What I’m really trying to do is show the MTF in object space (what I would get if I reversed the lens and plotted MTF). I believe all I need to do is scale the cycles/mm axis by the magnification. Not sure how to do that without exporting the data to some other application. Can it be done in ZPL alone?
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Easiest way to scale x-axis values in MTF plots?
+1Best answer by Jeff.Wilde
I don’t know of any way to simply replace the x-axis data in a standard analysis plot window. However, you could try the following. Use a pair of paraxial lenses following your image plane to implement a magnification change (via the ratio of the lens focal lengths).
Then the MTF frequencies scale accordingly. Here’s an example with a 2X magnification adjustment:
In the first graph the surface is chosen as the original image surface, while the second graph uses the new (magnified) image plane. It’s very simple and doesn’t require any programming.
+3Yes, I think writing a ZPL script to do this should be relatively straightforward. You can loop through a range of image-space frequencies, using GETMTF inside the loop to find the sagittal and tangential response values for the field(s) of interest. Then the system magnification can be extracted using GETSYSTEMDATA. Lastly, a new plot using the scaled frequencies can be generated using the PLOT keyword.
+1Thanks Jeff! Do you think there’s any way to directly replace the axis values of the default MTF plots, rather than create new plots?
+3I don’t know of any way to simply replace the x-axis data in a standard analysis plot window. However, you could try the following. Use a pair of paraxial lenses following your image plane to implement a magnification change (via the ratio of the lens focal lengths).
Then the MTF frequencies scale accordingly. Here’s an example with a 2X magnification adjustment:
In the first graph the surface is chosen as the original image surface, while the second graph uses the new (magnified) image plane. It’s very simple and doesn’t require any programming.
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