graham_martin2 Posted October 10, 2011 Share Posted October 10, 2011 <p>Why is that on the Fuji GA645 the fastest shutter speed is 1/400 at apertures ranging from f/4 to f/9.5 and is 1/700 from f/11 to f/22? Intuitively one would have thought that the faster shutter speed of 1/700 would have been when the aperture is larger instead of the other way round. This is the first camera I have owned that has differing max shutter speeds based on two different aperture ranges.</p> Link to comment Share on other sites More sharing options...
joseph_wisniewski Posted October 10, 2011 Share Posted October 10, 2011 <p>It has a leaf shutter. That's like "petals" that open outward. It can open quickly when it only has to open far enough to accommodate a small aperture. It takes more time to open up wide enough for large apertures, so you get a slowdown at large aperture.</p> Link to comment Share on other sites More sharing options...
graham_martin2 Posted October 10, 2011 Author Share Posted October 10, 2011 <p>Thanks Joseph. I will have to give some thought to which film speeds to use depending on what I plan on shooting. Most of the time I don't shoot at the smallest apertures.</p> Link to comment Share on other sites More sharing options...
brett_rogers Posted October 11, 2011 Share Posted October 11, 2011 <p>Ansel Adam's classic title "The Camera" contains some details about this facet of leaf shutter operation and compares the relative efficiency of different shutter types. A lot of the information is still just as relevant today as when it was written.</p> Link to comment Share on other sites More sharing options...
q.g._de_bakker Posted October 11, 2011 Share Posted October 11, 2011 A leaf shutter can open quicker for small apertures only if the shutter physically only opens up far enough to clear the aperture.<br>The typical leaf shutter does not do that, opens all the way at any and all speeds and apertures. It does not open faster or slower either, but takes the same time to open at all speeds and apertures.<br>The result of that is that at speeds for which the time it takes to open (and close) is relatively long compared to the total duration the shutter should be open, the speed is effectively slower, not faster, at smaller apertures. Because it takes less time to clear a small aperture, then still has to go on opening fully (and the same extra duration when closing again).<br><br>I don't know the Fuji's shutter, but it being a leaf shutter doesn't explain why the speeds at smaller apertures are faster, instead of slower. Link to comment Share on other sites More sharing options...
francisco_disilvestro Posted October 11, 2011 Share Posted October 11, 2011 <p>One possibility is a design like a "Studio Shutter" (used in some old LF lenses) where the shutter blades are at the same time the aperture blades. In this design, it will take less time to open and close for smaller apertures.</p> <p>I really don't know if this is what the Fuji GA645 has.</p> Link to comment Share on other sites More sharing options...
graham_martin2 Posted October 11, 2011 Author Share Posted October 11, 2011 <p>I don't think the camera is more than about 12 years old. It was the first P&S MF camera that Fuji made with auto focus.</p> Link to comment Share on other sites More sharing options...
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