Super Zoom? Tamron SP 150-600mm F5.0-6.3 Di VC USD Field Test

Tamron SP 150-600mm F5.0-6.3 Di VC USD
$1069 / £800

Tamron announced the SP 150-600mm F5-6.3 Di VC USD at the end of 2013, and as one of the cheapest ways to reach past a 400mm focal length, it quickly became popular with amateur wildlife and sports photographers. We've previously published a lab test review for this lens, but in order to get the complete impression, I wanted to spend some time with it out in the field, doing what this lens was designed for.

The SP 150-600mm F5-6.3 Di VC USD is available with either a Canon, Nikon or Sony Alpha mount. All three versions are identical, apart from the lack of image stabilization in the Sony-compatible version, which relies instead on Sony's in-camera SteadyShot Image Stabilization technology. For this test, I was shooting with the Canon EF mount version of the lens on both full frame and APS-C bodies.

At 10" long (without the lens hood), and weighing in at 4.3lbs (1.95kg), it isn't a small lens by most people's standards. It will definitely garner a good number of 'you must be able to see craters on the moon with that lens' comments when in public. Though considering that a Canon 70-200mm F2.8 weighs 3.45lbs, it suddenly doesn't seem so heavy. With the weight nicely distributed along the barrel length, it feels well balanced, and most people will find it possible to shoot hand-held with it for short periods of time if you are simply picking up the camera to take a shot. If your chosen subject requires prolonged periods of actually looking through the viewfinder and waiting for the right moment, a tripod or monopod will be a necessary accessory.

In Use

During the test period for this lens, I took it on two wildlife trips to try it with both my full frame 5D Mark III, and also my APS-C 7D Mark II. On both of these trips I also had my own personal Canon EF 200-400mm f/4L IS USM with me. Whilst this would be far from a fair, direct comparison, I was extremely curious to do some side-by-side shooting to gauge the Tamron's performance, relative to what is seen by many Canon photographers as the ultimate wildlife lens. Can a lens that costs one tenth the price of the 200-400 really hold a candle to it in any way?

The first of my two trips with the lens saw me in the Chilcotin mountains of British Columbia in search of grizzly bears. I chose to photograph the bears from a kayak, in order to get down on their level and really give the sense that I was a part of their environment. As with most wildlife, these bears were active in the early hours of the morning and the late hours of the evening. With low light levels, and the ever present bobbing motion of my kayak, this presented a tough challenge for Tamron's Vibration Compensation system.

Grizzly bear in the Chilcotin Mountains, British Columbia. Tamron 150-600mm @600mm + Canon 5D Mark III - f/6.3 , 1/500, ISO 3200 - Raw file processed in Lightroom CC. Highlights +3, saturation +11, exposure +0.4.

In an ever-changing, real-world shooting situation like that one, it's almost impossible to do repetitive scientific testing on something like image stabilization. However, with enough usage, and the well-known benchmark of my Canon 200-400 to compare it to, I'm still confident in drawing conclusions. Tamron says that the VC system gives you 'up to a 4-stop advantage', but in practice I would say that, when used at the long end of the zoom, I was getting a good ratio of sharp images at something much closer to 3 stops under a regularly hand-holdable shutter speed. Everyone's definition of a good keeper rate will vary, and I was certainly able to get some usable shots in 4-stop range, but I was never confident with it.

The image in the viewfinder does jump when the shutter button is pressed to engage it, but I didn't find it overly distracting, and the VC system is impressively quiet. Overall, in terms of stabilization, the lens does a solid job. It didn't set the world on fire, but it provides some much needed assistance when shooting at longer focal lengths.

Since this could very well be many people's first long focal length lens, it's worth underlining just how much harder it is to get a sharp shot at 600mm, when compared with a shorter telephoto such as a 200mm. If it's your first time working with a lens in this range, you should expect to take a little time getting used to it and perfecting your long lens techniques. Even though the Tamron 150-600mm is relatively small compared to many other super telephoto lenses, its light weight means it can be significantly affected by gusting winds, particularly when zoomed out to 600mm with the large lens hood on. On the wide open lakes of British Columbia in my kayak, this is something that required a small compensation with additional shutter speed on several occasions.

