K10d - what are my options for correct exposure with manual lenses?

dlacouture · 07-08-2009, 01:31 AM

Quote:

As for the error at narrow apertures...this is to be expected. The amount of light reaching the meter at those apertures is often below its sensitivity.

Steve : this is a pretty common statement, but it's totally false... Try this in plain sunlight (on a very bright objet), and you'll still see the same behavior, even though the light coming through the lens is way above the Ev bottom limit of the sensor...
Moreover, using a LL60 removes this flattening... So this is really an effect of the stock screen.

Steve Beswick · 07-08-2009, 02:36 AM

Originally posted by stevebrot

Interesting. What firmware version are you using? I tried to implement this fix, but could not find that option.
Steve

Version 1.30.

Duck Dodgers · 07-08-2009, 02:55 AM

Version 1.30 options for "Green Button in TAv & M:"

1 Program Line
2 Tv Shift
3 Av Shift

stevebrot · 07-08-2009, 09:20 AM

Originally posted by dlacouture

Steve : this is a pretty common statement, but it's totally false... Try this in plain sunlight (on a very bright objet), and you'll still see the same behavior, even though the light coming through the lens is way above the Ev bottom limit of the sensor...
Moreover, using a LL60 removes this flattening... So this is really an effect of the stock screen.

Totally false? Well, perhaps I should redo my controlled exposure series tests that the statement was based on. My results showed that the severe underexposure at smaller apertures (3 stops under at f/22 on one test), essentially went away in bright light. With adequate light at f/8 and narrower, the general pattern was for correct exposure or a mild over-exposure (~0.5 stop).

As far as the LL60 removing the flattening...I don't particularly want to be contrary, but I calculated the EV at the sensor and it was below EV 0 (ISO 100) at those smaller apertures. According to the published specs for the K10D, I think that is below meter sensitivity. Moreover, my tests seem to indicate that the K10D sensor becomes non-linear at about EV 1.5 (ISO 100) which does not help matters any.

Steve

(I guess I really should publish my exposure series graphs...)

Steve Beswick · 07-08-2009, 10:51 AM

Originally posted by Duck Dodgers

Version 1.30 options for "Green Button in TAv & M:"

1 Program Line
2 Tv Shift
3 Av Shift

I set it to #2, Tv Shift. Sorry if I caused any confusion.

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07-08-2009, 01:31 AM	#31
dlacouture Veteran Member Join Date: Jul 2008 Location: Var, South of France Photos: Albums Posts: 1,074	Quote: As for the error at narrow apertures...this is to be expected. The amount of light reaching the meter at those apertures is often below its sensitivity. Steve : this is a pretty common statement, but it's totally false... Try this in plain sunlight (on a very bright objet), and you'll still see the same behavior, even though the light coming through the lens is way above the Ev bottom limit of the sensor... Moreover, using a LL60 removes this flattening... So this is really an effect of the stock screen.

07-08-2009, 02:36 AM	#32
Steve Beswick Veteran Member Join Date: Apr 2009 Location: Ontario, California Photos: Gallery Posts: 1,736 Original Poster	Originally posted by stevebrot Interesting. What firmware version are you using? I tried to implement this fix, but could not find that option. Steve Version 1.30.

07-08-2009, 02:55 AM	#33
Duck Dodgers Veteran Member Join Date: Dec 2007 Location: in the 24½th Century! Photos: Gallery Posts: 439	Version 1.30 options for "Green Button in TAv & M:" 1 Program Line 2 Tv Shift 3 Av Shift

07-08-2009, 09:20 AM	#34
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by dlacouture Steve : this is a pretty common statement, but it's totally false... Try this in plain sunlight (on a very bright objet), and you'll still see the same behavior, even though the light coming through the lens is way above the Ev bottom limit of the sensor... Moreover, using a LL60 removes this flattening... So this is really an effect of the stock screen. Totally false? Well, perhaps I should redo my controlled exposure series tests that the statement was based on. My results showed that the severe underexposure at smaller apertures (3 stops under at f/22 on one test), essentially went away in bright light. With adequate light at f/8 and narrower, the general pattern was for correct exposure or a mild over-exposure (~0.5 stop). As far as the LL60 removing the flattening...I don't particularly want to be contrary, but I calculated the EV at the sensor and it was below EV 0 (ISO 100) at those smaller apertures. According to the published specs for the K10D, I think that is below meter sensitivity. Moreover, my tests seem to indicate that the K10D sensor becomes non-linear at about EV 1.5 (ISO 100) which does not help matters any. Steve (I guess I really should publish my exposure series graphs...)

07-08-2009, 10:51 AM	#35
Steve Beswick Veteran Member Join Date: Apr 2009 Location: Ontario, California Photos: Gallery Posts: 1,736 Original Poster	Originally posted by Duck Dodgers Version 1.30 options for "Green Button in TAv & M:" 1 Program Line 2 Tv Shift 3 Av Shift I set it to #2, Tv Shift. Sorry if I caused any confusion.