[jayman_1975]

If the flash duration was the same, the high ISO picture's foreground would have been massively over-exposed by the flash.

I do get that a lot when I use the flash in TAV.

[Apet-Sure]

Can someone explain why this happened? I went for a walk to try out a new-to-me zoom lens. After mounting the lens, I turned on my K10D and set the ISO to 400. It was a sunny day but I anticipated shooting a fair amount at the 200mm end of the zoom and wanted fast shutter speeds. Now, I don't remember if I changed from Manual mode to Av mode before or after I changed the ISO setting to 400. I go out and shoot some pictures at various manual aperture settings and focal lengths. When I get back the EXIF says they were all shot at ISO 1000! I've set the camera up to warn me if it tries to go above 800, but Av mode shouldn't be arbitrarily changing my ISO setting anyway should it? All of the shots were overexposed. I couldn't tell while shooting because the sun was washing out the images on the back of the camera. The lens was a Tokina 80-200mm SZ-X.

[stevebrot]

Can someone explain why this happened?

I will give it a shot...

After mounting the lens, I turned on my K10D and set the ISO to 400. It was a sunny day but I anticipated shooting a fair amount at the 200mm end of the zoom and wanted fast shutter speeds.

If you need a particular shutter speed, I would suggest using Tv, M, of TAv mode.

Now, I don't remember if I changed from Manual mode to Av mode before or after I changed the ISO setting to 400.

Av mode??? Using ISO to constrain shutter speed in Av mode works only as well as your diligence in monitoring the EV warning in the viewfinder.

When I get back the EXIF says they were all shot at ISO 1000! I've set the camera up to warn me if it tries to go above 800, but Av mode shouldn't be arbitrarily changing my ISO setting anyway should it?

It will if you are set for Auto-ISO or not in Av mode (TAv or green perhaps?) or switched from USER mode*

All of the shots were overexposed.

Several possible causes:

• Exposure compensation set to overexpose
• M mode with wrong exposure set
• Any mode where the amount of light exceeds available exposure automation. For example: Av mode with aperture set to f/2 and ISO = 400 in full sun. In that example the display will blink, but allow the photo to be taken anyway.

The lens was a Tokina 80-200mm SZ-X

This might be a clue. Is there any chance the aperture ring was off the "A" position? In which case, (assuming aperture ring is enabled in the settings menu) the camera will default to Av with the lens wide open unless in M mode.

Hmmmm...no definitive answer. Can you provide an example image with full EXIF intact?


Steve

* There are other possibilities, but I don't have a K10D in front of me and it has been a couple of years since I last shot with one. That being the case, I won't speculate.

[excanonfd]

Can you shoot the same scene or similar without the flash, curious to see what the result will be like in either mode.

[jayman_1975]

Can you shoot the same scene or similar without the flash, curious to see what the result will be like in either mode.

I shot the same two again, this time without flash. ISO is identical this time.

[Apet-Sure]

I will give it a shot...

Thanks for, eh, shooting at me. I didn't care what shutter speed the camera chose. I used Av mode because I wanted to manually change the aperture ring (permission in camera turned on) to judge sharpness of images at different aperture settings. I implicitly set the ISO to 400 after turning the camera on, either before or after moving the mode dial from M to Av. Because I was zooming, I had turned SR off. I figured on a sunny day the camera would choose fast-ish shutter speeds to help freeze camera motion.

Av mode with aperture set to f/2 and ISO = 400 in full sun. In that example the display will blink, but allow the photo to be taken anyway.

That may have happened. I was expecting the camera to kick the shutter speed up high enough to cope with the amount of light.

Can you provide an example image with full EXIF intact?

Unfortunately no. They were experimental shots, and the experiment failed, so I deleted all the files.

Bottom line, I'm sure it was some sort of operator error. I just don't understand how the camera changed itself from being deliberately set to ISO 400 to ISO 1000 while in Av mode. Oh well...one of the mysteries of life. Thanks for trying to unscramble my confusion.

[mcgregni]

You can only use an automatic exposure mode (Av, P, Tv, TAv, Sv) with an aperture ring in the A position. Without that set to A then the lens functions as an M or K type, and requires stop-down metering with the green button, in Manual exposure mode. So really, no exposure accuracy or any logical automatic settings can be expected without the lens set to the A position.

You wanted to make the lens stop down manually? In fact, I don't think this is possible with any auto - aperture type lens attached to the camera, where the aperture is always helps open until stopped down by the camera. I believe the lens would need to be the type with a special 'Auto - manual' switch or lever to allow this.

[Apet-Sure]

That must have been what I did wrong. I shoot in manual mode 95% of the time. I was trying out the Tokina lens for the first time. With it off the 'A' setting I guess I was giving the camera/lens conflicting instructions. I should have set the lens to 'A' and controlled the aperture setting with the e-dial. Live and learn--as long as we're learning we're making progress. Thanks for pointing out the error of my ways.

Here's a shot done in manual mode with this lens.

[excanonfd]

I shot the same two again, this time without flash. ISO is identical this time.

Where are the pictures?