Sunday, 20 May 2012

Photographing Earthshine

Crescent Moon with Earthshine (revisited)

I generally try to avoid going back and tinkering with old photos because - as with any creative endeavour, whether it's writing a story, composing some music, or making a film - there comes a point where you have to say, "Enough's enough," and walk away from it. However, I was recently contacted by a production assistant at Popular Photography magazine saying they were interested in using my image "Crescent Moon with Earthshine" for a "How-to" feature in the June 2012 issue*.

The original image was composed back in April 2007 and close inspection shows quite a lot of noise and signs of oversharpening (as well as some obvious artefacts from where the two stacks were spliced together). I've learnt a lot about processing since then - and newer tools have become available - so I decided I could do a much better job if I went back to the source files and reprocessed them from scratch.

For those who are interested in the technical nitty-gritty, the images were taken using a Canon 350D (Rebel XT) DSLR connected to a Vixen SP-102 achromatic refractor (focal length 1000mm). Earthshine (which is the reflected sunlight from the earth illuminating the shadowed part of the moon) is easy enough to capture on camera, but normally results in a severely over-exposed crescent. To retain the detail on the crescent I shot 31 images at 1/60 sec, ISO 200, and to expose the earthshine I took 11 images at 0.5 sec, ISO 800. I then stacked and sharpened these images separately using the freeware tools AviStack and RegiStax, before combining them in Photoshop using a layer mask to create the finished version you see above.

This new "redux" version is a big improvement on the original, and is probably the best I could do given the quality (and quantity) of the original 350D image files. Some flaws are still apparent: the dark band between the earthshine and the crescent is a little distracting and the earthshine itself could be brighter. These are issues that could be fixed by capturing more images at a wider range of exposures - and then combining them using HDR software.

But that's a project for another day...

*And in case you're wondering, yes they did use it, and yes they did pay me.

See also:
Shooting the Moon: Lunar Photography with a DSLR and a Small Refractor
Earthshine (NASA Science)
Planetshine (Wikipedia)

Wednesday, 16 May 2012

Digital Darkroom: Liven up dull photos

Sometimes, despite your best efforts, what you hoped would be a good photo comes out looking a little dull. In my case it's usually because I wasn't able to get enough separation between the bird and the background, and/or it wasn't in direct light. Fortunately there's a four-step technique you can apply in Photoshop that will restore some life to your image without adding extra noise.
  1. Duplicate the background layer. (If your image already contains adjustment layers, combine them all into a new layer by pressing N followed by E while holding down the Shift, Ctrl and Alt keys.)
  2. Boost the Saturation by +75.
  3. Apply Gaussian Blur with a radius of 5 pixels.
  4. Change the blending mode of the layer to Screen and reduce the opacity to 10%. (You can control the strength of the effect by changing the opacity, but don't overdo it!)
Here's a before-and-after example for comparison. Move your mouse over the image to toggle the effect.

Eastern Black Redstart, Palm Bay, November 2011

The beauty of this technique is that you can record these steps as an Action in Photoshop and then apply them to any image with just a single click.

...or you could just download the Action I've already prepared for you here:

To install the file in Photoshop, go to the dropdown menu in the upper right corner of the Actions palette, click on "Load Actions..." and navigate to wherever you saved the file.

Of course, no amount of digital trickery is going to turn a bad image into a good image; nor is this method a substitute for proper adjustment of Levels and Curves etc., but it is a quick and easy way to improve images which require that little extra "punch".

Monday, 7 May 2012

2.5-Dimensional Slideshow

Those of you who visit my Flickr page may have already seen this, but a lot of work went into it, so I make no apologies for airing it again. All of the birds in this presentation were photographed in East Kent, and all of them were wild (even the Kestrel):


I say a lot of work went into it, but how much? Well, to create the pseudo-3D effect, you first have to isolate the foreground element (the bird) from the background. This is done in Photoshop by duplicating the background layer, adding a mask and painting it so only the bird is revealed. You then have to remove the bird from the background layer by careful application of the clone brush (or the Content-Aware Fill tool if you're lucky enough to own a newer version of PS). The next step is to import these layers into Adobe After Effects, place a suitable distance (z-space) between the foreground and background elements, create a virtual camera to track in (or out), choose positions for your start and end keyframes, decide on the length of time it takes the camera to move between these keyframes, and render the animation.

