On 11/7/2014 4:47 AM, Chuck Norcutt wrote:
OK, I looked. You may well be correct that there is sufficient change of focus due to day/night temperature changes
to warrant refocusing at night. However, I don't think one can positively draw that conclusion from the two Tamrons
you pointed to in the Rockwell link.
I downloaded the owner's instruction sheets for both lenses and both have the following comments regarding the
focusing distance scale:
"The distance scale is marked for guidance purposes. The actual focal point may slightly differ from the distance
marked on the focal length index."
"At infinity make sure the image in the viewfinder appears sharp. The infinity position is made with certain
allowances to insure proper focus under a variety of conditions."
While that may well refer to temperature change effects there is only one marked infinity position
I think you misunderstand the markings. "|___" or the reverse, depending on direction of rotation - an L on it's back? -
means that infinity may be found anywhere between the upright and the physical end of rotation. I'm pretty sure I've
seen it on other brands, and in MF film days, but that's what I could find quickly on the web. I do recall the
illumination when I found out what it was for. I'm not going through my old longish lenses looking for more examples and
taking pix.
This did start, after all, just as a caution for Brian to check.
Over the Moon Moose
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What if the Hokey Pokey *IS* what it's all about?
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