL feet







Also, it will be possible to create straightforward flight plans without having to change the flight altitude to cope with terrain height variations and remain within the project specifications. Instead of planning a lower or higher strip above lower/higher ground, simply increase or decrease the focal length to maintain the GSD. Those who are painfully planning projects in the mountainous areas will immediately understand what an improvement this will bring to them.


To conclude, within the scope of our products, Lead’Air’s mission is to stretch the operational window available to the aerial surveyors. Our new multi-focal lenses contribute to this goal by allowing the operator to remain airborne longer, more economically, and more efficiently. Multi-focal lenses will save many days of being grounded by ATC or weather.

We believe that multi-focal lenses will transform the way our clients operate, which is why Lead'Air is filing for a patent to protect our clients' interests.

About Lead’Air, Inc

Lead'Air Inc., a USA Corporation, based at 113 Hangar Road in Kissimmee, Florida, provides professional oblique Aerial Survey Camera Systems to capture metric quality imagery for 3D modeling of cities and disaster relief areas. Our MIDAS (Multi-Image Digital Acquisition System) is the most recognized and most used system in the world with over 150 systems capturing millions of images every year. These systems and the MIDAS name itself have become synonymous with quality 3D modeling around the world. Our extensive line of products incorporating from one to twenty-five cameras and more, along with LiDAR, flight management systems, fully stabilized mounts and precision Applanix Inertial Navigation Systems makes Lead’Air the Premier Oblique Aerial Survey System Company in the world. Find out more at www.trackair.com

Lead’Air, October 2019

Lead’Air Inc

113 Hangar Road

Kissimmee, Florida 34741 USA

Tel 407 343 7571

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