Arjay
Time Traveller
Distortion correction software for hybrid workflow
Distortion correction software for hybrid workflow
It does indeed appear that the prime lenses used for film cameras are less prone to produce distortion than the zoom lenses deployed on digital cameras. However, virtually any lens exhibits some kind of distortion, so corrections do make sense even for prime lenses if one wants to produce clean, absolutely rectilinear images e.g. for architecture.
For those of us who use a hybrid workflow, there is a correction software that is much more powerful than Photoshop's correction function, yet that software is quite affordable: PTLENS
The software author maintains a database of distortion characteristics for hundreds of lenses used on DSLRs and digital P&S cameras. Unfortunately, at present, there are absolutely no entries for Leica-M bayonet lenses.
We can change that if we like: The program's author is very responsive in evaluating and integrating lens test images into the software's data base (Go to the above link and select 'Calibration/Overview' for more info). Test pictures have to be submitted to the program author.
The software normally uses the lens data which are embedded in the image file's EXIF data (this is specific to true digital cameras). However, scan files should do as well if the corresponding lens data are supplied separately (lens maker and name, focal length, largest aperture). When subbmitting scans, I don't think it is necessary to use highest scan resolution. Sub-16 megapixel image files should be sufficient. Scans should be submitted completely unprocessed, except for a crop which should precisely comprise the full image (negative) frame - no straightening or any other corrections.
Please consider that the software's correction algorithm is focused on the respective camera's full image size, so that crop formats need to be handled separately. M Bayonet lenses are used on
Distortion correction software for hybrid workflow
It does indeed appear that the prime lenses used for film cameras are less prone to produce distortion than the zoom lenses deployed on digital cameras. However, virtually any lens exhibits some kind of distortion, so corrections do make sense even for prime lenses if one wants to produce clean, absolutely rectilinear images e.g. for architecture.
For those of us who use a hybrid workflow, there is a correction software that is much more powerful than Photoshop's correction function, yet that software is quite affordable: PTLENS
The software author maintains a database of distortion characteristics for hundreds of lenses used on DSLRs and digital P&S cameras. Unfortunately, at present, there are absolutely no entries for Leica-M bayonet lenses.
We can change that if we like: The program's author is very responsive in evaluating and integrating lens test images into the software's data base (Go to the above link and select 'Calibration/Overview' for more info). Test pictures have to be submitted to the program author.
The software normally uses the lens data which are embedded in the image file's EXIF data (this is specific to true digital cameras). However, scan files should do as well if the corresponding lens data are supplied separately (lens maker and name, focal length, largest aperture). When subbmitting scans, I don't think it is necessary to use highest scan resolution. Sub-16 megapixel image files should be sufficient. Scans should be submitted completely unprocessed, except for a crop which should precisely comprise the full image (negative) frame - no straightening or any other corrections.
Please consider that the software's correction algorithm is focused on the respective camera's full image size, so that crop formats need to be handled separately. M Bayonet lenses are used on
- full-format 35mm cameras (e.g. any analog M cameras such as M1 thru M7 and Hexar RF and such), plus digital full-format M9,
- 1.33 crop format cameras such as M8 and M8.2, and
- 1.5 crop cameras like Epson R-D1.