Pentax User Archive: Zooming Marvellous

David Askham was excited when he received his new Pentax 50-135mm lens as it filled an important gap in his digital armoury.

21/09/2012 - 00:00

Pentax smc DA* 50-135mm f/2.8 ED IF SDM Zoom Lens

The launch of the Pentax K10D camera was a milestone in many photographers' lives. Its build quality and specification marked it out as a serious camera for professional and ambitious amateur use. Yet its launch was unmatched by new technology lenses for which many photographers craved. True, there were a lot of current and older lenses that would work well with the camera but users hankered after something better.

In order to pacify global demand for new generation Pentax lenses, several new designs were announced early in 2007, including two zoom lenses with desirable specifications.

At that time I mentally earmarked my interest in the new 50-135mm and waited. The lenses were many months coming, but in September 2007 my order was satisfied and I set about exploring its handling and performance. This article reflects my early experience with the lens.

Red roses
Red roses well out of reach at the top of a barn, but accessible with the new lens.

First impressions

Straight away it was clear that the highest build quality and materials had been employed. It feels every bit a professional quality lens. It's not so big and bulky as I had anticipated, for such a relatively fast lens; although once the sizeable lens hood has been fitted it becomes a fairly chunky object. Nevertheless the lens handles well, is well-balanced and in no time I was in business.

At this point I should explain that two new kittens had recently joined our household. So it was unsurprising that they should be a target of my attention. Up to that point I had been using my two favoured prime lenses, the Limited Edition 43mm and 77mm which are firm favourites and will not be displaced by the new lens. But I had noticed that invariably I had the wrong lens on the K10D to capture their antics. That is why the zoom became so important.

Although handling is easy and smooth, I realised that I was not getting the benefit of the new SDM ultrasonic automatic focusing. I checked and found that I needed to upgrade my camera firmware to version 1.30. Once updated, focusing is virtually silent and quick. In fact if you have inadvertently switched off the autofocus, you get no audible reminder of your omission. However the kittens didn't even notice the lens in action!

Autumnal Leaf
Close-up detail of an autumnal leaf in dull lighting with lens set to 135mm handheld.

Ergonomically my only slight criticism is that when altering the zoom setting my instinct is to adjust the focusing mount because my left hand naturally supports that part of the barrel. In some ways I wish the zoom barrel was slightly longer, even at the expense of reducing the length of the focusing mount.

Most of my photography involves the use of wide-angle to normal focal length lenses. It's rare I exceed 105mm focal length, so why should I be tempted by this new zoom lens?

The first reason is hinted above. Once you aim to shoot head and shoulder portraits or similar subjects, a longer focal length lens is needed to avoid distortion of features. You simply need a stand-off distance. Sometimes you have no choice, such as shooting animals in open spaces. For my type of photography the 50-135mm lens is perfect. It's an ideal companion to my Pentax 16-45mm which, although an older design, is very good and meets all my requirements in this range (I have faster primes if necessary).

It's worth noting that I do have a Sigma EX legacy lens which I used with my MZ cameras. Its range is from 100-300mm at f/4.0 and I have used it successfully with the K10D. But I find its bulk and weight (1440gm - more that four times the weight of the new Pentax lens) a deterrent to use on trips away from home. Granted, it has longer reach, but I rarely need a telephoto lens longer than 200mm.

Three-year old
Catching an active three-year old running on the lawn (ISO 400, f/3.5, 1/320sec at 135mm).

Bright boy

Another advantage of the 50-135mm lens is it can be used at f/2.8 throughout its zoom range. This is a distinct advantage when working indoors in available light, particularly when using the K10D with the ever-useful SV setting (dial in a higher ISO, if necessary).

Possibly the biggest advantage of a telephoto zoom lens is its better ability to control depth-of-field. With sensors smaller than 35mm full frame, it has been a perpetual bugbear making a subject stand out clearly against an out-of-focus background.

Work-arounds in Photoshop are time consuming and call for a lot of skill. So, if you can achieve the desired result at the taking stage, life is much easier. With a maximum aperture of f/2.8 and lens performance to match, the photographer has much greater control of imaging. I have been pleasantly surprised at how well this works in practice.

One quirky feature of the K10D needs a mention. For some reason the camera anti-shake reduction feature needs to be turned off when the camera is mounted on a tripod. I forgot once and was puzzled why some portraits, under settled conditions, were not quite sharp. There was consistent loss of definition which was restored when the SR function was disabled. Of course, you have to remember to switch it back on when you need it!

One of very many shots of one of our new kittens (Indoors, ISO 400, f/3.2 at 135mm)


The new Pentax 50-135mm lens is an exciting new addition to the range of optics available for use with the K10D and slightly earlier models. The balance struck by the designers to achieve harmony between lens bulk, weight and performance is highly laudable and I can see it being a regular on photographic trips as well as around the home. Although supplies of the lens have been problematic in the past, the situation should be much better  by the time this article is published early in 2008. I cannot believe anyone would be disappointed with its performance.

Related Photos


Link Posted 03/07/2018 - 12:35
I would absolutely love to get my hands in on one of those Pentax 50-135mm lenses. The lads from were saying that especially this time, these lenses had fantastic power behind them. These samples are only proof of that.


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