In article ,
says...
I am getting one of these old M42 manual lenses for use on a slightly
newer 1.3x crop DSLR via an adapter. The price for the Super Takumar
is considerable higher than the price of the Pentacon - but neighter
will break the bank - so the price doesn't matter. The Pentacon is
mint, the Super Takumar shows some wear, but the glass is in good
shape and the controls are smooth.

Which one is the best (resolution, contrast, colour)? I am aware
that the Super Takumar is almost one stop faster, so I am leaning
towards that one - but would like to hear from someone that has
actually used either lens.

I understand that the old lenses have some limitations compared to
modern lenses - e.g. that there is no aperture coupling, and that they
won't meter on a modern camera. But how do these 30 year old (?)
lenses compare /optically/ to modern 50 mm lenses such as a Canon or
Nikkor 50mm f/1.4?

From experience I would go with the super tak. Check to see if it has
yellowed which can be fixed but is time consuming.