Heron in the Chilcotin Mountains, British Columbia.  Tamron 150-600mm @600mm + Canon 5D Mark III - f/7.1 , 1/160, ISO 2000 - Raw file processed in Lightroom CC. Highlights -30, shadows -2, whites -27, saturation +4.

Autofocus

From an operational standpoint, the weakest point of this lens is definitely its autofocus. It is accurate when it locks on, and it even tracks much better than I had anticipated, but it seeks for initial focus far too often, and for too long. Even when presented with a good amount of nicely contrasting light, if the current focus position of the lens is a long way off what you are trying to lock on to, it often seeks back and forth several times before finding its target.

Phase detection autofocus can be an iterative process for such long focal lengths, as often a distant, out-of-focus subject provides too little contrast for the AF system to make a phase measurement (in order to tell the focus element where to jump to to lock focus). Hence, some focus seeking with such long lenses would be expected of any super telephoto. What I was seeing from the Tamron 150-600, though, was a much more prolonged seek time compared to any other lens that I have ever used, particularly at longer focal lengths. The amount that the lens elements moved back and forth during this initial stage of focus was much more than with my 200-400, and it caused me to miss several shots.

Grizzly bear in the Chilcotin Mountains, British Columbia. Tamron 150-600mm @600mm + Canon 5D Mark III - f/8 , 1/640, ISO 1600 - Raw file processed in Lightroom CC. Highlights -28, vibrance +10, saturation +6.

Since returning the lens to Tamron, I've also taken delivery of the new Canon 100-400 f/4.5-5.6 L IS II. After two weeks of shooting with that lens, one that is far closer to the Tamron's price point than the 200-400 is, I can say that the Canon's AF performance is superior. Certainly, initial time to lock onto a subject is barely distinguishable to the performance I get from the 200-400, whereas the Tamron typically felt very slow. 

On the first trip with the Tamron lens, I used it exclusively on a 5D Mark III and ran into some AF troubles when only using the central AF point. The lens would sometimes fail to lock onto a target at all, until a cluster of AF points was used instead of the central, single point. Tamron replaced the lens with another which worked much better, but still fell short of what I would have hoped for. I do believe the first lens I tested was genuinely faulty, but the second one still gave me the initial focus hunting issues described in the previous paragraph, and on occasions caused a few missed shots when used with the 5D Mark III.  

Halfway through the testing period, I purchased a 7D Mark II and was excited to test the Tamron on the new APS-C body. The 5D Mark III, 1D X and 7D Mark II all share several characteristics when it comes to autofocus systems, but they aren't identical. The 7D Mark II features 65 AF points that are all cross-type down to f/5.6, where the 1D X and the 5D Mark III have 61 points, of which up to 41 can be cross-type, depending on the lens that's in use and its maximum aperture. Importantly, peripheral points on the 5D Mark III and 1D X are only cross-type with f/4 or faster lenses, potentially giving the 7D Mark II an advantage with slower lenses like the Tamron.

Elk, Jasper National Park, Alberta. Tamron 150-600mm @600mm + Canon 7D Mark II - f/8 , 1/500, ISO 1250 - Raw file processed in Lightroom CC. Exposure -0.25, saturation +4, vibrance +5, highlights -90.

The 7D Mark II also has the widest spread of AF points across the frame, for any Canon DSLR. This makes it much easier to stay locked onto an erratically moving subject that might move towards the edge of your frame. On top of this, the 7D Mark II employs an updated version of the iTR AF system that was first introduced with the 1D X (Intelligent Tracking & Recognition AF). This system makes use of the camera's 150,00-pixel RGB metering sensor to relay color information for cross referencing with phase detection data from the AF module. In essence, it's able to help the camera understand the whole scene in front of the camera, and aid with object tracking in AI Servo mode by allowing the camera to automatically pick appropriate AF points to follow your subject around the frame. The 5D Mark III has a primitive version of this feature that primarily relies on distance data from the AF module's phase-detection data (since its metering sensor is far too low resolution at only 63 zones). The result is that AI Servo tracking with the 7D Mark II is noticeably more accurate.

Switching the Tamron 150-600 over to the more powerful AF system of the 7D Mark II gave a marked improvement in my experience with the lens when tracking moving subjects. The 7D Mark II's AF system really is first class, and with the Tamron lens, it made a potent pairing that gave me a 240-960mm focal length equivalent. I wouldn't say that any AF issues were entirely eliminated with this combination, but they were certainly pushed further back in my mind, allowing me to get on with the job at hand.

