Phase One P25 Back Field Report

January 13, 2009 ·

Michael Reichmann

This is the final part of a three part review of the Phase One P25 22 Megapixel back.
The first was of apre-production prototypein the summer of 2004, and the second was
a comparison with the Canon 1Ds Mark II. I have now been working with my own P25 in a Contax mount
version for several weeks, including a major landscape shoot in Big Bend Texas and a commercial assignment in Canada.
Here are my impressions.

The Bottom Line

I’m going to start with the conclusion first, so as not to keep you in suspense. ThePhase One P2522MP digital back is the finest instrument for recording photographic images that I have ever seen or used in 40 years as a photographer. I knowthem’s fight’ words, but possibly by the end of this report you’ll understand why I’m making this bold statement.

Of course the cynical among you (and I would be too), will say –sure, after buying a $30,000 digital back what else is he going to write? But, my purchase of the P25 wasn’t based on blind faith or guesswork. I have personally tested almost every medium format back available during the past 18 months, and have owned and worked with aKodak DCS Proback 645for the past year, so I have some small familiarity with what’s out there. I had also previously tested thePhase One H25, as well as aP25 prototype.

My choice of the P25 was based in part on the fact that as of October, 2004 when I placed my order withVistekin Toronto, the P25 was the only all-in-one 22MP back available for field work. Yes, Imacon and Leaf have untethered solutions, but none are as small, light weight and self-contained as the Phase One P Series. Both of these other companies have new and more compact backs coming, but not until the Spring of 2005. I didn’t want to wait. Also, my testing of Phase One backs against those of the other companies showed them to be as good as if not in some cases superior in most respects of image quality. And finally, I have been a long-time fan of Phase’s excellentCapture Onesoftware, which meant no learning curve when it comes to Raw file processing.

Of course the question will be asked – how does the P25 compare to the newCanon 1Ds Mark II, arguably the finest 35mm format DSLR? We’ll, that’s been answered already in mycomparative review. The Canon is an amazing machine, but in terms of absolute image quality the P25 comes out king of the hill.

Cactus and Mountain. Big Bend National Park. Texas. December, 2005

Contax 645 with Phase One P25 Back @ ISO50
Zeiss 110mm f/4 Apo-Makro Planar


In the Box

Production P25 (and P20) backs are shipped in a custom fitted Pelican case, as befits a precious product of this size. The rear of the back, which has the delicate sensor, is protected by a heavy metal fitted plate.

In the case are…

– P25 back

– 1GB Compactflash card

– a two-battery charger

– two batteries

– a long Firewire cable for optionally using the back tethered to a computer

– a sync cable for use when triggering the back remotely

– a sensor cleaning kit

– a Firewire card reader

– printed manual and training manual CDs

– screen masks and a Lens Cast plate

This is a generous package, as befits such an expensive product. I find that the metal protective plate and Pelican case are largely redundant. Most photographers will likely just put the back on a camera body and leave it there. Unless the back is being regularly swapped with a film or Polaroid back (remember Polaroids?), the most practical and safe place for it is attached to the camera body.


Fit and Finish

Unlike in the pictures that Phase One used for advertising in the days leading up to the product launch, and for a time afterward, most P25 backs are black, not gray. The gray coloured backs are only the ones designed for use with the Hasselblad H1. Backs for the V Series Hasselblads, Contax 645 and Mamiya 645 bodies are all black. (Following Hasselblads merger with Imacon in the Fall of 2004 I would expect Phase One to change the version that it uses in its advertisements from gray to black).

It needs to be mentioned that unlike some MF digital back makers, Phase One does not make a single back and then adaptor plates for each camera model. Instead, at least for the popular Hasselblad, Contax and Mamiya models, it makes separate versions for each mount. These cannotsubsequently be retrofitted to a different camera if you change models at a later date (at least not at anything resembling a reasonable price).

But each of these backs can also be used attached to a large format camera via an appropriate adaptor. The Phase OneFlexAdaptorallows for focusing and composition and then slides the back into place for the exposure.

The P25 back is just about the same size as a 645 format film back. The chassis is metal alloy, and a favourite demo of Phase One reps is to put the back on the floor and stand on it – its that strong. I can personally attest to the back’s robustness, as I once watched one fall five feet onto an asphalt highway and survive, with no damage whatsoever. (No, it wasn’t mine, thank goodness).

