Build

Both lenses are mainly metal and glass, with the SMC Tak 50/1.4 sporting a rubberized focus grip. Despite the much later production - the SMC Takumars are from the 1970s - the SMC Tak 50/1.4 focuses as smoothly and finely as all the wonderful Takumar lenses before it, including the Auto-Tak 55/1.8. The SMC Tak 50/1.4 is slightly bigger than the Auto-Tak 55/1.8, and it weighs 25 grams or so more, but both lenses are compact and solid-feeling. The top-of-the-line SMC Tak 50/1.4 has eight aperture blades, while the Auto-Tak 55/1.8 has six.

The Auto-Tak 55/1.8 has one distinct quirk - the aperture ring turns backwards from all other Pentax lenses. This can be somewhat strange when shifting between any other Pentax lenses (like, say, performing a lens test) especially if you try to memorize aperture clicks rather than looking down for each change. This certainly isn't an issue if it is the only manual lens that you own, but could be annoying if you own several.

I generally don't prefer the 'SMC Takumar' line, with its rubberized focus grip, to the previous 'Super-Multi-Coated Takumar' line, with the scalloped metal focus grip. But, in this case, the SMC Tak 50/1.4 is in excellent shape and is of an excellent build quality.

Physical Usage

The aforementioned reversed aperture ring aside, both of these lenses are very similar in use. They are both manual focus, and work stopped down. They both focus to about 0.45 meter.

For those who own other Auto-Takumar lenses, the Auto-Tak 55/1.8 is not one of the earlier versions with the stop-down lever on the side. It is essentially like the later Super-Takumar version.

Side view of both the Asahi Optical Co. Auto-Takumar 1:1.8 55mm, left, and the Asahi Optical Co. SMC Takumar 1:1.4 50mm, right.
Click here for to see the front elements.

This shot (warning - clicking on the image links to a 1.6 MB full-size file!) shows the sharpness and smooth bokeh the SMC Takumar is capable of, even at f/2.
Click here to see the Auto-Takumar 55/1.8 version of the same shot.

Sharpness

Both of these lenses are admirably sharp. To demonstrate this, I uploaded several full-size, unsharpened^* pictures, like the pair at f/2 for the SMC Tak 50/1.4 here and the Auto-Tak 55/1.8 here.

Bokeh

Unlike in Match 4 where neither was spectacular in its out-of-focus rendering, both of these lenses deserve their reputation. At f/4 and smaller, I find virtually nothing to nitpick with either lens. They have a slightly different character, but both offer smooth transitions to a creamy blur.

At widest aperture, both lenses have slight bright rings around their blur disk, as can be seen in the crops of the wheat field. But just one stop down from maximum, both lenses solidify nicely. Of course, the SMC Tak 50/1.4 is one stop down at f/2 - whereas the Auto-Tak 55/1.8 is essentially still wide open at that aperture. This is where the distinction between the two becomes quite obvious. The SMC Tak 50/1.4 at f/2 is already producing the sought-after creamy blur while still at a decent light-gathering aperture.

The SMC Tak 50/1.4 also gains an advantage with its two additional aperture blades. In the same crops of the wheat field, you can see the Auto-Tak 55/1.8's 6-bladed aperture more clearly than the same SMC Tak 50/1.4 shots.

Color

As you can see from all of the many samples, the SMC Tak 50/1.4 has a noticeably warmer (temperature) color than the Auto-Tak 55/1.8 does. In the digital age and with RAW files, this simply means sliding the temperature bar in post-processing, but could be an issue for those who still shoot film or shoot only JPEGs.