Why the ZEISS DTI 4/35 thermal imaging camera is great for birdwatching

Birdwatching is an amazing and life-changing hobby and as you delve deeper into the world of birding, the challenge of locating and observing certain species intensifies. This is where the ZEISS DTI 4/35 thermal imaging camera comes into play, providing birdwatchers with a cutting-edge tool to enhance their experience. With its advanced features and capabilities, the ZEISS DTI stands out as an invaluable asset for birding enthusiasts and professional ornithologists.

I recently had the pleasure of testing out the ZEISS DTI 4/35 so I thought I would take the opportunity to write down some of my thoughts and experiences. In this article, I will delve into the myriad ways in which the ZEISS DTI thermal imaging camera can assist birdwatching, exploring its technical aspects, unique features, and practical applications in the field.

Getting started with the ZEISS DTI 4/35

It is pretty simple to get started with the ZEISS DTI 4/35. I pulled it out of the very nicely packaged box, attached the strap and fired it up. Pointing it outside, I quickly realised that our windows reflect infrared light really well as all I could see was a reflection of myself in the window!
Infrared reflection in a window using the ZEISS DTI 4/35
There are only five buttons on the ZEISS DTI 4/35 so it doesn’t really require much learning to get started. The buttons are also really well sized so it didn’t take me long to do what I needed to do without looking at the DTI to see what button needed pressing.
The first button closest to the lens is the power button, long press it and it takes a few seconds for the DTI to power up. Once it is on, you can just single-press the power button to toggle between sleep mode and on.
The second circular button is used to take photos or video of what you are seeing. You can even stream the video feed it produces, amazing! Short pressing the circular button and the DTI captures an image. Long pressing starts a video recording. What’s great is you can even take photos in video mode by short pressing the same button.
The third and forth arrow buttons control the zoom on the DTI. Pressing on the right button zooms in from 1x magnification in increments all the way up to 4x magnification. Pressing the right arrow button on 4x magnification jumps you back to 4x magnification which I found pretty handy. Alternatively, you can just step back down through the increments by pressing the right arrow button.
Finally, the hamburger icon ☰ controls the colour modes of the DTI. Pressing this button cycles you through the eight different colour modes. Each of these modes seem to work better for specific conditions. My favourite is the ‘Red hot’ mode which makes birds stand out, even if the vegetation is really thick.
In addition to the buttons, there is also a focusing dial for the eyepiece and a focusing ring on the lens. You only really need to use the focusing dial for the eyepiece once to calibrate it for your eye. The focusing ring on the lens, however, needs to be used to adjust the focus depending on how far a subject is from you.

Getting out birding with the ZEISS DTI 4/35

After spending some time getting acquainted with the ZEISS DTI 4/35 thermal imaging camera indoors, familiarizing myself with its settings and features, I was eager to test it out in the field. Here’s a recount of my experiences on three different trips:

Local Walk with the Dog:
My first outing with the ZEISS DTI 4/35 was a casual walk down the road with my dog. The camera’s capability was immediately apparent. I spotted a wren in a nearby bush, a bird that is virtually invisible to the naked eye. The DTI’s thermal imaging made it stand out distinctly against the background. Further along, in a field, I detected another bird, possibly a brambling, standing on the field’s edge. This bird was indiscernible without the DTI, barely visible even with binoculars. It was a clear demonstration of how the DTI could reveal the unseen in birdwatching. I then ventured into a woodland in search of owls but unfortunately didn’t find one. I am, however, convinced that I would have seen an owl if there was one in there at the time.

