Lens Focus Calibration Tool Alignment Ruler Folding Card(Pack of 2)

...and a great value, but note: first be sure your camera allows microadjustments to calibrate autofocus, because not all inexpensive or older camera bodies do. Look in your manual or search online to see if your camera offers this feature. Normally you can do this, if possible, at the MENU button and in Canon camera bodies that allow it, in a Custom Function submenu for Autofocus. If your camera can't adjust calibration, you can still use this to test, but you'd have to send equipment in for repair to get any problem corrected, and don't be surprised if the mfr. tests your gear and sends it right back unadjusted, saying it's within tolerance limits (happened to me). With adjustable gear that works properly, you can dial it right in, at least at your tested setting.Also even if your camera body allows adjusting the calibration of autofocus, if you just have inexpensive f/4+ kit lenses, you may not get much benefit from calibrating, whatever tool you use, because the depth-of-field on those lenses is usually close enough for autofocus jazz. These tools are most helpful for calibrating lenses that will be shooting wide open at f/2.8 or wider (smaller f/ number) which work with a very narrow depth-of-field, making autofocus often seem to just miss.You will get NO benefit in calibration accuracy buying a more expensive calibration tool than this one. All these tools just show you whether your lens is back- or front-focusing or dialed in. If it's off, you guesstimate a correction and try again, until it's right. (No tool can tell you exactly what correction is right. It's trial and error.) It's your *setup,* not the cost of a calibration tool, that is key to good results. There is at this writing a competing product that costs over 13 times as much as this one on amazon, and this one will perform just as well as that one. Yikes. You can even build a free one with materials around your house instead that will work just as well, but at this price, it was easier for me to just get this.You do need to learn how to use the tool. This one doesn't come with instructions, it's not intuitive, and if you try to wing it, some gotchas will probably getcha. Other reviews here go into the how-to, and there are a number of good free videos on YouTube demonstrating this product and others that helped me a lot. Just be aware, calibration tools are not plug'n'play; setup is critical, as I said; there are about a dozen guidelines to follow. But once you have it figured out, it goes pretty quickly, taking maybe ten minutes to calibrate a lens' autofocus.No calibration tool can fix photographer technique that is not optimal. Look for some YouTube videos on autofocusing to make sure you're doing it right. One important thing I learned watching one: my old-school technique of holding the shutter release halfway down to prefocus and then recomposing is a poor technique to use with a large-aperture lens wide open, because when you recompose, you change the focal plane just enough to frequently throw your "locked-in" subject out-of-focus. You're better off using Live View, or manually focusing, or at least dialing in one autofocus point on the subject and not recomposing after prefocusing through the viewfinder... or even better, try to avoid shooting wide open (but sometimes you need the extra light).

Works great and good price. You could do as well with a sheet of newspaper and some sort of focus target (a playing card propped up facing straight towards your camera lens, for example) placed in the middle of it. But this is more convenient. Similar products (those with just a slanted scale and a focus target) that cost a lot more (some are a lot more) are kind of a rip-off. Some of the expensive alternatives include software, but I don't see where software would save any work or provide more accurate results unless maybe your computer monitor is too pathetic to show better detail than the tiny screen on the back of your camera. You need to view the focus test photos you take on the larger screen of your computer, and you already have software that does that, right?No instructions included which is OK. You are really better off doing some research online to learn and understand how to do "AF Fine Tune" (that's Nikon speak. Canon, Sony, etc. each use a different name for the same thing). Just following some instruction list without understanding would be frustrating and error prone. It's really a pretty simple process after you understand it. Basically, you let your camera auto-focus on the little vertical card in the middle of the tool, and your test photo will show where on the slanted scale is in-focus or blurry and hopefully the in-focus part is right next to the little vertical card. If not, then adjust AF Fine Tune in the camera & take another shot. I was at first concerned this tool might be too small, but it's really just the right size to show where your camera is actually focused. You don't do this procedure at 50 yards range (that would require huge targets).

The most importance thing is that it works. I was able to calibrate some of my portrait lenses and prove that calibration correct empirically, in subsequent photo shoots. I was also able to confirm some front-focus issues with a teleconverter I have, which I'd previously tried to prove without a purpose-built calibration target, but couldn't get nearly as unambiguous (and damning) results as with this target.I haven't compared it with other (and much more expensive) focus calibration tools. It is just cardboard, and not particularly stiff cardboard at that, so it does bulge and flex and requires a bit of coercion to set up such that the centre target is actually perfectly vertical. More expensive targets are made of stiffer cardboard, or plastic, and will surely be much quicker to set up and use confidently as a result. It also doesn't have any of the alignment aids that some of the competing calibration targets have, which puts the onus on the user to give proper care to alignment. Presumably this limits its precision somewhat, though I found it was at least as precise as the random focus error in various Nikon lenses & camera bodies, so I deem it sufficient whether or not it's ideal.One other limitation to note - and this is true of the majority of these sorts of focus targets - is that it doesn't suite all focal lengths or focus distances. It's not a particular big target, and seems intended for roughly 'mid-range' focal lengths - perhaps 35 - 100 in 35mm terms. e.g. for telephoto lenses, your working distance is perhaps going to be tens of metres, and even with the long focal lengths (and consequent 'magnification') this target is too small at those distances - e.g. with a 300mm on a DX sensor (1.5x crop) it doesn't really work beyond about six or seven metres. Since lenses can have different amounts (and directions) of systematic focus error at different focus distances, this can be limiting.Likewise it's useless for macro lenses at their nominal working distances (<1m), or for wide angle lenses.