Around Binnend

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After serendipitously discovering a lot of heritage information about the abandoned former village of Binnend, on The Binn outside Burntisland in Fife, I spent much of Sunday afternoon exploring the area.

It was smaller than I expected from the maps – about 30x30m or so – and very overgrown. The central region is a mix of thick gorse and fallen boulders, so not really accessible by foot. Use of the drone was hampered by several factors: being immediately adjacent to the Alcan landfill waste processing site, still an active commercial operation; by being a few hundred yards away from Craigkelly transmitter which caused significant radio interference (warnings in the DJI Go app and actual loss of video signal above a few meters’ altitude), so I did not get the fly-over video I’d intended.

Still. Herewith, a few still photos instead:

Approaching Binnend:

Within Binnend itself:

Above Binnend:

Glen Artney

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Just one photo from a quick afternoon excursion to explore Glen Artney earlier in the year. Well, one photo, processed 3 ways.

This was the first, and so far only, time I’ve felt the urge to invert the tripod centre column; in the process I discovered that the Pentax K-1 live-view display will happily invert the image correctly, but leaves all the exposure and histogram overlays the wrong way up – as if trying to use the thing upside-down was not hard enough itself! Oops.

A pleasant waterfall in the Allt na Drochaide burn, a tributary to the Water of Ruchill, Glen Artney.
This was the first, and so far only, time I’ve felt the urge to invert the tripod’s centre-column and dangle the camera millimetres above the water. In the process, I discovered a bug with the Pentax K-1: if you use live-view upside-down, the image inverts itself correctly but all the settings controls (histogram, etc) do not. It’s tricky enough wondering where the control dials have gone, let alone where the numbers they control are to be found on screen. D’oh!

A pleasant waterfall in the Allt na Drochaide burn, a tributary to the Water of Ruchill, Glen Artney.
This was the first, and so far only, time I’ve felt the urge to invert the tripod’s centre-column and dangle the camera millimetres above the water. In the process, I discovered a bug with the Pentax K-1: if you use live-view upside-down, the image inverts itself correctly but all the settings controls (histogram, etc) do not. It’s tricky enough wondering where the control dials have gone, let alone where the numbers they control are to be found on screen. D’oh!

A pleasant waterfall in the Allt na Drochaide burn, a tributary to the Water of Ruchill, Glen Artney.
This was the first, and so far only, time I’ve felt the urge to invert the tripod’s centre-column and dangle the camera millimetres above the water. In the process, I discovered a bug with the Pentax K-1: if you use live-view upside-down, the image inverts itself correctly but all the settings controls (histogram, etc) do not. It’s tricky enough wondering where the control dials have gone, let alone where the numbers they control are to be found on screen. D’oh!

My Strathearn

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I’m very fond of the views along the length of Strathearn – from the Knock at Crieff or above Monzie joinery on the A822 road looking west, the view to overlapping hills in the distance is deeply pleasant.

This is an unashamed dump of a load of photos made over the course of two strolls up and down Torlum Hill outside Crieff – the first mid-afternoon with a variable-ND / polariser filter, the second immediately afterwards with a regular 2-stop circular polariser instead. The same technique has been applied to all  – auto whitebalance and handheld HDR with a 1EV bracket either way. All are presented here in chronological order to compare the difference the light and a proper filter make in the landscape.

On the way back home after strolling up and down the hill, I saw a colourful Earth’s Shadow (aka Belt of Venus) developing, just as I happened to be passing one of my favoured characterful trees outside Muthill.

How Many Megapixels?

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There are several cliches in the field of megapixel-count and resolution required for acceptable photographic prints.

In no particular order:

  • 300dpi is “fine art”
  • you don’t need as many dpi for larger prints because typically they’re viewed further away
  • my printer claims to do 360dpi or 1440dpi or …
  • 24 megapixels is more than enough for anything
  • “for a 5″ print you need 300-800pixels, for medium to large calendars 800-1600 pixels, for A4 900-1600px, for an A3 poster 1200 to 2000px, for an A2 poster 1500 to 2400px, …” (taken from a well-known photo-prints website guidelines)
  • it’s not about the megapixels it’s about the dynamic range

There are probably more set arguments in the field, but all are vague, arising from idle pontificating and anecdote over the last couple of centuries.

Here’s a key question: in a list of required image resolutions by print size, why does the number of dpi required drop-off with print size? What is the driving factor and might there be an upper bound on the number of megapixels required to make a print of any size?

We can flip this around and say that if prints are expected to be viewed at a distance related to their size, then it is no longer a matter of absolute measurements in various dimensions but rather about how much field of view they cover. This makes it not about the print at all, but about the human eye, its field of view and angular acuity – and the numbers are remarkably simple.

From wikipedia, the human eye’s field of view is 180-200 degrees horizontally by 135 degrees vertically (ie somewhere between 4:3 and 3:2 aspect-ratios).  Its angular acuity is between 0.02 to 0.03 deg.

If we simply divide these numbers we end up with a number of pixels that the eye could resolve.

At one end of the range,

 180*135 /0.03 / 0.03 / 1024 / 1024 = 25.75 (6000 x 4500)

and at the other:

200*135 / 0.02 / 0.02 / 1024 / 1024 = 64.37 (10,000 x 6750)

In the middle,

180*135 / 0.025 / 0.025 / 1024 / 1024 = 37.1 (7200 x  5400)

Significant points:

  • this is no longer about absolute print sizes; it’s simply about being able to view a print without one’s eye perceiving pixellation
  • the numbers correlate reassuringly with numbers of megapixels seen in real-world dSLR sensors today
  • you can reasonably say that if you have 64 Megapixels then you can make a print of any size from it
  • you can make an image with more than 64 megapixels if you want to, but the reasons for doing so are not directly to do with resolution – they might be
    in order that you can  crop it – either to physically crop the image in post-processing or to view it from a closer distance than that required merely to fill your eyes’ field of view
    or maybe for pixel-binning to reduce noise, give smoother tonality, etc
  • 24 megapixels is not enough for much; rather it’s is a turning-point: the bare minimum number of pixels for a person of limited acuity to resolve assuming they slightly less than fill their field of view with the print. 36MPel is more usable and 64 will keep you in business selling fine quality wall art.

Now we know how many megapixels are required for various real-world purposes, all that matters is making them good megapixels. Physics to the rescue.