Inverary: A Tale of Three Techniques

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In August I called in on an old friend in Inverary for a small guided tour around the local forests with camera in hand.

There was one particular photo I had in mind – ever since I first saw an old ruined barn with disused farm machinery, it was crying-out for the bokeh-panorama (aka Brenizer) technique – instead of one straight shot composed with the final focal-length in mind, one uses a longer lens (preferably a fast prime) and stitches the results into a panorama, to give an image with narrower DoF than was possible at the focal length in question.

Here’s the straight scene, taken on the Fuji X-H1 on the 16-50mm f/2.8 at 18mm – even wide open there’s no significant blurring in the background.

So here’s the stitched result, taken using a Helios 56mm f/2 wide open – drastic focus drop-off:

It took 100 frames at source – 2.4Gpx – but the result would be the equivalent of an 18mm lens at f/0.6. 

The second technique was keystone/perspective adjustment. On seeing a stone waterworks in the woods, my friend challenged me to get a view of it straight-on without using the drone. That’s simple enough – even though it’s several feet above head-height.

The third technique was simple long exposure: night had long fallen before I left the town but the clouds moving across Loch Fyne/Shira looked pleasantly ominous. Keeping base ISO, f/6.4 gave a 7s base exposure – with HDR 5*±2/3EV this became 7+18+30+27+10 = 92s combined total, retaining exposure from brightest point of clouds into shadowy areas in the mountainsides. (Contrast is not just a daytime problem!)

Several long exposures blended together into an HDR image of clouds and smooth water, Loch Shira from Inverary.

Focus-Stacking with the Fuji X-H1

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For years I’ve been a fan of superresolution – taking multiple images of a scene with subtle sub-pixel shifts and upscaling before blending to give a greater resolution photo than any one source.

One of the features I used occasionally on the Pentax K-1 was its pixel-shift, whereby the sensor moved four times around a 1px square; this gives an improved pixel-level resolution and full chroma detail at each point.

Having exchanged that for the Fuji X-H1, I still look to perform super-resolution one way or another. Hand-held HDR always works – in this case even better than either the K-1 or the X-T20 because the X-H1 permits 5 or 7 frames per bracket at ±2/3EV each, which is ideal.

But I thought I’d experiment with a different approach: focus-stacking. This way, the camera racks the focus from foreground to background in many fine steps. Keeping the focal-length the same, the effective zoom changes subtly between successive images. Essentially, where hand-held HDR varies the position stochastically in an X-Y plane, focus-stacking means pixels from the source frames track a predictable radial line in the superresolved image.

The X-H1 has focus-bracketing but leaves the blending up to the user in post. That’s OK.

First, an overview of the scene:

Scene overview: Fuji X-H1, 18-135mm lens at 127mm, f/8 narrow DoF

The X-H1 made 50 frames, focussing progressively from front to back. These were blended using enfuse:

time align_image_stack -a /tmp/aligned_ -d -i -x -y -z -C [A-Z]*.{tif,tiff,jpg,JPG,png}
time enfuse -o "fused_$base" /tmp/aligned_* -d 16 -l 29 --hard-mask --saturation-weight=0 --entropy-weight=0.4 --contrast-weight=1 --exposure-weight=0 --gray-projector=l-star --contrast-edge-scale=0.3

The results are a little strange to behold – while the effective DoF is much increased (the distant wood texture is clear) the rock detail is quite soft; I suspect some of the above numbers need tweaking.

However, with a bit of work – both enhancing the local contrast and using in-painting to tidy up the rock itself – a pleasant image emerges:

The final polished result: banded rock on wood, Fuji X-H1

A definite improvement. I may have to use it in my landscape work a bit 🙂

In the Woods

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It’s been a while since I made photos of closeups in the woods – and for the most part, last time around I avoided contrasty light for the purpose too. Last night, I took a single prime lens (my favourite Pentacon 50mm f/1.8 of old) and one of my favoured strolls over Craigie Hill around the golf course, seeing what there was to be seen under the trees…

Glen Affric: Rockery

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There’s an impressive outcrop of rocks (psammite and semi-pelite, looking rather like limestone) near the waterfalls in the River Affric. Some kindly soul had balanced these pebbles on a boulder on their way past previously.