Product Description

Steiner NightHunter H35 GEN II Thermal Imaging Monocular

Basics of Thermal Imaging

All objects emit some kind of infrared radiation – this is one of the basic principles of how heat is transferred, it is a form of electromagnetic radiation.  Imagine holding your hand near hot BBQ coals.  This hot feeling is infrared radiation. This is emitted in waves, the shorter the wavelength the hotter the image and vice versa. The infrared wavelength is part of the invisible spectrum.  The infrared range was discovered in 1800 by Sir William Herschel.

A thermal device simply converts this infrared radiation through a sensor to an image.

THERMAL JARGON EXPLAINED :

Thermal Sensor Resolution

The resolution of a thermal sensor is easier to explain if you think about our home TV’s.  Before the advent of HD we used to have 4:3 or 16:9 tv displays which were a lower resolution which meant the image quality was not great and you could see the pixels quite easily that made up the image, when HD TV’s 720p, 1080P and 4K etc the resolution of the image improved, and even at close distances the pixels were so small that the image looked more natural and detailed.

The thermal sensor resolution is effectively the number of pixels on a sensor array.  The “size” of the sensor if you like, with the larger the resolution, the better quality the sensor.

A thermal imager with a sensor resolution of 160×120 pixels provides 19200 pixels.  If you compare that to a sensor with a resolution of 640×480 it provides 307,200 pixels and you will see that the image at the same distance has considerably better detail and image definition.

For example a roe deer at 400m with a 384×288 is a collection of pixels formulating a blob of heat which has the rough outline of deer species, but with the 640×480 sensor at 400m that deer is a roe buck or a doe and you can see hair and facial details to identify a particular animal in a herd.

Resolution

Thermal detector resolution is the first thing for evaluating the actual quality.  The highest resolution delivers sharper imagery without a “pixelated” display on the targets.  A unit with a 640×480 resolution thermal detector will have better overall image quality than the 384×288 resolution model, simply because more resolution is applied to enhance the image performance.

On the other hand, a higher resolution thermal detector typically has smaller FOV and magnification with the same size of lens.

A higher resolution thermal detector offers sharper imagery.

Thermal Sensitivity – NETD Value Explained

The Noise Equivalient Temperature Difference or NETD value effectively governs the slightest differences in temperature that your thermal camera will detect.  The higher the number such as “40mk NETD” the less sensitive, and the lower the number “sub 25mK NETD” the more sensitive the camera will be, allowing you to see minute differences in temperature.

This equates to a few different outcomes in your hand held thermal primarily the cameras ability to distinguish between thermal differences, so with a lower NETD rating, the fox you are watching with a wooded background becomes an image which is clearly a fox and clearly a forest behind, where as on a higher NETD value the differences in temperature become less noticeable to the fox and wooded background merge into one, making it more difficult to discern differences in the image.

This also comes to play in rain, fog, mist etc. the lower the NETD value of the sensor, the less “noise” in the image and the more able the camera is to still deliver a clear image of the target with lots of adverse weather conditions which would impede higher NETD value devices, and totally eliminate effectiveness of natural vision and night vision.  NETD values can also be subject to change by internal heat generated through use.

The lens aperture of the thermal scope influences the NETD at the square root of its value.  The F-stop corresponds to the amount of light collected by the lens. It is defined as an F-number—from 0.8 to 1.6 for most thermal scopes in thermal imaging.  For a detector alone, the NETD is generally given for F/1.0. For modules or cameras, the NETD depends heavily on the F-number.  It is related to the thermal detector NETD as follows: Overall NETD = NETD of Detector x F².

For example, for an original thermal detector with a NETD of < 40mK @F/1.0, the NETD is 57.6mk @ F/1.2 and 25.6mK @ F/0.8.  Thus, especially for a beginner seeking a thermal scope in the market, you need to be cautious with the manufacturer who claims their scope’s NETD is equal to <40mk but with F1.2 or F1.1 aperture on their lens system.

A good example of this is in the search and rescue industry, a fire fighter in a smokey room can use thermal to find a person on the ground when his natural vision or indeed a night vision camera would be impeded.

