The GFX Cambo Actus

The whys and wherefores followed by a few pointers

I have now been using the Cambo Actus together with the Fuji GFX 50S as a digital back for nearly two years and I thought I would share a few reflections. The system is unquestionably better than my old 5x4 Linhof Technikardan setup and better than any other digital setup I have seen or used for my style of photography.

Firstly the 'whys and wherefores'.

1. It is a digital view camera. I got to the Cambo Actus GFX via attaching my Sony A7R to my old Linhof Technicardan and then trying out the medium format Pentax 645Z. Neither worked for me. The TK/Sony combination was only good for long lenes. There was no wide angle option. And it was large and heavy, especially with a digital adapter added to the bag. The Pentax had no movements and the lens registration distance was too long to use it with tilt / shift options. Other digital back options (e.g. Phase) are ludicrously expensive for personal use. The Cambo Actus is light, small and has front tilt and swing and rear shift, rise and fall. There is an option to add rear tilt though I haven't felt the need. There is also the option of a longer bellows for close up work on large format lenses (I carry this and the standard bellows) and a neat trick where the front standard can be reversed 180 degrees to gain extra rail length. The rear movements render image stitching a simple and precise act.

2. The ratio is very close to my favourite 5x4 shape. At a 4:3 sensor ratio the conversion to 5x4 is only a small crop and the GFX has the option to work in 5x4 mode (inexplicably unlike the sony alpha series which has no such mode and has a much bigger crop to get to 5x4 from 3:2).

3. The GFX Sony sensors. These sensors have amazing dynamic range and excellent quality. I have now completely dispensed with graduated neutral density filters, though I carry a set of NDs to help control shutter speed when necessary.

4. The electronic viewfinder on the GFX. Using an electronic viewfinder for view camera work especially in low light is transformational for one brought up on focusing a view camera on a ground glass with a loupe and dark cloth. Also the electronic viewfinder is 'what you see is what you get' unlike the Pentax Z screen which means focus can be critically examined. And as my close up eyesight begins to fail, the adjustments possible are a godsend.

5. Lenses. The Cambo gives access to a range of medium format and large format lenses. The first advantage over my old 5x4 large format setup is that many of these lenses offer, relative to the image capture size, a far greater degree of lens coverage and thus movements. And many of these lenses, especially the wide angle medium format lenses are good value, have plenty of character and are usually optically superb. With the help of Dave Tolcher I narrowed down my lens choices during my Pentax Z days. I shoot a combination of Pentax 645 and Hasselblad V lenses and a macro LF lens for close up work. Each lens is perfect at its job. In the bag I have a 35mm Pentax 645 lens (one of the newer models). A 60mm Hasselblad CF. A 100mm Hasselblad CF. A 120mm Nikon macro large format lens. And the old style (and tiny) 150mm Pentax 645 lens. This setup closely mirrors my old 5x4 lens range. Stability in kit and lens choices is vitally important for sustained creativity. If I need something in between my focal lengths I either stitch or resort to the old fashioned and trusted approach of moving my feet.

6. I can switch between view camera and medium format photography mode at will. I have two lens adapters for Pentax 645z lenses and hasselbald V lenses (the Cambo adapter in fact). Hence if I need to react quickly or I want to setup without movements I can. Its the perfect blend between my old Linhof and my Mamiya RZ67 setups.

And here are some pointers after using the system for some time.

1. Set focus peaking to red low. This creates red pixels whenever part of the scene is in focus. It makes setting movements quick and easy compared to the old days.

2. Tripple check the focus regardless of the red pixels. In all four corners and especially the left and right middle. I can not fully rely on the neutral movements being zero, particularly the swing movement. Small adjustments have a much bigger impact compared to my 5x4 days due to the relative reduction in size. A diagonal line of red pixels with the lens fully open is usually an indicaction the swing movement is not fully zeroed.

3. Map one of the GFX buttoms to trigger the zoom focus magnification. I can also double click the screen at the back which works a treat.

4. Map another button to the histogram - it makes setting exposure easier. I shoot in T mode (manual) and set the option to swap the dials around so that the front dial changes the shutter speed. Apature is set in the lens. There is so much dynamic range I shoot everything with the histogram highlights at about 70-80% to the right, well off the risk of clipping. Even for high dynamic range scenes with deep shadows and bright clouds I have yet to encounter unacceptable noise.

5. Dont forget to set the mode that allows shutter actuation without a lens being attached and to set adobe RGB colour space. If you shoot in raw + jpg the 5x4 crop mode is activated in the viewfinder and transfers to Adobe Lightroom on import.

6. Get someone who understands Lightroom to teach it to you. It took me about three years to get the hang of things. I am still learning. A few things to try: The new Adobe landscape colour space in Lightroom is excellent. Reduce the clarity and contrast by around 20-40 points as a starter as lightroom seems to add far too much by default. And adjust the radius sharpening from 1.0 to 0.6, it is set too high by default in my experience. And the new mask functionality is excellent. (Thanks to David Tolcher and Guy Aubertin for these tips. They have taught me everything I know digital processing wise).