Setup guide
One Thermal, Three Jobs: Using the DNT Hydra as a Scope, Clip-On or Handheld
A lot of buyers assume a clip-on thermal will work in front of any scope they own. The DNT Hydra's clip-on role is designed for an LPVO kept at the lower half of its magnification, or a low-magnification prism sight, not a high-power hunting scope. Get that right, and the Hydra really does cover three jobs: a riflescope on its own, a clip-on in front of your day optic, and a handheld scanner, all from one unit and one QDM150 mount.
For most hunters with a conventional scope, we'd use the Hydra as a standalone scope and lift it off for handheld scanning. Clip-on use makes the most sense if you already run an LPVO or prism sight.
The QDM150 does the switching
DNT supplies the QDM150 quick-detach mount with the Hydra, and it's what makes the three roles practical. It sits the Hydra's centreline 1.5 inches (about 38 mm) above the rail and has Picatinny slots on both sides. One side clamps to your rifle; the other holds the Hydra. A latch locks the two together with a click, and pressing the latch and flipping the lever releases them without tools.
The diagram below shows the three setups side by side. In each one, the mount base stays on the rifle, so the Hydra always returns to the same spot.
DNT lists torque settings for the mount's screws: 35 in-lb (about 4.0 N·m) for the Picatinny adapter screws and 30 in-lb (about 3.4 N·m) for the side-plate screws. Use a torque driver rather than guessing. If you're not sure what rail your rifle has, our guide to choosing between Weaver, Picatinny and dovetail rails will help.
Standalone: a thermal riflescope
On its own, the Hydra works like any thermal scope. You aim with its built-in reticle (eight styles in five colours), zero it like a riflescope, and use its 65 mm of eye relief to set your head position comfortably. This is the simplest setup and the one we'd start with if you don't own an LPVO or prism sight.
Clip-on: thermal in front of your day optic
In clip-on mode, the Hydra sits on the rail in front of your day optic, and you look through the day optic at the Hydra's thermal picture. You aim with the day optic's reticle, so the zero you already trust stays in charge.
The day optic matters. The diagram below sums up DNT's recommendations.
The two units also need to line up. The QDM150 puts the Hydra's centreline 1.5 inches above the rail, so mount your day optic at a matching centre height. If the two sit at different heights, the thermal picture won't sit centred in your day optic.
Clip-on suits shooters who already run an LPVO or prism sight on a pig or fox rifle and want to add thermal without changing their aiming system. If you shoot through a high-power hunting scope, use the Hydra as a standalone scope instead.
Handheld: scanning before you commit
Say it's the night before a trip and you're working through the setup at the kitchen table. Clip the Hydra on, take it off, put it back. With the QDM150, the Hydra lifts off the rifle and becomes a monocular, while the mount base stays on the rail. DNT says you can clip it back on without re-zeroing. The steps below show the sequence.
Even with a good quick-detach mount, we'd confirm the zero with a shot before you rely on it, especially after transport. The 3-in-1 Hydra models weigh 371–516 g, so it's light enough to scan by hand for long stretches. Its 65 mm of eye relief and forgiving eyebox help too, because your eye position changes more when you're holding it than when it's on a rifle.
Handheld scanning is where most hunters will feel the benefit day to day. You can glass a paddock from the ute without lifting the rifle, then clip the Hydra back on once you've found something worth a closer look. For which Hydra suits your hunting, see our DNT Hydra review.
Mounts for the DNT Hydra
Check the current price and availability, or ask us which mount suits your rifle.
DNT QDM150 mount DNT QDS150 mountDNT Hydra setup FAQ
Do I need to re-zero the DNT Hydra after using it handheld?
DNT says no. The QDM150 mount's base stays on your rifle, and the DNT Hydra locks back into it with a latch, so DNT states it returns to zero without re-zeroing. We'd still fire one confirming shot before you hunt, especially after the rifle has been knocked around in transport. Any quick-detach mount is only as good as its last check.
How high does the QDM150 mount the DNT Hydra?
The QDM150 places the DNT Hydra's centreline 1.5 inches, about 38 mm, above the rail, measured with compatible DNT optics. That height matters most in clip-on use, where your day optic should sit at a matching centre height so the thermal picture stays centred. DNT says its digital scopes share a similar base-to-centreline height across models.
What is the difference between the DNT QDM150 and QDS150?
Both are DNT quick-detach mounts with a 1.5-inch height. The QDM150 is the multi-function version, with Picatinny slots on both sides, so the DNT Hydra can lift off for handheld use while the base stays on the rifle; DNT designed it specifically for the Hydra. The QDS150 is DNT's standard quick-detach mount. Ask us which suits your setup.
Which reticle do I use when the DNT Hydra is clipped on?
In clip-on use you aim through your day optic, so its reticle is your aiming mark and your existing zero stays in charge. The DNT Hydra supplies the thermal picture in front of it. That's why DNT recommends pairing it with an LPVO at the lower half of its magnification range, or a low-magnification prism sight.
Does clip-on use change my point of impact?
It shouldn't, because in clip-on use you aim with your day optic's reticle and the zero you set with it stays in charge. What can shift things is a poorly matched setup, such as a Hydra and day optic sitting at different centre heights or a mount that isn't tightened properly. We'd confirm with a shot after fitting the Hydra in front of your day optic.
What torque should I use on the QDM150 screws?
DNT specifies 35 in-lb, about 4.0 N·m, for the QDM150's Picatinny adapter screws, and 30 in-lb, about 3.4 N·m, for the side-plate screws. Use a torque driver set to those figures rather than tightening by feel. Over-tightening can damage threads, while under-tightening lets the mount shift under recoil and wander off zero.
Does the QDM150 fit DNT ThermNight scopes?
Yes, in most cases. DNT lists the QDM150 as compatible with the Hydra, ThermNight and ZULUS HD ranges. The exception is early versions of the ThermNight TNC225R, which have a square mounting base that doesn't fit the QDM150 or QDS150. If you're moving a mount between DNT optics, check your model's base first.
Can I record video when using the DNT Hydra handheld?
Yes. Recording works the same whether the DNT Hydra is on the rifle, clipped on or in your hand, and the HS225, HS325, HS635 and rangefinder models store footage on 32 GB of built-in memory. Through Wi-Fi and the DNT app you can also watch a live feed on your phone, which is handy when a mate wants to see what you're glassing.
Can the DNT Hydra be mounted on a helmet?
Only the Hydra-Mini HS210M. DNT designs it for helmet use as well as standalone, clip-on and handheld roles, and it needs a helmet with a compatible shroud and a dovetail binocular bridge in Wilcox or KVC/RQE format. The 3-in-1 Hydra models, such as the HS225 and HS650R, are designed for rifle and handheld use.
This guide is based on DNT's published Hydra and QDM150 information.