How many calibration charts do I use -- per calibration -- with Adobe Lens Profile Creator?

styletramps  wrote Hi there, I want to create a Lightroom Lens Profile for my Nikon 28mm f/2.8 Ai-S lens because Lightroom does not seem to come with one for this lens. I've been reading the instructions from for how to do this, and there's one thing that was not clear to me. They state that the calibration should be done at a few focal distances (e.g. 1 x minimum focal distance, 2x, and 5x). They state that you should select a calibration chart that takes up 1/2 to 1/4 of the image frame when shooting. And they state to take the 9 shots for the image set to get the chart in every region of the frame. Got it. But what is not clear to me is if I should swap calibration charts for each of these sets, so that the chart always fills ~1/2 to 1/4 of the image frame. If I were to choose a chart that is ~1/2 the frame at minimum focal distance, then obviously the grid would get smaller and smaller as I take the farther-away sets. I do not see a specification about which way to do it in the instructions. The fact that the Profile Creator Tool has a single input area for specifying the chart characteristics leads me to believe that it is, in fact, one chart for all distances... but this seems odd (see screenshot). Anyone have experience with this? Thanks in advance! Here is the link to the documentation I am attempting to interpret: https://download.macromedia.com/pub/labs/lensprofile_creator/lensprofile_creator_chartshoo ting_qs.pdf

If you are going to do a number of focal distances then you will need need multiple sizes of the chart indeed. You simply print the chart larger and smaller. It is essential that the chart is big enough in the frame to get a good model for the lens distortion. Now in general you really only need to do one typical length and the recommendation is a bit over the top. It is relevant mostly when your lens has a lot of focal breathing (real focal length changes with focus distance) but I doubt this lens has a lot of that. My guess is that you will get a reasonable profile with a single focal distance. I've done a lot of profiles years ago before there were many profiles available and I've only ever done a single distance.