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3 May 2013

After Conservation: Ultra High Definition Photography

Staffordshire hoard photography

Documenting the discovery

The Staffordshire Hoard was discovered by Terry Herbert in July 2009 and delivered to Birmingham Museum and Art Gallery for initial cataloguing and documentation by the collections care department. At this stage I was required to simply photograph the items in order to record this rare find as quickly as possible. Working closely with a conservator this initial cataloguing work was carried out in virtual secrecy. As most of the Hoard objects were in a freshly discovered, pre-conservation condition, the majority still covered in earth, we quickly produced basic high-resolution images, usually with a basic metric scale included in each shot. These files are single focus, uncompressed 117Mb 8 bit RGB files.

Early 'pre conservation' pommel cap

Following the formal announcement of the discovery to the world in September 2009 and the subsequent media explosion that followed, key partnerships were established to fundraise and work towards the acquisition of the Hoard. Thanks to the support of the public, trusts and foundations the Hoard was purchased for £3.3m in March 2010. Based at Birmingham Museum and Art Gallery, a dedicated conservation team was formed and the extensive conservation, analysis and interpretation of the collection began.

At this stage  it became obvious as items began to filter through the meticulous conservation workflow, that this was an extraordinarily powerful and visually stunning collection of objects, with exquisite detail and unusual features. So the brief was clear,  that we should attempt to create an equally powerful and visually stunning series of photographs of this exceptional and unique collection.

I wanted these new images to cater for the partnerships’ current and future needs as much as possible, as well as meet these fundamental criteria:

  • To resolve the fine details in order to support the curatorial and conservation teams’ needs to scrutinize tiny surface features of the objects if possible, for analysis and interpretation purposes.
  • To create high quality, high resolution macro images of a collection primarily consisting of very small objects and tiny partial fragments, in order to make large prints or large scale gallery based material for exhibitions development and public consumption.
  • To produce highly finished, beautiful images using contemporary photography and lighting techniques similar to styles found in contemporary fine art photography or high end advertising. The images should become valuable, sought after assets that people would find desirable in their own right.
  • To photograph the objects within a comfortable amount of space or background, in proportion to the objects themselves, so fine art prints, posters or other forms media could be produced easily and in combination with typography or graphic design if required, as well as for use as single images in their own right.
  • To create images that exhibit a large degree of aesthetic realism so the audience perceives the photograph as an accurate or semi photo-real document, rather than a computer generated model or rendering.
  • And finally create the best images of the collection available anywhere in the world, with a visual consistency across the collection.

Building the workflow

During 2010 as the conservation team worked on conserving, researching and revealing the collection itself, the finished objects started to become available and new photography could take place.

Primarily I needed to produce this work within the on site studio space at Birmingham Museum with existing capture equipment and I set up a temporary working area within the conservation labs. Although limited for space, the conservation labs were close to the collection itself and therefore better for speed and security. For production and logistics, there was a very small budget of up to £1000 to purchase consumables, pay for any hire costs, software or hardware that was required.

The need to produce images with full surface detail across the object dictated that I work with a focus stacking workflow, as ‘regular’ close range macro photography will only allow the production of images with a very ‘shallow depth of focus’. Focus stacking would composite many raw files into one ‘finished’ image, making the capture and workflow process much longer than usual, but enabling the production of  ‘fully sharp’ objects.

Having never worked in this exact manner before, I purchased a copy of Helicon Focus, the widely used focus stacking software, via good recommendations and reviews from other industry professionals. It seemed to be the best software of its type available.

In order to help light the small items, I hired a fiber optic lighting kit for the studio flash heads we have in house. These are small diameter fiber optic cables that attach to the front of our studio flash heads. This allows a tiny directional light source to light the object, rather than a larger light source, which would light the background and object and produce unwanted shadows. These lights are regularly used in the production of high end commercial advertising images of small decorative arts.

Note that these objects are photographed on a sheet of 7mm thick black perspex, purchased for the project. It is lit from above with a key light and soft box, and for diffusion, a piece of 5mm white perspex is between the overhead light and the object. The black perspex sheet appears grey in the photograph with a dark reflective shadow under the object.

A single flash head was used in combination with the fiber light heads, small white foamex boards were used as reflectors and masks to bounce and fill light into specific areas of the object, as well as ‘flag off’ or hide any unwanted reflected light. So, we actually used only two flash heads, with one head split into two directional sources with the fiber lights.

