Quote Originally Posted by Daniel Browning
Right now, most cameras cannot resolve the full resolution of the chart (4000 L/PH), but the 24 MP D3X comes closest, and it's just an aliased mess. When we get cameras above 24 MP, we'll start to lose the ability to see how the aliasing artifacts look, but there's a long way to go before we'll lose the ability to determine the alias-free resolution. And even when that happens, this chart will still be useful for showing differences in contrast and aberrations, even if it can't show the ultimate limit in resolution.

Note that the "full resolution of the chart (4000 LW/PH)" applies to the visual resolution features, i.e. the hyperbolic curves that are shown in Bryan's ISO 12233 crops. The standard ISO 12233 chart allows visual estimation up to 2000 LW/PH, while the derivative chart that Bryan uses doubles that, but only for the center hyperbolic curves (the mid-frame and corner ones go only to 2000 LW/PH).


However, the ISO 12233 standard includes slant-edged features intended for spatial frequency response (SFR) analysis - that's an image analysis approach which provides greater sensitivity and accuracy for measurement of spatial resolution than the visual 'estimation' method also available with the charts. Imatest is a commonly-used piece of software that performs a variety of relevant analyses, including SFR analysis (I infer that Bryan has Imatest, since his vignetting images look like they come from that software). Although Bryan doesn't report SFR analysis data, his charts have the ISO 12233 standard slanted-edge features, and also have a lower contrast set of slant-edge features for better correlation with grayscale images from dSLR sensors. Some other sites, e.g. photozone.de, derive their MTF data from SFR analyses performed with Imatest.


For those who are interested, I believe the charts Bryan uses are the Applied Image QA-77. Ihave the -3 version, and it's just shy of being large enough for proper framing at 16mm (on FF) at the MFD of the 16-35mm II, but fine for all my other lenses. From the Specs & Measurement tool he provides, it seems Bryan has all the sizes, as smaller ones are better for supertele lenses unless you have a football field-sized testing area).