Monday, May 25, 2015

Forgotten Pioneers of colour photography


Ask most photographers about early colour photography and they'll probably mention Kodachrome, some might point to the Autochrome process from the early part of the 20th Century but most will be un-aware of the work of one of the colour pioneers Louis Arthur Ducos du Hauron.

Ducos du Hauron worked on the theory of colour photography in the early 1860's writing papers and publishing a book Les couleurs en photographie, solution du problème in 1869.
To start with most of his work was purely theroretical because the photographic emulsions of the time were blue sensitive only and Ducos du Hauron's process required three exposures with different colour filters placed over the camera lens; one green one orange and one violet.
So for the moment the process was purely theory as the materials needed (film sensitive to green and yellow/red) didn't exist.

Then in 1873 a German scientist called Herman Willhelm Vogel made a discovery that would change photography forever. He discovered that the addition of a dye called Corallin when mixed with a standard emulsion extended the sensitivity into the green and yellow regions of the spectrum.

This had a massive impact, for the first time photographers could record clouds and images that differentiated between blue and yellow, this also meant that that now we could record a wide colour spectrum in B&W they could create negatives of differing density with colour filters; the possibility of tripack colour was born.

So now with his process a practical reality he published a paper detailing the process called:
Traite Pratique de Photographie des Couleurs (Paris, Gauthier-Villars, 1878)

A colour image from 1877

 In it  Ducos du Hauron details exactly how the image above was created.
He found that eosin, a new dye announced in 1876, sensitized to green, orange and blue. A very small amount of the dye was added to collodion and cadmium bromide. This was  then poured over the clean glass plate, which, while still damp, was plunged into a solution of silver nitrate and acidified with a few drops of nitric acid; albumen and glycerine were used as preservatives.

The resulting negatives were exposed with three different filters over the lens giving three B&W negatives representing the scene; each negative then had a colour positive made which was then dyed in the complementary colour of the filter used i.e the orange filtered B&W was dyed blue, the green red and the violet yellow.
The resulting images being sandwiched between glass and viewed with a light behind, rather like slide films of today.

Much of Ducos du Hauron's process is used today although gelatin panchromatic plates are used instead of collodion and  RGB filters are used instead of green orange and violet.
Most modern processes owe a lot to the colour innovation of Louis Arthur Ducos du Hauron a man who shot colour images thirty years before the first colour process became available and over 50 years earlier than Kodachrome.

Friday, May 22, 2015

Colour perception and the role in making photographs three dimensional.


Take a look at the image above a reddish circle on a grey background. After a while the red will start to stand out with a 3D like effect you might even imagine the circle border is lighter on the left and darker on the right.
Now take the image and de-saturate it

 The circle has become invisible because the red had the same luminance value as the grey surround, that was one of the reasons it stood out from the background  in an almost three dimensional way.

So what practical use has an optical illusion in photography? How can the trick be utilised.
Take a look at the image below.

 
Notice how the rocks in the foreground seems to stand out from the sea? Normally you might achieve this by point of focus blurring elements in order to make the focus point stand out.

 Not really possible here as the foreground and background are beyond the infinity focus of the lens.
Instead colour can come to the rescue, briefly the yellow sun has fallen on the rocks and contrasted against the blue sea.
Blue and yellow are opposites, and have a special role in our visual perception look out for this as it often occurs in landscape photography.

Friday, May 15, 2015

B. B. King 1986



It was with great sadness that I learned of the death of Mr King this morning, I had been a fan since the early 1980's.
In 1986 he came to a city near to my home, so tickets were purchased so myself and a friend could go to the gig.
It was a fantastic evening, the man was on great form, very polished and entertaining.
Most of these photo's were taken from close to the front while sitting on my friends shoulders; I used a Canon film camera with 50mm lens and Kodak Tri-x which I pushed a stop (EI800)
After the show we stuck around and actually got to meet Mr King, shake hands and have a little chat-he was a true gentleman and a legendary performer.
God bless and many thanks.

Monday, May 11, 2015

Better Than Real Life

Those were the words used by my daughter while looking through the waist level finder of my Rolleiflex TLR. She found herself captivated by the large viewfinder 'it looks just like a film (movie) - like watching your life on a cinema'
'Can I have a camera like this one'?

The large reasonably bright screen with built in magnifier is a very attractive system, the focus 'pops' in nicely and is especially easy with the built in magnifier.
The viewfinder shows the minimum depth of focus, so some imagination is needed to judge the sharpness through the finder although there is a DOF indicator on the focus knob.
The only other caveat is the laterally inverted image which makes it harder to track moving objects as everything is reversed left to right.

That said the view is marvellous and has a three dimensional tangibility that makes it look like a focussed window on your world.

