Missed the original post. > -----Oprindelig meddelelse----- > Fra: David Oswald [mailto:[EMAIL PROTECTED] > Sendt: 15. februar 2005 18:07 > Til: [email protected] > Emne: *istDS built-in flash overexposure problem > > > Let's take, for example, the case of the SMC-Pentax FA 50mm f/1.4. > Shooting at a distance of five feet, at ISO equivilancy of 200, in fully > automatic (smart picture) mode, the frame will come out completely > burned out. The camera is choosing settings of 1/60th and f/2.8. > Anybody with any understanding of photography will know that a > guide-number 15 flash, at a range of 5', with ISO200, shouldn't be > shooting at f/2.8, but rather somewhere more in the neighborhood of f/11.
While I don't agree with your calculation (because it assumes a non-TTL flash which just fires), I am surprised it picks 2.8. The -5n with the FA50/1.7 generally picks 4.5 (and 45, but there is a crop factor here, so I understand the increase in speed). Are the MTFs of these two lenses so different? > This problem persists, with slightly less severity, with other lenses > too. For example, with the SMC-Pentax DA 18-55 f/3.5-5.6, at 55mm, the > camera leaves the lens wide open (f/5.6) for the same shot, and doesn't > stop it down at all. That's all to do with MTFs, I guess. > Now here's the crazy part. When I attach my trusty, tried and proven > AF330-FTZ flash instead of using Pentax's built-in flash, the shots come > out wonderfully exposed. > > This is a problem that I never faced with my ZX-5n. It almost seems as > though the built-in flash is NOT benefiting from TTL. There must be something happening with the RTF. I believe it was mentioned previously that on the -Ds it does not do TTL if you don't have an AF lens. This is a limitation induced with extortion in mind, and they may have introduced a bug as a result. Anyone with a -Ds and FA50/1.4 to verify David's findings? Kostas
