[pentaxnood]

I dont know what I changed lately, but for the last few weeks, I could not shoot photos properly in TAv mode. Its always too bright, like +3 or more f-stop bright.

When I use Auto, P, T, M, Av there is no problem. What can be the cause?

[SKwan]

TAv Mode means you need to set the shutter speed and aperture first and then the ISO is automatically adapted and changed according to the exposure value needed for the scene you are going to take the photo. However the automatic ISO has got a limitation. When the ISO needed exceeds the limitation, it will twinkle until you set the shutter speed and/or aperture again to make the required ISO within the limitation of automatic ISO.

Hope this can help you!

[pentaxnood]

thanks Skwan,

Well I set iso limit to 100-800 , and in TAv mode the camera sets the ISO higher than it needs to be. This issue has started recently, I had been doing fine up until recently with TAv.

[Na Horuk]

What lens are you using? Is it stopping down properly? And what is the metering mode?

[pentaxnood]

Well I have been using DA 50mm and SMCA 35-70 manual lens. Everything started after I bought the manual lens. I didnt understand second part? metering mode was spot metering (actually I never changed it, and I just learnt what it is now, I think that is the reason)

But I understand SKwan your point now, well yeah I think I set shutter to low, aperture too open, so that even an ISO 100 would be high. So I was going through the pictures, but I saw that ISO was set to 200 in some of these, and photo is ALL white (Lens is DA 50).

So I was wondering why it did not set to ISO 100 for example instead of 200?

[Na Horuk]

You usually want ISO to be as low as possible. But if you use Av or P mode, the camera will do everything for you. I think the problem was spot metering, switch it to center-weighted or matrix.

[SKwan]

thanks Skwan,

Well I set iso limit to 100-800 , and in TAv mode the camera sets the ISO higher than it needs to be. This issue has started recently, I had been doing fine up until recently with TAv.

For your reference ...

1. If the automatic ISO is too narrow in TAv mode, the occurrence of over/under-exposure may be more if the twinkle ISO can not easily get your attention.
2. In Av and Tv mode, the aperture and shutter speed are mutually compensated and so the over/under-exposure may happen few even if the automatic ISO is too narrow.
3. If you push the AE-L before framing, the locked exposure value may not be fit to your final framing.
4. As what Na Horuk said, the metering mode need to be addressed. You are suggested to use center-weighted mode and then use exposure compensation to get a right exposure.
5. if you have switched on the highlight correction, the minimum ISO is 200 if you haven't switched on the expanded sensitivity.

[Franky2step]

in TAV mode you need to adjust your shutter speed and aperture. Have you done that ?

[pentaxnood]

thanks all, I just realized this twinkle thing upon SKwan suggestion and it totally clears everything up. Also I will use center-weigthed from now on.
So it is good now. Also yes highlight was on, that explains well.

[Sagitta]

TAv won't work with a manual setting lens or with an A lens not set to A. You'll always be shooting wide open. Check to see if you bumped the lens off the A setting.