Sunday, August 28, 2016

Wet days can be productive

A rather on/off weather day today, coupled with a need to stay at home. But this allowed me to grab this experimental image using a light box, bracketing and some Photoshop layers.

Friday, August 26, 2016

The Invention of Photography

Having just returned from a business trip, and two 10 hour international flights, I thought I would let readers of this blog into a little secret, get the podcasts from 'In Our Time', to make long haul business travel tolerable.

Wiki will tell you that In Our Time (IOT) is a live BBC radio discussion series exploring the history of ideas, presented by Melvyn Bragg (The Lord Bragg, of Wigton in the County of Cumbria) since 15 October 1998. It is one of BBC Radio 4's most successful discussion programmes, acknowledged to have "transformed the landscape for serious ideas at peak listening time".

As of 7 July 2016, 727 episodes have been aired and the series attracts a weekly audience exceeding two million listeners: me being one of them!

In the latest episode Melvyn Bragg and guests discuss the development of photography in the 1830s, when techniques for 'drawing with light' evolved to the stage where, in 1839, both Louis Daguerre and William Henry Fox Talbot made claims for its invention. These followed the development of the camera obscura, and experiments by such as Thomas Wedgwood and Nicéphore Niépce, and led to rapid changes in the 1840s as more people captured images with the daguerreotype and calotype. These new techniques changed the aesthetics of the age and, before long, inspired claims that painting was now dead.

Those joining Melvyn Bragg in this episode were:
  • Simon Schaffer: Professor of the History of Science at the University of Cambridge 
  • Elizabeth Edwards: Emeritus Professor of Photographic History at De Montfort University 
  • Alison Morrison-Low: Research Associate at National Museums Scotland
If you don't know about IOT, you may be interested in scanning the archive of podcasts.

Personally I think IOT is one of, if not, the best podcasts that the BBC offer.

Monday, August 8, 2016

Couch-based Practice makes Perfect

As readers of my blog are aware, I believe in practice, especially when in comes to knowing the limitations of your equipment: and where better to practice, than in your own armchair!

My current 'focus' is my Canon EOSM APS-C mirrorless, which I love using with my Sigma 10-20mm crop lens; especially at the 10mm end.

The downside of the EOSM is that the lens can't currently be controlled by Magic Lantern. With a normal length lens, his would create problems if I wanted to auto focus stack using one of my Lua scripts. However at 10mm things get simple, even on an APS-C camera.

Assuming I'm 'just' publishing on the web, ie via a PC monitor, and not creating a print for a competition, I can afford to use a total blur spot (a combination of the sensor limit and diffraction in quadrature) of, say, 19 microns. This gives a maximum depth of field sweet spot at between F/8 and F/11.

Using F/8 and focusing at 1m, gives a near depth of field limit of just under 0.5m. which leads to a second focus point at just under 0.4m. On the Sigma 10-20mm the 1m and 0.4m marks are clearly identified and thus convenient to use, although with ML I could use the on-screen focus feedback as well, as the Sigma reports this as it has AF.

Thus, using these two manual focus marks, gives me a two image focus stack that goes from just under 0.3m to infinity. A pretty impressive coverage. 

The following couch-shot, taken with room lights on, used the above settings, at ISO100. I also used Magic Lantern's auto exposure bracketing at each focus point, resulting in a 2 x 4 image set: with the 4 exposure brackets 2Ev apart. The second focus bracket was set manually.

Post processing followed my normal workflow: ingest into Lightroom, use LR's HDR feature to create two 32-bit DNG images, undertaken basic exposure correction in LR on one of the images, sync to the other image, do a round trip to Zerene Stacker and finish off in Photoshop and LR.

As usual, a boring image. But what it does show is the power of using a wide angle lens and Magic Lantern to achieve full exposure and focus control, ie over a high dynamic range and from less than 300mm to infinity. It clearly shows the sharpness of the image, ie the newspaper was placed at just over 300mm from the sensor's plane and is clearly readable, as are the books, and the outdoor background is tack sharp (ignoring the wind movement in some of the tree branches).

Although I understand that not everyone likes the WA-look. For me, 10mm on my ASP-C and 12mm on my FF cameras, is great, if you want a dramatic look, with a strong near field feature, and the entire scene to infinity, tack sharp.

Sunday, July 31, 2016

The Getty Center

Wiki tells us that Getty Center, in Los Angeles, California, is a campus of the Getty Museum and other programs of the Getty Trust. The $1.3 billion Center opened to the public on December 16, 1997 and is well known for its architecture, gardens, and views overlooking Los Angeles. The Center sits atop a hill connected to a visitors' parking garage at the bottom of the hill by a three-car, cable-pulled hover train funicular

This post is an opportunity to publish a few images taken with my new best (travel) friend: my Magic Lantern enhanced EOSM, with my 10-20mm Sigma lens.

Friday, July 29, 2016

Couldn't get it out of my mind

In the last post I hinted at not being content with the blown out highlights in the All Saints church images: after all Magic Lantern Auto Bracketing should have taken care of things.

So, within an hour of getting home, I popped up to our local church, Christ Church in Ramsdel, to do a quick experiment, ie in a relatively high dynamic range environment: although the weather was a little flat, so the Church windows were not really ultra-bright. Nevertheless, a reasonable test scene.

