Right! That's the way I do it with simple K-Bayonet lenses. Works perfectly for me (K10D and DS) Jos
J. C. O'Connell wrote: > THIS IS ALL MOOT, I HAVE FOUND WITH K AND M LENSES TO JUST > ESTIMATE EXPOSURE BASED ON YEARS OF EXPERIENCE OR USE GREEN BUTTON > > > AND THEN > TWEEK FSTOP OR SHUTTER SPEED SETTINGS > > > BASED ON THE FIRST TEST EXPOSURE HISTOGRAM. THERE IS NO WAY YOU ARE > GOING TO GET BETTER RESULTS THAN TWEEKING. ONLY ISSUE IS > SPEED. BUT IF SPEED IS OF THE ESSENCE, YOU SHOULD BE > USING KA OR KAF NOT K OR M. > JCO > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John > Francis > Sent: Saturday, May 10, 2008 12:28 AM > To: Pentax-Discuss Mail List > Subject: Re: K20 and manual aperture lenses > > > > It's also got something to do with the angle of incidence of the light on > the metering screen. The K10D (and later cameras) have a screen that's > quite different from the one in the D bodies. The K10D compensates for the > non-linear response of the system, but it assumes metering is being done > wide open (I don't know what it assumes for a pre-A lens, but I'd guess > f/2.8 or f/4.0). But if you're using stop-down metering at a small aperture > the K10D calculates the exposure incorrectly. > > I'm glad I decided, back when I got my PZ-1p in 1995, to stick with a > guideline of "A or later" for lens accquisitions. > > > On Fri, May 09, 2008 at 11:03:57PM -0500, Bob Sullivan wrote: > >> Bill, >> >> I've found some exposure error as well with K and M series lenses and >> the green button. Somebody else mentioned it, and I don't understand >> it? >> >> I thought the green button closed the aperture down and measured light >> exposure values. I can't imagine how this is off, but here is an >> example with K35/2 lens. (The lens was set at different apertures and >> green button pressed before exposure.) >> >> http://picasaweb.google.com/rf.sullivan/K352ApertureTestOnK20d >> >> As you move away from wide open (f2) to smaller apertures (f12.8), >> light moves toward overexposure. (You can see more light in the big >> shadow on the right.) This did the same with an M400/5.6 although I >> didn't post the details. >> >> All I can figure is that it has something to do with the aperture >> lever being linear. Since the A lenses (and later), the movement has >> been linear. With the earlier M and K lenses, the movement is >> non-linear. Is it possible that the K20D measures the right exposure, >> and then sets a matching A lens aperture, >> not closing the lens all the way down to the f12.8 we have set? >> >> Regards, Bob S. >> >> >> >> On Fri, May 9, 2008 at 8:56 PM, William Robb <[EMAIL PROTECTED]> wrote: >> >>> One of the guys on the Pentax Dysfunctional Web Forum chalenged me >>> to test my K20 exposure system with manual aperture lenses (green >>> button manual). The camera failed miserably, over exposing by quite >>> a large amount at all f-stops but maximum and minimum. Would it be >>> possible for some others of us to run the following test: >>> >>> Put a non A series lens onto their camera doesn't matter which, but >>> it would be nice to have details, and run a series of exposures from >>> maximum aperture to minimum aperture to test the linearity of the >>> metering and perhaps report back. >>> >>> Sorry if this has been discussed before. >>> >>> I ran the test with several lenses, and then put an original >>> equipment istD screen into the K20 as buddy thought that the screen >>> itself was at fault, and insisted that it had been a problem with >>> every DSLR since the istD. The screen was not the problem. >>> >>> Thanks >>> >>> >>> -- >>> 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. > > -- 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.
