Film or Digital discussion

Written by Peter Eastway  

Totem Pole. An early morning start found me stumbling around in pitch darkness, trying to find an interesting foreground for the Totem Pole. A patch of dune and a wide-angle lens worked well, the sand ridges leading the eye. As this was the first time I had used the camera and I wasn’t sure what the depth-of-field would be like with the 24mm lens and the larger format, so I set the focus to infinity and stopped down to f22. In hindsight, I could have brought the focus point a little forward. There is simply so much detail in the Phase One files that any error or mis-judgement in technique can be seen, but equally so, the quality is such that the foreground doesn’t need to be tack sharp for the image to work. I have desaturated some of the colours in Photoshop for the result you see here.

Exploring Phase One Digital Backs

Is near enough good enough? Today, the best image quality in the world comes from ‘medium format' digital camera backs. Is it time you moved up in quality? Peter Eastway investigates.

Recently a photographer called me with a problem. He was taking group shots with his digital SLR camera, but found there wasn't sufficient quality in each of his subject's faces when an enlargement was made. The results didn't meet his expectations as a professional photographer.
Being relatively new to the profession with around eight years experience, he had possibly forgotten how professional photographers used to work with film - and how they used to choose different format cameras that were most suitable to the job. It's not that one format was ‘better', rather they had different characteristics and purposes in life. This is the clue to his answer.

History Lesson

Film photographers can avail themselves of three basic formats: 35mm, medium format and large format. Historically, modern photography began with large format cameras and today are represented by 4x5 inch and 8x10 inch models which take sheet film. Medium format, at 6x4.5 cm to 6x9 cm is smaller, but with improvements in film quality over the years, it easily matches what large format used to do. Of course, the same improvements in film quality are also used by today's large format cameras and so large format remains the king of film quality.

Improvements in film quality also assisted the ‘miniature' 35mm format. It was originally embraced by professionals because of the smaller and more versatile cameras which in turn enabled photographers to take their equipment into situations that were seen as very difficult if not impossible with the larger format cameras of the time. News, sport, war and documentary photographers loved 35mm, but studio, landscape, advertising and architectural photographers tended to stay with the larger formats because of image quality issues.

Bigger Is Best

The one thing all professional photographers knew and understood was that bigger formats produce a higher quality result. If your client wanted a photo for a small reproduction size, then you could use your 35mm camera, but if a billboard were required, then you shot on large format. And if your client didn't know how big the photo was going to be reproduced, then you'd shoot with a larger format just to be on the safe side.
Without getting lost in the science of optics and image resolution, a simple fact held true: the larger the negative or transparency, the less the image had to be enlarged, and the less the enlargement, the better the quality.

Even with the fantastic improvements in film quality, enlarging an image degrades image quality. To produce a 20x25 cm (8x10") print from a 4x5" negative requires only a moderate amount of enlargement, whereas to produce the same size print from a 35mm negative requires a much greater enlargement. As the image is enlarged, the grain structure in the image and the shortcomings in lens resolution are also enlarged. Problems are easier to see.

In addition to straight resolution or image clarity, there is also a ‘feeling' of quality found in medium and large format images. Tonal transitions are more rounded and image detail clearer and truer. There is a sophistication in a larger format image that is missing in a 35mm frame.

This is not a criticism of the 35mm format, rather an acknowledgement of its differences. There are many types of photography that are highly suited to 35mm equipment, but with the move to digital cameras, some photographers are pressing 35mm-equivalent DSLRs into jobs they are not really equipped to handle.

Digital Size Matters

Just as different film formats have different qualities, the same can be said about digital formats. The most obvious difference results from the number of pixels. When it comes to digital photography, digital camera backs like the Phase One P45+ lead the field with a 39-megapixel sensor. Nothing comes close to the quality that can be achieved with these backs and, to get the most from them, high quality lenses are essential.

However, pixel count on its own isn't the only reason digital camera backs produce the highest quality. Image quality isn't just about resolution, it's also about tonal and colour reproduction. In addition to the number of pixels, these backs can capture a 12-stop dynamic range, whereas the best you can expect from a digital SLR is seven or eight stops. A wide dynamic range, meaning the ability to capture a wide range of tones in a scene, allows subtle nuances in highlights and shadows to be retained, whereas in cameras with shorter dynamic ranges, these nuances of tone are compressed and lost.

Colour depth on the latest digital camera backs is 16-bits, rather than the 12 or 14-bits found on digital SLRs. Once again, it's the ability to capture a greater number of in-between colours that produces an image of unmatched colour fidelity and beauty.

These significant differences might be glossed over when you look at camera specification sheets, but they translate into the highest image quality currently available to professional photographers.

So, will the smaller sensors found on digital SLRs be able to catch up? It is unlikely, especially in terms of dynamic range. This is a physical issue which is dictated in part by the wavelength of light. Smaller pixel sizes simply can't hold as much light as larger ones, so larger sensors with commensurately larger pixel wells will always be capable of a greater dynamic range. Just as ‘full frame' digital SLRs claim a benefit over the smaller ‘APS' size sensors, so do digital camera backs with their larger sensor sizes outperform digital SLRs.

The Software Equation

The correlation between film and digital continues after the image is captured. The manner in which a film is processed and printed greatly determines its final quality. Inappropriate processing means the high potential of a film exposure may never be seen and the same applies in the digital arena.
When shooting with a digital camera back, images are generally captured in a RAW format and then processed on a computer using special software. Exactly how the image is processed is fundamental to the quality of the final result. Speaking non-technically, aspects such as colour fidelity, colour range, tonal range, tonal distribution and image sharpness are all controlled by the RAW converter software.

There are many RAW converters available, although not all are equipped to process all RAW files. However, having invested in a digital camera back, it makes sense to start with the software written by the back's manufacturer to ensure you get the best quality result. For instance, Phase One's RAW converter software, Capture One, is highly regarded in the profession, for both its own digital camera backs and for processing other manufacturers' RAW file formats.

The Professional Edge

Professional photography used to be ‘special' in that it required technically precise equipment and specialised knowledge to produce a ‘professional' result. With the introduction of digital photography, everyone, whether a photographer or not, believes that they are ‘good' at taking photos and that their prosumer digital camera produces ‘great' results. It can be a leap of faith for our clients if we turn up to a job with the same type of camera they use themselves.

One way to clearly differentiate ourselves as professionals from the snapshooters is to reintroduce medium format and large format photography, not with film of course, but with a digital camera back. And depending on the type of camera you choose to use with your digital camera back, you can shoot with DSLR convenience or large format precision.

In both scenarios the quality of your files will excel and while your clients might not fully understand why your images look so much better than their's, they will notice a difference.

Which brings us back to the question posed at the beginning of the article: how do you achieve high quality in each individual face with a group shot? The answer is to use the right equipment for the job. There is a huge difference between an 8-megapixel DSLR sensor and a digital camera back with 16, 22 or even 39 megapixels.