Archived posting to the Leica Users Group, 2000/05/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I personally think (at least myself and LUG folks that I converse privately with) look at the "name" of the person posting a message. If it happens to be a person that babbles on relentlessly, message after message, and believes that he is the definitive answer to "every" question and topic, then they soon get relegated to the "filter-to-trash" list. Which is probably why I missed the original "No, just the opposite. It moves the focus back (toward the film) by its own thickness, essentially by "delaying" the light as it passes through the glass." message. Does this mean that all Range Finder cameras need "filter goggles?" I mean, without equal filters over the RF on an M camera, the lens with a filter would be focused at a different place than the RF without a filter. Some folks even have a UV filter on their Noctilux and manage to take sharp photographs at f/1.0 . How is this possible...? ;-) Jim At 11:32 PM 5/19/00 -0700, Dennis Painter wrote: > >I am speechless, well nearly so, to learn the you think a filter shifts >focus at the film plane by an amount equal to the thickness of the >filter. > >No wonder images made with the wide angle lenses on my M are hopefully >out of focus with a filter attached ;-) > >Yes, the speed of light is less through glass than air, but if the glass >has flat parallel surfaces then when we focus on an object at infinity >the delay is equal for all rays of light. Thus about all that happens is >there is a time 'parallax' of perhaps a few picoseconds, between >exposure made on two identical setups, one with a filter, the other >without. > >Seriously, what you said just doesn't hold water. Maybe what you said is >not what you meant but I think the listmembers must be tired of deleting >this by now. > >Best of light, > >Dennis > >Takeshi Hashimoto wrote: >> >> No, just the opposite. It moves the focus back (toward the film) by its own thickness, essentially by "delaying" the light as it passes through the glass. >Takeshi