Please bear in mind the NETD numbers won’t tell you the whole story.  In fact, the image quality you could see from a unit mostly depends on the thermal algorithm the developer implements.

Thermal Sensor Pixel Pitch

Commonly referred to as the sensor Micron value or μm value, the Pixel pitch is the distance between the centres of two pixels of a microbolometer.  In thermal imaging sensors, it is measured in microns (µm) and the smaller the µm value the more detail you will observe on the target image.  With most thermal sensors in our range we see the µm values of 25, 17 and 12.

Lens Size

Thermal Imagers come in all shapes and sizes and a crucial component is the lens size.

As a rough rule, the smaller the lens, the less magnification, the larger the field of view and therefore a larger lens provides a narrower field of view, with increased magnification but with the benefit of improved detail.  The larger surface effectively acting like a larger satellite dish, capturing more thermal information.

How does this affect Field of View

The field of view defines the size of space that can be viewed through the optical device at a defined distance.  Field of view is usually given in degrees or in metres for a specific distance (M) (usually 100M) to the observed object.

The field of view of a digital night vision device is defined by the focal length of the objective lens (f objective lens) and the physical size of the sensor.  The wider the field of view, the more comfortable observation as there is no need to move the device constantly to view the necessary part or space.  It is important to understand that field of view is inversely proportional to magnification – meaning that when magnification increases field of view shrinks.  This is one of the reasons why infrared systems (thermal imagers in particular) with high magnification are not manufactured.

At the same time, it is important to understand that an increase in the field of view leads to a decrease in detection and recognition range. 

Frame Rate

The frame rate is one of the main characteristics of a thermal imaging device.  From the user’s point of view, it is the number of frames displayed on the screen in one second.

This is usually measured in Hertz (Hz) where 1Hz is equal to 1 frame per second.  The higher the frame rate value, the less visible the effect of lagging of image produced by thermal imager in respect to the real scene.

Observation of dynamic scenes with a thermal imager that has 9 fps rate shows a blurry image and object movements may seem laggy and “jerky”.  On the contrary, the higher the frame rate, the smoother will be the rendering of dynamic scenes and 50hz frame rate is common place on virtually all our hand held thermal devices.

Refresh rate

The refresh rate indicates the number of times per second that the frame of an image is refreshed. It is expressed in Hertz (Hz) or frames per second (fps).  A higher refresh rate provides dynamic movements of your targets, without ‘dragging’.

A good quality thermal unit provides at least 50hz to ensure the best picture of targets in the move.

Thermal Imaging Displays 

The thermal display of your device is effectively the “screen” that you view through the eye piece, and they can come in all sorts of display types and resolutions.Like everything in life, people will argue over one method being better than the other whether its OLED, LED, LCD, ,CLOS, AMOLED, and which one has the best factors over another.

This display transmits the visual information that has been converted by the thermal sensor, effectively showing an image of the heat map the lens and sensor has collected, and like your TV screen at home, the higher the resolution, the better quality the image, for example some thermal sensors have a 640×480 display and some have a 1920×1080 HD display.

OLED offers a wider field of view on the display effectively delivering a larger image on the screen.  This type of device are less expensive and usually relates to the overall cost of the unit.

An AMOLED display often has a higher refresh rate meaning the image is translated from the sensor to your eye quicker so there is less noticeable lag in the image, so a smoother image is observed with less “lag or stutter” when panning across a scene quicker.

The main differences between LCOS, OLED and AMOLED screens are:

1. OLED stands for Organic Light Emitting Diode, and AMOLED stands for Active Matrix Organic Light Emitting Diode.
2. AMOLED has a higher refresh rate and consumes less power compared to OLED.
3. OLED displays have better color accuracy than AMOLED displays.
4. OLED displays are thinner and lighter than AMOLED displays.
5. AMOLED panels can support much larger display sizes and can produce faster refresh rates than OLED displays.
6. LCOS (Liquid Crystal on Silicon) is a variation on a LCD display (LCOS lasts approx. 10,000 hours, Oled 50,000 – also OLED has better contrast, more quickly (1,000 times more quickly)).

