HD Pentax-D FA* 85mm F1.4 ED SDM AW

Comparison with the FA 77mm F1.8 Limited

As a short tele portrait lens, it is inevitable that the D FA* 85mm will be compared to the other current Pentax lens close to that focal length, the FA 77mm F1.8 Limited.

The new D FA* lens is two-thirds of a stop faster, and impressively larger and heavier. The FA 77mm was introduced in 1999, 21 years before the D FA* 85mm. Still, even now, the FA 77mm is among the most beloved lenses in the Pentax lineup.

In this section we take a look at differences in the images produced by those two lenses. Instead of comparing test charts, we photographed the same scene with the two lenses, without moving the tripod. This results in a slightly wider field of view for the 77mm. We captured the same image at F2, F4 and F8. We selected an image with a busy background, a subject with both smooth and complex textures, and sharp brightness transitions.

Comparison at F2

The following images illustrate the complete scene. You can click on the thumbnails for larger views, and see full-sized versions.

D FA* 85mm	FA 77mm Limited
Full size	Full size

Looking at the global picture, the differences between the two images are minimal. Mainly, the background blur appears marginally smoother with the 85mm. The longer focal length can explain this, in part at least. The bright forehead seems to show more tonal gradations with the 77mm, but really the difference is hard to spot.

We then take a look at five distinct sections:

• the black eye where the focus point was set
• the base of the unicorn's horn
• the braided hair
• the background at the top right
• the background at the center left

As above, thumbnails can be clicked for larger views.

D FA* 85mm	FA 77mm Limited

At F2, the 77mm shows some purple fringing, something not visible on the 85mm's images. This explains in part why the 85mm's image appears sharper.

Looking at the horn, the 85mm creates subtle ring patterns on the blurred glitter spots, while the 77mm produces a more uniform result.

In truth, apart from the lack of purple fringing and the higher resolution on the 85mm, images produced by the two lenses are close in appearance.

Comparison at F4

We captured the same scene at F4. You can click on the thumbnails for larger views, and see full-sized versions.

The following images illustrate the complete scene. You can click on the thumbnails for larger views, and see full-sized versions.

D FA* 85mm	FA 77mm Limited
Full size	Full size

Again, the images do not show important differences when seen as a whole.

We then take a look at the same five sections as above. Again, the thumbnails can be clicked for larger views.

D FA* 85mm	FA 77mm Limited

At F4, the purple fringing is gone, but the 85mm still produces sharper images. Note that the in-focus elements are close to the center, where the D FA* 85mm excels.

The out-of-focus rendering is essentially indistinguishable between the two lenses.

Comparison at F8

Lastly, we look at the scene at F8. You can click on the thumbnails for larger views, and see full-sized versions.

The following images illustrate the complete scene. You can click on the thumbnails for larger views, and see full-sized versions.

D FA* 85mm	FA 77mm Limited
Full size	Full size

For all practical purposes, there is no difference between the two images, apart from the tonal difference on the bright forehead where the 77mm still shows gradation.

We still consider the same sections. As above, thumbnails can be clicked for larger views.

D FA* 85mm	FA 77mm Limited

Here, the crops are almost completely identical. One could argue that the background highlights are slightly smoother on the 77mm, but again this is splitting hairs.

Conclusion

The first takeaway from this comparison is that, concerning the rendering, the older FA 77mm Limited and the newer D FA* 85mm are extremely close together. This is both a testament for the quality of the 77mm, since it can hold its own against a completely new product, and to the 85mm which is far from being overshadowed by one of the stars of the K-mount.

The newer lens does pull ahead on two aspects. First, it controls purple fringing better than the 77mm. Second, at wide and medium apertures it is sharper in the center. Of course, it is also two-thirds of a stop faster, offering F1.4 against the 77mm's F1.8.

These three perks could be enough to sway potential users. On the other hand, the 77mm is cheaper and smaller, two perks that should not be neglected.