URGENT HELP REQUIRED!

For no apparent reason, my in camera exposure dial display has stopped working in TV and AV Priority Mode. It still works in full manual mode. Can't think for the life of my what has caused this. I was using a very old flash on my camera last night but it is still a Speedlite so can't think that this is the problem.

Can anybody help PLEASE?

Do you mean the actual display has disappeared or the control wheel on the back just has no effect? Did you remove all batteries, that would do a complete reset?

When in TV or AV priority mode, I press the shutter release halfway, the exposure display does not move, I turn the rotation wheel to adjust settings and it still doesn't move. Am i having a complete mind blank, it did used to move I'm sure????? I've been using full manual mode for ages to try and increase my learning curve. The display is still there, it just doesn't move when adjusting settings.

Take out the batteries and do a complete re-boot type thing. Put on a different lens, preferably a Canon one, don't use the external flash. Go thru the menu to find the 'restore to factory settings' option - I'm assuming your camera has one but I've never used a 300.
Use the green square setting, take a few pics of something and see what they are like. then move to the P setting and do the same. Then got to Av, set a range of apertures and see what the camera comes up with in terms of shutter speeds, and how the pictures turn out. Then try the Tv setting, set a range of shutter speeds and see what the camera does for aperture, and how the pictures work out.
then do the same for manual. check your LCD screen through all of this to see how the display changes. If after all this you are not happy, there are 2 options, either the display is malfunctioning but the camera is working otherwise OK, or the camera is not working. either way, repair time.
Good luck!

PS also check your ISO settings, if the camerq cannot give the correct exposure it may give nothing at all. just a thought!

Thanks for the advice guys but I feel like a complete idiot now. To dial in exposure compensation while in priority modes, I need to press the Av +/- button which I wasn't doing I think I'll stick with full manual mode - was learning more that way!

I'm sure my camera appreciated the reboot though!
Thanks again
Yours embarassingly.......

No worries, good news that nothing was actually wrong. Often it's the simple answer that fixes things. I know that sick feeling of worrying that I have broken something all too well

Glad you got things going

FWIW, It's not a good idea to try 'an old flash you have lying around' without knowing the voltages that it has on the pins. Some flashes can have over 400 Volts.. This can damage an EOS DSLR which doesn't want to see much over 5 volts.

Below is a page you can go to in order to check out a flash before using it:

http://www.botzilla.co​m/photo/strobeVolts.ht​ml

You can adapt a high voltage flash to work on a low voltage system, using something like the Wein safe sync, but old flashes whether they are high or low voltage, don't have the E-TTL capability that Canon DSLR cameras require. Non E-TTL flashes will always flash at full power, leaving you to manually meter.

Thanks for that Jim T - you had me running scared for a little while. I checked out the link you gave and I was using a 200E Speedlite which is EOS safe - phew! A lesson learned for the future though!

Thanks again