Build

Both of these lenses originated at roughly the same time; the Helios 44M-4 started production in about 1982 and the Pentax-A 50/1.2 two years later. As such, they are both made of metal, glass, and rubber - the only plastic on them is the lens caps! Both lenses feel well-made, sturdy and secure. They have long, smooth focus throws, although the Helios 44M-4 is a bit too stiff. The Helios 44M-4's vulcanized rubber scallopped grip doesn't have the same fine feel of the Pentax-A 50/1.2.

The Pentax-A 50/1.2 has 9 aperture blades compared to the Helios 44M-4's 6. Both are straight, not curved, blades. Some Pentax 50/1.2s have asymmetrical aperture blades but mine is fine in this regard.

Size & Weight

The Pentax-A 50/1.2 is slightly heavier than the Helios 44M-4 at 345g vs. 290g. While there is impressively more glass on the Pentax-A 50/1.2, they both feel substantial and balance nicely on both the K10D and *ist DS.

Conveniently for this comparison, both have 52mm front threads.

Physical Usage

The Helios 44M-4 lacks even an auto/manual switch, making it slightly less convenient than a normal M42 lens. Thankfully I have a modified adapter allowing me to use auto-aperture M42 lenses in stopped-down mode on my cameras, but the lens is thus restricted to a single adapter.

The Pentax-A 50/1.2 allows all 'auto' features of both the K10D and the *ist DS (except - obviously - focus) and is therefore much easier to use on those cameras. Simply being able to dial in exposure compensation via the e-dials is alone important enough to give the edge to the Pentax-A 50/1.2 in this regard.

Side view of both the KMZ Helios 44M-4, left, and the SMC Pentax-A 1:1.2 50mm, right.
Click here for to see the front elements.

This 100% crop (click on the photo for the full-size version), taken at f/4 by the Pentax-A 50/1.2, shows good sharpness even at wide-ish apertures.
Click here for a gallery of pictures comparing the sharpness of these two lenses.

Sharpness

While both of these lenses are acceptably sharp at all apertures, when compared at comparable f-stops, the Pentax-A 50/1.2 has a slight edge. Neither the Pentax-A 50/1.2 nor the Helios 44M-4 leaves anything to be desired as far as sharpness goes.

Bokeh

The Helios 44M-4 renders out-of-focus areas, if not outright attractively at all apertures, at least surprisingly neutral. Shooting the Helios 44M-4 at f/2 can lead to semi-circular bright rings around specular highlights, and at f/4 and smaller the 6 aperture blades are clearly visible. Yet the Helios renders a smooth focus-to-out-of-focus transition and low-contrast scenes render pleasantly with both foreground and background bokeh.

The Pentax-A 50/1.2, by comparison, has a distinctively pleasant bokeh at f/2 and smaller apertures. Even at f/1.2 the Pentax-A 50/1.2 is less prone to bright rings and the axial color that is a hallmark of Pentax lenses.

The Pentax-A 50/1.2 does suffer more from purple fringing on slightly out-of-focus objects than on those in the plane of focus, which can be a problem in difficult high-contrast subjects This is a small enough percentage of situations that it rarely will show in 'normal' shooting conditions.

Click here for a gallery comparing the bokeh of these lenses.

Purple Fringing

The Pentax-A 50/1.2 shows very slight purple fringing at f/2 that trends upwards as you move towards f/1.2. I have found the focus point to be critical in this regard - a front- or back-focused image will display more purple fringing than a focused shot on the same subject.

The Helios 44M-4, impressively, is virtually free from purple fringing at any aperture.

Click here for a shot demonstrating the purple fringing possible on the Pentax-A 50/1.2. At f/2, the Pentax shows considerably less (click here) and the Helios shows none at f/2 (click here).

Specular Highlights

Rendering bright highlights can be problematic for many lenses. For out-of-focus highlights, both the Pentax-A 50/1.2 and the Helios 44M-4 perform well at f/4 and smaller. At f/2 the edge goes cleanly to the Pentax-A 50/1.2 (which at f/2 is one-and-a-half stops down from maximum aperture) and the Pentax-A 50/1.2 performs decently even at f/1.2.

The Pentax-A 50/1.2's 9 aperture blades promote a more circular and less noticeable shape than do the 6 for the Helios 44M-4.

Looking at in-focus highlights shows a much more pleasant pattern in the Pentax-A 50/1.2 than in the Helios 44M-4.

Close Focus/Magnification

Both the Pentax-A 50/1.2 and the Helios 44M-4 focus to similar magnification. Neither is useful for macro work without extension tubes.

Low-light Capabilities

At widest apertures, the Pentax-A 50/1.2 is one-and-a-half stops faster than the Helios 44M-4. Even with shake reduction, high ISO, and a relatively shallow focus plane, I still find it comforting that I can shoot between f/1.2 and f/1.8 in really low light. This is obviously impossible for the Helios 44M-4, although it should be noted that because the Helios 44M-4 is sharp at f/2, it certainly is usable at that aperture.

The Pentax-A 50/1.2 also has the acclaimed 'SMC' coatings, which lead to greater light transmission than the lesser coatings on the Helios 44M-4.

The 6 aperture blades of the Helios 44M-4 can make specular highlights more noticeable as in this 100% crop.
Click here for a gallery showing how each lens renders specular highlights.