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04-24-2016, 08:26 PM   #1
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Can someone explain why this happens?

I have taken two identical pics one in TAV mode and one in AV mode. Identical settings both on Auto ISO. I cant figure out why the camera chooses to use such different ISO values between the two pics. This is with my K5iis but also does the same thing with my K-01.





The first was taken in TAV mode, second in AV mode. I have noticed that this happens all the time but i dont know why.

04-24-2016, 08:38 PM   #2
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Don't have an answer, but looking at the pictures it seems like both were taken with flash. Was it the onboard flash, and what mode was it in? I wonder if there's a difference in how the camera estimated the lighting in the two shots because of that....
04-24-2016, 08:41 PM   #3
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QuoteOriginally posted by jayman_1975 Quote
I cant figure out why the camera chooses to use such different ISO values between the two pics.

The EXIF data for each photograph would help us to help you !!
04-24-2016, 08:43 PM   #4
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QuoteOriginally posted by pjv Quote
The EXIF data for each photograph would help us to help you !!
I thought the exif shows up in the Flickr link. Otherwise I wouldn't know how to get it on there

04-24-2016, 08:49 PM   #5
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QuoteOriginally posted by jayman_1975 Quote
I thought the exif shows up in the Flickr link.

No link there I think.
04-24-2016, 08:55 PM - 1 Like   #6
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QuoteOriginally posted by jayman_1975 Quote
I thought the exif shows up in the Flickr link. Otherwise I wouldn't know how to get it on there
It does. Click on the picture and it takes you to Flickr where there's a link to view the data.
04-24-2016, 08:57 PM - 1 Like   #7
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Per the flickr page:

1st picture exif: Pentax K-5 II s ƒ/2.8 35.0 mm 1/80 3200 Flash (on, fired)

2nd picture exif: Pentax K-5 II s ƒ/2.8 35.0 mm 1/80 125 Flash (on, fired)
04-24-2016, 08:57 PM   #8
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QuoteOriginally posted by Quartermaster James Quote
It does. Click on the picture and it takes you to Flickr where there's a link to view the data.

Thanks Q.J.

---------- Post added 25-04-16 at 02:08 PM ----------

QuoteOriginally posted by PentaxCats Quote
Per the flickr page: 1st picture exif: Pentax K-5 II s ƒ/2.8 35.0 mm 1/80 3200 Flash (on, fired) 2nd picture exif: Pentax K-5 II s ƒ/2.8 35.0 mm 1/80 125 Flash (on, fired)

I could not see any shutter speed values, so I don't know why the ISO's would be so different.


Last edited by pjv; 04-24-2016 at 10:19 PM.
04-24-2016, 09:09 PM - 1 Like   #9
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Did you took both pictures by using same metering mode?
Could the Fluorescent light flickering cause the inconsistent exposures between 2 photos?
04-24-2016, 09:19 PM   #10
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I just did some more testing and have noticed that while in TAV mode, the auto ISO value doesn't change when I flip the flash up. It will use the same values for flash on and flash off. Strange. But in AV mode, when I flip the flash up, I can instantly see the ISO value drop to account for the extra lighting from the flash. I'll have to research this more.
04-24-2016, 09:20 PM   #11
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My K-5 IIs does that too. In TAv mode, the camera tries to adjust ISO for correct ambient exposure, ignoring the fact that the flash will be used. In Av mode, the camera knows that flash will be used and thus selected a lower ISO for better image quality (i.e. less noise, etc.)
04-24-2016, 09:23 PM   #12
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QuoteOriginally posted by sbc Quote
My K-5 IIs does that too. In TAv mode, the camera tries to adjust ISO for correct ambient exposure, ignoring the fact that the flash will be used. In Av mode, the camera knows that flash will be used and thus selected a lower ISO for better image quality (i.e. less noise, etc.)
Yes this is exactly what I have found. I wonder why they would have it act this way. I prefer to shoot in TAV mode but when I use the flash I find it over over exposes badly because it doesn't account for it. Seems like a bad design flaw
04-24-2016, 09:34 PM - 1 Like   #13
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Actually if you think about it, it is not really a design flaw but just the way the algorithm works. You choose the Av and Tv value and the camera will select the correct ISO. I understand that you may want the flash to lower the ISO for less noise but others may want the camera to balance the foreground and background exposure - e.g. flash fill-in on a cloudy day.
04-24-2016, 09:49 PM   #14
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QuoteOriginally posted by jayman_1975 Quote
I just did some more testing and have noticed that while in TAV mode, the auto ISO value doesn't change when I flip the flash up. It will use the same values for flash on and flash off. Strange. But in AV mode, when I flip the flash up, I can instantly see the ISO value drop to account for the extra lighting from the flash. I'll have to research this more.
That is the general difference in using manual setting vs auto settings with flash. In manual mode the camera let you control all settings and only add fill in flash when flash is used. I guess Pentax use the same logic for both manual mode and TAv mode (even though the ISO is auto in TAv).

So you need to use exposure compensation in TAv to adjust ISO (and the mixture between between ambient and flash light). Or switch to manual mode and set ISO manually to get full control over the flash.
04-24-2016, 11:45 PM   #15
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Could the white balance be changing between shots if using Auto?
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