In today's used market, the Chinon 55mm f1.7 lens simply don't get no respect, to para quote Rodney Dangerfield; the f1.4 version is far better known but still quite inexpensive. Does the f1.4 version justify two to three times the price of the 55mm f1.7 for half a stop of more light? Would you be missing out much by using the cheaper f1.7 lens? The short answer is no. The Chinon (and many other makes with the same design) 55mm f1.7 is simply a superb lens for the price. In fact, I think the f1.7 version is a better lens in terms of sharpness across the frame in larger apertures.
Please keep in mind that I am shooting with one copy of each of these lenses. They are at least 30 years old and who knows what kind of abuse they went through before I got them. So, take the test images with a grain of salt, and test them yourself if possible.
Shooting side by side, the two lenses behaved very similarly in terms of bokeh, but the f1.7 version has a lead on the edges from the wide open on. Strangely, the 55mm f1.4 lens seems a tiny bit shorter than the 55mm f1.7. This is more apparent when flipping between the pictures taken by both lenses.
Note the colour temperatures of the images from the two lenses. The f1.4 version is warmer than the f1.7 version, but the colour changes slightly to the cooler side as the lens is stopped down on the Chinon 55mm f1.4. These images were converted from RAW but with no adjustments for the white balance, or sharpness.
A note of Auto White Balance. I have used digital cameras long enough to not to trust the consistency of automatic white balance. The colours sometimes change seemingly without any change in ambient temperature. This happens with Canon, Nikon, Pentax, and Sony, in my experience. I always shoot RAW and if necessary, adjust colour before the RAW conversion, but NOT in this test.
Wide open, both lenses are very good in the centre, with the f1.7 version slightly better at the edges. On both lenses, the left side is less sharp than the right side, a possible cause of the adapter that I use is not perfectly flat. Not shown in the crops, but the Chinon 55mm f1.4 vignettes quite a bit more than the 55mm f1.7. You can see the left edge of both lenses are quite poor wide open, but on the 55mm f1.7, it's quite a bit sharper on the right side. Both lenses show good sharpness at the center but contrast is a bit low.
Wide Open. Click on the picture to see a 100% crop.
By f2.8, both lenses sharpened up quite a bit more at the center, but the left edges are still poor on both lenses. Contrast has improved markedly and the right edge has become very good on the 55mm f1.7 but remains blurry on the f1.4.
f2.8. Click on the picture to see a 100% crop.
At this aperture, both lenses are quite sharp across the frame. Note the 55mm f1.4's left edge. The change is like day and night, though the right edge is still no match for the 55mm f1.7, which by this time, is as sharp as the center.
f5.6. Click on the picture to see a 100% crop.
This is probably the optimum aperture for sharpness across the frame for both lenses. A very slight softness caused by diffraction can be seen in the center of the frame, but not enough to cause concern. Even at f11, the 55mm f1.4's right edge is still out performed by the 55mm f1.7. Note the colour of the 55mm f1.4 is approaching that of the 55mm f1.7. Strange how aperture affects white balance.
f11. Click on the picture to see a 100% crop.
In Part III, we will compare the bokeh of both lenses.