Technology Tales

Adventures in consumer and enterprise technology

TOPIC: ZOOM LENS

All that was needed was a trip to a local shop

5th March 2011

In the end, I did take the plunge and acquired a Sigma 50-200 mm f4-5.6 DC OS HSM lens to fit my ever faithful Pentax K10D. After surveying a few online retailers, I plumped for Park Cameras, where the total cost, including delivery, came to something to around £125. This was around £50 less than what others were quoting for the same lens, with delivery costs yet to be added. Though the price was good from Park Cameras, I was wondering still about how they could manage to do that sort of deal when others don't. Interestingly, it appears that the original price of the lens was around £300, but that may have been at launch and prices do seem to tumble after that point in the life of many products of an electrical or electronic nature.

Unlike the last lens that I bought from them around two years ago, delivery of this item was a prompt affair, with dispatch coming the day after my order and delivery on the morning after that. All in all, that's the kind of service that I like to get. On opening the box, I was surprised to find that the lens came with a hood but without a cap. However, that was dislodged slightly from my mind when I remembered that I neglected to order a UV or skylight filter to screw into the 55 mm in front of it. In the event, it was the lack of a lens cap needed sorting more than the lack of a filter.

The result was that I popped into the local branch of Wildings where I found the requisite lens cap for £3.99 and asked about a filter while I was at it. Much to my satisfaction, there was a UV filter that matched my needs in stock though it was that cheap at £18.99 and was made by a company of which I hadn't heard before, Massa. This was another example of good service when the shop attendant juggled two customers, a gentleman looking at buying a DSLR and I. While I would not have wanted to disturb another sales interaction, I suppose that my wanting to complete a relatively quick purchase was what got me the attention while the other customer was left to look over a camera, something that I am sure he would have wanted to do anyway. After all, who wouldn't?

With the extras acquired, I attached them to the front of the lens and carried out a short test (with the cap removed, of course). When it was pointed at an easy subject, the autofocus worked quickly and quietly. A misty hillside had the lens hunting so much that turning to manual focussing was needed a few times to work around something understandable. Like the 18-125 mm Sigma lens that I already had, the manual focussing ring is generously proportioned with a hyperfocal scale on it, though some might think the action a little loose. In my experience, though, it seems no worse than the 18-125 mm, so I can live with it.

Both lenses share something else in common in the form of the zoom lens having a stiffer action than the focus ring. However, the zoom lock of the 18-125 mm is replaced by an OS (Optical Stabilisation) one on the 50-200 mm and the latter has no macro facility either, another feature of the shorter lens though it remains one that I cannot ever remember using. In summary, first impressions are good, but I plan to continue appraising it. Maybe an outing somewhere tomorrow might offer a good opportunity for using it a little more to get more of a feeling for its performance.

No autofocus?

25th March 2009

Sigma 18-125mm f/3.8-5.6 DC HSM zoom lens

Recently, I recently treated myself to a Sigma 18-125 mm f/3.8-5.6 DC HSM zoom lens for my Pentax K10D. There was a wait for the item to appear, only then for me to find that the lens' autofocus facility wasn't compatible with the body when it arrived. Standard wisdom would have it that I sent the thing back and ask for a replacement or a refund.

Perhaps inexplicably, I did neither. In fact, I came to the conclusion, that since I make photos of landscapes anyway, that been slowed down by the lack of autofocus was no bad thing except perhaps when appealing light makes fleeting appearances. While it is true to say that a used Pentax manual focus lens would have been cheaper, I did what I did.

The camera's autofocus indicator still works and the 18-55 mm zoom that came with the camera wasn't impressive anyway, so taking matters into my own hands was something that happened a lot. Now, I have better quality glass in front of the sensor and with a metal mount and longer range too. The lens comes with a petal hood too, though I keep that for when I really need it rather than keeping it on the lens and stopping myself focussing the thing.

Speaking of zooming and focussing, the controls work well and smoothly without being at all loose. The AF setting gets used to lock the focus and the zoom can be locked at the wide end so that the lens doesn't get into the habit of zooming under the influence of gravity, not a bad thing. For future lens purchases, I might be more inclined to ask about compatibility next time around (I may have been spoiled by the Canons that I used to use) but I remain content for now.

All in all, it feels like a quality item, so it's a pity that Pentax saw fit to make the changes that they made, or that Sigma didn't seem to have kept up with them. Saying that, my photographic subjects usually don't run off so being slowed down is no bad thing at all, especially if it makes me create better photos.

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