WOW! This is very peculiar to me for something so "delicate" to be so exposed. Just plain weird. Yea, i'll definitely not be handling it as loosely as i'm able with other lenses (more a concern about dust/dirt/etc than pushing my finger through...).
I'm excited to use the lens, but now all the more "concerned" with an even greater need to exercise care w/my gear. I'm usually *very* careful with my stuff, but a delicate, exposed assembly like an aperture takes things up another notch...
And that's why God, in his infinite wisdom, created lens caps and saw that they were good--especially for the Mamiya 180...
Steve, i hadn't noticed it either until i was looking to make sure the aperture was in it's "released" state to protect all those internal springs (and delay an inevitable trip to Ron Paul for a tune up!).
I don't mean to spread my OCD tendencies! I should be quarantined!!!
As noted above, the 135mm lens for my Mamiya TLRs has a similar configuration. I've used mine for decades, including doing wedding work.
It isn't that fragile!
The focal plane shutters on most 35mm SLRs (and many medium format SLRs) are similarly exposed, and they seem to be able to handle the situation.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2