Contruction vs. glass: this is the issue I had with Sigma lenses.
The glass was great; the 105mm 2.8 was actually sharper, in my opinion, than the Nikkor 105 2.8.
The multicoating was NOT the same; the Nikkor, if memory serves, was warmer. The Sigma zoom lenses ( I had the 35-70 2.8, and the 100-300 2.8) became noticeably wobbly after just 2-3 weeks of use. The glass is good, but the lens bodies are not up to professional standards.
Japanese lenses tend to have a warmer rendition than German lenses.
This is because Japanese lenses and coatings are calibrated for photos involving people with warmer skin tones,
and vise versa. This is why I prefer Fuji for some things, particular people photos, and Zeiss for others (nothing like
still life photos). With regard to lanscapes, it depends on what I am trying to do. Neither is a poor choice.
Don't know much about Rokinon, so I cannot comment.
But I do not discount what you are saying. There are some "sleepers" that can be had for a song:
One of the greatest lenses I ever used (in 35mm) was on a cheap Yashica 35 Electro: the Yashinon Color, 45mm 1.7.
The micro contrast is spectacular, it is sharp right out of the gate at 1.7, gets sharper up to about f8-f11.
Some research led to the discovery that Yashica, waaaay back in the day, at one point was actually making some of
the lenses for Zeiss. The Yashinon is nothing more than a Zeiss Tessar under a different name.
Tessars are sharp in the center at maximum aperture, but soft around the edges. As you stop down (f2/2.8) the edges begin to sharpen as well.
The planars (also a Zeiss design) are sharp across the image plane right off the rip, and just get ridiculously sharper as you stop down.
Now that enlargers are no longer popular, a source of good CHEAP used lenses is the wide array of enlarging lenses.
Enlarging lenses are critically sharp; they HAVE to be in order to enlarge 35mm negs. I still have a Schneider 75mm Componon,
a lens made for enlarging. It is frighteningly sharp at all apertures. I used to play around with it on my large format cameras years ago. They are spectacular for photography, but the image circle they project was not big enough to cover a 4x5, let alone an 8x10 image plane. Then again, the lens was made for the 6x9 format.
As for the sharpest lenses I have owned, I would call it a toss up among:
75mm Fujinon on the GS645 Fuji rangefinder. (fixed lens)-I have shot 11x14, 8x10, 5x7, 4x5, 6x9, 6x8, 6x7, 6x6, 645, 35mm and digtal, full frame and cropped sensor formats, and NOTHING made by ANYONE exceeds the clarity and biting sharpness of this lens.
100mm Carl Zeiss 3.5 for the Hasselblad V system. Most people who own a Hasselblad V opt for the 80mm Planar, a spectacular lens. the 100mm is recommended by Hasseblad "when critical sharpness" is necessary. It is actually too sharp for portraiture, in my opinion.
Zuiko 45mm 1.7 G, a spectacular lens for 35mm. (fixed on the Olympus 35 SP rangefinder.)
Zuiko lenses are generally on the level of Canon and Nikon's best in terms of sharpeness, but THIS lens is
so sharp that the 35mm negs can pass for medium format at a quick glance.
There is a 3D quality that the 35mm 1.8 has. This lens can be had for as little as 50 bucks, but it s manual focus only.
A lot of artist types use the lens for cine because of the unique way of drawing a scene some of the Zuiko lenses have.
I am STILL looking for a good, clean
example of this camera to replace the one I foolishly sold years ago.
That being said, it is relatively easy to make a sharp lens. It is not sharpness alone that attracts me to a lens, but character.
Olympus Zuikos are sharp enough, but the old school Zuikos have a dreamy quality to the out of focus areas (bokeh) that none of the others have. I love the microcontrast of zeiss lenses, rivaled only, in my experience by Fuji.
If I had to have only one lens to shoot everything it would have to be a Fujinon or Zeiss. Why? Warmth, critical sharpness, and tonality. Zeiss lenses are clinically sharp; Fujis are just as sharp but seem to dig into shadows deeper, yielding a distinctive tonal character to black and white images. If sharpness alone is your thing, NOTHING made by ANYONE beats a Carl Zeiss lens. If I could only have ONE: Carl Zeiss 80mm Planar for Hasselblad V system. Unbeatable lens.
Sorry to be so long winded, but I could go on about glass for days.
