The Phase One P25 medium format digital back and related Capture One software - part one

April 2005 (other articles)

A beginner's guide and field review

If you are reading this then you probably know what a P25 back is. The title of this article is so un-snappy that you are unlikely to have stumbled this way without having at least a rough idea of what Phase One backs are all about. If you want to know some of the nuts and bolts details then the best thing to do is visit the Phase One site.

There are a few facts that you will need to bear in mind in reading this article, so at risk of sounding like a catalogue here they are:

- the P25 is a digital back that can be clipped to many medium format cameras in place of the film holder. I was using it with a Contax 645 but there are only minor differences between the backs designed for different cameras.
- the imaging chip is 22 megapixels and has nearly the same surface area as 645 film.
- the back costs as much as a car. A rather good car. In fact if you were modest in your automotive aspirations you could easily buy three cars for the price of one of these backs. Put another way, some retailers will give you the medium format camera of your choice if you buy a P25.
- there is a smaller, cheaper, P20 back. My conclusions about general features would equally apply to the P20, although the chip is smaller so some of the conclusions about image quality would not be transferable.

Moss has clearly grown on this rolling stone - a detail from the ditch at the bottom of a fragmenting cliff face.

Why on earth would anybody want a beginner's guide to such a piece of equipment? Well, I did and I couldn't find one. There are a couple of informative articles on www.luminous-landscape.com but these have the slightly defensive air of someone who has actually bought one. Other web content is mostly in the form of forum postings essentially saying "I want one".

Anybody currrently using medium format gear must be aware that film is dying. And whilst rumours of its death are much exaggerated and it will go on for some time in mass use and for longer in niche use, there are many photographers who are considering if and when to switch to digital. For some genres digital is already de rigueur and there is a mass of information about the pros and cons of different hardware and different workflows. This article aims to fill one of the gaps in this information universe. Can digital do the business in the fine art and landscape field?

Until recently, for all its many attractions and advantages digital did not have a serious challenger in this area, even ignoring costs. Small chip cameras were agreed not to have the capabilities of the large prints that landscape photographers wanted and large chip camera backs needed to be tethered to computers and power supplies. Canon has been slowly increasing the chip size and pixel count of its top end cameras to the point that they are commonly said to equal or surpass medium format film results whilst Phase One (and Kodak before it) has been working on freeing the digital back from the constraints that had been keeping them in the studio. A Phase One retailer will tell you that the P25 equals 10 by 8 film and Phase One sells adaptors to fit the backs to a range of large format cameras.

All the normal points in the film to digital debate apply to these backs. If you clients want digital files then they want digital files. Film costs can exceed the price of new digital gear if you use a lot of film (a very lot of film in this case, but some people do) and travelling with film is increasingly difficult. Negatives on the other hand are easier to store and retrieve and monochrome ones at least are archival. Darkroom workers have a large investment in skills that must be relearned in Photoshop. The keeping qualities of a silver print are known whilst those of an inkjet print are still subject to a few iffs and buts that only time will deal with. All of these points and debates apply to the Phase One kit and I don't intend to elaborate further than the above. The questions I aim to deal with are:

- does this kit work in the real world?
- does the quality at least equal medium format?
- do final prints come at least as easily as from film?
- what quirks should potential users be aware of?

The first three of these questions are logicially separate and are dealt with in sections below. The quirks question I deal with as I go along.

My qualifications and the loan

What qualifications do I have to write this beginner's guide? Well, I'm a beginner (never used one before. Indeed relatively little digital camera experience at all). And I had the back for a week on loan. During this time I used it for landscape photography, some documentary photography and some still life work. About 450 captures in total plus a hundred negative exposures taken in parallel to enable some direct comparisons. I had intended to concentrate wholly on landscape work but the weather in the week I had the back was appalling. Freezing temperatures, snow, very high winds, almost constant rain. Definitely not much golden light. In fact not much light full stop. This is what led me to bring some landscape indoors for some impromptu table top work and also meant that the landscape work had a tendency towards details not grand vistas. The documentary work was opportunistic. You can walk around with a P25 camera so I did.

The loan was organised by Roger at www.hpconsultants.co.uk (Scotland's Phase One reseller) and Eric at Phase One. My thanks to them both. Phase One's attitude to me as a potential customer was what you would expect given the price of the product. My almost casual initial enquiry was taken seriously and followed up by their local retailer. This contrasted markedly with the response I got from Kodak a year or so earlier when I was told to go away and read the web site.

I have no connection with either company except as a potential customer. Phase One did not know I was going to write this review. There were no constraints put on my use of the back (except for the time limit........) and given my out of the way location they put a lot of effort in getting the back to me.

I was loaned the complete kit as a purchaser would receive - the only exception was that I did not get the mask to fit in my camera that reduces the frame area by the amount needed to come down the the dimensions of the chip. This was assumed to have gone awol on a previous loan. The extensive kit list is available on the Phase One web site.

P25 in the real world

Although the weather meant that my photographic opportunities were limited it also meant my testing opportunities were enhanced. The P25 is a complicated piece of electonic equipment. A computer in all but name. In my efforts to break it (only joking Eric) I used it in rain, hail and gale. So the simple answer to question number one is that it works.

