the nikkor 105mm f/2 DC lens..what's teh story here?

Qarik

the DC stand for defocus control which allows you to control focus over the foreground or background blur..what does that mean? how does this work?

http://www.nikonusa.com/Find-Your-Nikon/ProductDetail.page?pid=1932#tab-ProductDetail.ProductTabs.TechSpecs

ziggy53

According to the Nikon description of the lens, "Photographer can control the degree of spherical aberration in background or foreground elements for more creative control."

In addition to the rear elements which move together for focusing, some of the other elements move/shift with the "DC" control ring to induce spherical distortion into the optical properties of the lens. When you apply a stronger level of spherical distortion, you are encouraged to also stop down the lens, countering some of the induced distortion with the smaller "circles of confusion" consistent with the smaller apertures.

If you try to shift the DC control much beyond the recommended aperture settings (i.e. too much DC and not enough aperture), things get ugly quickly. Chromatic distortion also increases with high levels of DC, so moderation is generally preferred.

Using the DC ring also affects prime focus, so the procedure is; set the desired DC level and direction, then focus.

Matthew Saville

It's Nikon's voodoo, techno-jargon way of making up for not being able to match Canon's bokeh. :-P

Okay but seriously, that *kinda* sums it up. Canon enlarged their mount so they can cram as much glass as they please into their lenses, making both an 85 1.2 and a 50 1.2 that have truly gorgeous bokeh. They also make a gorgeous 100 f/2 and 135 f/2 L, with equally creamy background blur, and almost equally stunning sharpness.

For whatever reason Nikon primes are CLOSE, but not quite. We might be able to blame the smaller mount, or we might be able to blame a more conservative design philosophy in general, considering that Nikon has not had a very good history with expensive, massive primes. They probably felt hurt by the lack of 28 1.4 AFD sales, and decided that the big bucks were in f/2.8 zooms at the time. Which is what they focused on for quite a while, making some dang sharp 2.8 zooms while Canon's 2.8's were slightly lacking as digital came around and megapixels started to climb. (I think that at 21 megapixels, they're totally out-resolving slightly older lenses like the 16-35 mk1, the 24-70, etc...)

Anyways, I digress, sorry about the opinions / history. Bottom line- The Nikon 105 f/2 and 135 f/2 are GREAT lenses, very sharp with GOOD bokeh that does rival the Canons quite closely. I can highly recommend either of them, with the 135 being my favorite on full-frame. Great for candids. If you get one of these lenses, you'll probably play with the DC controls once or twice, and then never touch it again. (Though I guess that does depend on your line of work...)

=Matt=

Qarik

ziggy53 wrote: »

According to the Nikon description of the lens, "Photographer can control the degree of spherical aberration in background or foreground elements for more creative control."

In addition to the rear elements which move together for focusing, some of the other elements move/shift with the "DC" control ring to induce spherical distortion into the optical properties of the lens. When you apply a stronger level of spherical distortion, you are encouraged to also stop down the lens, countering some of the induced distortion with the smaller "circles of confusion" consistent with the smaller apertures.

If you try to shift the DC control much beyond the recommended aperture settings (i.e. too much DC and not enough aperture), things get ugly quickly. Chromatic distortion also increases with high levels of DC, so moderation is generally preferred.

Using the DC ring also affects prime focus, so the procedure is; set the desired DC level and direction, then focus.

so in effect you can make the bokeh "rounder"? for lack of better word?

sethny

Matthew Saville wrote: »

It's Nikon's voodoo, techno-jargon way of making up for not being able to match Canon's bokeh. :-P

Okay but seriously, that *kinda* sums it up. Canon enlarged their mount so they can cram as much glass as they please into their lenses, making both an 85 1.2 and a 50 1.2 that have truly gorgeous bokeh. They also make a gorgeous 100 f/2 and 135 f/2 L, with equally creamy background blur, and almost equally stunning sharpness.

For whatever reason Nikon primes are CLOSE, but not quite. We might be able to blame the smaller mount, or we might be able to blame a more conservative design philosophy in general, considering that Nikon has not had a very good history with expensive, massive primes. They probably felt hurt by the lack of 28 1.4 AFD sales, and decided that the big bucks were in f/2.8 zooms at the time. Which is what they focused on for quite a while, making some dang sharp 2.8 zooms while Canon's 2.8's were slightly lacking as digital came around and megapixels started to climb. (I think that at 21 megapixels, they're totally out-resolving slightly older lenses like the 16-35 mk1, the 24-70, etc...)

Anyways, I digress, sorry about the opinions / history. Bottom line- The Nikon 105 f/2 and 135 f/2 are GREAT lenses, very sharp with GOOD bokeh that does rival the Canons quite closely. I can highly recommend either of them, with the 135 being my favorite on full-frame. Great for candids. If you get one of these lenses, you'll probably play with the DC controls once or twice, and then never touch it again. (Though I guess that does depend on your line of work...)

=Matt=

true , everything

still canonians don't have the 180 2.8

we don't have the 1.2 85

while sony gives stabilization to all the lenses , and the best FF sensor (to us too)

ziggy53

Qarik wrote: »

so in effect you can make the bokeh "rounder"? for lack of better word?

Normally a lens designer will try to create a lens corrected for spherical aberration. The Nikon DC lenses are corrected for spherical aberration in their center/neutral position of the DC ring, but they allow adjustment of spherical aberration via the adjustment of some of the elements, and that adjustment is controlled via the DC ring.

The following link shows spherical aberration (top, "A") versus a properly corrected optical design (bottom, "B"):

http://131.229.114.77/microscopy/images/var12.jpg

Think of it as more of a light scatter property, but it can also create color fringing because the different wavelengths are also shifted in focus by the aberration.

Matthew Saville

sethny wrote: »

true , everything

still canonians don't have the 180 2.8

we don't have the 1.2 85

while sony gives stabilization to all the lenses , and the best FF sensor (to us too)

Each has plenty of advantages, and each plays up those advantages in ways that the others can probably never match. If I were a rich camera geek instead of a poor one, I'd own at least three full DSLR systems I bet. :-)

=Matt=