Re: If You Get A Good Copy It's AMAZING
poppyjk wrote:
EXIF shows that this photo was taken at 34mm and not 24mm.
Would be interested in seeing a 24mm given the reported distortion issues at 24-26mm.
Basically, the 24-240 was designed assuming correction so you will not see distortion unless it is opened in say Adobe RAW with no correction deliberately (as far as I know there is no option to not corrected it with Canon's DPP4).
The digital corrections do a great job of preserving contrast. What you end up losing, unlike a "conventional lens" is resolution. At the outer parts of the image, the elements of the image are crammed together so to speak. As the distortion correction resamples/scales the image, you A) have lost the resolution and B) there are additional losses in the scaling process (good old Nyquist sampling issues). All this said modern software seems to do a good job.
Because there is a resolution loss and not simply due to focusing softness, past a certain point you can't improve the corners with a higher f-number like you would with a "conventional lens. You do gain a little by stopping down but not as much as you would with an old lens. You quickly reach a point where the sharpness is limited by the resampling.
I would be curious to see a study on the effect of using a lower and higher resolution camera with this lens. In theory, with a higher resolution sensor, stopping down would give more of an advantage.
I did a little comparison myself about 1 month back with a Canon RP, I should add that the test pattern was about 2/3rds of a meter wide so at 24mm it was from pretty close range:
https://www.dpreview.com/forums/post/64556610?image=1