The back attaches to the camera just as does a film back. On the Mamiya, Contax and Hasselblad H series bodies no cables or other connections are needed. The back and the camera communicate though the camera’s digital interface pins. On the Contax version, at least, there is a locking lever which engages to prevent the back release button from being accidentally released.

Fit and finish are exemplary. The case’s casting is of the highest quality, and the four rear control buttons are positive in their touch. The battery slides into its opening on the right side of the case with a perfect and almost invisible interior fit, and has a positive release lever.

The CF card door on the left side opens with a finger nail under the latch. I would have liked to see a somewhat more accessible latch, usable when wearing gloves in winter – something like the new CF door latch on the Canon 1D MKII and 1Ds MKII, which was specifically designed to be usable with gloves on.



The battery used by the P25 is a common Canon video camera battery. Models BP-911/914/915 can be used. Kudos to Phase One for not foisting off another proprietary battery on us. Replacements and extras can be bought in just about any camera store anywhere in the world that sells Canon video gear. These are 7.2 Volt 2000MAh Li-ion batteries, and a number of third party vendors make them available as well.

The charger that Phase One provides is small and light, and multi-voltage, and will charge two batteries at once.

Battery life is very good, about 2-3 hours of constant use, or a couple of hundred shots with moderate screen review. I’ve bought a couple of extra batteries on top of the two provided with the camera, and feel that I could confidently shoot all day without having to worry about batteries. Not the power stinginess of the latest Canon 1Ds MKII, but excellent for an MF back with a large CCD chip and large LCD screen.



The LCD on the rear of the camera is designed to be viewable in both daylight and under subdued lighting conditions. It does both reasonably well, but not exceptionally. When I was shooting alongside the Canon 1Ds Mark II I found the Canon’s LCD to be more viewable in most situations. But, the P25’s screen is quite a bit larger. Visibility is an area which Phase One has to improve.

You can view the image alone, with a shooting data overlay, with a flashing highlight warning, and with a three colour histogram. The histogram is particularly well executed, showing a luminance area as well as separate lines for the R, G and B channels. This is far superior to the three separate small histograms used on the latest Canon cameras.

One nit that I’d pick with the P25 set-up is that you can’t have a flashing highlight warning and a histogram at the same time. Come on Phase. Please fix this.

There is a magnify mode with three levels of magnification. You can navigate around the screen using the four buttons. Nicely done.

The fourth screen mode is single file delete.

On the screen as a default display is a simple B&W text screen showing the current function of each of the soft keys (Play/ISO/Menu/WB). Also in the center of the screen is an icon showing the state of the battery and also how many frames can can still be shot on the current card. (When you shoot tethered it displays the number of frames that can be shot on the computer’s current hard drive). The screen also shows the current ISO setting, the current White Balance Setting, and the current File size mode (Raw L or Raw S).

Next to the LCD is a small green LED. This is always on when the back is powered. It flashes while a shot is being taken, and a small red LED beneath it lights while a shot is being saved to the CF card. There is a similar red LED inside the CF card compartment so as to alert you not to remove a card while it is still being written to.

There is an option to have the back beep whenever it’s "ready" for the next shot. I find this very reassuring, and use it all the time.

Kevin shooting in Big Bend N. P. with a Contax 645, P25 back and Zeiss 350mm lens


Menus and Buttons

The P25 has the simplest and most elegant control system that I’ve yet seen on a digital camera or back. Surrounding the rear LCD screen are four soft keys. Their functions change depending on what you are trying to accomplish. At any time though you can press the top left button for a couple of seconds and return to the main shooting information screen.

There are settings available for just about everything that you might imagine, including power-down time, instant review time and the like.

I won’t show screen shots of all of the available screens, there are a dozen or more, but I’ll simply note that they are logically laid out, and one never has to go more than a layer deep to find what’s needed.

I’ve shown the back to friends and let them shoot with it, and none needed more than a minute or so of instruction to get the hang of it. Excellent interface design, and one that the major Japanese companies should consider as an example of elegant programming.


No Dust!!

