Scribbles and Snaps

Lens distortion is a fact of life. You can mitigate this problem, but you can’t avoid it completely (unless you are willing to invest in seriously expensive professional-grade lenses, that is). Fortunately, digiKam provides a set of tools that can help you to fix lens distortion with relative ease. In fact, the application sports the Auto-Correction feature that attempts to fix lens distortion with a minimum of tweaking. So if you have a photo that suffers from barrel¹ or pincushion² distortion, you might be able to fix it quickly using the Auto-Correction tool. To do this, open the photo in the image editor (choose Image | Edit or press F4) and choose Enhance | Lens | Auto-Correction. digiKam then automatically pulls the camera, lens, and other relevant information from the photo’s metadata and attempts to fix the distortion based on the obtained data. Besides the lens distortion, the Auto-Correction feature can fix other problems, too, including chromatic aberration and vignetting. So if the photo exhibits any of these problems, you can apply fixes to it by ticking the appropriate check boxes.

Usually the Auto-Correction tool does a decent job of fixing lens distortion, but if it fails to do the job, you can try to fix the problem manually. To do this, choose Enhance | Lens | Distortion and adjust the Main and Edge sliders to correct lens distortion.

¹ Barrel distortion is a lens effect which causes images to be spherised or “inflated”. Barrel distortion is associated with wide angle lenses and typically occurs at the wide end of a zoom lens. The use of converters often amplifies the effect. It is most visible in images with perfectly straight lines, especially when they are close to the edge of the image frame. (Source: Digital Photography Review)

² Pincushion distortion is a lens effect which causes images to be pinched at their center. Pincushion distortion is associated with tele lenses and typically occurs at the tele end of a zoom lens. The use of converters often amplifies the effect. It is most visible in images with perfectly straight lines, especially when they are close to the edge of the image frame. (Source: Digital Photography Review)

I love my Kenko extension tubes, and I keep them in my photo bag at all times. They are great, but somewhat cumbersome in everyday use: you have to detach the lens, add a tube, and put the lens back. This may not sound like a complicated procedure, but it takes time and there is always the risk of getting dust on the sensor.

In my search for a more convenient solution, I stumbled upon the Raynox DCR-250 Super Macro conversion lens. At first sight, it looks a bit like those cheap and useless close-up filters you can find on eBay, but it’s most definitely not. Raynox DCR-250 consists of three high-quality coated elements in two groups that provide +8 diopters magnification.

The quality of the glass seems to be top-notch (I don’t have a dedicated macro lens for comparison) and the lens produces pleasing results. DCR-250 comes with a clever snap-on adapter for lens sizes from 52mm to 67mm. Attaching Raynox DCR-250 to the lens is as easy and fast as putting a lens cap on. The price is right, too, so Raynox DCR-250 is an excellent solution for macro shooting on the cheap.

There is one thing you should keep in mind, though: the lens has a razor thin depth of field, so you must use a steady tripod to get sharp photos. While you can get away with shooting handheld with Kenko tubes, it’s virtually impossible to do that with Raynox DCR-250.

Of course, Raynox DCR-250 won’t replace a dedicated macro lens, but it’s the next-best thing you can get. It’s not expensive, it produces excellent results, and it’s extremely convenient — what’s not to like?