I got the idea for this from fellow Click Pro, Erica Williams, who created some amazing freelensed images using this effect on top and then she posted a tutorial on the Clickin' Moms forum so others could have a go too. The effect is trying to replicate a "light leak" which might have occurred when using film in a creative way, I think it looks great and of course, anything that adds rainbows to my more basic shots of the kids on swings for example is a winner for me! I love the burst of colour and it can be more subtle or stronger depending on the light at the time, the way you shoot and of course, how you edit the photos after.
I only watched the tutorial after I had a play about with my own straws so did mine slightly differently but it's basically the same technique, I'll be taping my straws together like Erica next time though and I haven't tried it while freelensing yet. I added a couple of photos at the end which demonstrate how I held my straws in front of my lens for these effects.
Here are my first attempts at creating these rainbow style light leak effects, I'll definitely be trying this again with better light and maybe more sun flare next time as the park was mostly in shade when we arrived...
I managed to get a friend to take some photos of me on my phone holding the straws as I used them. Here are those photos showing how I did it and an example photo I took of her at the same time...
I've since taped my straws together with one straight edge and one curved (I trimmed them with scissors). The taped edge is tightly bound but I left the curved end free to flare out so the effect with be very different with each end and depending whether I hold it at a corner of the frame or the top/bottom/side edges. I could also bend some colours out of the frame at that end if I wanted to vary the colour effects. Basically just do what you like and play about, experiment and see what you end up with! It's fun! :D I got my straws here for £1.69 (affiliate link).