Its one thing for me to flush a toilet without knowing how it operates, and another for me to favor (or oppose) an immigration ban without knowing what Im talking about. Elizabeth Kolbert, Why facts don't change our minds
It seems a rule among camera manufacturers, at least all but Olympus and Panasonic, to use a proprietary lens mount. But there can be an escape from this lock in since some lens mounts can be adapted to work with a body expecting a different mount. Whether this will work depends on where the lens places its focus point.
My goal was to see if I could use a Nikon fish eye on a Fuji. The Nikon is designed for the same sensor size so I thought perhaps an adapter could save me the cost of a new lens.
Here is why some lenses can be adapted. Every lens focuses to a plane that is outside of the lens itself, it is where the sensor is positioned. If a foreign lens focuses too far into the camera body, behind the sensor, a spacer can be added to hold the lens away from the body, just enough to absorb this extra distance. But if the lens doesnt focus far enough into the body youre screwed, the lens won't work.
This distance, from the sensor to the body's lens mount, is the flange focal distance. Fuji's flange focal distance is 17.7mm whereas Nikon's is 46.5mm so a Nikon lens should work on a Fuji body (though not vice versa).
Since the base of a Nikon lens needs to be 46.5mm away from the camera sensor and the Fuji body provides only 17.7mm, it takes a 28.8mm spacer to position the Nikon at the correct distance from the sensor. Sure enough, there are several available adapters, ranging in price from about $50 (the K&F Concept shown in the pictures below) to almost $500.
I'm showing this 2014 photo as an example of why I like a fisheye. I bumped into it while looking for a photo of Mt Etna, it's erupting right now and it's quite view able from Castelmola.
The picture was taken from a patio near Castelmola, Italy, using the 10.5 lens on a full frame Nikon. The photo shows the path we'd just walked up, starting from Taormina which is the town just visible in the upper right. Taormina is located about half-way up the side of this mountain. It's an eye-candy town, every where you look it's pretty.
An alternative is to make a panorama but each has its pluses and minuses. The fisheye doesn't need stitching and it captures one moment in time but it's distorted. A panorama has less distortion but takes time to process and the components of the shot are captured at different points in time.
Coming up: testing the lens.
After a couple weeks shooting the Nikon 10.5 on the Fuji I'd say the combination works well, so well I might even take it on my next trip. But I'm not saying using any adapted lens is a cakewalk. It just so happens that this particular lens' strengths hide the adapter's weaknesses, which are the lack of auto focus and a poorly marked aperture control.
So why is this lens so well suited for this application? Even if you don't have the lens and the body you can go to dofmaster.com to run the numbers, and they show that this lens is going to be easy to use.
Let's try it out. Choose an APS-C body such as Fujifilm x100, x-pro1, select the 10.5mm focal length, a f/2.8 aperture, and then enter a subject distance of 2m. The results show something interesting: everything between 0.99m and infinity should be in focus.
Now change the subject distance to 2000m, which would be infinity on the lens. Dofmaster shows depth of field is 1.95m to infinity. In other words, if you just leave the lens on infinity and don't touch the aperture ring you'll get everything in focus from 6 feet to infinity. As a touristy landscape lens this pretty much covers most of my needs for a fisheye.
Mind you, If I didn't have the Nikon I'd buy the Fuji-mount Rokinon 8mm. Like the Nikon it's a fish eye and strictly manual focus, but unlike the adapter it offers a marked aperture ring. Even though you can shoot all day at 2.8 it seems a little odd to me not to step down a bit on a sunny day.
I'm in Ubud, staying with friends for a few days after which I'll be off on my own. This morning I woke early to the sound of ducks of roosters. Scroll past the maps to the photos which were taken from my bedroom deck.