(Leaf) Shutters and Aperture blades in SLR's

[l_a_k_h_i_n_d_e_r]

Greetings!

 

Are the (leaf) Shutter blades and Aperture blades always two seperate

modules, or is there any lens where these two functions are working

together from same leaves. The reason I ask is, I have wondered many

times why some (leaf shutter based) lenses have 5 bladed aperture ring

(and I am not talking of just Hasselblad, but also Rollei and Fuji

GX680). I presume shutter blades are more or less always 5 blades. Is

this just a coincidence? (Please note, I am not talking about

Rangefinders or Focal plane shutter based cameras-- including many MF

SLR's.)

[Rob F.]

Combining the two functions into one set of leaves might be a great idea. Here's one thing that might be wrong with it, though. I think it would be difficult to maintain a uniform shutter speed at all the various aperture settings, because it takes longer to open to a wide aperture, starting from the closed position, than it takes to open to, say, f/22. The mechanism would somehow have to compensate for this variable time.

[l_a_k_h_i_n_d_e_r]

Rob, the time taken by even a seperate shutter has same issues. A leaf shutter will reach f/22 before f/2.8. (Actually I think this is the reason for Rollei offering its fastest lenses (i.e 110mm f/2.0) but not in fastest PQS (i.e 1/1000 sec) shutter, but in PQ (i.e 1/500 sec). I have seen most PQS shutters limited to lenses with f/4.

[jim_chow]

I seem to recall there being some optically degrading phenomenon occuring w/ an even number of aperture blades (this from a photo buddy of mine, who has a doctorate in physics).

[Aoresteen]

The last commercially release camera that I can recall that combines shutter/aperture was the Pentax Auto 110. The exposure range was limited do to shutter spped issues. You might want to did up a copy of Modern Photograpy's review of the Auto 110 as I recall them disscusing this issue in depth (1980 or 81).