I don't have that lens but it doesn't sound good...
I have checked with all my lenses again, and the seriousness of rattling when shook goes like this (most serious first):
FA*24/2, FA100/2.8 -> F*300/4.5 -> FA*200/2.8.
I checked the parts manual of F/FA*300/4.5 and the rear element group is guided by 2 teflon washers of different sizes (determined during assembling in factory). So either the washers were worn, or actually within tolerance. Who knows (until I handled another sample in the unknown future)?
Another discovery is that the magnitude and the duration of the vibration when using the tripod collar with F*300/4.5 is more serious than without the collar. I tried both settings on tripod and tapped the legs. With the collar, the lens/camera will vibrate more violently (left-right) and last longer. This finding confirms the results I got few days ago on slides. Since the FA*200/2.8 with hood weights as heavy as the F*300/4.5 (0.9kg), they should pose the same amount of stress on the camera mount. If Pentax thought the 200/2.8 was okay, the 300/4.5 should be fine as well (the reason to remove it from the FA*300/4.5?). So I guess I will not be using the tripod collar anymore with my F*. But it puzzles me that they chose 2x3mm screws for the lens mount of the FA*200/2.8, but only 2x2.5mm for the F/FA*300/4.5 which are just as heavy.
Regards, Alan Chan http://www.pbase.com/wlachan
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