New optics find their way to the market every so often and these are generally improvements over their predecessors. We know that the expensive professional grade lenses are best in terms of build and optical performance. But it is possible to find some excellent lenses which are modestly priced, or at least vaguely affordable (if you don’t mind losing out on weather sealing and rugged construction).

As a full-time professional my needs can be more complex than that of the average user. I need lenses for work which meet my demanding expectations and quality requirements. I also take a lot of photographs when I'm out and about - and I still want good quality glass. But I also want small size, light weight, and lenses which are easy on my pocket as well.

I'm a great believer in owning an ‘everyday walkabout’ lens covering a wide to telephoto range whilst offering good sharpness (at least across most of the frame). There are some good kit lenses which often accompany the purchase of any new camera - a case in point is the Canon EF-S 18-55 IS STM lens and virtually all of the Micro Four Thirds kit lenses. The little Sony E mount 16-50 PZ isn't as bad as some will have you believe (it suffers from distortion at the wide end and softness at the long end, but it’s pleasingly sharp in between). Another walkabout lens I’ve rated highly is the Panasonic 14-140ii and the Sony E 18-200 (the original silver version). The latter is a great lens but I found it slow to focus at the tele end. Until now, Sony’s E mount 18-105 f4 G lens has been their best offering for general purpose use.

Sony have finally caught up with some of its competitors and have just released their own ‘multipurpose’ lens in the shape of an 18-135 f3.5-f5.6 optic, specifically for E Mount Sony APS-C cameras. This is a classic choice and there are similar offerings from Fuji and Canon (the latter being less than half the price of the Sony). As with most Sony lenses, it isn't exactly cheap. But is it any good?

‘Kit zooms’ are generally known for being less sharp than their professional equivalents, particularly at the long end. They’re also known for chromatic aberration around high contrast points, and soft corners and edges. In fact most zoom lenses, even expensive ones, are likely to suffer from this to an extent. Prior to getting hold of the Sony 18-135 I’ve been happily using the Sony 18-105 f4 G - this is a very nice lens indeed. It's sharp, very light weight considering it's consistent f4 aperture, and it has pretty good edge to edge performance as well. I'm not a big fan of its electronic zoom mechanism, but it's ideal for videographers. Even though it's light, it's a little too large to fit comfortably into my handbags and this was one of the motivators in trying the new 18-135. The new lens means I'm giving up a stop on aperture (this hits f4.5 by 27mm and f5.6 at 55mm) but it's smaller, a bit lighter (at 325g) and it has more reach. Therefore the big question is - will it be enough to prompt me to sell my 18-105 f4 G?

As you can see from the following photograph there is a noticeable difference in size between the two lenses (the 180104 f4 G is on the left). The weight difference (102g) isn't as obvious as I’d expected though. The 18-135 balances very nicely on my Sony a6300, which is the camera I've chosen for these tests. You can also use the Sony e-mount APS-C lenses on the Sony E Mount full frame cameras (thanks to the very useful Super 35 mode).