...and that's just one shot completed; now you have to do the same again for all the other images.

Here's a behind-the-scenes screenshot showing a typical camera move being set up in After Effects:

There's a lot of trial and error involved in getting it just right, but the process does become simpler once you've worked through a couple of images.

While synching all the shots to the cues in the soundtrack*, I found I had more clips than I needed, so here - for those who are interested in extras - are the "Deleted Scenes":

If I haven't put you off and you want to try making your own 2.5D slideshow, a step-by-step PDF tutorial can be downloaded from this page:
Note: Even making just an 85-second video was very time-consuming; this is not the sort of project you can knock off in a single afternoon.

Incidentally, if anyone knows where I might find a tutorial that explains how to replicate all the After Effects steps in Blender, I'd very much appreciate it if you left a link in the comments.

*The music for the slideshow is of course Aquarium from Saint-SaĆ«ns's Le carnaval des animaux, used to such memorable effect in Terrence Malick's 1978 film Days of Heaven.

Saturday, 5 May 2012

Sand Martin Colony at Bishopstone

Walking along the stretch of coast between Reculver and Herne Bay can feel like stepping into another world when you're used to the white chalk cliffs that otherwise dominate the East Kent coastline. Here, the cliffs are comprised of soft clay and sandstone, which leaves them very vulnerable to erosion - but also makes them the perfect habitat for Sand Martins to build their summer breeding homes.

Sand Martin Colony

The Collins Guide rather wonderfully describes the Sand Martin's call (an audio clip of which can be heard on the RSPB page) as "a dry voiceless rasp as from coarse sandpaper" - which seems appropriate when you consider their building material of choice. Although the Bishopstone colony is easy enough to locate, the birds themselves are not so easy to photograph as they fly in and out of their nest-holes like winged bullets. During a visit last week I witnessed the results of a mid-air collision as two semi-dazed Sand Martins slid halfway down the cliff before regaining their senses and immediately rejoining the others. Fortunately, such incidents are rare, and sometimes a lull in the action presents a photo opportunity:

Sand Martin

Otherwise, trying to track individual birds in the midst of this aerial chaos is a big ask for even the fastest camera/lens combination, so the best technique would seem to be to set your focus slightly in front of the cliff and keep firing away until you get lucky. I'm not a great fan of this shoot-and-hope style of photography, but sometimes there's no other choice. Also, given that the cliffs (which are north-facing) are in shadow most of the day, you may find you'll need high ISOs to adequately freeze the action. And, as you'll be aiming above your head for prolonged periods, a tripod or monopod might help to take the strain off your arms. I hope I'm not making this process sound like an exercise in futility, but when you do get a shot worth keeping it can be a very rewarding experience.

Evasive Action

Anyway, whether you're there to take photographs or to just enjoy the spectacle of a few dozen noisy hirundines flying over your head, the Sand Martin colony at Bishopstone is well worth a visit.

See also:

Tuesday, 1 May 2012

The Company of Kestrels

Getting sharp photos of birds in flight is difficult enough with conventional lenses, let alone with a manual-focus telescope, which is why - as much as I appreciate Marsh Harriers, Sparrowhawks, Hobbies, Buzzards and the like - Kestrels will always be my favourite bird of prey.

Kestrel (Falco tinnunculus)

I saw this handsome specimen working the cliff-top at North Foreland, but I had to follow it all the way to Kingsgate Bay before I got the shot I was looking for (above). It then proceeded to tail me all the way back to Stone Bay. A case of a raptor using a photographer to flush out potential prey? Wishful thinking on my part perhaps, but it's nice to imagine that it wasn't just me who got something out of the encounter.

Hovering Kestrel

Now if only other birds could master the art of hovering in one spot...