Zeiss’s DTI review with Chris Parkin

Chris Parkin gives his verdict on Zeiss’ first foray into thermal imaging, with the new DTI.

It was only a matter of time before some of the big European names began to seriously flirt with night vision and thermal imaging, and my first encounter with such a product is the Zeiss DTI 3-35 thermal imaging monocular.

There is no escaping that Zeiss have clearly displayed the device is made in China but before this seems a little worrisome, I have to say my overall opinion of the product is that its performance is a respectful reflection of the brand’s name and heritage – it is rather good in fact.

This monocular is unlike many others in that it is truly ambidextrous. The tube is slightly tapered in shape with a tactile rubberised finish coating the tough inner metal structure.

Zeiss DTI 3-35 Specifications

Focal length: 35 mm
Sensor resolution: 384 x 288
Thermal sensitivity (NETD): ≤50mk
Display resolution: 1280 x 960
Display frame rate: 50 Hz
Display type: LCOS
Range: 1235 m (1350 yd)
Field of view of the ocular: 30.25°
Field of view at 100 m: 19 m (62 ft)
Optical magnification: 2.5
Maximum digital zoom: 4x
Zoom steps (in 0.5x): 1.0x – 4.0x
Battery type: Li-Ion
Battery run time: 7 h
Internal storage: 15 GB
Lifestream function (Video & Photo): +
Resolution (Video & Photo): 384 x 288
WLAN Frequency: 2.4 Ghz
WLAN Standard: IEEE 802.11 b/g/n
Operating temperature: − 10°C | + 40°C (+ 14 °F | + 104°F)
Length x Width x Height: 193 x 60 x 65 mm (7.6 x 2.4 x 2.6″)
Weight: 450 g (1.01 lbs)

The taper makes up for hand size variation and those at the extremes of this range will be used to compromise but my average-sized hands were comfortable with no need for a lateral strap to help accommodate an angular shape.

Starting at the front, the 35mm objective lens is recessed about 3mm within the surrounding serrated rubber collar which is turned to sharpen image focus.

A rubber lens cap is supplied which stays in position when wanted and avoids the annoying habit of accidentally re-covering the lens when you don’t want it to; it hangs clear below on a rubber strap to free up space for your hands and fingers.

Focus is tactile and lightweight yet remains mostly frictionless so once positioned, stays sharp. It’s better controlled with the free hand with the DTI held in the other but in fact it’s not impossible to focus with the holding pinky or third finger due to its delicate tactile feel.

On top of the body, you find a power switch needing a short hold for ‘on’ and a longer hold to power down. A fast press turns the internal screen off to save battery life and avoid shining light up into your own face when not in use.

The camera control button is next, it has a raised centre dot for ease of detection and short presses start or stop the video, longer presses flip the DTI from stills to film and single presses in the former activate each snapshot.

The eyepiece shield and lens quality were notably well designed

Next are the magnification controls: these digitally zoom in on the internal picture beyond the base 2.5x optical magnification in 0.5 increments up to 4x which is effectively 10x overall magnification. Being digital rather than optical magnification, pixellation increases accordingly.

I quite like the fact you only really need to use one side button as zoom is displayed in the upper right corner of the internal screen and when you get up to 4x, the next press goes round, back to ‘1x’ for fast target acquisition from a broader field of view.

The rearmost button is the mode control, short presses scroll between white, black or ‘red hot’ and finally rainbow colour palettes. A long press enters the menu function where brightness and contrast are controlled from 1 to 4.

Further control within the menus are the ‘PIP’ or picture in picture function which zooms the centre of the screen in a small upper window, a handy function in some circumstances but I find more so when searching for available aimpoint detail quickly on riflescopes, and slightly less useful, although still appreciated on a spotter.

Image focus can be done with your opposing hand or, if necessary, the pinky finger of the carrying hand

Next is the auto calibration mode that is notably quieter and smoother than other thermals I have used before, less noise from the internal shutter blanking across and allowing the sensor to be thermally neutralised. WiFi is available allowing the DTI to pair with smartphone app to use live view or transfer video and stills with reliable pairing when required.

The most interesting feature is the ‘Hot Tracking’ which, when engaged, allows a small white inner square to dodge around the screen looking for and locking on to the hottest zones to either prioritise the former, or self-detect and inform you of other quarry you might not have seen (no matter how small) if they stand out thermally from their background.

The left side of the DTI’s tube shows a control for dioptre focus on the internal screen which, once done, does not need messing with again. The rearmost eyecup is oval shape and quite soft. It is truly ambidextrous, just like the rest of the body shape and can be switched from left to right eye instantly with no external light entry.