Let’s face it. Dust on the sensor is one of the great annoyances of working with 35mm format DSLRs. On a shot like the one below, with a mostly clear sky filling a large percentage of the frame, I might spend 15 minutes or more with the clone tool spotting out the dust bunnies. The problem of course is that the sensor on a DSLR is buried deep within the mirror box, and gaining access to clean it effectively and safely is awkward at best.

Branches – Big Bend National Park, Texas. November 2004

Contax 645 with Phase One P25 Back @ ISO50
Zeiss 110mm f/4 Apo-Makro Planar

Now, dust isn’t a new phenomena. Scanned film offered the same hassles, and in the traditional darkroom we had the addedpleasureof having to spot each individual print.

But with a medium format back, cleaning the sensor is simply a matter of removing the back and cleaning it. A blower brush, and Pec Pad and some cleaning fluid are all that’s needed. I calculate that at an average of 5 minutes of spotting saved per image, I can recoup the cost of using the $30,000 P25 in just 135 years. Not a bad return.

Seriously though, there are days after shooting with a DSLR in dusty conditions, and changing lenses often, that I groan inwardly at the prospect of all the spotting that will be necessary in the days ahead. With medium format digital this simply isn’t an issue, as I can remove the back from time to time, check it visually for dust, clean it, and put it back – all in less then a minute or two in the field.


Raw Only

The P25 only shoots in Raw mode. Actually, every digital camera and back in the universe also only shoots Raw mode. But, to state it more accurately, the P25 doesn’t do any in-camera (back) JPG processing. This is not as big an inconvenience for those that require JPGs as one might imagine, as the Capture One software included has a superbQuickproofcapability that makes generating a folder full of JPGs the work of just a few minutes.

Needless to say, the files from the P25 are large. The camera has two levels of compression for Raw files, lossless (IIQ Raw L) andalmostlossless (IIQ Raw S). The completely lossless files run between 20MB and 30MB in disk, and open up to be 127MB in size. The slightly lossy smaller size files are about 15MB on disk. I see no advantage to working with the smaller sized files, unless I was running out of space on the available cards.



The P25’s "native" ISO is 50. It also has settings for ISO 100, 200, 400 and 800. At ISO 50 noise is totally nonexistent, even in the deepest shadows. At 100 it is almost the same, and one would be hard pressed to tell the difference. At 200 there is the slightest bit of shadow noise, and at 400 a very small amount of noise is visible, but certainly not an issue. At ISO 800 the noise is actually better than at 400 because Phase uses a technique called binning, which combines the output from adjacent pixels to reduce noise, but also reducing files size. Since the files are so large, even reduced to a quarter of its regular size still gives you the equivalent of a 6MB file, but with very low noise.


Dynamic Range

As we get deeper into the world of high-end digital I am becoming increasingly convinced that it is harder then ever to really quantify the differences between competitive products. I am finding that, for example, dynamic range is something that everyone is interested in, but no one really knows how to adequately measure.

Dynamic range is linked to noise. But, it’s also subjective. If I see detail and no noise in a shadow area then I can say that the shadow is clean and consequently the camera has respectable dynamic range. But, as the noise increases, at some point it dominates the shadow detail (assuming that there is any) and at some point one declares it unacceptable. But, the point at which one makes this determination is highly subjective and also highly dependant on the particular image that one if examining. (All of this assumes that highlight levels have been normalized).

In the end one is simply left with a subjective evaluation, and in that area I feel that the P25 is as good as anything that I’ve ever shot with, either film or digital. At ISO 50 and 100, and much of the time even at 200, the shadows are totally clean and free of any visible noise. Even at ISO 400 I have never found the need to use a noise reduction program like Noise Ninja. But having said that, a camera like the 1Ds MKII is superior by at least 1 to two stops when it comes to low noise.


Shooting Tethered

It needs to be remembered that when it comes to shooting in tethered mode (attached to a computer) the new P25 works in exactly the same manner as its older brother, the H25. By incorporating a CF card slot and self-contained battery Phase One didn’t reduce any of the back’s studio capabilities.

For studio photographers, working in tethered mode has some significant advantages. It means that the client or art director can set behind a monitor and judge images as they are shot. This removes a lot of the second guessing that takes place on a commercial shoot. With the Capture One software, it also means that with a two monitor set-up one of the monitors can be set to have a large 100% magnification window open while the other monitor is showing the full frame. Add to this Capture One’s "Composition Mode" of shooting, where the image is displayed but not stored to disk, and it means great flexibility at no cost or wasted disk space when setting up a shot.

