old lens vs new--actual side by side comparisons?

[Armin Seeholzer]

Hi Mark

I did a testing of all my lenses about 2 years ago and I have a Symmar convertibel single coated tested against a new APO Symmar booth are 210mm and I was surpriced how good the almost 30 years older lens was in sharpness against the really deadly sharp 210mm APO Symmar.
I could not see a difference in sharpness with a 7x loupe only with the 8x the APO was a tiny bit sharper and contrastier.
I still use booth lenses beccause the older has the smaller back diameter so it fits on my Horseman HF the APO would not fit!
Between the 2 example the contast difference is much larger then the sharpness difference. So the APO is much contrastier then the single coated one.

[paulr]

Armin, I'm curious about what you mean when you say the contrast difference is much larger than the sharpness difference. Are you talking about contrast under high contrast light conditions (where you'd expect an uncoated lens to exhibit flare), overall contrast under all conditions, or edge contrast?

I ask because contrast is the primary optical ingredient in what we perceive as sharpness. In a print, it's the contrast of moderately high resolution image details that gives us a sense of a print being sharp.

[Armin Seeholzer]

Hi Paul

I did my test on a overcast day on a house wich is about 300-400m away. So on the APO the blacks where stronger then on the older lens and the print was contrastier from the APO but the details resolution was really only a tiny bit better on the APO.

[Madsen]

Zeiss Historica once made a comparison between a pre-war uncoated 50 mm 1.5 sonnar,
a post-war coated 50 mm 1.5 sonnar and a modern multicoated (t*) 50 mm 1.4 planar.

The resolution in center was nearly the same for all, but the flare level was higher for the
pre-war uncoated lens. Contrast was better for the multicoated planar.

The edge resolution and contrast was much better for the planar compared to the sonnars.

Unfortunately the comparison is partial because the sonnar did not exist in a multicoated version
and they did not test a single coated post-war planar. The pre-war uncoated planars was known
for a high flare level.

I think the improvements is mainly on the edges and regarding flare. It is also more
posible to tailor all lenses from one vendor to the same spectal responce (i.e. same color
response) than before.