Barnsdale at Rutland Water: On my second trip to the dense forests of Barnsdale near Rutland Water, the DTI proved its worth once again. I was able to spot several birds that would have been challenging to detect otherwise. This included two Goldcrests, a Nuthatch, and a variety (collective noun!) of Long-tailed Tits. I could hear the Goldcrests in some really dense bush, but I was having a lot of trouble placing their location until I pulled out the DTI. While scanning the forest floor, I also noticed a small Muntjac deer, superbly camouflaged in the undergrowth. Without the DTI, there is no chance that I would have seen the Muntjac despite it being only 20m from the footpath. The DTI’s ability to penetrate dense foliage in situations like this is one of the things that make it so impressive.
Egleton Adventure: My third excursion took me to Egleton, where the DTI showcased its prowess in a different setting. It was instrumental in spotting species like the Reed Bunting hidden deep in the reeds. A highlight was observing a Kingfisher perched on the opposite bank, about 250m from the Redshank Hide where I was stationed. Another birder had been in the hide for over 30 minutes without noticing the Kingfisher, despite it being out in the open, albeit at a considerable distance. The DTI’s ability to detect the bird at such a range was truly remarkable.

A summary of my experiences using the ZEISS DTI 4/35

The ZEISS DTI 4/35 thermal imaging camera has proven to be an exceptional tool for birdwatching, offering significant advantages in various challenging situations:

  • Spotting Species in Dense Cover: The DTI excels in revealing birds hidden within dense foliage, making it easier to spot species that would otherwise be concealed from view.
  • Identifying Well-Camouflaged Species: Its thermal imaging capability is particularly effective in detecting well-camouflaged birds, highlighting them against their surroundings regardless of their natural concealment.
  • Observing Distant Species: The DTI reduces the need for extensive scanning with binoculars by effectively spotting birds that are far away, saving time and effort in locating distant species.
  • Enhanced Visibility in Poor Light: In conditions where light is suboptimal, the DTI’s thermal imaging shines by providing clear visibility, a feature especially useful during dawn, dusk, or in shaded areas.

Thermal imaging cameras like the ZEISS DTI 4/35 are invaluable for birders at any skill level. They add a new dimension to birdwatching by unveiling aspects of the avian world that are typically hidden. After thoroughly testing the DTI in various environments and situations, I am convinced of its value. It’s not just an addition to my birdwatching toolkit; it’s a transformative device that has reshaped how I engage with this hobby. The ZEISS DTI 4/35 will definitely be on my Christmas list, and I highly recommend it to fellow birdwatching enthusiasts who are looking to elevate their birding experiences.

How Thermal Imaging Camera like the Zeiss DTI 4/35 are being used in Conservation and Research

Thermal imaging cameras, such as the ZEISS DTI 4/35, are revolutionising the way conservation researchers study and protect the natural world. These state-of-the-art tools enable researchers to monitor nocturnal and cryptic species without disturbing their natural behaviours. Whether it’s locating well-camouflaged species during the day or elusive animals at night, cameras like the ZEISS DTI 4/35 provide unparalleled insights and give researchers and citizen scientists the ability to conduct population surveys more accurately. Furthermore, in regions prone to human-wildlife conflicts or areas vulnerable to poaching, thermal imaging becomes a vital surveillance tool, enhancing the ability to detect threats and ensure the safety of both wildlife and humans. In the ever-evolving world of conservation technology, the ZEISS DTI 4/35 stands out as a beacon, illuminating the unseen and offering new perspectives on preserving our planet’s biodiversity.

Some questions and answers about the ZEISS DTI 4/35

Aren’t thermal imaging cameras only used at night?

When I first heard about people using thermal imaging cameras for birdwatching, my first impression was that they were being used at night and therefore not very useful for most birders. Seeing how they can be used during the day is what’s really revolutionary about using these cameras for birding.

The ZEISS DTI works so well during the day because the thermal image it creates highlights the temperature differences/gradient of everything you are looking at. Because your surroundings are more or less the same temperature, it would show up as a single colour, whereas a bird being warm-blooded would show up as a distinctive colour. So, however well-camouflaged a bird may be, the difference in temperature between the bird and its background will almost always make it stick out like a sore thumb on the ZEISS DTI!

How do Thermal Imaging Camera work?

