Category Archives: software

Redundancy and Failure

We’ve all encountered failure at some point in our lives. I write this thinking about failure in the equipment that we use to take our images. In particular I’m looking at the aspect of redundant storage cards in a camera vs the system as a whole – and providing some thoughts for you to take away.

Many of the higher end mirrorless and DSLR cameras are providing two slots for either SD or CF cards and the option to write out to both cards at once. This is seen quite rightly as the classic case of good redundancy to guard against card failure… and here is where we get to some detail.

Firstly the lifespan in number of writes that one leading manufacturer quotes is around 100,000 – that is writing once a day to the whole card for 270 something years will eventually wear the card out. So let’s assume at the outside they only last 10% of that – that still 27 years of daily work. So we hear the stories of photographers that experienced card failure in a year or two of writes a few times a week. The summary of these failures tends to be like: a statistical significance of failure of several cards at 200 writes into 100,000 write lifetime. Compare this failure scenario with the multitude of mobile phones, IOT, network, PC’s and servers that write to the same SSD technology for years on end with extremely low failure rates.

This is where we see a logical failing – why should one application of the same storage inside a camera result in grossly poor reliability? Why when we see this reliability issue are we blaming the storage technology rather than another aspect unique to digital photography?…  We shouldn’t rush to blame the card against all logic because it’s at the mercy of unique external forces – batteries going flat, cards being ejected while being written to, salty sweaty pockets and a lot more.

But some say a redundant card will fix this. Two cards at the same time equally are at the mercy of flat batteries, card doors opening and being ejected while being written to, salty sweaty pockets. From the analysis above, they still are inside a device with demonstrable history of making cards fail early in life. Here’s where we start to discover the difference the difference between redundancy and the risk of failure.

The easiest way to see this is with an analogy – very few multiple engine planes crashes happen due to both engines failing. Think about that…carefully. A lot of crashes are bad judgement, bad weather, bad engineering and so on. The moment the plane crashes one or two of the engines are usually perfectly fine and running reliably – but still all is lost.

By all means I’ll allow you to be suspicious of the reliability of one solid state encapsulated microchip – add a second different model as a redundancy if you wish. But the risk here is focussing on those two cards rather than the dozens of switches, electro mechanical mechanisms, connectors, apertures, focus motors, cables, batteries, displays, shutters, humans… that make up the entire single camera system.

Keep your mind open to the risk of only having a single body with you. Think about thieves, drops, one bag with all your kit next to the water, single lenses with no alternative, no insurance. If you understand the risks and mitigate all key things – that will be your true redundancy and reliability.

Also posted in Photographic IT Tagged , , , , , |

Photogrammar

One of the most iconic images of the 20th Century has to bee Dorothea Lange’s image, Migrant Mother…

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She took this as part of her work for the US Farm Security Administration – who were tasked amongst other things of documenting the effects of the great depression on the poor – a task generally considered as a platform to provide political support for the social reform of the rural poor in America in the 1930’s.

Believe it or not a vast number of images of this era from the FSA have been digitised but like all things a large collection of 170,000 images is nothing without some way of finding your way around. At Yale University they have created Photogrammar which for the meta-nerd in us does a spectacular job of bringing a decade of photographic  history to us in a wonderfully time-spacial way. Enjoy.

Photogrammar

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The times they are…

..changin’

One of the small damnations in digital photography is that when you travel you sometimes forget to adjust the time on your digital camera when you travel. Thankfully Lightroom has a solution in hand to keep the image libraries organised.

In the Library module select all the images you want to adjust. Go to the metadata menu > choose edit capture time

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from here you get the adjust capture time dialog box

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I used the shift by a set number of hours option. The head hurts bit is finding out the correct number of hours to adjust by. In this case it wasn’t too bad since Europe is GMT and I could add an hour for daylight savings time to get me to -11.

After this is done you can then filter your library to confirm that you can tell sunset from sunrise in Paris.

time_adjust_3

One of the small issues remaining, as the name implies, is that only the metedata of the file is changed – file operations are not performed so you have to move the files to the correct dated folder yourself.

 

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