From the features tab of the review.
The FZ38 / FZ35 has a focal ratio of f2.8~4.4, compared to f2.8~5.7 on the SX20 IS. While the Canon is optically slower when zoomed-in, due in part to its longer focal length, it’s useful to compare the points in the range where the maximum aperture changes.
The FZ38 / FZ35 only offers its brightest f2.8 aperture between 28 and 34mm. F3.0 kicks-in between 34 and 48mm, followed by f3.2 between 48 and 65mm. Next comes f3.4 between 65 and 98mm, followed by f3.6 between 98 and 155mm. After this comes f3.7 which operates between a longer range of 155 and 414mm, followed by f3.8 between 414 and 452mm. F4.0 kicks-in at 452mm up to 461mm, after which it’s f4.4 up to the maximum equivalent focal length of 486mm.
It’s revealing to compare portions of this range with the SX20 IS. For example between 155 and 414mm, the FZ38 / FZ35 offers a maximum aperture of f3.7, while the SX20 IS operates approximately one stop slower with a maximum of f5.0 between 168 and 560mm. Since the SX20 IS operates at f5.7 for the final 100mm of its range, the FZ38 / FZ35 is around 2/3 of a stop faster when both are set to the Panasonic’s longest focal length of 486mm. So the FZ38 / FZ35 definitely has light-gathering advantages over its rival, although as seen in our results and gallery pages, its Program line does have a habit of selecting smaller apertures rather than quicker shutter speeds under bright conditions.
From the design tab of the review.Shutter Speed
The Panasonic Lumix DMC-FZ38 / FZ35 offers shutter speeds from 1/2000 to 8 seconds (or 60 seconds in Manual), along with 10 apertures from f2.8 to f8 (when zoomed-out), and you have complete control over both settings in its Manual, Aperture or Shutter Priority modes. Exposure bracketing is also available, but still pretty limited with three frames at up to only 1EV apart.
Hope this helps.