Digital BW, The Print

Peter,

> 
> I think your criticism is simply of the particular Canon shift lens you
> own,

The fact that the lens is both a shift and tilt exacerbates the problems.
It suffers from the wider image circle as well as the greater rear element
to film distance (more radical retro-focus design).

> and unfair in that you are talking of using it for something it was
> not designed for.

I have owned 5 Canon tilt shift lenses, all of which were for film cameras.
I love what then can do, but optically, the wide angle ones are just not up
to the standards I expect of good 35 mm lenses.

> For years I shot almost everything I took on 35mm on
> an Olympus shift lens, and it was an excellent performer, sharp into the
> corners even at full shift. Just a pity it doesn't fit on my Nikon.

The shift-only lenses only have half the problems of the tilt-shift.

But, to get equal quality from a larger image circle, it takes a better,
more expensive lens.  I'll bet you paid a premium for that lens.


> There are a lot of reviews that do seem to show the 'sweet spot'
> argument is a good one,

The "sweet spot" of especially a wide angle lens is going to be better than
it's edge.  But, again, all else being equal, a designer could make a better
lens all the way to the edge if the circle could be smaller.  It's a
trade-off.  More money, of course, can allow them to make great retro-focus
lenses with huge image circles.  But they would cost a bundle.  Cost is a
huge factor.

I'd guess, for example, that the Canon 16 - 35 L is about as good as the new
Tokina digital 12-24 -- but the Canon is 3 times the cost.

> However the main point of some of the reviews is that some lenses
> designed for film are not capable of getting the best out of some
> digital cameras (even full-frame digital.) This is true of some very
> expensive glass that performs well on film. Lens designers do usually
> now claim to be designing for digital, and this does seem to mean
> something, not just marketing talk.

> Although the lack of a mirror made it possible to design great
> wide-angles for rangefinders (and I'm a great fan of some of these, with
> a 15mm, 21mm, 24mm and 28mm that are great as well as an 'interesting'
> 35mm f1.4) unfortunately they don't seem to suit digital cameras.


Exactly, in addition to the greater need for anti-reflection coating on the
rear element, I assume you've seen the un-processed wide angle shots on the
Epson Leica copy.  They are outrageous.  The light fall-off is terrible.
The obtuse angle of the light that the non-retro-focus (outstanding) Leica
or Cosina lenses result in produces a huge problem.  While raw processing
can take care of it, in part, this is yet another factor that robs our very
scarce dynamic range.  Until there is a major advance in digital sensors,
symmetric wide angles are probably not serious contenders, which means those
who buy these digital Leicas for their great wide angles may be
disappointed.

Paul
www.PaulRoark.com