[pentaxk10duser]

I set my speed to 125 , f4.0 it gave me 400 iso using the pop up flash in the first flash setting . I didn't use the flash in the second photo with the same settings and it gave me a 320 iso . and the photo was darker . why didn't the iso go to 400 or higher to keep exposure from being so much darker than with the flash on . to me the photo with flash looks right but with out it its darker. I wanted to see what it would take to get the same exposure as it did with the flash so I put it in Manual mode and left every thing the same except the iso I tried a shot at 400 but it was still dark but when it was at iso 800 it was the same exposure as it was with the flash .so there was a difference from 320 iso with out flash to 800 iso to make it the same as with the flash. Why doesn't the camera try to keep the same exposure as it did with the flask on . I was taking the photo standing up and looking down at a few things on the desk so I was about 3 feet way . How does the flash and the iso work together when the flash is in the first setting the setting that just said flash in TAv mode I have my iso range set to 100 to 52000

[Sandy Hancock]

In my hands, TAv mode does not work well for flash; it has been most useful in low light situations where flash is to be avoided.
I get the best results with the camera in manual and the flash in auto.

By the way, try to format your posts in a more readable way. It was hard work wading through that slab of text. Punctuation and paragraphing go a long way.

[paraben]

I get the best results with the camera in manual and the flash in auto.

Me too (with a K-5 and Metz MB 44 AF-1). It gives me more exposure control and more predictable results.