Whenever I buy a new lens, I have to calibrate it and AF fine tune five different DSLRs. Two are my primary stills shooters, and three are for video. But if I only have the video DSLRs out with me, and want to grab a few quick behind the scenes shots, I need to know their AF is spot on. So, I use the SpyderLENSCAL to calibrate every lens with every body. For me, it’s worth the cost.
If you’ve only got one camera and one or two lenses that you’ll only need to calibrate once, though, it might seem like a bit of a high expense. You buy it, use it once or twice, and then it just sits in a box. Well, there are other options. You can make your own. This video from Crafty Cams has been out for a while, but it’s recently become popular again and it’s well worth a watch.