When you select a photo and then click view image you can make the image show at it's biggest size by putting your cursor over it and clicking the image. Clicking it again will return it to the smaller view. Images that are already shown at the full size will not enlarge by clicking them. Not sure how things work in other browsers but with Firefox you can also press
Control + to make smaller images appear bigger on the screen (at a loss of clarity).
Control - shrinks them and
Control 0 returns them to normal size.