When the back is connected to a computer (Mac or PC) via Firewire it derives its power through the Firewire cable, so batteries for the back aren’t an issue. Shots take just 3-4 seconds to be downloaded to the computer and to appear on screen. ISO can be set from the camera and, of course, the camera can be triggered from the Capture One software as well as from the camera itself. If you’re going to trigger shots from the computer you need to connect the provided cable between the camera and the back, because unlike in the usual situation where the camera triggers the back, here the back is triggering the camera, upon itself being activated from the computer. (At the time of this writing there are issues with triggering the back from a computer. Updated firmware is promised soon).

When shooting in tethered mode it needs to be borne in mind that the camera’s settings are overridden by the computer’s Capture One software. So, for example, you set the camera’s ISO from the keyboard and also the white balance is best set by taking a shot of a gray card and then setting Capture One to use this for subsequent shots. Auto White Balance does not work. It’s a different way of working, but once you understand what’s going on it works very fluidly in a studio setting.

Note that power is only supplied via the Firewire cable if a six pin to six pin cable is used. This is standard on Macs, but most PCs, when the have Firewire, only use a 4 pin connector, and these do not carry power.

Incidentally, the P series backs can also be used on a 4X5" view camera. A device from Phase One called a FlexAdaptor is available. This is a carrier that holds a P25 back (any mount) and then fits it to the rear standard of view cameras from Sinar, Arca Swiss, Cambo and several other makers. The device also has a viewfinder, and the P back and finder slide side to side for focusing and then shooting. The P back itself can also be moved around the full 4X5" frame in discrete increments so that multiple shots can be taken and then stitched together while in Raw mode in the Capture One software.

Obviously this is a very comprehensive and mature capability which I can’t explore here now, but I intend to work with it in greater depth in the days ahead.



I’m not going to delve into a technical analysis of the resolving capability of the P25. I don’t have the tools or the inclination. (DxO Analyzeronly works with in-camera generated JPG files, and the P25 back doesn’t generate them) So, all I can offer you is anecdotal evidence and a sample image.

I hesitate to make a generalized statement or to stir the flames of controversy. But, my honest opinion is that this back, coupled with the Contax’s Zeiss lenses, produces images as detailed as those that I’ve ever seen from any photographic system that I’ve used in some 40 years as a photographer – and I include 4X5" film, either darkroom printed or drum scanned. Of course probably a Leaf or Imacon back, and Fuji or Mamiya lenses would do equally as well – I can’t say for sure. But the only point that wants to be made is that the current generation of 22MP backs really do produce stunning images. What more does one need to know?

Yellow Generator. Toronto Brickworks. December, 2004

Contax 645 with Phase One P25 back and Zeiss Distagon 35mm f/4 lens @ ISO 100

At 240ppi this back produces roughly a 16X20" print. I’ve easily made stunning 20X24" fine-art prints with a bit of upward interpolation, and that’s about as large as I ever need to print. For commercial assignments these images could be used for billboards, and indeed this shot is one of a commercial series that will be used in that manner in 2005.


Failings and Annoyances

The Scream. Big Bend National Park. Texas. November 2004

Contax 645 with Phase One P25 back and 45mm f/4 Hartblei Super-Rotator. ISO 50

It needs to be remembered that though Phase One has been designing and building digital backs for some ten years, the P20 and P25 are their first units designed for untethered outdoor use. Recognizing this, it’s surprising that they got so much right.

But, there are a few things which need to be addressed. Firstly, although the LCD is supposed to have low power demand (a good thing), it isn’t all that bright and readable in daylight. It’s of trans-reflective design, so that it’s actually visible with direct light on it, but otherwise it’s neither here nor there; a bit dim indoors, and not quite bright enough outdoors. Competitors are bringing out backs with much better screens. This definitely needs a fix.

While the back seems to be very ruggedly constructed, and certainly no worse than any other when it comes to use in inclement weather, it doesn’t have the weather sealing of a Canon 1 Series camera, for example. Also, I was concerned that the three external connectors, including the sync plug and the 6 pin Firewire socket, do not come with protective plugs. I’ve complained to Phase One about this, and they’ve said that they’ll investigate solutions, but until then when working in wet or dusty conditions I’ll be placing some electrical tape over the connector holes.


