The 3.5 and the 5.6, are referring to the maximum aperture the lens can achieve for each end of the zoom range. This clever multi-purpose zoom lens was released back in 2014 and was one of the first all-rounder lenses ever produced by Fujifilm for their X Series cameras.A popular all-in-one lens covering a massive 11x zoom range that costs around £410 and includes a silent ultrasonic focusing motor and image stabilisation.For example, 'f/3.5 - f/5.6' will be noted on the lens barrel as 1:3.5-5.6 (below left). In this article, I’m going to review the Fujifilm XF 18-135mm f/3.5-5.6 R LM OIS WR (that’s quite a mouthful). It’s also the most expensive and vignettes. The Canon 10-22 f/3.5-4.5 is arguably the most flare resistant, the smallest and lightest when that’s important, and has low distortion. Not quite as sharp in the corners as the others, and lower maximum aperture, but it’s really pretty good, especially considering it’s the widest of the wide.
These numbers, the 3.5 and the 5.6, are referring to the maximum aperture or widest opening the lens can achieve for each end of the zoom range.A high f-stop like f-22 means that the aperture hole is quite small, and a low f-stop like f/3.5 means that the aperture is wide open. Sigma also make an 18-250mm lens, which is similarly specified to their 18-200mm lens, but costs £400 and adds a silent focusing motor and 50mm extra to the telephoto end of the zoom range.Some zoom lenses will detail something like f/3.5-5.6 on the lens barrel or 1:3.5-5.6 (below right). Also the maximum aperture at 200mm is a third of a stop slower, being only f/6.3, versus the larger f/5.6 aperture at 200mm on the Canon lens. Sigma's 18-200mm DC OS costs around £300 and includes optical stabilisation, but lacks the silent focusing motor of the Canon lens. (f/2.8, below right).Both Sigma and Tamron offer similar super-zoom lenses.
Unfortunately, this also means the lens suffers with zoom creep, making it difficult to use on a tripod with the camera pointed up or down at anything but 18mm. The lens mount is metal and as it is an EF-S has a baffle protruding from the rear to prevent mounting of the lens on incompatible cameras, such as the EOS 10D.The zoom action is smooth, requiring little force to move it through the range. Build quality is good, with much of the lens barrel being constructed from high quality textured plastics, typical of Canon's higher-end EF-S lenses. Remember, the lower the number, the wider the aperture.Canon EF-S 18-200mm f/3.5-5.6 IS: Handling and featuresWeighing 595g, this lens isn't overly large or heavy for one that covers such a range and it balances extremely well on the EOS 7D used for testing. This lens also sports a silent focusing motor and vibration correction.For example, one 50 mm lens might only be able to open to an aperture of f/3.5, while another might be able to open all the way to f/1.2. If you take a picture and it's too dark at f/5.6, would you choose a lower f-stop number or a higher oneTamron's 18-270mm Di II VC PZD adds 70mm to the telephoto end of the zoom range over what the Canon optic offers and costs around £495.
Lowest Aperture 3.5 Full Time Manual
As a result care needs to be taken not to catch fingers on the focus ring as it rotates back and forth. The focusing ring rotates during AF, and there is no way to disengage it. Full time manual focus isn't available with this lens and it has to be switched over to manual focus before adjustments can be made.
Imatest detected 6.13% barrel distortion at 18mm, which is quite a pronounced level and may pose issues in images with straight lines towards the edges of the frame. At 200mm falloff increases as the corners are 1.7 stops darker than the centre and visually uniform illumination isn't achieved until the lens is stopped down to f/11 at this focal length.Distortion is often an issue with high ratio zoom lenses like this. At 18mm and f/3.5, the corners are 1.5 stops darker than the image centre and visually uniform illumination is achieved by f/5.6 at this focal length. It can be cured in software.Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more.Falloff of illumination towards the corners of the frame is reasonably well controlled.
Sharpness levels hold up well for a lens of this type and the four-stop image stabiliser greatly increases the usability of this lens making it a perfect travel companion.Although this lens isn't the cheapest of the bunch, the good build quality and optical performance will certainly make this a compelling choice when compared to the competition.Canon EF-S 18-200mm f/3.5-5.6 IS: Pros Good optical performance for a superzoomCanon EF-S 18-200mm f/3.5-5.6 IS: Cons Zoom creepCanon EF-S 18-200mm f/3.5-5. Shooting into the light can cause a loss of contrast, especially at 200mm.Wide angle - ISO100, 1/400, f/8, 18mm (35mm equiv – 28.8mm)Telephoto - ISO100, 1/400, f/8, 200mm (35mm equiv – 320mm)Contrast holds up reasonably well shooting into the light - ISO500, 1/60, f/5.6, 40mm (35mm equiv – 64mm)The minimum focus distance of 45cm can be handy for close-up shooting - ISO320, 1/320, f/8, 200mm (35mm equiv – 320mm)ISO100, 1/500, f/8, 70mm (35mm equiv – 112mm)ISO100, 1/250, f/8, 90mm (35mm equiv – 144mm)ISO100, 1/250, f/8, 28mm (35mm equiv – 44.8mm)ISO100, 1/250, f/5, 60mm (35mm equiv – 96mm)Canon EF-S 18-200mm f/3.5-5.6 IS: VerdictOverall this lens offers a good quality compromise for those looking for a convenient alternative to carrying multiple lenses. Even without a hood, this optic seems reasonably resistant to flare and loss of contrast caused by strong light sources just outside the frame although the lens does seem more susceptible to flare at 200mm than 18mm. Luckily the distortion pattern is uniform across the frame, so correcting curved lines should be relatively straightforward in image editing software afterwards.Canon don't supply lenses at this level with a lens hood, which is a shame as the optional EW-78D petal shaped hood would be a welcome addition.
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