What's the "floating optic ring" for?
Thanks for posting this. I went with the 65mm but at some point will probably take a look at the 50mm. What's the "floating optic ring" for?
thanks,
Retrofocus wide-angle lenses of the shortest focal lengths tend to produce a curved field of focus about the subject at extreme close focus. It’s shaped like a portion of a sphere where we expect a lens to produce a flat plane of focus. Some of the better lenses of this type use a single element or two-piece compound element between the front and rear optical units that moves independently of the rest of the lens. The independently moving unit is known as a field flattener. By moving it to the proper position inside the lens assembly, the curved field of focus is flattened as we’d expect of a good lens. The independently-moving field flattener is sometimes described as a “floating element”.
These are moved as necessary by a cam assembly as you turn the focusing ring on helicoid-focusing lenses like 35mm SLR lenses. But the RZ67 is a bellows-focusing camera. In this case we have to turn a “float ring” to manually adjust the position of the field flattener after first focusing the lens. Some close-focusing macro lenses also have an independently-moving field flattener unit. Some examples are the 105mm Micro Nikkor and the Mamiya 140mm macro lens for the RZ67.
I know this is an old thread but I'm researching a future purchase and had a quick question. The vignetting that appears in a few of the images, was it caused by a filter, multiple filters, hood, or something else? I ask because I'm considering the hitech modular 85mm filter holder(a lot cheaper than the 100mm) and was not sure if this would cause vignetting on the 50mm with a single filter. I have the 65mm L-A now so not a problem, but might consider picking up the 50mm in the future. Thanks for the help!
I tested my 50mm with 1 filter and i didn't see vignetting as long it is not big stop and not stopping the aperture al the way to say f16-22, if i use more filters then i can expect vignetting, but if you shoot in bright days it will show very slightly vignetting, i tested on color films, B&W film is way more forgiving for vignetting.
Thanks! As I said, I don't currently have the 50mm but will likely pick one up at a later time and was curious if I'd have problems with the smaller filter system; so good to know.
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