My understanding of SEO is that fresh, and relevant, content is the most important part. So even if it's just a couple of photos and saying that you've been doing "stunning landscape photography at XXX" then you'll be on to a winner.
There's no need for long posts, and if you do then think about the target market of your posts: are you expecting it to be read by other photographers? Then include the technical details. If you're writing for potential clients who might commission you, then add a bit of detail about the work process from commissioning through to delivering.
Also, depending on what blogging software you use, you can normally write posts and get them to automatically become live a future date. That way you could spend a couple of days when you have time, writing blog posts about the work you've been doing over the last few months, and then get the software to publish one a fortnight for the next few months.