smc Pentax-DA 18-250mm F3.5-6.3 ED AL [IF]

First of all, this test is absolute subjective. It only represents the very limited impression of a single user in combination with a single Pentax camera. A couple of other lenses will also be mentioned, however, this review is not intended as a comparison of this lens with those other lenses, simply because they were never used at the same time under the same conditions.

When I got the Pentax 18-250mm lens it was together as a kit with the Pentax K20D camera, both purchased back in 2009.

Originally I was very happy with the lens because of the wide range of 18mm to 250mm that promised the versatility to cover from wide angle scenery like landscape or architecture to situations where an extreme tele lens is needed, while avoiding the hassle of having to change lenses, and I used it for quite a while as my lens of choice. However, that feeling changed drastically after I compared it with a Tamron 28-75mm, Tamron 24-135mm and a manual focus Pentax-M 135mm. In terms of IQ the Pentax 18-250mm seems to loose against them all. At the short end the Tamron 28-75mm was miles ahead in every single quality images producing factor, and at the long end the much older manual focus Pentax-M 135mm, though a budget lens which can be found used for very little money, has way better resolution to the point that even cropping an image taken with the prime lens to the smaller frame of a 250mm lens results in sharper and more pleasing images despite the lower resolution after cropping than the longer range Pentax 18-250mm can produce at the long end. In other words, there didn't seem to be any advantage of the Pentax 18-250mm at all.

So my initial feeling was that in the Pentax world, the later introduced Pentax 18-135mm might be a better choice (though I never used it). However, many technical reviews I consulted online actually put the Pentax 18-250mm before the Pentax 18-135mm. Which surprised me, as I wouldn't have thought so. That made me start thinking of what exactly it was that I didn't like about the lens. Before I come to this, just as mentioned before, I only used the lens on the K20D with JPG straight from the camera. I didn't take RAW at that time, nor did I indulge myself, apart from a few exceptions, with post-processing. I quickly browsed through a couple of my few thousand images from that time, and here is the summary.

Basically I had two major issues. One is heavy distortion. This is so significant, and as I've said without post-processing it was annoying. Now the newer bodies may be able to correct this straight out of the camera. The other major issue is a certain kind of dullness and flatness. Images taken even on the brightest day with the bluest sky never looked truly appealing. The to-be-blue sky had always been a rather blue-greyish tone. At that time I could only compare it to a Panasonic point-and-shoot that I owned, that lacked resolution but with it's Leica branded lens produced much more appealing images. Originally I didn't know whether to attribute it to the camera or the lens, but the comparisons mentioned before told me that it's also the lens. Now here again, I'd assume that the newer bodies produce better quality images and that RAW converters or post-processing can compensate for this flaw. Sharpness is actually generally quite decent in ideal conditions, bright day, no movement. I've got tons of unsharp images too, but mainly due to the slow nature of the lens and caused by motion blur. Now I repeat myself but with the newer bodies and higher ISO settings that these bodies can use for producing almost noise-free images, one has got much more range at their fingertips than what I allowed myself to use at the time.

I sometimes wondered, if using filters with this lens would improve the IQ though never tried it. At least it worked in the age of film. About distortion it is throughout almost the full range, changing from heavy barrel distortion at the wide end to pincushion at the long end with a sweet spot at somewhere between 24-50mm without distortion. But I mostly disliked the barrel distortion at the wide end, that is when taking wide-angle pictures of architecture or a city scene with buildings.

Below are a couple of images to illustrate the "dull" character of the colours. These were all taken in absolutely ideal weather conditions, so as soon as the weather wasn't ideal, the images became even less appealing.

And two more images to illustrate distortion.

All images JPG straight from the camera with standard settings. Of course with post-processing (and in body distortion correction) these issues can be corrected.

And last but not least an example @250mm straight from the camera and with light post-processing applied.