TGIFridays: the new Alpa 12 STC Silver Edition – : sample photographs

Follow up to our gear review of the Alpa 12 STC Silver Edition last week, we continue to explore with you the photographs we took over the month or so the camera was on loan to us from Alpa in Zurich.

TGIFridays: the new Alpa 12 STC Silver Edition Part 2 – sample photographs

Lest I were not clear on our review last week, I came away mightily impressed with the camera, lens and back after spending considerable time with it. When we first got the camera, I wondered about the raison d’être for a camera which only offers either a shift or a rise/fall of +/-18mm. The STC is only able to either shift or rise/fall, and not both together, and only on the rear standard. And there is no tilt or swings on any of the standards. This seems limiting, especially in consideration that I have been learning to use my Sinar X large format camera. The Sinar is a full monorail camera, and is a lot more flexible than the STC. It is able to do any combination of shifts, rise, fall, swing and tilts at the same time to both the standards. It does pay for this ultimate flexibility by being large, and heavy. It has a very steep learning curve, and takes a considerable time to setup.

The Alpa STC shines particularly because it is limiting. It is only able to shift a maximum of 18mm in both directions. And rise and fall is only available when the STC body is rotated 90°. But the key is that because of this simplicity, it is very focused in its use case, and consequently does an excellent job. The STC as the name suggests – Stitch Travel Compact is rather compact and lightweight for a technical camera. And is the perfect choice of a camera for the use case of stitching precise panoramas and use of rise and fall in architectural photography. Its simplicity makes it easy and fast to setup.

The Alpa 12 ecosystem

The base STC is able to accept all manners of digital backs – from the Hasselblad which is part of the Silver Edition package to digital mirrorless cameras like the Fujifilm GFX and digital backs from Phase One. Or indeed discontinued digital backs from Leaf, Mamiya or Sinar can also be adapted. The STC can even accept roll film backs. The system is very flexible and can be built to suit many budgets.

And other than the superb Alpagon/Rodenstock HR 4.0/40mm which is part of the Silver Edition package, the STC can be used with other digital lenses from Rodenstock or Schneider Kreuznach. And indeed can be adapted for use with even a Leica M lens or any large format lens, either with or without a shutter assembly. When using other lenses, it is important to check that the lens has enough coverage for the chosen sensor, and with some room to spare for movements. For most cases, medium format and large format lenses will work well, and 35mm lenses (like the Leica M) may or may not cover the sensor. A tilt adapter can also be added to add functionality of 0° – 5°.

Architecture

As discussed, the principal use case for the STC is in architecture and cityscape photography. And in this it truly excels. The precision in which the camera is manufactured, and the ability to make small, accurate and repeatable movements makes the camera shine. In the Silver Edition package, the lens chosen – the Alpagon/Rodenstock HR 4.0/40 is an outatanding all rounder, with superb performance in all critical aspects throughout the aperture range.

The rise and fall feature is the key feature required for architecture. Typically, to get the entire building in the frame will require the camera to be tilted up. This will cause the vertical lines in the building to converge. And the building looks like it is tipping over, falling backwards. To avoid this, the sensor plane needs to be kept parallel to the building, and to capture the entire building will mean that a wider lens need to be selected, or the camera position placed further back, resulting in a smaller subject image. The added field of view coverage will also include foreground which is not useful, and cropped in the final image. In the behind the scene photograph above, this is clear. The iPhone is set almost vertical to the scene to avoid converging vertical lines of the building. If you examine the image, you will still notice some converging of the building’s lines as the phone and building are not perfectly aligned and the image has more foreground. In this case, the foreground is not interesting, and will end up being cropped.

But in the photograph above, I used the STC the the back lowered the appropriate amount, in this case the full 18mm, the building takes up almost the entire frame. And all vertical lines remain vertical with no convergence.

Note that because the system is mirrorless, a fall of the back will cause the image to rise in LiveView, cropping off the foreground. The camera electronics flipped the image to present an upright and laterally correct image. The image as it is cast on the sensor is upside down and laterally inverted, just like the image on the ground glass of the Sinar.

Stitching images

Stitching is often used to create a panoramic image. And the STC is designed especially for this purpose. The body is designed to quickly slide from either extreme position to the other, with detents at both ends and the center position. Making it very easy to take three photographs, each in each of these positions will give a wide panorama image.

As an example, consider the two panel panoramic image below. This is made with the Alpa 12 STC Silver Edition. The left panel is taken first and then the entire camera assembly rotated about the lens’ nodal point, and a second image is taken for the scene on the right. Quite a standard procedure for cameras without rear movement. And frequently used to provide the two or three images for stitching. The image is then stitched in Photoshop. The resultant image is shown. Note that the image is not rectangular, as the coverage of the lens on the left side of the scene is wider than the right. The image can be cropped to give the regular rectangular image, but at the expense of some loss in information.

Using the STC in stitch mode, the image below is made. The back is slid full right +18mm and then back to the center position. Because of the detents and the quick release mechanism, the entire back moves on the STC’s rails and is precise in framing. The resultant image is perfectly aligned.

Note also the difference in perspective in the far objects which is exaggerated in the rotated image, but is retained more linear in the shifted image. Either can be used for creative effect as needed by the photographer.

Below are two additional images showing the same effect.

