Quote Originally Posted by Klainmeister View Post
I do know this: with BW I find the difference to be not quite as apparent (adjust development, printing, etc) but with chromes I hugely can see a difference. One has a punch and the other looks dull, and when it's all said and done, I could compare the same scene with same conditions and film and clearly tell which one had better glass/coatings in relation to contrast. A side effect of a higher contrast lens is apparent sharpness too. Whether or not it's actually sharper isn't the issue, but the perceived sharpness because of the high contrast lens will definitely stand out.
With chromes you cannot control black point. With prints you can. Besides, the overall contrast of a chrome is higher than that of a print, so differences show more. When printing the black point can be rendered as desired by the printer and up to a certain extent the "overall contrast" of a "low-contrast lens" can be recovered. For "overall contrast" I mean the absolute difference between black point and white point. The "low-contrast lens", at that point, will show an image with a deep black but not much detail in the shadows. The "high-contrast lens" will have the same black point, but more details in the shadow.

With slides, the low-contrast lens will not reach the level of "blackness of the blacks" of the other lens. That will immediately appear as a "less lively" image to the eye when the two are compared. Colours will appear less saturated. In my experience perception of colour saturation is well dependent from overall contrast. The distance between black and white point determines how "lively" an image is.

As said, the soft-contrast lens (or at least the non-coated lens) will probably also lack some acutance, or "micro-contrast", which is perceived as "sharpness".

The simple, real-life test mentioned in this thread could be made, perhaps, by taking pictures with the same camera, same light conditions, same exposure, different lenses and slide film, and then measuring the difference between higher density and lower density points, which gives the "overall contrast".