Thermal imaging cameras, often referred to as infrared (IR) cameras or thermal cameras, are designed to detect and measure infrared radiation, which is emitted by all objects above absolute zero temperature. This radiation is invisible to the human eye but can be “seen” or detected by thermal imaging cameras. Here’s a basic overview of how these cameras work:

  1. Infrared Detection: All objects emit infrared radiation as a function of their temperature. The hotter an object is, the more IR radiation it emits. Thermal imaging cameras are equipped with sensors (usually made from materials like mercury-cadmium-telluride or microbolometers) that detect this radiation.
  2. Conversion to Thermal Image: The detected infrared radiation is then converted into an electronic signal. This signal is processed and translated into a visual image. The temperature differences detected are represented as different colours or shades of grey in the image, with each colour or shade corresponding to a specific temperature range.
  3. Colour Palette: Most thermal imagers offer multiple colour palettes. The most common palette uses black for the coolest areas and white for the hottest, but there are others such as the ZEISS DTI where warm areas can be depicted in reds, oranges, and yellows, while cooler areas might be blues and greens. The choice of palette often depends on the specific application or user preference.
  4. Display: The processed image is then displayed on the device’s screen, allowing the user to see the temperature differences in the scene.
Applications for thermal imaging are vast. They include building inspections (to find insulation gaps or water leaks), electrical system checks (to find hot spots indicating potential issues), medical diagnostics, night vision, surveillance, and many more.

It’s worth noting that thermal imaging cameras don’t “see through” objects in the way X-rays do. Instead, they detect the heat being emitted from the surface of things. So, for instance, they can’t see a bird hiding behind a branch, but they can detect the heat from a recently perched bird or even warm footprints left on a floor.

Downloading photos and videos from the ZEISS DTI 4/35

There are two ways to download photos and videos from the ZEISS DTI 4/35. The first is the ‘old-school’ plug it into your PC via the USB port. This works really well and transfers media quickly.
If, however, you want to access photos and videos while you are out in the field, then you can do so wirelessly via the DTI’s wifi. This is a little more fiddly though as you have to download the ZEISS app and connect your phone to the DTI 4/35. The initial setup takes a bit of time but once that is done reconnecting is a lot more straightforward.

ZEISS DTI 4/35 Colour Modes

Black hot: The warmest areas are black and the coldest areas are white giving the images a high level of contrast.

White hot: The warmest areas are white and the coldest areas are black giving the images a high level of contrast.

Red hot: The warmest areas are red allowing for quick detection of birds, especially in areas with lots of vegetation.

Rainbow: Is ideal for identifying the smallest differences in temperature.

Red hue: Easily adjusts your eyes to the darkness.

Dark hue: Is easier on your eyes as it uses low luminescence colours.

Green hue: Show plenty of detail at low screen brightness.

Night Eye: Highlights the warmest areas of the thermal image with a pleasant sepia tone.

Technical Aspects of ZEISS DTI Thermal Imaging Cameras



Focal length

35 mm



Field of view at 100 m (yds)

26 m (85 ft)

Objective viewing angle

13° x 10°

Sensor resolution

640 x 512

Sensor pixel pitch

12 μm

NETD value

≤ 25 mK

Display resolution

1024 x 768

Display frame rate

50 Hz

Display type


Optical magnification


Maximum digital zoom


Zoom steps

1.0x – 4.0x

Comparing The Range To Other DTI Models


Range (Metres)

Range (Yards)

ZEISS DTI 4 4/35






ZEISS DTI 1 1/19



ZEISS DTI 1 1/25



ZEISS DTI 3 (GEN 2) 3/25



ZEISS DTI 3 (GEN 2) 3/35



ZEISS DTI 6 6/20



ZEISS DTI 6 6/40




How much does the ZEISS DTI 4/35 cost?
You’re generally looking at a price of around £3,050.

Can you really use the ZEISS DTI’s during the day?

Yes, the ZEISS DTI 4/35 works during the day and at night. During the day it is more useful finding species that are well camoflaged.

What is included in the box?

You’ll receive the following when purchasing the ZEISS DTI 4/35, including:

  • ZEISS neck strap and pouch
  • USB-A toUSB-Ccable
  • USB-A toUSB-Cadapter end
  • ZEISS cleaning cloth
  • Quick guide
  • Safety instructions
  • Warranty Card
  • EULA document

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