Still using my EOSM with the 10mm end of the 10-20mm Sigma, I decided to expose for the highlights and let the Auto Bracketing in ML handle the rest. Here are the two test images - one with the chandelier lights on and one with them off:

In both images, the windows are fully captured, with no 'highlight end damage'.

Bottom line: I think I'll switch my ML bracketing strategy, at least in churches. Rather than expose for the shadows and let ML handle the highlights, I think I'll set the exposure for the highlights myself, eg a stop down from the highlights being clipped, and let ML handle things from there.

Sometimes it's best not to plan

Although today, as a non-working Friday, I was hoping to get out and do some photography: when I looked at the flat-white sky I knew the day would have to unfold in its own way. So the first decision was where to have breakfast?

So it was off to the Saddleback Farm Shop at Brightwalton

Once we were suitability refreshed with Eggs Benedict and a Cappuccino, and we had purchased some bespoke Gin, we were ready to return home: but then we saw this church in the distance, which we found out was All Saints in Farnborough, ie Farnborough in Berkshire not Hampshire. 

Farnborough was apparently held by Abingdon Abbey before and after the Conquest, and up to the Dissolution. The manor was assessed at 10 hides before the Conquest but only 4½ in 1086.  The church is in the centre of the village, and has a Perpendicular West tower of ashlar, squared blocks of masonry cut to an even face, and single nave and square chancel of flint rubble. The church has opposed North and South doorways, with a South porch.

It has a ring of 5 and the largest and oldest bell, the 8 cwt tenor, was cast at the Wokingham foundry sometime around 1400.

We found out that stained glass of the west window of the nave was designed by John Piper as a memorial to his friend John Betjeman, who lived at the Old Rectory at one time. They collaborated on architecture books; such as “The Berkshire Architectural Guide ” 1949.

The inscription in Delabole slate beneath the window was cut by Simon Verity and placed there in 1986. It reads: In memory of

1906 - 1984 Poet Laureate
sometime resident at the Old Rectory Farnborough
This window, designed by his friend John Piper
and executed by Joseph Nuttgens, was placed here
by the Friends of Friendless Churches.

I am the Resurrection and the Life
As far as the photography side, I used my EOSM and my 10-20mm EX DC HSM Sigma, via a EOSM-2-EOS adapter. In all the images I first ETTRed via Magic Lantern and then used the ML Auto Bracketing. Focusing was a non issue at 10mm, F/8, ie I focused at about a meter to ensure acceptable (hyperfocal-like) sharpness from about 0.5m to infinity.

Post processing followed my normal workflow: I first ingested the images into Lightroom; I then use the native HDR feature in LR to create 32-bit DNGs; I then made basic adjustments in LR and did a round trip to Photoshop, to undertake some luminosity masking and local tonal tweaks.

The one thing I was not happy with is that Auto bracketing didn't give me enough 'protection' at the highlight end, hence the window above, for example, is a little blown out for my liking. This is something I intend to explore further, ie how to guarantee full highlight capture in high dynamic range scenes such as one finds in churches.

Over all: an enjoyable Friday :-)


Monday, July 25, 2016

Getting Ready for a Trip

I'm off to the US next week for a business trip and want to travel light: so I've decided to make use of my EOSM, which, of course, comes with Magic Lantern :-)

The current weakness of the EOSM is that the lens focus features in Lua don't work. So my landscape focus bracketing script is a no go. But, I have other options for achieving great depths of field: namely my Rokinon 12mm Full Frame Fisheye, which fits the EOSM via the Canon Adapter.

The great thing about the 12mm, on the EOSM cropped sensor, is the huge depth of field. For instance at the hyperfocal distance of about 5ft at F/8, everything from about 2.5 ft to infinity is at acceptable sharpness. 

But is the HFD the right approach? Are there other focusing strategies? There is one that all photographers should try and remember and it follows from the work of Harold M. Merklinger of Halifax, Nova Scotia, Canada. Merklinger stated that by focusing your lens at infinity, the smallest object resolved in your image will effectively have the same width as the focal length divided by the aperture of your lens.

So for my 12mm lens at f/8, this size is 12mm divided by 8, or 1.5mm.

Yes, I can carry on using the HFD, but this will mean the distant details will not be optimally sharp, just acceptably sharp according to the Circle of Confusion criterion I have selected.

Using the Merklinger strategy, I simply focus for the farthest object, ie towards/at 'infinity' and that's it. Details greater than 1.5mm are resolved from near to far.

To test things out, and show the power of the defishing software, here is one bracket from a six bracket Auto Exposure Bracketing capture, taken with Magic Lantern.

You can clearly see the fisheye distortion.

Post processing followed these lines:
  • Ingest all six images into Lightroom;
  • Use LR's Merge to HDR to create a 32bit DNG;
  • Correct the basic exposure for this 32bit DNG, before exporting a 16bit TIFF to Photoshop;
  • Once in PS-CC, use the Fisheye-Hemi Plug-in to correct the fisheye distortion;
  • Return to LR and finish off, finally arriving at this test image, with no fisheye distortion and everything looking 'crisp' from near to far.
I've got the rest of the week to 'muck about' with the EOSM, deciding what other gear to take with me. But one thing is clear: the Rokinon 12mm Fisheye is the one thing I will not be leaving at home!