My Canon 100-400MM L lens has done me well for nearly 12 years now. However, I'd always wanted a bit more reach, as aircraft is my main subject. The longer Canon lenses are out of my price range, also their size and weight make them impractical to use without support & I like the freedom to shoot handheld.

When it started to become available I couldn't resist the new Tamron 150-600mm. The price at under £1000 was good (less than the Canon 100-400) and I convinced myself its size and weight would be just within my limit to want to carry and use handheld. So I clicked "buy" when I found a retailer (Jessops) with stock.

While the initial reports where positive I started to get nervous when shortly after clicking that 'buy' button I started to read reports that it was soft at 600mm, particularly wide open and that in continuous, 'AI-SERVO', focus mode (the mode I'd normally use with this lens) it was poor at maintaining focus. Though, fortunately for me, reports suggested that focusing was OK on some Canon bodies, including my primary body, a 5DMarkiii, hopefully I'd be OK!

Well, I've had the lens for nearly 2 weeks now. During which time opportunities to try this lens have been minimal, due to work and the poor weather.

However, I've now had a couple of opportunities to try it out - the results are presented in this gallery. So ...... my initial conclusions.........

1) Physical : yes it is bigger and heavier then the Canon 100-400, but it is manageable. On my riverside walk/photo-shoot yesterday I found it wasn't too bad to carry mounted on my camera using the standard camera strap. The construction feels very good, it feels like quality, though probably not as robust as the big Canons? time will tell!!?

2) Handheld : All of the photo's I've taken so far have been handheld. Yes it is heavier than my Canon, but I didn't notice it as much as I thought I would. The image stabilisation (VC) seems to work very well. The biggest issue is to ensure a shutter speed fast enough to freeze any subject movement.

3) Image quality, is it sharp? Yes, from these initial results it appears at least as sharp at 600mm as my Canon was at 400mm. What do you think?

4) Image quality wide open: again, I'm happy, see my images. At 600mm F6.3 the depth of field is very shallow, so focus needs to be spot on, and a smaller aperture may be required to get sufficient of the subject in focus for the picture to appear sharp.

5) Focus: A bit of a mixed bag here. Initial focus most of the time seems very good and quick. Most of the time when panning around to find/track my target in 'AI-SERVO' mode it kept focus pretty well. However, at times if it changed focus from a very distant point to a nearer point it would then be very reluctant to change back to a more distant focus point, without forcing a refocus (releasing the trigger and half pressing it again) - sometimes a manual nudge of the focus ring on the lens towards infinity was also required. Too my surprise if anything it seemed to work better using area focus point selection then using a single selected point. I was relieved when I was able to acquire and maintain focus on a couple of aircraft that had just take off from Southampton airport. Focusing on subjects near the minimum focal distance for the lens (the butterfly shots) was much easier then I expected and seemed better than on other long lenses I've used. I reserve final judgement on focusing, particularly in AI-SERVO mode until I've had chance to use it more, I suspect on a 5Diii it is usable but possibly slightly frustrating! (I also have a 7D as a 2nd body, others have reported issues with this combination, I've only very briefly tested it, it seemed usable like the 5Diii ... but more testing is required).

..... Overall, so far I'm pleased with this lens and think it will replace my Canon 100-400, am looking forwards to the air-show season starting (FRIAT ticket booked for Fairford in July!).Ian Hardy