Well the short answer is any text will help your search engines optimisation but really specific text will help it a lot more. Read on...
We understand that you want your photos to be the main content on your web site after all that is why the visitor is viewing your site, however having some text on your pages will really help the search engines understand what your web site is about and help include your site relevant results pages, ultimately driving traffic to your site.
With so many web page now on the web it is important that you add readable content that will give the search engine (and your visitor) all the information they need; what you are, what you do and where you are are just a few of the very basic requirements they will need to understand.
Imagine you are looking for a camera to hire. If you went to a search engine and simply wrote "camera hire" the search would take a guess at giving you the best results. Looking at where you were and giving you results that are near you for sites that include the words camera hire. But if you were based in the UK and looking to hire a camera in Finland for an assignment the results would be of no help to resolving your problem. So, you would make another search "Camera Hire in Finland". Now you get a better more accurate result. However, for your assignment you need a particular underwater camera and the millions of pages in the search engine results will take an age to filter through. So you return to the search page again and add a far more specific search term: "Sk5900 underwater high resolution digital camera hire Helsinki Finland". Now you get the exact result you are looking for because the search has been very specific.
When you are authoring the words on your web pages make sure you include all the keywords for your business and the location you are located in. Tell the visitor/search engine that you are a wedding /commercial / portrait / schools / glamour / news / events photographer and where you are located, all weaved into a few interesting paragraphs about what you do, your unique selling points and so on. Don't leave it to the visitor to guess or give up. Include town names, County towns, County, Districts and Country. Don't try to do it all from one page, use all available pages and make the text content relevant to the page titles used on the page.
Take a moment to watch this video: