Magnification is achieved by a combination of focal length and focus distance.
Took a few days to come up with the right equations to use DOF equivalent focal length & focus distance combinations. Basically started with the DOF equations for a series of focal lengths. Then determined an increase in distance that would result in the same DOF for each step in the series. This allowed creating the chart below which shows a similar DOF as focal length and focus distance are increased incrementally. The front and rear portions are nearly equal beyond 200mm, and gradually move apart from 100mm down to about 50mm before becoming dramatically different below 30mm. I would encourage anyone to use a DOF calculator to check the table or better yet, take a few photos and see if it plays out.
Edit: Added a second table that has the focal length / focus distance combinations set to achieve the same magnification.
View attachment 100464
View attachment 100571
Took a few days to come up with the right equations to use DOF equivalent focal length & focus distance combinations. Basically started with the DOF equations for a series of focal lengths. Then determined an increase in distance that would result in the same DOF for each step in the series. This allowed creating the chart below which shows a similar DOF as focal length and focus distance are increased incrementally. The front and rear portions are nearly equal beyond 200mm, and gradually move apart from 100mm down to about 50mm before becoming dramatically different below 30mm. I would encourage anyone to use a DOF calculator to check the table or better yet, take a few photos and see if it plays out.
Edit: Added a second table that has the focal length / focus distance combinations set to achieve the same magnification.
View attachment 100464
View attachment 100571
