Thermal Monocular Review: Topdon TS004

Background, Year 12

I have been trying out a friend’s thermal monocular for a few days. These devices have made amazing advances in the past few years both in terms of capabilities and price drops. While I am NOT recommending the purchase of this device, the Topdon TS5004, that is not because I was not impressed with the thermal vision scope. I was impressed. Let me explain …

From a practical standpoint because of the high prices that had to be paid to obtain decent thermal imaging, thermal scopes used to only be available for the military. For us “non soldiers” the cost did not justify the price. However, prices have fallen dramatically. As of today, the Topdon TS5004 can be bought for around $400 (Amazon link … for your benefit … not sponsored).

My tests involve multiple trips into the forest to try out the device on Les and Amy, my resident Great Horned Owls. Given Amy has now nested, I always knew where she was located; and both afternoons that I spent hiking right before sunset, I knew where Les was perched. Thus, I cheated. I already knew where two owls were located, which allowed me to easily test the thermal scope. Amy lit up like a Christmas tree. Compared to her surroundings the scope showed that something was definitely throwing off all kinds of heat … infrared light. However, I could NOT tell that what I was seeing was an owl:

  • I was close to the nest … within 30 yards, but obviously not up in her nest tree
  • Amy was the ONLY item within my field of vision with a heat signature. This would not be unusual in the Minnesota forest in the middle of the winter. It is a tough environment. Not a lot of life can survive our extreme winters. It is actually -18F right now as I type out this post at 6:00 am … long before sunrise at 7:20 am. Thus, the scope definitely made it obvious something was alive within my field of view.
  • I have talked about “field of view”. The Topdon has a narrow field of view. In its best quality mode there is zero magnification, but still a narrow field of view. It does have digital zoom of 2x, 4x, and 8x, but you would never be able to uses those magnifications if you were in a search mode (i.e. you did not already have some object pre-located upon which you wanted to zoom the monocular)

I also looked for Les, the male Great Horned Owl, which I knew was perched on the other side of a very tall white pine. Although I knew the bird was at the top of the tree, the thermal scope could not tell something was perched on the other side of a large tree trunk … not surprising or unexpected.

In my estimation a thermal scope will not assist your birding efforts. It obviously can not be used while driving. Even upon stopping, the field of view is small. A better use of your time and resources will be to better learn bird habitat, and invest in a really good pair of binoculars. I like Nikon Monarch binoculars. Good binoculars have a decent field of view, and allow you to quickly scan thick cover for birds.

I have, however, seen some cool thermal scope setups. A local bird guide has two scopes mounted outside his car pointing towards each side of the road, and the scopes are in turn each connected to tablets within his car. Thus, this guide can drive roads slowly and obtain the benefits of thermal scopes. Please understand these scopes do not work through glass; they must be outside. Understand that thermal scopes definitely work during the Minnesota winter. The heat difference makes living animals jump out even in daytime. During summer months, or in warmer climates these devices may not work as well during daylight hours.

Here are a few more links, videos and an image which will allow you to learn more about the Topdon TS004. Once again, for the price I am supremely impressed with the technology obtained for the price, but I personally would not yet find one useful. My Topdon photo shows you my hand because I wanted everyone to understand the size of the thermal scope. My image shows the device is not complex … only four buttons: Power, Mode (different kinds of light displays), Magnification and Picture. {this device does NOT take good night photos … it is a scope, not a camera}

If you would like to learn more about Les and Amy, my local Great Horned Owls, including downloading a free PDF version of the children’s picture book I authored and photographed about their owlets, browse to this page on my website. Amy is pictured immediately below. The image was taken at exactly the same distance as from where I evaluated the thermal monocular, but with a 350 mm zoom lens on my Sony A6300 (530 mm full sized sensor equivalent)

Thank you for visiting 365DaysOfBirds. Rich Hoeg, the owner of this blog loves nature. You will never find a single advertisement, sponsored link or pop-up on this site. Learn more about Rich and his quest to bring the outdoors to his readership.

Owl Notes … the Irruption and Locals

Year 12,

The Owl Irruption is changing. While there are still Great Gray Owls in the Duluth / Two Harbors region, the numbers are down dramatically. The days of seeing an owl on almost every sign post and pole seems to be over. I suspect this change was caused by just too much hunting pressure, and the Great Gray Owls needed to move on because the local meadows and wetlands were hunted out.

In addition, an owl adventure that began on exciting high note on Sunday morning has ended poorly. I received a phone call at 9:15 am describing an owl which I believed needed help. I found the Great Gray, hand captured and delivered the bird to Wildwoods Rehabilitation Center in Duluth. It was interesting once more to have an owl, which was secure in a box, riding next to me in my Subaru. Unfortunately the owl did not survive past Monday. While the bird was not injured, it was starving and could not be saved. As a fyi, I do not photograph birds that I am involved with rescuing. Taking time out for photography would be wrong when the animal needs my help.

Nature must have known I needed a pick me up after the downer of the owl’s death. While quite cold yesterday, during a hike I discovered my local Great Horned Owl’s nest. Les and Amy are back for a seventh year nesting near my home. Here is a photo of Les keeping watch over his lady love. For the time being I will not be posting images of the nest to protect Amy. As a reminder, this is the time of year to take walks after sunset in the dark … listen to your local owl’s hooting … triangulate the sound … find the nest. The Poppa Owls will always perch very near (as in only yards away in a different tree). By triangulating the the hooting you can really zero in on the nest area. I then return after sunrise when I am better able to see.

And Amy … image taken two evenings before she nested.

The local Snowy Owls which winter here on the Arctic Riviera must have also decided to help cheer me up. An hour before sunset yesterday I found not one but two Snowys.

Snowy #1

Snowy #2

Minnesota Owl Irruption and the Magic Lighthouses!

Year 12

When one lives in the middle of the Great Gray Owl irruption of 2025, one can be very picky about when to head out and look for owls. Yesterday morning was beautiful, albeit very cold, but with clear skies long before sunrise. The day prior we had experienced a snowstorm with 40+ mph winds. Thus, I knew that Great Gray Owls which hunt by hearing voles running beneath the snow, had gone hungry during the storm. I expected my local owls to be out before sunrise looking for food. Thus, I took the short drive to Two Harbors, ignoring other owls because I wanted the sunrise and both of our two lighthouses in my photographs. I really can’t believe I have become this “picky” on when and where I will look for owls!

Regardless … Great Gray Owls and the Two Harbors Lighthouses at Sunrise

Lighthouse #1 and Great Gray Owl

Lighthouse #1 and Great Gray Owl

Lighthouse #2 and Great Gray Owl

10 Minutes After Sunrise … Owl Hunting … I’m Leaving (going home)