A couple of weeks ago I bought a second hand Sigma 18-35mm f/1.8 from a shop. On my first outing with it it was great, I couldn't believe the sharpness of the images from this zoom lens. Unfortunately, since then and for seemingly no reason, it almost never focusses correctly, whether using auto focus or manual focus (although I get better results with manual focus, they're still nothing compared to what they were). This issue happens regardless of aperture, focal length or anything else. It doesn't happen with very close subjects. I have attached two images as examples. One show a closeup adequately focussed at 35mm f/2.8 1/800 sec ISO 400, and the other shows a landscape completely out of focus at 18mm f/4 1/2000 sec ISO 400. Although the example attached is very close up, any subject within about 2m seems to focus fine, and likewise when trying to focus on a subject further than 2m away the focus window on the top of the lens never shows over 2m. What could have caused this to happen so suddenly? Is it fixable? And if so, how? If I need the dock to fix it, I don't have one but my local Wex has one in stock.
possible the lens is of a type that has a short and long focus pair of motors and the long one has gone, i checked mine and there isn't a focus limiter on it which would rule that option out, might have to go to sigma to be repaired
Thanks for you reply, I don't think it's this though because it's virtually impossible to manually focus it either. I took it into Wex earlier and they tested it on one of their cameras, and they think it's probably broken (I didn't buy it from there). I was asking about buying the dock from them because I think it might be front focussing which can be tuned using the dock and associated software, but they didn't seem to think that that would fix the issue (I might still give it a try though)
No just this one. I got the dock today so I've updated the firmware and reset it to factory defaults. I've done a bit of testing in my house because it's too dark to test it outside now and it seems sharp again. I'll test it outdoors again tomorrow so that I can test it at a greater range, because that's where it struggled the most, but fingers crossed that's all it needed
