In attempt to classify lenses word “sharpness” is the most frequent, meaning “very sharp lens” is very good lens.

Even and Zeiss advertise their ZF lenses, beside high resolution slogan, as "sharpest lenses ..." so it turns that lens vague term "sharpness" is to many the most important think in classifying lenses.

"Good lens" to me means a lens that consistently producing an image that coincides with my photographic requirement.

As photographic requirement (standard) are different to different people, so and the same lens can be good to one and not good to another. In that way and Leica is not the best manufacturer of photo lenses, but just a manufacturer among other.

What “GOOD LENS” means to you?

What “GOOD LENS” means to you?

Technically, to me, it first means accurate focusing, high resolution, without too much distortion and/or light falloff on corners, etc. Secondly the weight, the size, and the cosmetics matter. And I like and I like to shoot with a 50mm lens for 35mm film in general because you can't really go wrong with it. It's a good lens of all time for me.

One that allows me to achieve my vision. That mean the lens could be a total piece of crap regarding focus, resolution, distortion, or "sharpness."

A good lens to me is a fast lens (maximum apperture of 2.8 or below), it can be a zoom or a prime lens but must be sharp at most one stop down from maximum apperture. I don't mind light fall-off in the corners since it provides a natural vignette, distortion doesn't bother me either, just as long as it's fast focusing and doesn't hunt much in AF.

I find this mostly in prime lenses like the Sigma 20mm 1.8, Canon 35mm F2, 50mm 1.8 and lastly 85mm 1.8.

A good lens to me means a Sumicron 50/2 which I cannot afford.

A good lens takes good pictures. A bad lens takes bad pictures. Most of my lenses bounce back and forth between these categories.

A good lens takes good pictures. A bad lens takes bad pictures. Most of my lenses bounce back and forth between these categories.

No. You take good or bad pictures :) A good lens allows you to do what you want whether it is making soft portraits, ultrasharp landscapes or use flare, bokeh, vigneting or pseudo zoom effects to achieve a certain feeling/mood in your images. A fisheye is bad for traditional portraits, a slow lens is bad for low light street shooting etc eh? but that doesn't make them bad lenses altogether but its true a good lens to me is the one that lets me capture the mood I want a bad lens, whether its a Leitz or Sigma, doesn't. Second, a good lens is the one I have in my bag, a bad lens is the one thats always sitting on the shelf back home when Im out shooting no matter the reason e.g weight.
Cheers
Søren

A good lens is one I have with me, and that gives me the angle of view I want for a particular scene. Everything else is up to me, not the lens.

A good lens is one that is free from abberations and distortion.

A good lens is one I have with me, and that gives me the angle of view I want for a particular scene. Everything else is up to me, not the lens.

YES!

A good lens is one that is free from abberations and distortion.
No, that would be a perfect lens. And like most perfect things, this one doesn't exist either. All lenses have some degree of aberrations and distortion; in some cases these may even be introduced on purpose - q.v. fisheye lenses and portrait lenses.

I have some lenses that I would term good or favorite because they seem to me to be lucky. That is, regardless of their technical merits or not, I always seem to get great pictures with them when I use them.

Now I would be the first to admit this is not scientific and indeed not necessarily that rational - but, in real world situations this feeling does result in me reaching for these lenses. And as photography to me is more about the pictures that I produce than anything else this is quite an important feature of what I would call a 'good' lens.

As an example, I have a m42 Schneider 35mm f2.8 curtagon that I can see is not technically the best lenses but does seem to get the pictures and have a higher hit rate than other lenses in that focal length.

No, that would be a perfect lens. And like most perfect things, this one doesn't exist either. All lenses have some degree of aberrations and distortion; in some cases these may even be introduced on purpose - q.v. fisheye lenses and portrait lenses.A good lens wouldn't turn a straight line into a curved rainbow. Unless you wanted that for an artistic effect.

A good lens to me is one that I can afford that takes good pictures. As of yet I have not found any that would qualify as a bad lens.

To me a 'Good Lens' is acceptably sharp wide open, with decent contrast and colour. It's got low distortion, preferably barrel distortion rather than moustache or pincushion. The out of focus rendering is smooth and round. It's neither massive nor tiny, has a reasonably damped focus ring, a smooth and positive aperture ring and doesn't tend to come apart when it spends a week at the bottom of a bag.

By those standards, most of my lenses are good and a couple are bad. The exception to the rule is the Sigma 24/2.8 Superwide II, which is good by optical standards, but a little recalcitrant from a handling perspective.

I've owned a few 'bad' lenses. Still have 2 (Kenlock 135/2.8 screwmount, Soligor 35/2.8 screwmount) as they aren't worth getting rid of, and the Kenlock actually produces decent images as long as I'm willing to scan them, add contrast and sharpen.

One that allows me to achieve my vision...... Exactly right. All lenses have unique capabilities. It's up to the photographer to match those capabilities with his vision. And like Ole said, you have to have that lens with you.....