Light stencils – long exposure, 72s.

It’s been a rainy Saturday afternoon and evening, which ruined my plans to shoot another ‘Long Exposure’ picture as I had planned.

So, I convinced the kids to give me a hand to try out a long exposure technique which I saw on F-stoppers – one which you can do indoors despite the rain!

You start with a shoebox and an off-camera flash.  I have this old Speedlite 300EZ, from my old film SLR (which unfortunately has shutter-stick problems now).  I can’t get the 300EZ to work properly with my 60D but it will be great for this.

Cut a fairly tight-fitting hole for the flash head to fit:

Next, line the box with a reflective surface.  I used leftover metallic gold cardboard from a previous craft project.  Remember that due to the inverse square rule, light intensity at the far end of the box will fall off quickly – this is why I have angled the reflector to try to equalise the total flash-head-to-stencil distance as much as possible (otherwise one end of the stencil would be much brighter than the other).

Aluminium foil works too – I used it in the box for the other stencil.  You obviously get a different sort of colour from the gold or from the alfoil. Cut a hole in the lid of the shoebox.  Do a neater job than I did, it shouldn’t be hard :P.  Get a piece of dark cardboard (preferably one which is not mangled like the one below – hey, I was working with what I had available!

Alternatively, you can cut directly into the box lid, but it’s harder to cut neatly since it’s thicker.

Cut out your preferred stencil shape.  Clearly my artistic ability is limited to photography :).  No doubt you will do a better job than this dodgy butterfly.

 Assemble as above with a couple of layers of cellophane of your preferred colour.

Tip: Unlike me, you should cut the shape in the middle of the card.  D’oh!

Assemble (patching your mistakes as necessary).  Cover any holes in the shoebox with dark card and tape the box seams.  You could also paint the box black but it’s probably unnecessary depending on the ambient light where you will be shooting.  This blue tissue paper was stuck behind the cellophane to change the red colour a bit and damp the flash.

After a bit more testing I stuck an additional piece of normal A4 printer paper behind all of that to damp the flash further.

Set up your camera on a tripod in a low light area.  I also used an 8-stop ND filter because it was still afternoon, so I needed to use Live View to compose and focus.

Using Bulb mode – trigger the shutter.  Fire the flash in the stencil box in your target focus zone.  Switch stencils – repeat.  Close the shutter.  Look at the back of the camera to see whether you have triumph, disaster, or (like me) something in between :).

Here are the results of my first proper attempt, after a few test shots (settings: ISO100, 18mm, f/7.1, 50s, 8-stop ND filter).

First attempt

Just to be clear – this is one exposure – no Photoshopping or merging images etc.  You can’t see my assistant Miss Eight who is holding and firing the flash in the stencil box because she is moving, and there is insufficient light on her for her to register on the sensor. Actually, if you look at the right-most flower, you can see her long hair getting across the front of the stencil while the flash is firing :).  The flash has fired 8 times in that exposure – 4 times in the flower stencil box and 4 times in the butterfly stencil box (which had a much worse light leak problem).

There is an obvious problem with this picture – the white vertical lines.  These are light leaks from the hole around the flash head – even though the hole is quite tight-fitting, it’s not tight enough to stop this.

I fixed this (mostly) with some black plastic garbage bag around the flash head hole – a bit awkward, but it did the trick. (I still had a light leak – much smaller – but I ‘healed’ it in Lightroom for the final print).

Also, the shot looked a bit ’empty’ to me so I added a green-cellophane torch waved on the rear wall (at the end of the shot, after Miss Eight had fired the flash off ten times and exited the frame).  Here’s the final result:

The final product – ISO100, 18mm, f/7.1, 72s exposure, 8-stop ND filter

I used Lightroom 4 to increase the exposure slightly, play with black levels a bit, and to fix the light leaks (most of them – you can still spot one) with a spot removal brush.

This will be my second photo for the Nick Exposed / Seeing Spots Photo Long Exposure collaboration :).  The girls had fun (most of the time) and made their own ‘versions’ of the shot – and I hope to have some improved versions of this kind of shot in future now that I have ‘proven the concept’.