Hey folks -- two unrelated questions. I'm still waiting to receive my K10D so they're somewhat moot, but here goes:
First, are there any Pentax lenses which aren't weather-sealed? If so, are they in the majority or the minority? What are the limits of the K10D's weather-sealing (the "weather-sealing ceiling", if you will) anyhow?
Second, I know that both tele converters and extensions tubes eat light and require aperture adjustment, but that doesn't affect the lens' focal "sweet spot" aperture, does it? In other words, if a lens has good focus wide open but is best a few stops in, that doesn't change (get worse) if it's on a converter or extension, does it? I can't explain why I think it might, but I just felt the need to ask.
Thanks for indulging the newbie!