I found this especially helpful as it allowed me to somewhat ‘share’ the loss of night vision (any illuminated screen temporarily diminishes human low light sensitivity both pupillary and chemically). Many people will happily keep it all to one eye but I’m not a fan of the imbalance this leads to and the ability to swap instantly on the DTI was a real benefit for me.

The eyebox from the lens is spacious which lessens the critical annoyance of having to perfectly position your eye for correct focus each time, especially on a device so fast to lift and spot with, perhaps alongside daylight binos.

Factors like these are subtle but for a name like Zeiss, an optical champion of so many markets, I was not surprised to see them seamlessly float over hurdles other more innocent new brands fall foul of.

The last little feature I want to mention is the neck strap. This might sound dull but it was a strong factor, it slots into two paired symmetrical loops on the underside of the DTI and allows the unit to hang central on your chest, perfectly oriented for grasping in either hand, no asymmetry of palm grips etc.

I really liked it and found the unit fast and utterly intuitive alongside the fact you could almost forget you were carrying it securely without hindrance, with or without daytime binoculars alongside if needed.

Two roe deer were caught on black=hot at about 50 metres

So, in use, well, it’s a while since I was parted from a thermal binocular and I liked the Zeiss far more than any monocular for the aforementioned visual balance reason. Yet the Zeiss, with ease and fluidity of movement, became an unquestioned compact companion.

Detection range was never in question. Zeiss quote 1,235 metres from their ≤50mk sensor for which the 30.25 degree (19m @100m) field of view combined to give plentiful scanning performance with no optical stress on my weary eyes.

I’m no fan of huge magnification and like thermal for scanning and initial spotting before moving over to more precise tools as and when required. Being able to walk and scan without undue effort allowed me to see more and see it faster with more appreciation of quarry movement in short instances. My preference is of assessing an animal though movement rather than attempting extreme detail in the darkness.

For deer stalking it was good to see the merest fractions of heat displayed though minor gaps in foliage, deer that were otherwise almost invisible without movement to daylight optics, making this a great item for stalkers with its appreciably compact nature.

The flip side was that for night-time shooting and primarily foxing (there seem so few rabbits anywhere near me now), I thought I would find weakness in the unit when compared with my favoured binocular.

Well, given the relative price jump up to a biocular, I didn’t feel outgunned when using the DTI and this surprised me. For long term, darkness viewing I would still prefer both eyes locked onto that internal screen but not everyone needs all the added functionality and necessary bulk.

I’m terrible for carting too much kit around and my most recent resurgence of hunting delight has been closely paired with cutting the luggage to a minimum, a factor for which the Zeiss is well paired.

The subtle ergonomic factors are something it’s hard to notice in a market where the latest specifications are paramount but I really liked the DTI in this element, a very good design but that’s not to say it is lacking electronically.

I found it gave slightly superior detection performance in poor air quality (damp or humid) than some more expensive competition and the internal screen, with distinctly superior ocular lens quality, gave a wonderfully textured image of scenery and topography, both close and at distance well beyond 700-800 metres where stags were ‘just’ distinguishable from encircling hinds.

Video and still footage never quite capture the excitement of use live during the hunt but the fluidity of movement on video is appreciable from the fast refresh rate and very noticeable when watching deer running or jumping walls at full speed, nothing at all staccato. I set them on auto refresh but never seemed to notice that short second of the screen freezing usually experienced.

The DTI highlighted topography, and the quarry on it, really well

A USB port on the underside handles charging and connection to a PC is needed. The on-board lithium ion battery promises seven hours of run time and I can’t disagree with this as my usual 4-5 hour maximum foxing forays never took it to less than 50 per cent remaining on the internal display. Regardless, with a USB, its easy to plug it in virtually anywhere with no requirement of an additional charger unit, which I personally like.

Internal storage is 15Gb which will hold several hours of footage although it’s quite low resolution, yet I don’t mind that, you get the idea of what has been seen without being overly dramatic and voyeuristic.

Lastly, there is also a ¼” socket for tripod mounting on what I think may end up being listed in one of my top five products of 2020; a sorted, well thought out ergonomic delight with more than comparable electronic functionality which, paired to a human via intelligent layout, punches hard enough above its weight to seriously impress even Picky Parkin; excellent. 

Hunt it down

Zeiss DTI 3-35
RRP £2,650.00

Scott Country International
01556 503587

To view the Zeiss hunting range visit: www.zeiss.ly/thermal-imaging-cam

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