Fun and Focus with the Nikon 135mm F2 DC AF-D

When I was a wee lad I followed Ken Rockwell’s website. I always used to salivate over the more expensive Nikon lenses as I puttered around with my kit lens on the D90, a crappy 70-300mm tele that ended up stolen, and at long last at the end of high school an 80-200mm F2.8 AF-D.

The one lens I was always super excited to try was the 135mm F2 DC. Often called “the” portraiture lens, it’s a relic from the bad old days of film photography in 1990 when men were men and Nikon still made lenses out of metal and used the old style screw autofocus.

First, the results

Returning for thanksgiving on a redeye from Seattle to Boston, I had one backpack plus this monstrous camera, so I had a vested interest in the results.

Evaluating Coolness of Lens

So what’s special about this lens?

  1. Sharp (some on the internet balk at lack of razor sharpness wide open at F2, but it will do just fine)
  2. 135mm focal length provides for great portrait framing on FX form factor (it can be a little tight at ~215mm equivalent on DX cameras)
  3. Has “Bokeh Optimization” control

I also had the perfect storm aka enough money from my new employment that I wouldn’t have to go hungry if I picked up one of these bad boys. I also feel a lot better investing in this than a more expensive DSLR due to resale value. I was able to pick this up used for just $1000 on Amazon.

Which camera to pair with it?

The D90 was getting a little long in the tooth (plus my sister somehow managed to break the half-press on the shutter release such that you had to use the AF/AE Lock button programmed as AF-On to get to focus in AF-C mode). I knew it was time for an upgrade.

I ended up deciding to go with a used D700 instead of a D810 or D750. The camera originally dates from ’08 and was made up until 2012. Of course, the current year being 2016, makes this a thoroughly out-of-date camera. Here were my reasons for making this decision:

  1. I cared primarily about the FX sensor size. The D700 is the cheapest Nikon (new or used) that provides that feature. I already had the 80-200 AF-D which would encourage me to continue down the FX path, and FX equipment tends to be more pro oriented (better manufactured, faster) not to mention the longer focal length gets better bokeh.
  2. It can pass just fine at 3200-6400 ISO.
  3. Reasonably up-to-date (second to last gen) AF module with 55 points.
  4. I prefer pro cameras that have multiple wheels and dedicated buttons for ISO, AF, etc.
  5. Works with the crazy grip that allows easier holding in portrait mode, better weight, and longer battery life. Can alternatively shed grip and go with the 50mm F1.8 for a standard setup.

The major downside is that better (all metal) construction means heavier. There are significant benefits to user experience with a DX rig like the D3400 and a collapsible kit lens simply due to weight (so I picked up one of those too 😛 ).

What is this Bokeh Optimization?

I’ll defer to Ken Rockwell’s explanation on the topic in more detail. Basically an ideal lens has perfectly circular bokeh, which are the little blurs the are created by out of focus points of light in an image. The collective shape of the bokeh determine the texture of the out-of-focus regions in an image.

The conundrum is that bokeh is more aesthetically pleasing when it is brighter in the center than at the edges. Lenses normally have fixed bokeh performance, which depends upon the optical design. Good bokeh behind the subject means bad bokeh in front and vice versa.

So apparently the “BO” acronym didn’t ring well to the Japanese, so they chose “Defocus Image Control” and then apparently DIC wasn’t a great acronym either so they went with “Defocus Control” or DC which makes no sense in English and seems to imply that the lens comes with an adjustable sheet of wax paper that can make the image softer a la Holga.

How does this difference look in practice? We’re now delving into the subtleties so most people will just say “eh” and not care, which you have every right to do.

The following is an example of an out-of-focus wine glass to the rear of the focal point. In particular, take a look at the upper right corner where there’s a much better blending of the little spheres.

