Originally posted by Dartmoor Dave Autofocus lenses. All of them. I've tried them again and again, and every time I've ended up either selling them or sometimes just throwing them away. They seem to give me only two choices: either I hope that the camera will randomly select a focus point that's somewhere close to what I want, except that it usually isn't so I have to waste time correcting it, or I have to focus and recompose. Either way, it slows me down and I miss shots that I'd get easily with a manual focus lens.
The only good thing about autofocus is that at least you've usually got some way of turning it off.
Now that's a radical statement right there
I think regarding focussing speed and precision, you'd be a candidate for a mirrorless camera system. Of course, that would take away the joy you're certainly also deriving from the process of manually focussing and photographing...
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Regarding the topic question, for me it'd be the 55-300 PLM that I haven't grown fond of in the (admittedly short) while I've had it so far. Sure, it's light and sharp, but the requirements that 300mm bring with them regarding stabilization -> fast shutter time -> and with a 6.3 max aperture -> high ISO... unless there is really much light, I see no point in using it at 300mm for something other than documentation, but the high ISO takes away all sharpness and brilliance the lens may be capable of. A newer body than my K-S2 like the KP may improve upon this a bit (through both better IBIS and better high ISO), but for getting better pictures from the lens I'll have to put in more work than I had hoped for
regarding quantity and quality of light, getting closer to the subjects, perhaps even using it with a tripod to be able to reduce exposure times... I guess I will have to work on myself and my technique after all instead of just buying new gear