Paul,

Thankyou for taking the time to answer my questions

I use manual most of the time - and 'program' when I'm in a 'point and shoot' situation (on holidays - just want a 'quick shot', for example).

My camera will zoom from 28mm to 300mm. If I use the automatic settings, I can see that the camera chooses a wider aperture as I zoom in ... but, when in manual mode, do I need to do this? Is this simply to allow more light into the camera in order to prevent camera 'shake'? If I choose a smaller aperture setting than what the camera wants to do automatically (if I want a larger depth of field, for instance), and have zoomed in to the scene, will that then have an adverse effect on my photo???? This is my dilemma! And I haven't been able to work out the answer either in practice or by reading about it!
I'm sorry to be so persistent and 'pestiferous'!