Here’s a basic example of this kind of lighting and background set up:

Conservation based photography set up

An example of a single image captured during production:

Shallow depth of macro image

You can see clearly the shallow depth of focus inherent in standard macro photography, with each individual RAW file featuring a small area of optical sharpness.

All images were captured with BMAG’s existing optical camera and digital back, in this case a 39MP Phase One P45+ digital back and Hasselblad H2 digital camera, with a Hasselblad HC 120MM macro lens, occasionally a 52mm extension tube was also used. Capturing ‘Phase One .IIQ format raw’  files directly into the dedicated Capture One Software, which allows us not only to capture tethered to a workstation computer, in this case a quad core Mac Pro, but also allows us to critique the images precisely and make lots of small image corrections and adjustments as part of the pre-processing raw file stage.

Between 30 and 50 raw images of each object were then captured to cover detail from the front edge to the visible rear of the object, and in most cases also focusing any detail captured in the shadow of the object. Basic colour and exposure adjustments were made at this point. This stage proved occasionally problematic, as focusing the lens manually meant a number of things could occur such as:

  • With tiny steps (of less than a few mm) in focus ring movement, it is possible to move the camera slightly, even if the camera is secure on a studio stand or secure tripod and head combination.
  • It is possible to overstep the focus increments, thus creating ‘gaps’ of out of focus area, which only become obvious after processing from RAW and then into Helicon Focus.
  • It is also possible to ‘under-step’ the focus, creating many more images than is actually required, increasing on capture and processing time unnecessarily.
  • Re-focusing the lens across the surface of an object in this way from front to back, depending on the type and quality of lens, actually changes the perspective and image shape throughout focusing. This can become more noticeable on certain sizes and magnifications of objects and their relative distance from the camera.
  • Without automating this ‘manual’ part of the process, it is quite demanding on the eyes and co-ordination, as the focus adjustments can be under 0.5mm each time. Its also demanding on your camera (making up to 600 captures per object) and on your flash system, which can reduce the life of the hardware. Consistent flash output and colour with each capture can be an issue if you are using cheaper flash heads. Elinchrom lights seem to be very reliable and I have used them for many years now, however there was on occasion some inconsistency in flash output.  With more expensive professional pack and head combinations, HMI, or constant light sources, this inconsistency could be reduced.

Raw File Stage

Files are adjusted to remove any lens distortion, moiré and other unwanted capture artifacts that may occur such as dust, colour casts, reflections, fringing or chromatic aberration. Many of these corrections can be performed in software, and can be automated across many images files at the same time, with the use of custom and built in pre-set parameters, and adjustments.
Although files are regularly manually adjusted in software.

These particular images only required the basic lens correction and white balance, adjustments to exposure, contrast and brightness all remained remain relatively minor, a minimal amount of sharpening was applied at this stage, as it became obvious later, significant sharpening isn’t really required when focus stacking.

The option at this stage to ‘batch retouch’ images was not required as were many of the other features available in the Capture One Pro software we used. All files were processed as 8 Bit RGB Tif, and as usual we worked with the Adobe (1998) monitor profile.

Once all the images were ready and corrections made universally across all the files, the images were processed into the individual uncompressed tiff format files.

These files are approximately 120MB each, and as a result even with a fairly new, high specification Apple Mac Pro, it took a little while to process everything and because each object had 3-5 different views, that’s up to 250 raw files for each object, and we photographed over 200 objects, totaling over 50,000 images, which again render down into roughly 400 complete, focus-stacked composite images took quite a while in post production.

Processed files are named numerically from 1 to 50, usually with the BMAG accession number of the object preceding the alpha number, e.g. K455 – 01 / K455 – 02 etc.

Files have to be numbered and processed in the same order as captured – without gaps or missing files, or Helicon Focus will find it problematic to import and composite in the correct order.

Files are then imported into the Helicon Focus software which, given the standard pre set – set of parameters, is generally able to piece all files into one ‘fully sharp’ composite without any problems at all.

If any of the possible errors mentioned earlier have occurred, then it will be obvious at this stage in the workflow. The software will warn you when there is poor positioning or inconsistency in your source files and be unable to render a composite image.

Presuming you are happy with this composite file rendered in the software, you are now able to save the helicon composition as an uncompressed .psd, .tif or .jpg format image.

