My K20D on it self corrects exposure !

**fs999** · 03-03-2009, 03:26 PM

I noticed today when shooting the sun behind clouds, with my new DA 55-300, that my K20D, on it self, corrected the aperture from 5.6 to 18 despite I was in Av mode !
The aperture was set back to 5.6 after the shot.

The shutter speed was 1/4000" at 200iso. Click the image to see it on black !

Last edited by fs999; 03-03-2009 at 03:44 PM.

RBellavance · 03-03-2009, 03:44 PM

That is almost certainly the result of setting the custom function "Auto EV compensation" to "On".

**fs999** · 03-03-2009, 03:47 PM

That's an important feature ! Very intelligent !

Venturi · 03-03-2009, 03:53 PM

Originally posted by RBellavance

That is almost certainly the result on setting the custom function "Auto EV compensation" to "On".

Beat me to it.

Custom Settings Menu -> 10. Auto EV Compensation

falconeye · 03-03-2009, 04:44 PM

Originally posted by fs999

That's an important feature ! Very intelligent !

It can make sense. If you don't want to care if your Av setting is possible within bright light.
However, in your sample, the image is underexposed, too...

EDIT:
Ah, I now see, why. You dialed in an exposure correction of -4EV.
So, if ISO200, 1/4000, f/5.6 and -4EV was a mission impossible, why do you complain your K20D made the best out of it?

**jbinpg** · 03-03-2009, 10:21 PM

Falconeye - Could not the -4EV be the result of the Auto EV compensation?

Jack

sinnettc · 03-03-2009, 11:18 PM

Originally posted by jbinpg

Falconeye - Could not the -4EV be the result of the Auto EV compensation?

Jack

Based on my brief tests last week the Auto EV is done through aperture adjustment, at least if you're in AV mode.

Chris

losecontrol · 03-03-2009, 11:48 PM

The cameras starts to do our work

kristoffon · 03-04-2009, 01:30 PM

Originally posted by sinnettc

Based on my brief tests last week the Auto EV is done through aperture adjustment, at least if you're in AV mode.

Chris

that makes no sense

what's the point of av then?

**fs999** · 03-04-2009, 02:01 PM

Originally posted by falconeye

However, in your sample, the image is underexposed, too...

I would say it is correctly exposed for not blowing highlights... Did you look at the photo on black ?

Originally posted by falconeye

So, if ISO200, 1/4000, f/5.6 and -4EV was a mission impossible, why do you complain your K20D made the best out of it?

I am certainly not complaining, I was astonished, that's all

RBellavance · 03-04-2009, 02:08 PM

Originally posted by kristoffon

that makes no sense

what's the point of av then?

This "Auto EV compensation" function (if enabled!) only kicks in where the chosen exposure parameters get "out of bounds" (eg. if the shutter speed would exceed 1/4000s, for instance).

falconeye · 03-04-2009, 05:03 PM

Originally posted by jbinpg

Falconeye - Could not the -4EV be the result of the Auto EV compensation?

Jack

No. Exif says -4EV exposure compensation was active (EXIF field 9204 "ExposureBiasValue"). But I invite you to google what can influence this value (except dialing it in).

Auto EV compensation (as I understand it -- and I can be wrong) actually is no compensation. The opposite, actually. It tries to maintain a correct EV exposure value by changing "the other parameter" if the predefined paramater (exposure time or aperture) has reached its limiting value.

Therefroe, with 1/4000s and -4EV, the camera had to ignore the f/5.6 setting and aim for something smaller.

The -4EV, in the first place, are most probably a simple user error...

EDIT...

I had a look at the EXIFs again. This image was the darkest in a bracketed exposure series. fs999 "forgot" to tell us about and I'm not amused... So, the -4EV wasn't dialed in but choosen by the bracket series. All else as I've said.

Mike Cash · 03-05-2009, 06:45 AM

Originally posted by sinnettc

Based on my brief tests last week the Auto EV is done through aperture adjustment, at least if you're in AV mode.

Chris

That would explain why I've never been able to get it to do a damned thing with a Takumar mounted.

**fs999** · 03-05-2009, 12:18 PM

Originally posted by falconeye

I had a look at the EXIFs again. This image was the darkest in a bracketed exposure series. fs999 "forgot" to tell us about and I'm not amused... So, the -4EV wasn't dialed in but choosen by the bracket series. All else as I've said.

I am not amused either, I forgot it was in a braketing series, but this changes nothing to it, that at 1/4000" and f:5.6 the -2 EV shot was not possible without Auto EV compensation...

falconeye · 03-05-2009, 02:58 PM

Originally posted by fs999

this changes nothing to it, that at 1/4000" and f:5.6 the -2 EV shot was not possible without Auto EV compensation...

Franckly, I am now confused and don't understand your problem anymore. What did you expect, i.e., how did you want the camera behave?

Sidenote: I believe that the K20D, wehen doing an exposure bracket, changes both, aperture and exposure time, at least in M. Doesn't it do it as well in Av?

03-03-2009, 03:26 PM	#1
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,629	My K20D on it self corrects aperture ! I noticed today when shooting the sun behind clouds, with my new DA 55-300, that my K20D, on it self, corrected the aperture from 5.6 to 18 despite I was in Av mode ! The aperture was set back to 5.6 after the shot. The shutter speed was 1/4000" at 200iso. Click the image to see it on black ! Last edited by fs999; 03-03-2009 at 03:44 PM.

