av mode will work on pentax DSLRS using M42 lenses because the metering is based on actual light reaching sensor, so if you shoot a shot at F4, it will give a specific shutter speed, but if you stop down, less light reaches sensor and slower correct shutter speed will occur.
-- J.C. O'Connell (mailto:hifis...@gate.net) Join the CD PLAYER & DISC Discussions : http://tech.groups.yahoo.com/group/cdplayers/ http://launch.groups.yahoo.com/group/cdsound/ -----Original Message----- From: pdml-boun...@pdml.net [mailto:pdml-boun...@pdml.net] On Behalf Of Sam L Sent: Friday, November 05, 2010 10:01 AM To: Pentax-Discuss Mail List Subject: Re: m42 takumar 300/4 >On Thu, Nov 4, 2010 at 3:10 PM, Charles Robinson <charl...@visi.com> >wrote: On Nov 4, 2010, at 14:03, Subash wrote: > >> hi, >> >> anybody have experience with this lens? pretty heavy, a little over >> 1.5kg, but i saw one today for sale, it's in almost mint condition >> and so badly needs a caring home :) the one i saw today is the one on >> this >> page: >> >> http://www.pentaxforums.com/lensreviews/Takumar-300mm-F4-1962.html >> >> i guess what i really want to know is that once mounted with an m42 >> adapter, does one use this like a K/M lens with stop-down >> metering/green button? would appreciate any input you may have... >> > > It will be different. The aperture does not get held open, so if > you're dialing the lens down to f/11 you'll be looking through a lens > which is actually stopped down to f/11. > > On the bright (ha!) side, metering in Av mode would be real-time with > no need for the green button. Charles, forgive me for asking, but do you actually use m42 lenses on a recent pentax dslr? I ask because I think it is a little misleading to say that metering in Av mode is "automatic". Let me immediately state that I'm a nOOb at both dslrs and m42s. But my experience is that when working with pentax dslrs and m42 lenses: - Av mode will work correctly ONLY if your aperture is wide open. if you want to stop down the lens, then the metering gets helplessly inaccurate. - Manual mode: the meter works reliably but requires one extra push of your metering or green button. (focus, set your aperture on the lens such that the blades actually visibly stop down, press the green button, fire away). I'm not trying to be a jerk but trying to get a better understanding for myself as well as others. Everyone feel free to enlighten me! Thanks, --------------------------- Sam -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