Rendering with Helicon Focus:

Screen shot of Helicon Soft

The resulting images are astonishingly detailed and contain resolution capable of rendering visible detail of less than 0.25mm. And this is with a Phase One 39MP raw file, with the higher resolution Phase One 80MP full frame IQ digital back, more than double the optical and pixel resolution should be possible.

Of course this workflow may have also rendered any dust and marks on the background visible, also any dust or marks on the camera CCD itself.

So files are opened in Photoshop CS to clean up, it is a fairly simple job with the healing tool, but a very time consuming job to spot out images. I will also regularly select very close to the circumference of the object and shadow with the auto selection (magic wand) tool, adjust and refine the edge selection and apply an average blur to the background, as a quick solution to simply retouch the whole image artwork at 100%, which over hundreds or thousands of images, can become extremely time consuming, laborious and in some cases physically painful to complete.

The results speak for themselves:

Focus stacked composite of object K554

Focus stacked composite of object K699 (view 3)

Of course shown here are only small files, the full resolution images are truly stunning. There are more examples of these images on this website as well as on my own website here:

The images have been used to produce high quality large format exhibition prints, digital interactivity applications such as in-gallery multi touch tables and mobile apps and in a wide range of other types of media such as online, in publications and in art books.

These images have also been widely printed in fundraising, magazines, newspapers and used by news media world wide to accompany news reports and editorials about the Hoard find.

This work also features in exhibitions and media here in the U.K and in the U.S where the National Geographic exhibition was recently seen by over 55,000 visitors in Washington.

The future of the Staffordshire Hoard and Photography

We’ve learned quite a lot from working with this unique new collection and developing a new dedicated workflow to produce this specialist work. The total time spent over the last 2 years on this project alone is well over 9 months, no mean feat, considering we have had many other major projects and exhibitions to complete during this time.

In relation to the Staffordshire Hoard project, our work in photography is set to continue in liaison with the conservation and exhibitions teams for at least the next two years.

To improve on our focus stacking workflow we have just been able to purchase a motor based focus stacking system which speeds up and partly automates the multiple capture focus stacking process. We hope to upgrade our computers for the latest systems later this year, to be able to cope with the large files our new digital back can produce. Ultimately this is to create work that will allow all visitors as well as staff to be able to scrutinize images to an unprecedented level of detail and for us to be able to produce and supply this work quickly and efficiently. We hope to continue to develop and diversify the quality, range and style of our in-house photography as the images will no doubt once again span the globe and appear in numerous journals and publications. We also want to develop innovative in-gallery experiences based on this high quality core visual material.

Birmingham Museums are currently developing a new and ambitious permanent gallery for the Staffordshire Hoard which will open in 2014. With a variety of digital elements, it will utilise this specialist photography for everything from the object case labels and exhibition prints to rich, still and moving imagery, multi touch interactivity and 3D video displays. To support this, I am designing new workflow and new systems to ensure the capture, integration and inter-combination, of different types of new and innovative media to support the needs of the conservation, exhibition, curatorial and project development teams as they work together.

Focus stacked composite of object K699

About Me: Birmingham Museum Photographer

I began work with Birmingham Museums and Art Gallery as Museum Photographer in 2001,  developing and managing the photographic department and creating high-end professional photography of the art and history collections. Since then I have managed the organisation’s transition from analogue film to high-end digital capture and overseen the full digitization of the existing analogue photo-media archive. During this time, I have produced photography for many award-winning projects, as well as creating extensive material for hundreds of exhibitions, publications, projects and websites. I have also designed and installed Birmingham Museums’ digital image network, photographic systems, picture library and archive. This system now contains over 175,000 high-resolution image files.

My work supports the organisation’s range of photography and digital media needs, from specialist curatorial and conservation projects, to major exhibitions and publications. I also manage the work of freelance professionals and external organisations with whom we collaborate in order to produce media for permanent galleries or special projects. As well as responding to a diverse demand for new visual media, ranging from web projects to time-lapse animations, videos and fine art print for BMAG’s exhibitions and displays.

My key experience and specialist knowledge is as a professional photographer. I see my job as bringing the wider world of high-end professional imaging and contemporary photographic practice to this sector, in as relevant and cost-effective a manner as possible, while maintaining the highest imaging standards. This work is of course not without its challenges. However we have done exceptionally well over the years with limited resources available, not only to maintain standards, but to develop into one of the region’s leading facilities and become a centre of quality and excellence respected by our partners and photographic peers locally and nationally.

David Rowan
Birmingham Museum Trust Photography

For more about museum digital media and other projects take a look at my personal website:

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