Makes sense. My brain was barely on "simmer" last night. ;-( Don
> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of > P. J. Alling > Sent: Thursday, June 29, 2006 7:23 AM > To: Pentax-Discuss Mail List > Subject: Re: Seen on eBay > > > No it doesn't, that at all. Think about it. The system as a whole > transmits less light than expected. However the f stop changes the > amount of light transmitted by a known percentage. TTL metering systems > only have to know how much light is being transmitted at maximum > aperture and how much the lens will stop down when the exposure is > made. For example suppose the lens in question has a maximum f2.0. > It's actual t stop is equivalent to 2.38 (1/2 stop slower). You are > going to shoot at f2.8. The fact that the f stop is 2.8 while the > actual t stop is equivalent to f 3.3 is not a problem. As long as the > aperture sensor has a reasonably liner response all the system has to > know is the current amount of light passing through the lens and how > much the lens will be stopped down from there. > > Don Sanderson wrote: > > >I've never heard this. > >How would a TTL meter handle this when metering is done wide open? > >It would have no idea that one lens needed to be stopped down > >just a bit more/less than another.? > > > >Don > > > > > > > >>-----Original Message----- > >>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of > >>Paul Stenquist > >>Sent: Wednesday, June 28, 2006 7:15 PM > >>To: Pentax-Discuss Mail List > >>Subject: Re: Seen on eBay > >> > >> > >>If you're not using a through the lens meter, you have to calibrate > >>your lenses for exposure. I frequently used a handheld incident meter > >>when shooting transparency film with my 6x7. But I had an exposure > >>compensation factor for each lens. For example, I think my 300/4 > >>required 1/2 a stop of extra exposure, while my 105/2.4 was right on. > >>Paul > >>On Jun 28, 2006, at 7:10 PM, Don Sanderson wrote: > >> > >> > >> > >>>Uh guys, maybe I'm missing something but unless someome is lying > >>>about their product isn't f/4.0 always supposed to be f/4.0?? > >>>It'd pretty much leave slide shooters who use a manual meter SOL > >>>if it wasn't, wouldn't it? > >>> > >>>Don > >>> > >>> > >>> > >>>>-----Original Message----- > >>>>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of > >>>>Joseph Tainter > >>>>Sent: Tuesday, June 27, 2006 7:38 PM > >>>>To: [email protected] > >>>>Subject: Seen on eBay > >>>> > >>>> > >>>>"A prime 2.8 lens is actually faster than a 2.8 zoom because of the > >>>>increased contrast which you'll find remarkable in comparison to your > >>>>zoom lens." > >>>> > >>>>Got that? > >>>> > >>>>Joe > >>>> > >>>>-- > >>>>PDML Pentax-Discuss Mail List > >>>>[email protected] > >>>>http://pdml.net/mailman/listinfo/pdml_pdml.net > >>>> > >>>> > >>>> > >>>-- > >>>PDML Pentax-Discuss Mail List > >>>[email protected] > >>>http://pdml.net/mailman/listinfo/pdml_pdml.net > >>> > >>> > >>> > >>-- > >>PDML Pentax-Discuss Mail List > >>[email protected] > >>http://pdml.net/mailman/listinfo/pdml_pdml.net > >> > >> > >> > > > > > > > > > -- > When you're worried or in doubt, > Run in circles, (scream and shout). > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
