Fast And Slow In A New Light

Well I don’t know if Fujifilm X-series enthusiasts will be happy with the results from the Lawrence Liverwurst laboratories or not. For some it will mean that they need to buy a new lens and for some others it will mean that they need NOT buy a new one. To be frank, I LIKE buying new lenses and I recommend the practice to everyone I meet. Nevertheless, science is a hard mistress… Okay. The test with the modelling light on. The green rectangle is where the AF point rests. All three lenses were started up from infinity and fired when they finally found focus. The trials were repeated three times to give each lens a chance to do its best. a. The 18-135mm zoom. This is a general purpose lens that can do many things well, though it necessarily has a limited maximum aperture. When it was triggered it ran in and out for two cycles in one second and then fired. That's the feature image above. b. The 60mm f:2.4 lens is a sort of nearly-macro lens that is designed to do well in close-ups. It has a reputation for being slow to focus, but in this case it only ran in one cycle - about 1.5 second - and then fired consistently. c. The 56mm f:1.2 R lens is the big portrait length with the wide aperture to give soft background images. Here it, like all the other lenses, was set to f:16. It popped down in much less than a second into sharp focus. Much the fastest of the three choices. You must judge for yourselves whether there is any significant difference in the sharpness or resolution of the lenses. They certainly had a consistent colour rendition and no flare issues. For the second part of the test the Patton was turned round and the lights turned off. Focal point ended up in the soft shadows at the rear of the turret - just under the accessory rack. It was dim and undistinguished there. a. The 56mm f:1.2 R again snapped into focus in less than a second and fired off. I don’t think the lowered illumination affected the AF speed at all. b. The 60mm f:2.4 ground through 2 complete cycles of focus before it fired and even then the results are not sharp - it just finally triggered the camera when it had run out of alternatives. And optical equivalent of “whatever”… c. The 18-135mm zoom lens struggled manfully through the focus cycle each time and each time ended up signalling no focus with a red square. Didn’t even release the camera. If one were tasked with a shoot on a still subject in reasonable interior illumination, one could really choose any of the lenses - there would be enough light to allow the AF circuit to operate. A moving subject would be an entirely different matter - the 56mm f:1.2 would be your only chance out of the three. I hasten to add that there is a new 50mm f:2 lens that would probably be your saviour as well. Once the light drops past the level of deliberate photo illumination - past the level one encounters on stage or under a lecture - or goes below the level of a bright commercial or domestic interior - the slower alternatives are not going to work for you. You may be able to extend the sensitivity of the AF circuits with the newer models of Fujifilm camera, but you still have to feed something into those circuits. Choose the 56mm f:1.2R. Or other lenses with an f:1.4 aperture. Fujifilm make a number of them. I use a 35mm f:1.4 lens that can cope with Perth’s poorly-lit dance stages. Other people use f:1.8 or f:2 lenses to advantage as well. In the cases where people are prepared to use tripods, flashes, or the good old-fashioned manual focusing, then you can shelve some of this research - you will be doing it all yourself anyway. But there is one more thing, and that thing comes out tomorrow.