What Makes a Memorable Image?

I remember having a discussion, rather heated too if my memory serves me correctly, with another photographer about the merits of an image and what makes it important, memorable or special in any way to the intended viewer.

He was always critical of the technical elements of an image and judged the quality accordingly. He was very firmly of the opinion that if it wasn't tack sharp, exposed beautifully (read more on exposures here) and composed imaginatively then it couldn't be a good image.

I would agree that for some images this is true; art images, landscapes, still lifes etc. But given that the overwhelming number of image "transactions" are between photographers and clients (portraits and special events such as weddings, christenings, birthdays, etc) for me at least a good image, a memorable image is all about the memory and the emotion that it conveys and invokes.

Quite a lot of people in the past have shown me a photo and asked for my opinion. I used to give a nice critique (it's nicely exposed, interesting subject matter, it helps if Aunty Beryl is looking toward the camera) but after pondering this now for some time, I think this was the wrong way to go about it.

Now, when someone is after my opinion (and funilly enough it isn't as common an occurence!) I ask them, simply, what the photo means to them. Sometimes a smile spreads across their face as the reminisce, sometimes they stare blankly and have no feeling toward it. It is that reaction that I think is important.

What are your thoughts? What makes an image special to you, makes it memorable? I'd really like to get a feel for whether I'm just blowing hot air in a touchy feely group hug way, or wheather there's something to it.

Technically a fairly poor image: crooked horizon, boring sky,
slightly out of focus. But the emotion conveyed is simply
so powerful and as it turned out, sufficiently powerful
to help a nation win a war...