Target details

Target details mean what you expect to see on the main target within your field of view.  The more information/colour temperature you can achieve indicates its overall performance on ‘target details.’  It is hard to achieve a great level of target details as it requires a higher standard thermal detector with an advanced algorithm. Here are some questions you should ask yourself before deciding just how good the ‘target details’ are:

1. When you detect animals or humans, can you see them only in highlight, like a bright and over-exposed object?
2. Can you see their mouth, nose, and eyes clearly displayed?
3. Can you see the animal’s fur in short, medium, and long-range?
4. Are the animals’ bodies displayed with different colours, or can you only see a block/lump of white/black objects with the same temperature?

Target Edge

This is the term used to indicate how ‘smooth’ the edge of your target is and if the image is ‘pixelated.’ The ‘target edge’ is primarily smooth and sharper with higher thermal detector resolution, but sometimes also achievable through an excellent thermal algorithm.

Noise

The noise within the field view is referred to as ‘snowflakes.’  Original imagery captured was full of noise.  The algorithm reduces the noise level and offers a clear image. Some scopes have lesser quality detectors and are unable to use the proper algorithm to remove the noise 100%, clouding the screen with a layer of ‘fog’ on the image which you always want to blow away.

Magnification & FOV

Magnification level and FOV cannot be discussed separately for a thermal unit.  Some users love low magnification as they want a wider field of view.  Some need a high magnification scope as they wish to shoot long range.

The magnification level is decided on the parameters and mainly include focal length of the objective lens and eyepiece, detector pixel pitch, and size of the display screen.  Technology-wise, it is easy to achieve a high base magnification level for manufacturers, but why are their thermal scopes mostly at a relatively lower level?

The most important reason is that a higher magnification may reduce the image’s resolution, which means the thermal image quality cannot be maintained at the highest standard with a higher base magnification.

So the higher the base magnification the better the image.

Detection Ranges

The detection range of a hand held thermal imager is effectively the distance the unit can ‘detect’ a heat signature of a man sized object at a determined range in ideal conditions.  A detection range of 1800m does not mean you can identify a fox from a Labrador at that distance, it means that the display of the thermal device will indicate pixels of heat detection at that range, but the image will be a cluster of pixels and barely form a shape.

Thermal viewing ranges can be determined as Detection Range, Recognition Range and Identification Range with the latter being the range you can identify species.

Detection Range – The distance where the critical size of an observed object can be fit in two or more pixels of a thermal imaging sensor is called the detection range.  Detection only means that the object is visible at a certain distance but does not give any information about its characteristics (i.e. the type of object cannot be determined). 

Recognition Range – The recognition of an object means that the type of object can be defined.  This means that observer can discern what is being observed i.e. human, animal, car, etc.  It is considered that recognition is possible when the critical size of an object can fit into at least 6 pixels of the sensor. 

Identification Range – From the hunter’s point of view, the most useful range is the identification range.  Identification means that the observer can evaluate not only the type of object but also its characteristic features (e.g. wild boar male 1.2 m long and 0.7 m high).  For this condition to happen the critical size of an object should fit in at least 12 pixels of the sensor.

These factors are also influenced by weather, and device specification.  A colder night will often mean better identification ranges than on a warm summer evening.

Software Performance

The software performance is usually defined as how smoothly the function of the thermal scope performs.  Many thermal units are criticised by end users because their software is not user friendly or lags during panning.

Below are some questions you may ask yourself or the manufacturers to clarify if the software performs:

1. Can you easily adjust the brightness, contrast, and image gain?
2. Are those menu functions easy to use?
3. Does the unit lag while panning?
4. Does the unit boot in seconds?

Battery

A good quality thermal unit also comes with good quality batteries that should last for at least 7 hours.

Some manufacturers produce their own batteries, which you can only buy from them if you need an additional battery pack (Pulsar for example).

The majority of end users prefer 18650 type batteries as they have longer battery life than the CR123, and are easy to buy everywhere.  CR123 batteries are criticised a lot because their quality and battery life is poor.