The Future of Medium Format Digital

There’s an old though rude saying;Opinions are like -ss holes, everybody has one. It’s not uncommon to read people online who say that medium format is dead. That full-frame 35mm DSLRs like the Canon 1Ds MKII sound their death knell.


Talk to any of the medium format digital back makers and they’ll tell you that they are struggling to keep up with demand, even at today’s high prices. Yes, there is consolidation going on in the industry. The merger of Hasselblad and Imacon shows the weakness of Hasselblad far more than it does any failing of Imacon’s. Mamiya has seen the writing on the wall – big time – and is about to shake up with industry with their 22 Megapixel ZD camera, and moderately priced digital backs.

Bronica has bit the dust, and Pentax appears to have completely lost the plot. A shame really, since many of us in the industry have been telling anyone at Pentax that would listen for a couple of years now that they needed to make a digital move. No response. Sad really.

Contax is the dark horse. Their U.S. operation currently seems in disarray, but there are strong signs that Kyocera in Japan has awaken from its medium format lethargy and plans to take a proactive role in the digital marketplace in 2005. They’re the last unaligned force among the medium format camera makers, and in my opinion have one of the better products out there. It will be fascinating to see how this all plays out. (Oh yes, Eyelike and Sinar have joined forces. We’ll see how that one pans out). Leaf hasn’t married anyone yet, and neither has Phase One. Both are playing the field, but don’t be surprised to see additional alliances in the months ahead.

So why do I say that like Mark Twain, rumours of medium format’s death are highly exaggerated? The reason is that in photography, larger is always better than smaller, at least when it comes to image quality. There are professionals and their clients who will always pay the price for the utmost quality. This isn’t mainstream. Never has been, never will be. This is the high end, and the high end of anything is expensive.

The very high cost of MF digital is due to two main factors. The first is the fact that such large chips are very costly to produce. The second is that the marketplace is small by comparison with the consumer and prosumer markets. Smaller market size means high costs amortized over smaller production runs.

For example: As I write this one can buy a set-top DVD player for less than $35 in the U.S. or Canada. Can you imagine? What do these cost to make? $5? Yet you have the manufacturer’s cost and margin, R&D, packaging, manuals, government approvals, shipping from Asia to North America, warehousing, distributor markup, and retail markup; returns, repairs, warrenty allowances, etc, etc. DVD players cost many hundreds of dollars just a few years ago. Now they’re disposable commodities. Why? Simple – it’a market that measure in the hundreds of millions of units a year on a global basis.

The same is becoming true of digital cameras. As they increasingly become mass market items prices will continue to drop. And while there will be reductions in MF digital pricing as well, it will be nothing like we’ll see in 35mm reduced format DSLRs and digicams.

But, I predict that the market for MF digital will remain vibrant, though small. It isn’t for everyone. But for those that need it and can afford it, it offers photographic possibilities of unparalleled image quality.

The Phase One P25 back, is, for the moment at least, (Winter 2004/05), the king of the medium format hill – at least when it comes to portable units for on-location use. Imacon, Leaf and Eyelike all have new offerings in the wings, and Phase One likely has new models coming as well. It never ends. But at some point, if a product like this is what one needs and wants, one has to make a choice and jump onboard. I made mine with the P25, and so far at least, the results that I’m obtaining are exceeding my already high expectations. As time passes though I look forward to using and reporting on what comes next.

These are fun times.


Avatar photo

Michael Reichmann is the founder of the Luminous Landscape. Michael passed away in May 2016. Since its inception in 1999 LuLa has become the world's largest site devoted to the art, craft, and technology of photography. Each month more than one million people from every country on the globe visit LuLa.

You May Also Enjoy...

Camera & Technology

Rediscover – Sensor and Sensibility

January 29, 2018 ·

Michael Reichmann

FacebookTweet Sensor & Sensibility Understanding Sensor Issues Starting with apologies to Jane Austen fans for the title of this article, let me add as well

Sony F828 Review Part II

January 13, 2009 ·

Michael Reichmann

This is the second part of a two-part review of the new Sony F828 camera. Whereas thefirst partwas concerned with evaluating the camera’s features, functions