Well that just solves the riddle for me. Thanks for clarifying that! On Sat, Sep 20, 2014 at 1:33 PM, Alan C <c...@lantic.net> wrote: > Yes, that too. A lenses move 1 unit per stop (based on area), but pre-A > lenses move only √2/2 (0.7071) per stop (based on diameter) so the images > are progressively overexposed & a correction of about 0.3/stop is needed. > Some degree of manipulation is possible with false coding but re-engineering > the lens innards is the only sure solution. Some fanatics have actually done > just that. I may well have done so too if I was into this 10 years ago. > > Alan C > > -----Original Message----- From: P.J. Alling > Sent: Saturday, September 20, 2014 6:35 PM > > To: Pentax-Discuss Mail List > Subject: Re: Get with the times (FF DSLR, etc) > > It's not that the lenses have to be coded, the aperture is inconsistent > with the movement of the stop down lever in pre A lenses. The original > A lenses just supplied minimum and maximum stop information, coding that > is easy, all that takes is a drill and the proper sized bit, and knowing > where to put a pit on the lens mount, getting the lens to stop down > consistently in accordance with what the camera expects, that's the hard > part. > > On 9/20/2014 9:17 AM, Alan C wrote: >> >> When I went digital (only 4 years ago!) I started with a special offer >> Canon >> 1000D body & emf af confirm adaptors for my pentax M42 & K mount lenses. >> Set >> the desired f on the lens & the camera, open wide to zoom, focus, meter & >> lock, then stop down & shoot. It worked very easily with the M42's & their >> A/M switch but less easily with the K mounts (with no A/M you have to >> count >> the clicks) . After a while I found it a pain so I gave the Canon to my >> son-in-law & bought a S/H K110D on which AE-L performs the same function >> as >> the Green Button on later Pentax models. The aperture is stopped down & >> the >> available light used to determine the exposure. The metering is quite >> accurate. M42's with a K-mount adaptor can be used in AV mode if the A/M >> switch is set to M but AF confirm only works up to f5.6 (f8 in bright >> light). K-mounts would presumably also work like that in AV mode if the >> aperture lever was removed. I also tried the "tricking" trick with a strip >> of Al foil under the "A" pin on the camera body but, unless the lenses are >> coded, the exposures are all over the place. (A lot has been written on >> that!) The K7 with a Green Button I now have is similar but the metering >> is >> less accurate than with the K110D. For me, Sunny 16 is the easiest >> solution >> & it is good for the brain cells too. However, enough buggering around & I >> have decided to get rid of all my pre-"FA" lenses & move with the times. >> AF >> & AV makes life a hell of a lot easier. >> >> Alan C >> >> -----Original Message----- From: JC OConnell >> Sent: Friday, September 19, 2014 10:52 PM >> To: Pentax-Discuss Mail List >> Subject: Re: Get with the times (FF DSLR, etc) >> >> when I use the green button metering/setting, its only to get me in the >> ballpark. I then fine tune >> the exposure with either and or both the shutter speed and aperture >> setting using the histogram/lcd. >> works for me. >> jco >> On 9/19/2014 4:38 PM, Bruce Walker wrote: >>> >>> Pentax has definitely failed to promote the Green button. To me it's >>> just a Mystery Button that I could just as easily cover over with >>> black electrical tape. >>> >>> After it got talked about here a few years ago, I made the effort to >>> read up on it. The manual left me scratching my head, but folks here >>> insisted it was awesome. I think the issue with the manual is there's >>> no overview or Big Picture -- why it was added. >>> >>> When I tried it out, no matter what I did with it it just seemed to >>> produce random and inscrutable results -- incorrect exposures -- with >>> no apparent benefit to me. >>> >>> I think of it as the Do Not Press Me Ever button. It just presents one >>> more opportunity for me to fsck up the settings if I fumble-finger it. >>> >>> >>> On Fri, Sep 19, 2014 at 10:08 AM, Darren Addy <pixelsmi...@gmail.com> >>> wrote: >>>> >>>> On Fri, Sep 19, 2014 at 2:54 AM, Alan C <c...@lantic.net> wrote: >>>>> >>>>> If people really want to use pre-"A" >>>>> lenses, they can easily work in M mode and use Sunny 16 like we all did >>>>> long >>>>> ago (& waste no film). >>>> >>>> Pentax has actually given us a lot more than that. Most everyone knows >>>> that the Green Button can be set to give you the Program exposure >>>> setting while in Manual. But a lot of people still don't know about >>>> Hyper Manual. Hit the AE/L button after the green button and now you >>>> can change BOTH the aperture and shutter speed (together with only ONE >>>> dial) at your chosen ISO. Super handy. >>>> >>>> - - - >>>> Photographers must learn not to be ashamed to have their photographs >>>> look like photographs. >>>> ~ Alfred Stieglitz >>>> >>>> -- >>>> 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. >>> >>> >>> >> >> > > > -- > I don't want to achieve immortality through my work; I want to achieve > immortality through not dying. > -- Woody Allen > > > -- > 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. > > --- > This email is free from viruses and malware because avast! Antivirus > protection is active. > http://www.avast.com > > > -- > 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.