White Tailed Deer, Jasper National Park, Alberta. Tamron 150-600mm @309mm + Canon 7D Mark II - f/6.3 , 1/800, ISO 1600 - Raw file processed in Lightroom CC. Highlights -26, exposure -0.5, contrast +20.

When raising the camera to my eye, if the focus distance was a long way off my target, I would make a quick manual adjustment with the lens' focus ring to bring it roughly into the right area before pressing the AF-On button on the back of the camera. This technique definitely helped to minimize the initial focus seeking and difficulties were then really confined to tracking moving subjects in very low light, a situation that will trip up many systems. And on the point of shooting in low light, the 7D Mark II's center point is sensitive down to -3 EV, which likely helped focus in the dim conditions I was shooting in. 

In summary, I was able to get the best out of the Tamron lens with the 7D Mark II, but hunting issues did persist with both cameras I tested the lens on. Part of what might be causing the hunting may be the maximum aperture of the Tamron lens, which drops to f/5.6 when zoomed in to a modest (for this lens) 226mm. By 428mm, the maximum aperture drops to f/6.3. Since most of the AF points outside of the central ones only work to f/5.6 (with cross-type sensitivity only working to f/4 - i.e. never with the Tamron lens - at peripheral points on the 5D Mark III), it's quite likely that the hunting was due to the phase-detect sensors reaching a hard limit due to the maximum aperture. The best way to work around this would be to use the f/8-sensitive center point only as you zoom in and the maximum aperture decreases, but of course this means you sacrifice subject tracking ability (across the frame).

Focal range

Having such a huge zoom range in a lens like this is great for wildlife photography because it allows you to capture several very different looking images in quick succession. At 600mm you can grab a close portrait of your subject, and all the way out at 150mm you'll get a shot that really shows the animal in its environment. If you've traveled a great distance, or spent many hours waiting for the animal to show up, a zoom lens like this is an excellent way to maximize the opportunities of your encounter, and come away with a selection of very different looking images.

Grizzly bear in the Chilcotin Mountains, British Columbia. Tamron 150-600mm @375mm + Canon 5D Mark III - f/9 , 1/1600, ISO 1600 - Raw file processed in Lightroom CC. Clarity +1, vibrance +3, saturation +1.

For sports photography, a zoom works well when you are confined to designated shooting positions at an event. As the action comes closer to you, you can quickly zoom out to make sure nothing is lost from the frame. A super telephoto prime lens might be sharper and a bit faster, but the flexibility of a zoom lens can bring considerable benefits to counter those two factors.

One disadvantage of a long zoom lens is the necessity to have a variable maximum aperture. Whilst it would technically be possible to create a zoom of this range with a fixed aperture, it would be many times larger, heavier and more expensive. The Tamron's lens varies from F5 to F6.3, with the most important jump being from F5.6 to F6.3 at around the 420mm mark. From an aperture standpoint, F6.3 would definitely not be considered fast, although there are no other lens options at this price point that offer anything faster.

Side-by-side testing with this lens and my 200-400mm F4 proved an interesting point. With wildlife often tending to be active in the early and later parts of the day, there will come a point where you are limited by your aperture. With the shutter speed that is need for shooting at these long focal lengths, that point of limitation might come sooner than you expect. When shooting the grizzly bears from my kayak with the Tamron, I would reach what I consider to be the useable ISO limit of my camera, and then switch to shooting with my Canon lens and its wider F4 aperture. As the sun went further below the horizon, this wider aperture gave me at least another 15-20 minutes of workable light, in which I would often make several extra images that I was pleased with.

I mention this, not as a knock to the Tamron in any way at all, but simply as a way to demonstrate one of the big reasons why some people are willing to purchase lenses which are that much more expensive. The low cost of the Tamron ($1070/£800) is what I would consider to be a real enabler. It gives people an affordable way to explore a new type of photography, that possibly wasn't previously viable for them. Yes, you might not be able to shoot for quite as long as dusk comes, or start quite as early at dawn, but F6.3 is still good enough to get you out there and I still got a great many shots that I'm pleased with.