FinePix S3200 Aperture - Iris/ND Filter...
Just got myself (well, and the household) a FinePix S3200 to replace a S5600, which had taken quite some beating over the years and now consistently refused to focus correctly. This camera is NOT my primary camera, but will a be a sort of general purpose camera for point and shoot stuff in the family and I am fully aware about some of the conceptual compromises in such a camera.
One of the areas in which corners have been cut, is the optics, which otherwise is one of the significant selling points. While the optics provide a amazing zoom range (24x in the S3200 and 30x in the S4000), I have seen claims that the aperture implementation in the S3200 (and current S series) is purely done using a ND filter. However Fuji specification describe it in this way:
Full-aperture F3.1(Wide) - F5.9 (Telephoto)
F3.1 / F8(Wide)
F5.9 / F8 / F20(Telephoto) with ND filter
Could this be interpreted as physical iris diaphragm aperture can be set to F3.1/F8 (wide) and F5.9/F8 (tele) and F20 (tele) using ND filter? But then; why not have F20 (ND) at wideangle, where it is more relevant? Or is it rather a design with no traditional aperture mechanism and one or two ND filters? This way of dealing with aperture is somewhat different from traditional the iris diaphragm and can purely be used for controlling the amount of light passing through the lens, while depth of field remains the same.
Some testing had to be done, so I put the camera in A mode to check depth of field. At wideangle such a test would be pointless, so I tried at 135 mm and F5.6 and F14. Result was two identical images (with different shuttertime) - no apparent difference in depth of field, could indicate a ND filter doing the job.
In a second experiment, at 500 mm, the camera provides three different aperture values. And a bit confusing, at F20 and F8 images are identical, but the F5.9 image clearly show a more shallow depth of field. Take a look at the circles of confusion in the background - quite clear that the "hole" must be a bit bigger than for the F8/F20 image.
It leaves me a bit puzzled as to how the aperture mechanism has been constructed on this camera; which part is ND filter and which part is a sort of mechanical iris? At 135 mm, it seemed to be a ND filter mechanism (F5.6 to F14) and at 500 mm it would be mechanical iris (F5.9 to F8) and ND filter (F8 to F20).
Any ideas? Not that the rest of the family will ever care…
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