To quote someone seeing it for the first time "It's better than real life"



Friday, April 17, 2015

Rolleiflex factory sale

I recently read that the Rolleiflex factory was being liquidated, this might come as no surprise to some as sales must have been small, I bet not many were aware that you could even buy a new Rolleiflex in 2015!
Still the passing of one of the all time greatest camera designs should be at least noted and even celebrated for the iconic status the camera achieved.
The list of great photographers that used these wonderful camera's is a long one, celebrated British photographer David Bailey said if he could just have one camera it would be a Rolleiflex.
Personally I feel an incredibly lucky to have owned and used one for many years, these cameras are a joy to own and use, there are no automated features to fall back on you really do make images with this camera; like flying a single seated aircraft you are on your own with your skill will define the way the image will look, no auto anything.
Life is too short not to have shot with a Rolleiflex, I have two and hopefully they will last me the rest of my life.
Here are some images from the liquidator of the Rollei factory

CNC Lathe


It's sad to see it all go, and know that an era has passed I guess that's what some call progress.



Wednesday, April 01, 2015

Found Kodachrome


Here are a few Kodachrome slides from the early 1960's that I recently found, for a larger image just click on the photo.

Sponge Seller, Athens, August 1966
I have attempted to display them as found with little or no colour correction or spotting and damage removal.

Fish Stall, Vico Equense, Italy, September 1963
Some old cars in this scene an oval window (1953-57) VW Beetle in a street probably Barcelona 1964

Spain 1964
This one is Rome looking towards St Peters, no date stamp and 'KODACHROME'

Rome mid 1960's ?
These slides had been stored in a box which was in storage since the late 1970's! There are a few more to sort though which I may share in a later post.

Wednesday, December 24, 2014

The Great Dynamic Range Mystery

Backdrop
I have been a photographer for over thirty five years, and during that time have come up against many problems and hurdles whilst practising my profession.
Recently I met and spent a social hour with an old photographer friend who showed me his latest Nikon (a lovely camera) and during the evening the conversation touched the subject of the range of tones that modern digital cameras could capture and how this related to the films we used to use for wedding and portraits.


There seem to be a consensus that digital  can record a wider range of tones than  negative films, which seems strange as that is far from the experience of most photographers I know who still use both mediums.

My friend pointed me to a site often used to back-up this assertion:

A test of film vs digital dynamic range

The linked web page from Mr R Clark states:
"Digital cameras, like the Canon 1D Mark II, show a huge dynamic range compared to either print or slide film, at least for the films compared"

A huge dynamic range? This is not what most people I know have observed!

The evidence put forward was a series of photographs showing a black box with test charts photographed on each medium the digital showing great shadow detail and good highlights the negative film showed OK highlights and non existent shadow.
(see website linked)


My first thoughts were how very strange quite the opposite to what I have observed-what could have happened?
The clue is early on in the text, he compares a digital camera, a slide film and a colour negative film and states:

"the three data sets are registered at the bright end. This is why the curves in Figures 8 and 10 overlay each other at the high end"

Now it begins to make sense why the author only sees the film has a range of seven stops–he used the same exposure for all three mediums so he has exposed for the highlights.

Let me explain; both digital and slide film need to be exposed so you don't clip highlight information and just end up with either clear film or saturated sensor wells, so you effectively expose for the highlights
Negative film on the other hand needs exposing for the shadow info and let the highlights fall on the upper part of the curve.


Expose negative film so the shadow falls in the toe
The correct way for Mr Clark to evaluate the DR of each medium would need very different different exposures for each medium; the one for the negative should place the darkest shadow in the toe of the curve so the shadow will be perfectly reproduced and because of the compression effect of the negative films shoulder the highlights will still be recorded.

My experience (and Kodak's figures) has shown that most negative films have a range of about 12-14 stops (albeit the top of the range is compressed). Negative films have a shoulder that means the highlight roll-off is very gradual  on the other hand digital has better shadow recovery so more detail given the same exposure.

So what Mr Clark has done here is exposed to give good highlight retention on the digital and used the same exposure on the negative film; thus showcasing the shadow recovery of digital and showing up the poor shadow of film when underexposing (the exposure values for each are different)

He has either deliberately or by accident truncated the film curve (used only the left part of the curve and placed the highlight on the 'straight line' of the curve this caused his underexposure and that is why he gets only seven stops of useable data rather than the fourteen Kodak cite

You could conversely do this 'experiment' again exposing the film correctly (expose for shadows and stop down 2 stops) and then expose the digital with the same exposure values thus blowing the highlights; this would give us a very different conclusion from Mr Clark's test.

I could verify Mr Clark's results by making my own 'black box' (that might be a future post) and placing the negative exposure on the correct part of the curve for that medium.

Here though are a couple of tests that show the effect:

Film and digital compared over a wider range than Mr Clark's test

And
A test showing film vs digital over the complete range (mentions Clark in the conclusion)