Monday, August 29, 2016

Garlic Husk

A simple posting of a discarded garlic husk.


Photoshop: Exploring different looks

As all digital photographers know, capturing the 'raw' data is only the start of the photographic process. Although it is is not universally used: Photoshop and Lightroom are considered the 'go to' tools when creating your digital art.

Today, being a Bank Holiday, means that I have a few hours free in-between my household and gardening chores, and looking after my wife, who is struggling with crutches at the moment :-( 

Plenty of time to experiment with my new A3 LED lightbox :-)

The technique I've been trying, is to capture a high key bracket set and post process as layers in Photoshop: no HDR tone mapping here!

Once in Photoshop, it is a simple matter to explore different 'looks'. 

For example, in the first image below I went for a basic high key look; whilst in the second image I carried out some inversion and channel swapping.

Two different images: but both created from the same capture data.

...and finally: this interpretation.

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.