Sunday Evening 9.00pm & the sun has just set.

I'd already got a couple of 'Keepers' before the sun dropped below the horizon & with the wind starting to pick up there was quite a bit of cloud movement. 

What better I thought than to dig my rarely used ND10 filter out & have a play around with some long exposure shots.

So, all set up, meter read at 1/8 secs at F8, so using my trusty 'Longtime Exposure' app on my iPhone (now that is worth having & it's free!) I calculated that it would be a 2 minute exposure.

Now this is when my problems started, I composed the shot & was happy, however, whilst changing the filter Autofocus decided to refocus & I hadn't realised, before I switched to manual focus.  As such, what I'd metered & focussed on was no longer what the camera thought I wanted a picture of !!

With the ND10 slotted in nothing was visible, even in Live View, so I merrily waited for the 2 minutes & thought all was good.  At this stage, I should have checked the image in detail, however a cursory glance suggested that the colours / clouds were ok & as such didn't think any more about it.

As soon as I got home & started to process I realised my huge error, that I should have switched to manual focus when composing the initial image.  Whilst the clouds achieved the sort of effect I was hoping for, the foreground was completely out of focus.

Still, it was only 2 minutes & I've learned from my mistake.  Next time round, will all be fine but this is one shot I'll not be able to get again !!