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01-19-2017, 10:09 AM   #1
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f3.2 on TAv and M, f2.8 on Av and Bulb


I use a Sigma EX 105 2.8 Macro with my K-5. Up until now I used to use Av mode. Learning the K-5 I decided to try the unique TAv mode. But I can not go wider than f3.2. The same with Manual mode. When I switch back to Av mode I can go all the way wide to f2.8. In Bulb mode also aperture can be opened up to f2.8 Not with TAv and M. What's happening?

01-20-2017, 10:53 AM   #2
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That is weird. I can't duplicate that problem but I don't have that lens. I thought maybe it was a limitation of TAv but if it happens in M, the camera is not supposed to care that your settings don't agree with the meter. Do you have any other f2.8 lenses to see if the same thing happens? What happens if you switch Ev steps to 1/2 stops instead of 1/3?
01-23-2017, 03:29 AM   #3
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Original Poster
Problem explained.

I have found what is happening. I had set the two (2) images bracketing, the first underexposed for -0.3EV the second with no exposure compensation. In Av mode the K-5 makes the -0.3 compensation by reducing Time exposure and leaves the f2.8 as selected. In TAv and M modes the K-5 compensates by closing the aperture. So when I select f2.8 with this bracketing in TAv and M it takes the first image in f3.2 and the second in the selected f2.8 not messing with Time. In Bulb mode I think it ignores the bracketing.

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av, bulb, camera, f2.8, f3.2, f3.2 on tav, k-5, mode, pentax help, photography, sigma ex 105 2.8 makro, tav, troubleshooting
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