PRODUCT DESCRIPTION

The Nighthunter H35 Gen 2 F35/1.0 fast aperture lens, greatly improved image quality, extended battery life (offering up to 8.5 hours of power on a single charge) and impressive 2.4 GHz with 15 meter Wi-Fi range provides an incredible thermal imaging experience.

With a wide range of features packed into a compact and lightweight durable makrolan polycarbonate housing for a nearly indestructible surface, it is easy to grip and can be operated with ease, no matter whether the user is right or left-handed, thanks to the symmetrical design and in-line button arrangement on the upper panel.

Highly Sensitive Thermal Sensor
The Nighthunter H35 Gen 2 features a highly sensitive 640×480, 12 µm, NETD <35mK thermal sensor combined with a powerful Germanium F35/1.0 objective lens, to provide an impressive 2,200m detection range of a roe deer in total darkness, withstanding even the most difficult, adverse weather conditions, such as rain, snow and fog.

Fast Aperture F35/1.0 Lens
The fast aperture Germanium F35/1.0 lens ensures high infrared light transmission in a compact design, which transforms infrared radiation into electrical signals through a high end infrared sensor which transforms and enhances digital data into high resolution images.

Enhanced Image Processing
Enhanced image processing algorithms within the device provide high quality rendering of both target objects and background.  Three available levels of signal amplification, provide the user with greater opportunities in terms of long-range detection of an animal and its extremities in varying weather and temperature conditions.

Variable Magnification
8x digital zoom with a base magnification of 2x – 4x.

OLED Display
A high quality OLED display with a resolution of 1024×764 will help improve recognition and identification by providing a clear and smooth picture whilst on the move.

Makrolon Polycarbonate Housing
Despite its compact size, the Nighthunter H35 Gen 2 has been designed with constant and hard use in mind.  The makeolon housing, though extremely light, is also incredibly strong with a nearly indestructible surface which protects the internal components from shocks, drops, moisture, heat, or cold.

IP66 Rating
First digit outlines intrusion protection.  6 – totally dust tight.  Full protection against dust and other particulates, including a vacuum seal, tested against continuous airflow.

The second digit outlines moisture protection.  6 – Protection against heavy seas or powerful jets of water.

Up to 8.5 Hours Battery Life
The Nighthunter H35 Gen 2 uses exchangeable batteries (18650), which offer up to 8.5 hours of battery life.  Removing and replacing the battery is achieved easily in mere seconds thanks to the intuitive design.

8 Colour Palettes
A choice of eight colour palettes provides the user with the ability more effectively observe their field of view, optimising the Nighthunter H35 Gen 2 for specific tasks and allowing it to react to changing observation conditions.

For object detection use White Hot, Black Hot and Red Hot.

Built-In Video & Still Image Recorder
allows the user to take and transmit short clips or images to a device.

Built-In Wi-Fi Module
The Nighthunter H35 Gen 2 will also compliment the standard smartphone 2.4 GHz Wi-Fi frequency range with an effective 15 meter range.

In brief the Nighthunter H35 Gen 2 features:

1. 640×480 12µm <35mK NETD thermal imaging sensor
2. Long detection range – Red Deer 3,120 meters or Roe Deer 2,220 meters
3. Variable magnification from 2x – 4x
4. Fast aperture lens F35/1.0
5. 1024×768 OLED display
6. Makrolon Polycarbonate Housing (superior to Magnesium Alloy as used by many of our competitors)
7. The IP66 waterproof rating means that this thermal imaging monocular will work in heavy rain and high humidity (where an IPX rating is used the the item DOES not have a valid IP rating, many of our competitors products have an IPX rating)
8. 8 colour modes/palettes
9. Up to 8.5 hours battery life
10. Fast start-up within 18 seconds (in real terms slower than some of the competition)
11. Built-in video and still image recorder
12. Built-in WiFi module
13. Field of view 12.5 x 9.4
14. 32GB internal memory
15. User friendly controls
16. 50Hz refresh rate
17. Wide operating temperatures -10oC to 50oC
18. Shock resistance to 30G