Shooting hand held

The slower, contemplative process of the STC mounted on a tripod works very well, and is indeed how I would recommend using the camera. The camera can be used hand held as well. I took the photograph below while standing on a pedestrian bridge, hand holding the STC Silver Edition.

And even street style photography can be attempted, though probably more successfully by others more skilled in this art form than me.

Lens cast and correction

The Alpagon/Rodenstock HR 4.0/40mm lens on the STC Silver Edition is considered to be a very wide angle lens. The field of view works out to be about 30mm full frame equivalent on the long side. The physics of light results in light arriving at the edges of the sensor to strike it at an acute angle. This light is already filtered by the Bayer array, and thus already assigned a colour which is interpreted by the colour science used in the raw converter. And due to the acute strike angle, lands on the adjacent wrong CMOS cell, giving a lens cast which progresses across the end of the frame. This is a digital phenomena, and not present when shooting film. Also, a back with a BSI sensor, like the Phase One IQ4 150 or the Fujifilm GFX 100S has its sensor in a shallower pit, this effect is less obvious.

This lens cast is very difficult to remove in post processing. To successfully elimate this phenomena, a Lens Cast Correction / Calibration (LCC) frame is shot using a plain white translucent plastic panel completely covering the lens. This has to be done immediately before or after the shot is taken. To adjust for the loss of light of two stops, the shutter speed is reduced. The aperture is not adjusted, as this may cause additional shifts in the colour cast. At the extreme -18mm down shift of the back, this is full frame of the colour cast caused by this effect. 

Note the progressive nature of the lens cast introducing a magenta note to the colour palate and vignette. The resultant -18mm shifted image, uncorrected looks like this.

When the back is not shifted, the image is relatively free of this cast, as the light is incident more or less perpendicular to the sensor, and the Bayer Array does a good job separating the RGB information into the correct CMOS cell.

To correct for the colour cast, the LCC reference image is processed in Hasselblad’s Phocus software and a Scene Calibration is created. This calibration is then applied to the image and the software corrects for it. The image below is a 3 panel stitch, with the upper panel being -18mm and the lower panel being +18mm. LCC images taken at -18mm and +18mm. These reference frames are then made into Scene Calibration profiles and applied to the appropriate image. The middle panel is used as it is.

The same procedure can be used in Capture One or Lightroom for other backs. Shown below is the same procedure with the Alpa 12 STC and Alpagon/Rodenstock HR 4.0/40 but the the Phase One IQ3 100 back.

Concluding thoughts

It was with quite a bit of sadness when the time came to return the Alpa 12 STC Silver Edition. This is a camera which is superlatively excellent for its intended use case – architecture and cityscapes. The use for landscape, especially for stitching is also excellent. And when stretched, the camera can be used in hand held situations for street photography.

The Alpa 12 STC body is superb. A true mechanical marvel. Not only a pretty face, but one which is extremely well engineered. The Rodenstock HR 4.0/40mm lens is also outstanding. This is one of the best and most refined 40mm lens I have ever used. The Alpa HPF focus system is a real pleasure to use. Smooth. Precise. The Hasselblad CFV II 50C back is an essential component, and a proven digital back. In combination, the synergy when used for its intended use case is absolutely marvellous. It made me want to pick it up every time I head out as it is so satisfying to use.

The entire Silver Edition system is, needless to say, an expensive proposition. CHF 29k is a lot of money for a camera. The STC body itself has a retail price of CHF 4,200 and weighs in at 540g. But for this, we are at the haut de gamme of technical cameras. The very top of the top. Crème de la crème. Are there other options in the market? The landscape is rarified, but of course there are other cameras in the competitive landscape. Interestingly, all of which are able to use the same Rodenstock lenses and the same digital backs as the STC Silver Edition with the exception for the Phase One which is offered with only their own back. Here is a quick survey.

Cambo, a Dutch company offer a body very similar to the STC in the form of their RC400 which offers 20mm of movement in either rise/fall or shift. It weighs the same as the STC body, and considerably less expensive at circa GBP 1,800 for the RC400. However, the build quality of the RC400 is not at the same high precision level as the Alpa. Arca Swiss, a French company also has their RM3D which offers 15mm of shifting and an additional 0° – 5° tilt and is only 500g. Retail for the Arca RM3dii is about EUR 5,300. And the Swiss made Sinar offers their Lantec at EUR 3,900. The Sinar is able to shift from +25/-15 mm vertically, +20/-20 mm horizontally, but weighs 1kg. Silvestri also has an offering in their Bicam II, which retails for GBP 1,400 and weighs in at 750g with +/- 15mm of either shift or rise/fall.

And finally, the elephant in the room is offered by Phase One with their XT system. The XT body weighs in at 700g, and is made by Cambo as a collaboration. But it is considerably better built than the RC400. The XT offers both rise/fall and shift simultaneously, but also a bit more limited in the movement range at +/-12mm. (Edited to correct the Phase One XT specification) It also features an electronic shutter system and a mount which allows the camera to be rotated without having to remount the tripod foot. It also is fully integrated and the back’s EXIF records all the information including the amount of rise/fall and shift applied. But the Phase One XT more expensive than any of the competition at GBP 7,400 for the body alone. And as a full system, with the Phase One IQ4 150 back with any of the Rodenstock HR lens will set one back about GBP 56k, considerably more than the Silver Edition’s CHF 29k.