03-03-2009, 03:44 PM	#2
RBellavance Veteran Member Join Date: Nov 2006 Location: Near Montréal, Canada Photos: Gallery Posts: 1,716	That is almost certainly the result of setting the custom function "Auto EV compensation" to "On". Last edited by RBellavance; 03-03-2009 at 04:53 PM.

03-03-2009, 11:48 PM	#8
losecontrol Veteran Member Join Date: Jan 2009 Location: Gnesta, Sweden Posts: 373	scary future The cameras starts to do our work

03-04-2009, 05:03 PM	#12
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by jbinpg Falconeye - Could not the -4EV be the result of the Auto EV compensation? Jack No. Exif says -4EV exposure compensation was active (EXIF field 9204 "ExposureBiasValue"). But I invite you to google what can influence this value (except dialing it in). Auto EV compensation (as I understand it -- and I can be wrong) actually is no compensation. The opposite, actually. It tries to maintain a correct EV exposure value by changing "the other parameter" if the predefined paramater (exposure time or aperture) has reached its limiting value. Therefroe, with 1/4000s and -4EV, the camera had to ignore the f/5.6 setting and aim for something smaller. The -4EV, in the first place, are most probably a simple user error... EDIT... I had a look at the EXIFs again. This image was the darkest in a bracketed exposure series. fs999 "forgot" to tell us about and I'm not amused... So, the -4EV wasn't dialed in but choosen by the bracket series. All else as I've said. Last edited by falconeye; 03-04-2009 at 05:10 PM.

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03-03-2009, 03:47 PM	#3
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,629 Original Poster	That's an important feature ! Very intelligent !

03-03-2009, 03:53 PM	#4
Venturi Veteran Member Join Date: Mar 2008 Location: Tulsa, OK Photos: Gallery Posts: 2,636	Originally posted by RBellavance That is almost certainly the result on setting the custom function "Auto EV compensation" to "On". Beat me to it. Custom Settings Menu -> 10. Auto EV Compensation

03-03-2009, 04:44 PM	#5
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by fs999 That's an important feature ! Very intelligent ! It can make sense. If you don't want to care if your Av setting is possible within bright light. However, in your sample, the image is underexposed, too... EDIT: Ah, I now see, why. You dialed in an exposure correction of -4EV. So, if ISO200, 1/4000, f/5.6 and -4EV was a mission impossible, why do you complain your K20D made the best out of it?

03-03-2009, 10:21 PM	#6
jbinpg Site Supporter Join Date: Mar 2008 Location: Prince George, BC Photos: Gallery \| Albums Posts: 3,546	Falconeye - Could not the -4EV be the result of the Auto EV compensation? Jack

03-03-2009, 11:18 PM	#7
sinnettc New Member Join Date: Oct 2006 Location: Oregon, USA Photos: Gallery Posts: 9	Originally posted by jbinpg Falconeye - Could not the -4EV be the result of the Auto EV compensation? Jack Based on my brief tests last week the Auto EV is done through aperture adjustment, at least if you're in AV mode. Chris

03-04-2009, 01:30 PM	#9
kristoffon Veteran Member Join Date: Aug 2008 Location: Brazil Posts: 532	Originally posted by sinnettc Based on my brief tests last week the Auto EV is done through aperture adjustment, at least if you're in AV mode. Chris that makes no sense what's the point of av then?

03-04-2009, 02:01 PM	#10
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,629 Original Poster	Originally posted by falconeye However, in your sample, the image is underexposed, too... I would say it is correctly exposed for not blowing highlights... Did you look at the photo on black ? Originally posted by falconeye So, if ISO200, 1/4000, f/5.6 and -4EV was a mission impossible, why do you complain your K20D made the best out of it? I am certainly not complaining, I was astonished, that's all

03-04-2009, 02:08 PM	#11
RBellavance Veteran Member Join Date: Nov 2006 Location: Near Montréal, Canada Photos: Gallery Posts: 1,716	Originally posted by kristoffon that makes no sense what's the point of av then? This "Auto EV compensation" function (if enabled!) only kicks in where the chosen exposure parameters get "out of bounds" (eg. if the shutter speed would exceed 1/4000s, for instance).

03-05-2009, 06:45 AM	#13
Mike Cash Veteran Member Join Date: Jan 2007 Location: Japan Photos: Gallery Posts: 6,950	Originally posted by sinnettc Based on my brief tests last week the Auto EV is done through aperture adjustment, at least if you're in AV mode. Chris That would explain why I've never been able to get it to do a damned thing with a Takumar mounted.

03-05-2009, 12:18 PM	#14
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,629 Original Poster	Originally posted by falconeye I had a look at the EXIFs again. This image was the darkest in a bracketed exposure series. fs999 "forgot" to tell us about and I'm not amused... So, the -4EV wasn't dialed in but choosen by the bracket series. All else as I've said. I am not amused either, I forgot it was in a braketing series, but this changes nothing to it, that at 1/4000" and f:5.6 the -2 EV shot was not possible without Auto EV compensation...

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03-05-2009, 02:58 PM	#15
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by fs999 this changes nothing to it, that at 1/4000" and f:5.6 the -2 EV shot was not possible without Auto EV compensation... Franckly, I am now confused and don't understand your problem anymore. What did you expect, i.e., how did you want the camera behave? Sidenote: I believe that the K20D, wehen doing an exposure bracket, changes both, aperture and exposure time, at least in M. Doesn't it do it as well in Av?