Since I already owned a number of vintage camera lenses, I was able to extend my optical reach by purchasing an inexpensive adapter that lets you attach a Konica Hexanon lens mount to the Fujifilm body. (You can purchase similar adapters for Minolta and other vintage lens mounts.) So when I took a trip to California in January 2014, I brought along the adapter and my trusty old Hexanon 135mm f/3.2 telephoto. With the APS-C sensor, this effectively gave me a reach of 216mm. The lens and adapter worked beautifully, giving me the reach I didn't have with my kit lens. When I wanted to capture a beautiful moonrise the next summer, I grabbed a Konica 200mm telephoto lens, which on my Fujifilm body became a 320mm monster.
There are some drawbacks to using old lenses on digital cameras, particularly for those accustomed to digital gear. For starters, there's no electronic communication between the lens and camera, which means there's no EXIF lens data recorded in the file. On Fujifilm cameras, you have to specifically enable using the camera without a lens attached, since that's exactly what the camera thinks is going on.
It should go without saying that these vintage manual focus lenses remain manual focus when attached to a modern camera body. The same goes for setting the aperture - you must use the physical ring on the lens. While we've all gotten spoiled with the amazing image stabilization in modern lenses (and some camera bodies), these lenses have no such safety net, so keeping very still when taking the shot is critical to taking sharp photos. For the same reason, you also need to mind your shutter speed.
The upside to all this is that because of the way shooting modes work on Fujifilm cameras, you can let the camera make all of the remaining exposure decisions for you, or you can choose to adjust those manually as well. Even better, if you have an X-T2, when you switch the camera to manual focus, there are some digital tools that will enable you to nail the focus with greater precision than would have been possible when these lenses were new! Even if you have less than perfect eyesight, these tools should help considerably.
Two features that are particularly helpful are focus peaking (also available on the earlier X-E2), and a new "Dual" feature that shows two frames in the viewfinder: a larger one at full-size, and a smaller frame that displays a loupe view of the area around the focus point. Using focus peaking, you simply turn the lens until the edges "sparkle" in the loupe, and you've got tack sharp focus! I only learned about this feature in the past week, and it's going to be a game-changer in my macro work, where manual focus is the norm even for modern lenses that have autofocus.
Four years after making the switch, I'm still a Fujifilm fanboy. I've purchased a number of Fujinon (Fujifilm's lens mount) lenses, as well as a couple of inexpensive Rokinon lenses. I don't have any pressing need to "slum" around (as Ken Rockwell puts it), with lens adapters and vintage glass. Sometimes it's just fun to see what you can create with old gear.
Occasionally I'll pick up an old lens that I primarily intend to use on old cameras (as nature intended), and I'm curious to see how it works on a modern digital sensor. Such was the case when I bought my latest find: a Konica Hexanon 50mm f/1.4 - a fast and sharp prime released around 35-40 years ago.
The following comments and sample photos reflect my totally unscientific methodology: namely, attach lens to camera and go shoot stuff around the neighborhood. There are no control images for comparison, no detailed technical data, and I didn't even record what f-stop I used. All shots were handheld, so any softness in the photos is probably an artifact of my unsteady hand. Please keep in mind that this is more of cursory look at the kinds of results you might get than a proper review.
That being said, I was impressed with the overall performance of the 50mm on my Fujifilm X-T2 (which effectively covers the same field of view as an 80mm lens on a full-frame digital or 35mm camera). The colors looked good, sharpness was excellent. While I'm eager to try this lens for portraits, taking advantage of that wide aperture to make the subject pop, I haven't had a chance to try it with a human subject yet. I have no reason to think it won't work well for that purpose.
The only con I could see with this specific lens is that the lens coatings seem to be deficient from a modern standpoint. As you can see in these samples, the lens experienced some flares and streaks more typical of today's toy cameras. This might well have been mitigated by using a lens hood, however, and being the experimental type I found this technical shortcoming to be rather charming. Before the digital era, and the rise of the lomography movement, these flaws were to be avoided. For many shooters today, they merely add character.
I've applied my standard edits on these photos: camera profile, sharpening, straightening, exposure adjustments, and some cropping. All of the photos were shot in RAW.