See you're reading reviews about the center viewfinder. Of course you're wondering if this is going to work (it will, by the way), but let's be honest. Your first question is whether it's worth spending the bulk of $10 on something that can be done fairly well with a ruler. Let me tell you: it is. There are about zero tasks that require this tool, otherwise they cannot be completed. .but there are also about zero tasks that *can* use the center finder and be done just as accurately, just as quickly, or just as easily. This thing saves you those "well, I hope that's enough" and "damn it, a third hand would be awesome around here" moments of marking, math, math, and measuring. Finding the center isn't a tool you use to get a job done, it's a tool you use to make sure you're doing a job accurately and well. .and if that doesn't convince you, then hardly anything happens.