I took my 24mm TS lens to a local castle to see if there are any visual differences between using a shift lens, and correcting keystoning in post. The lens was on a tripod and in a fixed position. In one case the lens was shifted, in the other, shift was set to zero and the lens tilted to simulate a normal lens. I have never seen any sort of comparison in my textbooks or on the web, so I decided to do my own comparison to see if things change geometrically.
I looked at two cases: simple vertical shift and diagonal shift. I then made an approximate overlay of the images to get an idea of the differences using a pretty primitive hit or miss tool on the Web.
Simple vertical shift is pretty close, with very minor differences probably due to my approximations. Diagonal shift does have some more noticeable differences.
I just wanted to do a geometrical comparison. The merits of using a shift lens compared to correcting in post is an another interesting conversation.
The subject is the Rocca di Scandiano. Its ten minutes from home and I think its particular form will make a good test subject for some further self learning tests.
1- 24mm TS levelled and shifted upward. Camera centred perpendicular to the tower
2- 24mm TS levelled with zero shift and pointed upwards. Camera centred perpendicular to the tower . No correction in post
3- 24mm TS levelled with zero shift and pointed upwards. Camera centred perpendicular to the tower . Correction in post
4- Overlay - The match is almost perfect
5- 24mm TS levelled and shifted diagonally upwards. Camera centred to get the whole building into the frame
6- 24mm TS levelled with zero shift and pointed upwards. Camera centred to include the whole building . No correction in post
7- 24mm TS levelled with zero shift and pointed upwards. Camera centred to include the whole building . Correction in post in 2 directions
8 Overlay. This is pretty approximate as getting a good match was almost impossible.
9- 24mm TS levelled and shifted upwards. Camera centred to get the whole building into the frame
10 - 24mm TS levelled with zero shift and pointed upwards. Camera centred to include the whole building . No correction in post
11- 24mm TS levelled with zero shift and pointed upwards. Camera centred to include the whole building . 2 way correction in post
12 Overlay
