It is after having ordered this attractive product I've realized his lack of precision, but too late to cancel the order ... In fact, almost impossible to adjust the product exactly like the vertical plane of the objective camera; therefore measures and results totally inaccurate or erroneous waiting. So I did not even try !!! Moreover impressions on the scale does not seem quite clear and precise in order to draw anything very precise once the enlarged image in Lightroom ... I will therefore make these measurements with my boxes EOS 5D MkII and 7D + L series optics, Canon France that they have the right equipment and ultra precise! Unfortunately, this is the price to pay to have very accurate autofocus with high-end hardware. But the result for large prints will be optimum. Back made this day-and waiting for reimbursement that I hope will be rapid. So I do not advise buying this product, unless you have the time to spend a long time to adjust the vertical planes (which must be identical between the lens housing couples and the product in question) and that each Lens shift x the number of housing ...! For me: 4 x 2 = 12 endless settings and not 100% accurate! Also, for anyone who may have hours to do the combined vertical planes settings, it would of course have the utility of this product = print large format ...!