It is good to be conscious about this - but don't get too scared to use it when useful.
The thing to be more aware of is the file size of the image. A couple of 100kB images aren't a big worry - but a couple of uncropped, uncompressed images from a 12 megapixel camera aren't going to go down too well for those members with slow internet connections and/or capped plans.
If your images don't need all that file size, then reducing them in size will be appreciated by everyone. If, however, you DO have an image that really needs to be big to show what you want, then have it hosted somewhere else and put a link in for those who choose to have a look. Putting a reduced size image in the post is something you can do to give an idea of what the big picture is about, which is helpful.
Alternatively, if the image isn't too big, you can upload it to Dave's server as an attachment to a post. SMF automatically inserts a thumbnail which people can then click on to access the full image.