Test: Nitehog Gecko 35 Pro LRF thermal imaging monocular

Apr 30, 2023

What are the limits to what a thermal imaging monocular can do? All4shooters’ optronics specialist Franco takes the Nitehog Gecko 35 Pro LRF in the field in different situations and conditions to find out and try its features in depth. Fog? Rain? Heat and cold, so what happens with the Gecko? Let's find out.

I have reviewed the Nitehog Gecko 35 Pro LRF compact, handheld, hunting observation thermal imaging monocular in all4shooters, where you can find all its characteristics and specs. I was however very curious about the performance of this peculiar optic, in view of the various and different features it can claim, such as the integrated laser range finder, movement sensors, video recorder etcetera – the full list is available in the mentioned article, so don't miss out on it!

I took the time to carefully unbox the Gecko, finding a practical Cordura case with two compartments, containing the thermal monocular and the accessories, including two batteries, a USB C cable and the charger. Additional items are a HDMI cable, hand strap, neck strap and lens cleaning cloth. The objective is protected by a hinged, rotating flip-up cap that can be placed away from the LRF window and is quite silent in operation.

The "click" of the microbolometer automatic shutter calibration may spook game in absolute silence, however there is an option to calibrate silently with the cap, by pressing both up/down buttons at the same time.

The menu system is a lot more complex than it initially appears to be: each of the just four buttons, including the on/off switch, can have up at least four functions in different contexts, and there are also button combinations to add functions and commands. The menu tree is also extensive and reading the manual with attention is mandatory to take full advantage of all the features of the device. Learning curve is not steep, however.

I installed the free NitehogGecko app on my iPhone (it also available to Android users) to test the WiFI connectivity and the features of the app itself. I have to say, in perfect Nitehog tradition, the app is spartan, easy to use and robust. Ideal for the hunter in the field.

You are presented with just a few icons: a media gallery – both local on the iPhone, and on the Gecko; the menu system for connecting the Gecko, and a remote, streaming video view from the device. It is possible to download the recorded images and video from the internal memory of the Gecko to the smart device image roll.

Ergonomics are fine but could also be improved. The Gecko 35 pro feels good in the hand, there is only one rubber panel to improve grip though, and the very smooth surfaces could be improved with some checkering or additional rubber panels, since it could become slippery in wet environments.

The eyepiece has the diopter adjustment control on its left side, and it is a rotating knob with a dial indicator projecting out of the instrument body. It is easy to use and adjust but is placed exactly where the nose of the user is when looking inside the eyepiece and may cause mild discomfort during long watching sessions. Placing the same exact knob above or below the eyepiece would have been better.

Next to the eyepiece there's a sensor to shut off the display when the face is away from the device and the microphone for the integrated A/V recorder.

Another small issue could be caused during battery replacement in the field, especially if distracted or in haste. The battery has an indexing notch; it is however possible to force the battery with the notch outside its channel, resulting in a jammed battery that may be then difficult to remove and reseat correctly, especially with slippery hands. The battery itself also features a O ring, so that it has a good seal against rain and harsh weather conditions.

The view from the display is excellent, the definition offers a wealth of details and the different viewing options can improve the hunter's experience. A digital compass at the top of the image window gives the viewed target's bearing, and there is the option of motion sensor display, with inclination and tilt data displayed both graphically and in digits. Options to improve the image include contrast filters and a color palette. A bit of confusion may arise when choosing the digital zoom ratios or the palettes, as the "up" button scrolls thru the available magnifications and the "down" button scrolls thru the palettes. I found myself zooming in a target and when I expected to zoom out, I got a switch of palettes instead. You get used to it quickly, though.

The laser range finder function works both in scanning (the default I found it in) or as single reading. It is accurate and works well in the field. I compared its performance to a Leica CRF 2000-B and the readings agree. It is easy to forget the laser window is next to the objective and if you get a "0" reading it may well be your hand is in front of the window.

Now the actual performance. I used the Gecko for a couple months, in various weather conditions.

In normal conditions, the image is clear and detailed, with basically no lag and very fast framerate, no ghosting and the display in the eyepiece gives a great image with excellent sharpness and quality.

Obviously, the ambient lighting makes no difference, so at night and in the day the image is the same. At night, the fact that everything is cooled down (no sun) makes for better contrast and image quality – the same in overcast sky.

In the rain, the only difference is that the water cools the environment surfaces, making living objects actually stand out more. The falling rain affects only minimally the viewed image; alas, I did not have a situation of very heavy rain to test. Fog gets easily cut through with the Gecko: I pursued heavy fog situations, in the chilly morning and at nightfall, and it always managed to show me what was under the white haze. A difficult situation is when hidden rocks in a field or larger rocks in the open are heated by the sun, making identification of living objects more difficult, unless they move. Examples of all these are in the video.

In some cases, the Nitehog Gecko did have some difficulty in showing good images, for example when a large portion of the sky is visible and the dynamic range algorithm tries to balance the extremes in temperature readings, and in this case the environment and the woods can be obscured. Changing the palette on the fly can help. The Gecko in normal use lasts for about 6 hours, using wifi, LRF scanning or recording video may shorten battery life considerably.

In the end, a good product with a lot of interesting features and some rough edges that will be addressed by the manufacturer and a great performance in the various situations tested. The Gecko is available at a MSRP of 2,950 euro (the price could vary slightly in various EU countries due to different VAT applied).