|"Considerable" is a bit broad, any figures?|
I just zipped 24 jpg's too, for the heck of it. The 24 pics were 19.5M and the zip file was exactly the same size.
I then repeated this with some larger pictures. The 24 pics this time totalled 40.6M and the zip file was 40.5M
If I tried this with 24 poorly compressed jpg's it would make a small difference but the fact remains that jpg's are already compressed files.
Always pop back and let us know the outcome - thanks