OK, the candle version of the razor blade looks like that:

https://farm5.staticflickr.com/4606/390 ... a273_o.jpg[/img]
MTF mapper

MTF

BR, ADi
Moderators: Pau, rjlittlefield, ChrisR, Chris S.
Which part of the picture should be cropped out?I would crop out only about 10% of the image height
Should I really cut such small part from the 6000x4000 ?If you are using MTF Mapper with RGB tiff images (or JPEGs), then the I would aim for a minimum edge length of about 80 pixels (along the edge). If you use a raw image together with the 'Bayer channel' options in the Preferences dialog to process only, say, the green channel then I would aim for an edge length of about 200 pixels.
Well, I would start at the centre, but you can crop out any part that you would like to measure in more detail, probably one crop from the centre, one from the edge?Adalbert wrote: Which part of the picture should be cropped out?
Yes. You can probably go up to about 600x600, but more than that and you will start blending the different MTFs as they vary across the field.Adalbert wrote: Should I really cut such small part from the 6000x4000 ?
For a stacked image, you can just export each channel of your image (using whatever tool you have handy, but GIMP will work) as a grayscale image, and perform the slanted-edge analysis on those to get some idea of how well the separate channels are focused / stacked.Adalbert wrote: BTW, dcraw.exe cannot decode my stacks (neither TIFF nor JPG
Should I convert the CR2 to the Bayer mosaicked 16-bit instead of the conversion to the TIFF and before stacking?