[paul cotter (OP)]

On a tuned guitar playing a middle c note will give a tone of 256hz, until the string needs retensioning. I have always wondered how instruments like a violin, viola, cello or bass can produce accurate notes without frets. I realise this is entirely dependent on the player involved. What I seek to know is how accurate are played notes, in general. I would imagine high notes could be quite exacting concerning one's fingering as undesirable beats would occur either side of the correct position. Or maybe i'm totally wrong.

[Halc]

I have always wondered how instruments like a violin, viola, cello or bass can produce accurate notes without frets.

The accuracy there comes from the skill (and ear) of the player, but even an instrument with frets has variation in tone, hence the vibrato that comes from small variations in string tension.

Of course it's dependent on the player since the player determines the string length. And yes, small variations in positions have more effect at the high notes, so skill there is even more important. Fast notes also require skill since there's no time to adjust by ear.

Alas, I played a keyed woodwind, but even those can bend the notes, but a beginner sure sounds a lot better than a first-year student on a bowed string instrument.
I love watching the progression of the 10 year olds to say the one that got the lead in the high-school play doing fiddler on the roof.

[alancalverd]

I prefer to play fretless jazz bass guitar and double bass rather than the fretted bass precisely for the reasons Halc mentions - the ear is more accurate than the fret! You rarely have to play fast changes on bass instruments and, like my trombone colleagues (top of the bass clef) I can also make allowances for wobbly singers and dodgy trumpeters in a live gig! But once you get into semiquavers and treble clef, the residual inaccuracies of a fretted guitar are less important  than the speed of chord changes. 

I'm sure that the principle of superposition is what saves orchestral violin sections from ignominy as the audience hears the √N fundamental as they all get somewhere near the written note. But frontline players all think bassmen are idiots, so we get along by mutual contempt.

What still baffles me is why, at the end of a jazz gig, we get the piano, bass, drums, guitar and amps all stacked away in the van whilst the horn section are still comparing reeds and mouthpieces.