Originally posted by lytrytyr Since I'm shooting distant subjects a lot of the time,
test charts at a couple of feet don't really help.
That's a point that I think deserves stressing some more. Lens performance may in fact vary with subject distance, though usually close focus tends to be worse than infinity in such cases. It can be the other way round in macro lenses though (as they'd obviously be optimized for close-focus work).
I usually take a few shots out the window (with a few hundred meters worth of sight) while stopping down in full stops. No conventional tripod possible there, unfortunately, but it usually gives me a decent idea.
Semi-controlled testing with test charts or targets may still be very useful, alerting you to flaws that may not be as obvious in casual shooting and allowing for more accurate comparisons. Some 3D extension of targets is not necessarily a bad thing.
A little trick when working with manual lenses: Meter only once, then choose exposure time manually according to aperture setting. Then you'll always know what setting you used. As full and half-stop steps tend to be most common, set up the camera to use the latter.
A little example: Let's say we have a 50mm f/1.7 lens.
Metering full open may give the minimum of 1/6000 s (for a K-x @ ISO 200 = minimum with highlight extension on) when it's nice and bright outside in summer, so you may have to repeat that stopped down until it gives a longer time. (Shots at minimum exposure time can still be distinguished by brightness.) But ideally, it would look something like this:
f/1.7 - 1/6000 s
f/2.0 - 1/4000 s
f/2.8 - 1/2000 s
f/4.0 - 1/1000 s
...
f/8.0 - 1/250 s
...
f/16 - f/60 s
Anything beyond f/16 usually isn't worth it, being entirely diffraction limited. Plus, you really want a 1/f exposure time as a bare minimum when shooting handheld, preferably 1/2f or even 1/4f. Otherwise sharpness may be difficult to assess. Oh, and don't think a tripod will eliminate any and all camera shake. Your first tele lens may well beg to differ.
Focusing can be extremely critical in fast or long lenses. (My first 135mm f/2.8 showed me that even 100m does not quite approximate infinity yet.) It is best carried out in liveview with zoom. Many lenses should be fine when focused wide open, but it is not too uncommon to see some focus shift when stopping down very fast ones, so you may want to recheck an f/1.4 at f/2 or so. It also wouldn't be uncommon to shoot several times with slightly varied focusing (focus bracketing), going through all the aperture settings for each focus setting.