Another look at Sensor Bracketing: Part 3

In the last two posts (here and here) I discussed what I call 'sensor bracketing', that is exploiting a lens with a larger image circle, to allow moving the sensor relative the lens, without parallax or vingetting. In this way we can emulate larger sensor formats, say, like the Hasleblad XPan with it's 65x24 film size, via rectilinear pano merging in post.

Up until now, I've discussed exploiting my Canon 24mm Tilt/Shift lens, including the addition of extra shift via the Laowa Magic Shift adapter. 

In this post I'll be loking at how one can set up a digital 'XPan' using secondhand medium format lenses and manual shift adapters.

Let's first remind ourselves what the Hasselblad 65x24mm XPan film camera looks like, which is not manufactured any more, but remains expensive to buy on the secondhand market:

As for lenses, you can get three native primes for it, 30mm, 45mm and 90mm: shown below with the viewfinder that comes with the 30mm lens.

To emulate the above in a modern, full frame, digital, mirrorless camera, the Canon R or IR converted RP in my case, we need to first substitute out the XPan lenses. I decided to do this with Mamiya 645 lenses.However, the only Mamiya lens that matches the XPan’s primes is the Mamiya 45mm, I therefore needed to accept being 'close enough', by using the 35mm and 80mm Mamiya 645 lenses. Additionally, I also have a 150mm Mamiya 645 lens, which has no XPan equivalence.

To connect the Mamiya lenses to my Canon RF mount cameras, I decided on a Fotodiox shift adapter that has a foot, so that I can keep the lens stationary, allowing the camera to shift relative to a static 645 field of view. The adapter allows a +/- 15mm shift, ie 30mm, no parallax, total shift.

Pulling the above together with a few other gadgets, one version of the set up looks like this (note you don't need the pano rotator or the Canon R cage):

As for capturing two pano brackets, ie at + and -15mm, the biggest problem to address is the lack of a viewfinder. To overcome this, I make use of the Mark II Artist's Viewfinder, which you can download from here.

This iPhone App allows you to set up virtual cameras, so, in my case, I've set up a 35, 45, 80 and 150mm virtual XPan, with a 65mmx24mm sensor. This set up allows me to explore compositions and assure myself that the shifted frames will cover the scene of interest.

As an example, here is what the Artist's Viewfinder shows of a simple test scene:

Here we see all four lenses displayed within the digital XPan format, however, you can then zoom in on the focal length of interest  

As for the final image, here is an 80mm capture (with a field of view close to the XPan's native 90mm), taken by shifting the camera +/- 15mm.:

The merged image is 12020x4515 pixels in size, ie equivalent to an XPan's film size of 65x24mm.

So, there you have it, with the use of some secondhand 645 lenses and a cheap manual adapter, you can emulate different cameras: in this case an XPan.

As usual I welcome any comments on this post or any of my posts.