Review of the
M.Zuiko 150–400mm
F4.5 TC 1.25x IS PRO

Text and photos by
Kevin Loughlin
Yardley, Pennsylvania

June 20, 2024

Holy freakin’ cow! I have uttered those words quite regularly, and rarely quietly, from the moment I unpacked my new Olympus M.Zuiko 150–400mm F4.5 TC 1.25x IS PRO. Olympus Camera is now OM SYSTEM (a division of the newly formed OM Digital Solutions or OMDS), after splitting from Olympus Medical in 2021. Olympus has been a leader in the Micro Four Thirds (M43) sensor mirrorless camera system, and OM SYSTEM will continue with this compact and lighter-weight format. The M43 sensor is roughly half the dimensions of a typical full-frame digital single lens reflex (DSLR) camera, which translates into a higher (two times) apparent image magnification with the same focal length lens. In other words, the Olympus M.Zuiko 150–400mm F4.5 TC 1.25x IS PRO offers an equivalent focal length of 300–800mm when compared to full-frame systems. 

So what does the TC 1.25x in the name stand for? That’s another fun capability of this lens . . . it has a 1.25x teleconverter built in. Just flipping a switch multiplies your focal length by 25%, so the 300–800mm equivalent focal length becomes a 375–1,000mm f5.6 super telephoto birding lens.

As I unpacked my new lens, the first thing I noticed was the lack of weight. I expected a professional lens of this magnitude to have some heft, but instead I immediately checked to be sure the glass was intact. At just about four pounds, this lens sits comfortably in your hands, especially when attached to the flagship OM-D E-M1X body. The balance makes it quick to maneuver while following birds in flight. Matched with the E-M1X’s bird-tracking focus, my flight photo “hit rate” jumped exponentially!

Olympus M.Zuiko 150–400mm F4.5 TC 1.25x IS PRO, with OM-D E-M1X body. Photo © Greg Neise.

My first adventure with the lens was on the Galapagos Islands, followed by 10 days in the Andes of Ecuador. What a perfect combination of situations and environmental conditions in which to test all the features and capabilities of this lens. From sandy beaches, ocean waves, and rocky shorelines full of cooperative birds and wildlife to high-elevation, rainy cloud forests with fast-moving hummingbirds, dark forest dwellers, and some cool bugs, this camera always excelled.

The OM SYSTEM upper-level camera bodies, along with their PRO series lenses, offer incredible weatherproofing. This new lens did not disappoint, as on one morning while I was taking long-exposure images at Gardner Beach on Española Island. The 150–400mm hung on my side as I set up my tripod when a rogue wave crashed into me at waist level, drenching the camera and lens in sand and salt water! Most photographers would cringe as tears welled up in their eyes in this situation . . . I, however, calmly opened my water bottle and rinsed my equipment off with fresh water and kept taking photographs. That was in Sept. 2021, and I have not had to send anything in for repair. I would, of course, recommend avoiding situations like this, but knowing this equipment has a good chance of survival when accidents happen is reassuring.

With a monopod, this White-chested Puffbird was photographed using the OM-D E-M1X Olympus with the M.Zuiko 150–400mm F4.5 TC 1.25x IS PRO at 1,000mm, ISO 3,200 at a shutter speed of only 1/10 second at f/5.6. I tried this at a bit slower shutter speed, but got a slight blur. I learned that, as long as the subject is not moving, my personal limit is 1/10 of a second. Ecuador, 2021.

Some photographers may balk at the $7,500 price tag. But let’s do some comparisons with full-frame lenses. A typical Nikon or Canon 800mm lens has a maximum aperture of f/5.6 vs. the OM lens at f/4.5. The full-frame 800 f/5.6 lenses weigh about 10 pounds (4536g) vs. the OM at about four pounds (1814g). One of the biggest benefits, in my view, is the minimum focus distance of the OM lens at only 4.25 feet (1.3m). Compare that to the $12,000 800mm f/5.6 lenses from Canon and Nikon, whose minimum focus is nearly 20 feet or about six meters! The OM lens, especially with the 1.25x teleconverter activated, is great not only for birds in general, but especially for hummingbirds, as well as dragonflies and butterflies.

Having a minimum focus distance of 4.25 feet (1.3m), small subjects can fill the frame from a safe and unobtrusive distance. At an equivalent of 1,000mm at f/10.0, I got a bit of depth to capture this lava lizard eating a large painted locust. Ecuador, 2021.

The weight factor alone allows this lens to be handheld. This light weight,coupled with the OM SYSTEM’s image stabilization, allowed me to take handheld images in the dark forests of Ecuador at shutter speeds as slow as 1/25 of a second. Using a monopod, even slower speeds were attainable, as long as my subject wasn’t moving too quickly. Not requiring a tripod for low-light images, I could move more quickly to get on birds I could not have captured with a heavy lens encumbered by a tripod.

While in Panama, I did some additional testing using the M.Zuiko MC-14 1.4x teleconverter and the MC-20 2.0x both with and without using the built-in 1.25x teleconverter. Using a tripod at reasonable shutter speeds, I photographed a cooperative Double-toothed Kite using the effective focal length comparisons of 800mm, 1,000mm, 1,400mm, and 2,000mm. Although the image was slightly soft at 2,000mm, I still considered it better quality than I ever got using my previous full-frame professional system and lenses with a 2.0x teleconverter. So even though I would not recommend shooting at 2,000mm all the time, the option could come in handy at times.

A cooperative Double-toothed Kite allowed some fun test images using the MC-14 and MC-20 teleconverters in conjunction with the 150–400mm PRO’s built-in 1.25x teleconverter. With camera and lens on a tripod, I took this image equivalent of 1,400mm (built-in 1.25x TC+MC-14 1.4x). I was impressed. Panama, 2021.

The sale of the Olympus camera division left a lot of people wondering if the M43 system would perish. I, however, was quite excited about the move. Having been part of the photographic world for more than 50 years, 30 of those involved in camera sales, I am more familiar than most with all sides of this puzzle. I look forward to what OM Digital Solutions will do with the OM SYSTEM. While I was writing this review, a new camera from the OM SYSTEM, the OM-1 (paying homage to the OM-1 film camera released 50 years ago) had just been announced. The new technology in this camera body will be a game changer, and I cannot wait to put it to the test with the M.Zuiko 150–400mm F4.5 TC 1.25x IS PRO attached!

This review first appeared in the August 2022 issue of Birding.



Kevin Loughlin, owner of Wildside Nature Tours, has traveled the globe for over 50 years to enjoy and photograph birds and wildlife. His images and articles have appeared in Birding, Living Bird, Nature Photographer, and Audubon. His new book, Galapagos: A Natural History, co-authored with John Kricher, will be available in November 2022.