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