The story behind the moss picture (at the start of this article) is instructive. I was in the ditch because that was the only place I could get the camera steady enough in the wind. (Quirk: the back adds about a third of a kilo to the overall camera weight. This seemed to tip the balance against my lightweight backpack tripod - a Gitzo series 2 - and I needed to use a heavier tripod to be sure of stability. A Gitzo series 3 did the job). This was my second day with the back and my first one in the field. My concerns were: (i) the wind; (ii) the fact that tripod was resting on moss and grass which is about as stable as foam rubber; (iii) the difficulty I was having in translating the image I saw from the car into photographic reality; (iv) the very patchy light; (v) thoughts about whether the deer tick season had started; and (vi) the likelihood of rain. I was not thinking about the P25 at all. It worked. It was easy to use.

And it went on working. Although I carried a second charged battery with me I never resorted to using it. Phase One claims a battery will last four hours of continuous shooting. Sceptical of such claims, especially in cold weather (it was only one degree Celsius on the day that I took the waterfall picture), I was pleasantly surprised. Somewhat to the surprise of the Phase One rep that I was talking to, I did have two ocassions when the back told me that it had failed to write to the CF card. As different CF cards were involved and I couldn't repeat the crashes I had to put this down to the "computers do stuff like that" box of life's mysteries. Just something to be aware of - at least you get a nice clear message so if an exposure is important you know that you have missed it. I was using 1 gb San Disk Ultra 2 cards but as these are what Phase One supplies themselves I ruled out card compatability problems.

Another pleasant surprise was how low on gadget factor the P25 is. There are very few buttons and the function of each is clear and unambiguous. The buttons are big enough to be usable with cold fingers (or for the more prepared, with gloves on). The menu structure is all you would hope for - being both simple and short. The only default beep is a useful one in that it tells you when the back is capable of taking the next shot. Instant histogram review is easy to set up. The right information gets transferred through to the camera viewfinder (exposures remaining and camera ready) so if you want to work with the camera as if it still had film in you can. All in all the P25 is a serious tool devoid of fripperies which makes it easy to use in the field and reduces the chances of something going wrong.

Although Phase One may have worked wonders on power consumption and heat dissipation, they haven't managed to reinvent the LCD screen. Theirs is a useless in bright light as anybody's. They have at least made the exposure histogram high contrast and this remains visible long after the related image fades into electronic nothingness. I have some issues with the accuracy of the histogram, both on the LCD display and in Capture One (the raw conversion software) but I'll deal with this in part two of this review.

One wouldn't often choose to use a medium format camera handheld but it is possible and with the extra flexibility of being able to change the ISO at will I would be more likely to take opportunities that I might otherwise miss. As the following beach scene shows, man can, with the help of a winter storm or two, despoil the landscape quickly. Some of the people camping near this mess took too much of an interest in what I was doing for me to want to be using a tripod. At ISO 200 the Contax and P25 coped well.

Abandoned car and wrecked caravan on a beach in the West Highlands of Scotland. Not a shot for the tourist brochures but what these beaches looked like in early 2005. Handheld shot with 55mm lens at ISO 200. This shot could have been taken using a tripod and a slower film speed but the presence of campers made me decide to keep mobile.

In the interests of testing I ran through a couple of sequences of shots at a range of ISO ratings up to the maximum of 800. I can't see many photographers using much more than the slowest speeds, but if this was the camera in your hand when the martians landed at dusk then I suppose you might dial in ISO 400 or 800. Generally I found that the ISO ratings were optimistic, both against my Gossen incident light meter and the Contax's in built reflected light meter. This is partly, I suspect, because digital capture is more like slide/positive film in that over-exposure is to be avoided at all costs, whilst I am accustomed to using negative film. However, as I have a good example that I plan to use in part two I will restrict my comments here to the issue of grain (noise) and one very odd little problem that I came across which definitely counts as a quirk. ISO 800 captures appear to have a strong magenta colour cast both when viewed on the LCD and later in Capture One. I struggled to correct the cast on one capture and gave up, only to find that processing it without corrections resulted in colours identical to the ISO 400 and below shots taken at the same time. This was repeatable and in no way affected the use of the ISO 800 captures except that fine colour judgements can't be made at the time of raw conversion.

But what can I tell you about grain and noise? I started preparing a whole batch of files based on the above shot and another with large areas of even tones. This, however, is a boring task and I abandoned it, because surprise surprise, there is more visible noise at ISO 400 than at ISO 100. Cor, really? My thinking is that if you want to produce poster prints then you are going to be using a tripod and ISO 50 or 100 (between which there is very little difference). If you take a few hand held shots at around ISO 200 such as I did on the beach with the wreckage then you would be happy to discover that at A4 print size there is no visible noise. Larger prints would show it of course, but would you be printing these photos larger? And anyway the various noise reduction programs could deal with it. And the shot of the martians emerging at dusk? The picture desk wouldn't care about digital noise, and the readers of the Daily Tabloid would assume that a perfect picture was a fake anyway. What I am saying is that for me noise was not an issue.

One little quirk - at ISO 800 you get files with only half the pixels as you do at ISO 400 and below. Presumably the software is doing some pixel amalgamation resulting in pictures which are capable of lower degrees of enlargement but which have good characteristics otherwise.

I've no idea what this plant is (reproduced well over life size here) but this sheltered corner of my garden gave me some respite from the wind. The camera was pointed directly at the ground which meant that the P25 was pointed directly into the, albeit light, rain. No worries.

In part two I'll deal with the film comparison question and the Capture One software (as this is needed to get any files recognisable by any other software), together with some more thoughts on overall usability. But for the meantime, the P25 passes this real world test. Nobody is pretending that this is a waterproof all weather item, but it is capable of going anywhere that my Contax is and that is all that is needed.