Comparison of the lens bokeh on different Defocus Image Control settings
Comparison of the lens bokeh on different Defocus Image Control settings

It’s not going to make or break a photograph in the sense that your average Joe will point at it as an imperfection, but since photography is all about mood and aesthetics, these things matter 😉

It definitely enhances the appearance of the background, especially with contrast-y backgrounds. The added ability (should you ever have the bizarre need) to optimize for front-of-subject bokeh is a neat trick.

What do I think?

I really love this lens. Here are some basic reasons:

  1. It’s a fun focal length which makes you frame more interesting pictures. iPhone photographers do end up a bit distressed when handed this lens, but the frame encourages the photographer going to be more intimate. You’ll need to feel comfortable getting close up, and that’s what this lens is designed for. It’s too tight to frame lame and classic whole group shots or pictures of every pie on the table at Thanksgiving. In a world where smartphones have excellent picture quality, the DSLR has to bring something new and interesting to the photographic field and this lens does just that
  2. The pictures stand out because most people don’t bother to carry real cameras anymore. The contrast between the out of focus and in focus regions makes the pictures really pop.
  3. It’s fast enough to work with natural lighting even in difficult circumstances on older cameras.

A few problems I’ve had:

  1. The depth of field is devastatingly shallow at F2. I started out doing most of my shooting at F2.8 to get a bit more wiggle room and better sharpness, which I think gives a good compromise. I’ll post some real-world examples as I get more experience.
  2. You’re going to have to know this lens and work with it. The frame and depth of field require that you arrange the subject matter cognizant of the lens characteristics.
  3. Ergonomically, the control for Bokeh needs to be set independently of the aperture, so it’s best to leave the camera in A mode. Shifting requires two adjustments unless you give up on the Bokeh adjustment (but that’s why you bought the lens, right?).
  4. After one family holiday’s worth of shooting, I noticed that a distressing number of the pictures were focused more towards noses than eyelashes. Internet reports mentioned that this lens tends to “front focus,” i.e. focus in front of your subject. Therego:

This was the picture that made me realize:

A relatively controlled portrait
A relatively controlled portrait

Obviously in practice, focus is going to be a bit of a crapshoot, especially when your depth of field is paper thin. This is at F2.8, not even wide open.

This was one of a series of images taken while both of us were seated, and you’ll note that the tip of Ben’s nose is in focus while the eyelashes are not. Had it been one image I wouldn’t have worried, but this was a trend. At this point, I realized that the internet was right and I had to verify the lens was focusing correctly.

AF Fine Tune

In short time, I had found a website with a decent homemade focus calibration setup (as well as about a dozen trying to sell me one…which is like paying for pre-assembled tupperware).

It was actually the first project I’d ever assembled using almost entirely paperclips:

This is a focus target and distance ruler for testing purposes
This is a focus target and distance ruler for testing purposes

Basically the idea is that it provides a target to focus upon; then a tilted ruler with its center matched to the target distance will show you the plane of optimal focus and you can verify that it’s showing up where you expect it. Ideally, two “units” back will be just as fuzzy as two units in front if you’re focused at the middle.

Comparison of the AF performance after correction with the original
Comparison of the AF performance after correction with the original

As I suspected, uncorrected there’s a pretty clear front focus of about 2 “units” (probably 1-2 cm). After maxing the AF Fine Tune correction out at +20, it looks just about right.

As you can see, it’s not the most glamorous device ever created (the bold black line on the ruler is supposed to line up with the mark on the focus plane). The important thing is that the focus point on the target match the distance to the bold line on the ruler when viewed from the camera.

Here you can see the perpendicularityness of the jig
Here you can see the perpendicularityness of the jig

Importantly I’m not sure whether this is a lens thing or a camera thing or a lens+camera thing so I’ll repeat this with another lens to see if I get similar results. Supposedly lens + camera combinations with respect to AF can cause two in-spec devices to operate out-of-spec when their combination adds errors together.

Anyways, hopefully next thanksgiving’s pictures will have subtly better focus 😉

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