Back in the glory days of the Minolta manual focus system, cameras were normally sold with a 'normal' focal length lens as the standard lens to come with the body. These weren't the poor quality standard zooms that often come packaged with today's cameras, but high quality, single focal length lenses, of between 45mm and 58mm depending upon era and budget.

Many of the questions asked by owners of manual focus equipment relate to these lenses, and include such questions as "What difference is there between the 50mm MD and MC lenses?", "Is the 50mm f/1.2 better than the 58mm f/1.2?", "Will the 50mm f/1.4 be sharper than my 50mm f/1.7?" and innumerable variations upon these themes.

While there are numerous posts in various discussion groups answering these questions and many more, to the best of my knowledge until now no-one has published on the web a comprehensive test of the lenses side by side. Now you, the user, will have the chance to judge for yourself between them.

The lenses tested comprised examples of most of the normal lenses most commonly available, and my thanks go to Bob Flegg and Robert Hoehne for their provision of several of the test lenses for the comparison. The lenses tested were:

50mm f/1.2 MD Rokkor-X

vs.

58mm f/1.2 MC Rokkor-PG

The 50mm f/1.2 MD Rokkor-X and the 58mm f/1.2 MC Rokkor are the two big guns of the Minolta normal lens line up. Expensive and heavy, they have a reputation for being great performers in low light as well as being sharp and contrasty for general photography. Certainly the viewfinder image is a joy to behold when using one of these lenses. However how will they perform in the Ultimate Normal Lens Challenge?

You may have already seen my initial head to head test of these lenses conducted some time ago. In that test they performed effectively on a par against each other, but it was a very basic test, and conducted at a distance of only about 3 feet with files scanned at 2200 dpi. This test has been conducted at a greater distance, more in line with the types of distance that would commonly be used for portraiture or general photography. Additionally, my testing methods have been enhanced since that first test, with images scanned at 5400 dpi, and a more consistent test subject. Additionally, the bokeh and light fall-off of the lenses will be tested, so you can judge for yourself the results in this respect.

Above we can see the performance of the two lenses from centre and corner crops at f/1.2. Results show relatively poor detail with both lenses, and poor contrast. It should be noted however that this is a challenging test target (not particularly high contrast) and that this crop reflects an area of less than 1mm square on the original negative. At the screen resolution above (at standard 72dpi) the equivalent print size would be 6 feet by 9 feet.

Based upon my review of the images from which these crops were taken I conclude that at f/1.2 the 50mm is just the tiniest fraction sharper than the 58mm, but really, it's like comparing the sharpness of two kitchen spoons - sure, one might have a slightly sharper edge than the other, but you wouldn't want to have to peel vegetables with it.

The loss in contrast evident above is not immediately apparent in general photography, and in fact at reasonable enlargement sizes both lenses do deliver sound results wide open - just don't expect pin-sharp 16' x 24' prints.

However it is obvious that with both lenses at f/1.2 the resolution is unsatisfactory for high detail reproduction, as would be expected. At this aperture the lenses are designed to be used in extremely low light, enabling the photographer to achieve a result that would be otherwise unattainable. In fact with 3200 speed film and shooting wide open with the 50mm f/1.2 I have taken photos handheld that were virtually in the dark.

The shot below is an example of what can be achieved at f/1.2 with the 50mm f/1.2 MD Rokkor-X. While not bitingly sharp the shot is one of my favourites.

At f/2 the story is quite different. While both lenses have performed considerably better than at f/1.2, the later model MD lens appears to have pulled away from the 58mm in terms of both contrast and resolution. If you look closely in the centre crop you can actually see the double line of some of the highways. When you consider that these lines are approximately 0.5mm apart on the original poster that is a quite incredible result.

The corner sharpness of the 50mm also appears to be slightly better than the 58mm, with superior contrast as well. I feel comfortable saying that in terms of resolving power the 50mm outperforms the 58mm by a comfortable margin at f/2.

At f/8 the both lenses are performing very well, and at this level they both would be comfortably resolving well over 50 lppm. This is the best aperture tested in terms of sharpness for both lenses, but the 50mm is still clearly a superior performer when compared to the 58mm. Both lenses record excellent corner sharpness.

To test each lens in their rendition of bokeh I set up a challenging target with lots of distracting highlights in the rear. Note, this is an extreme bokeh test! The lenses were tested wide open at f/1.2, and again at f/4, what I would consider to be a normal portrait aperture when photographing in daylight.

In terms of bokeh the 50mm does do a good job. The test above is an extreme one with literally hundreds of highlight spots, and normal use would see a much nicer blur. The lens exhibits neutral bokeh, that is, the individual highlights are rendered as an even disc of light, but in this test there is no doubt that the 58mm is clearly superior, showing that creamy out of focus texture that it is famous for, despite the bright highlights in the background. A closeup of the individual highlights is shown below:

The performance of the 58mm in this respect may partly be due to the reduced depth of field caused by its longer focal length, but that is only a small part of the reason. What this lens loses from the 50mm in terms of resolution it makes up with this outstanding out-of-focus rendition.

At f/4 the area out of focus is of course better defined, and you might expect that the bokeh rendition of the lenses will be much closer. Let's examine the shots and see.

The bokeh of both lenses appears good, but the 58mm still definitely has an advantage. This is more obvious on closer inspection. The 58mm has an eight bladed diaphram, as opposed to the six blades of the 50mm. This means that at intermediate apertures such as f/4 the 58mm retains a much more rounded out of focus highlight, unlike the 50mm where the highlights are now obviously six sided.

The 58mm retains highlights that are near round.

Bokeh Summary

One of the issues when shooting with faster lenses is the natural light falloff that occures at the extremities of the frame when shooting at, or close to wide open. Most visible when taking photos of regularly toned subjects, like landscapes with blue skies or light coloured walls etc, it manifests as a darkening of the frame at the corners.

If you shoot with negative film this may not be an issue for you, as it can often be addressed in the printing process. However with slide film a drop of a stop or so in the corners may cause them to be irretrievably darkened, and can ruin a good slide.

Virtually all lenses exhibit a degree of light falloff at wide apertures, and the real sign of a lens that handles this well is when this falloff is gone after closing down a stop or two. Lets see how the two ultrafast Minolta primes handle falloff.

Methodology for this test is as follows. The test target includes an area of white at both the centre and the extreme top left corner. The centre area is selected and adjusted in photoshop to be the white point for the image. A crop is taken from this area, together with a crop from the corner, and the resulting crops are desaturated, and placed side by side below.

The image to the right shows two sets of crops. The top two are from the 58mm at f/1.2, the bottom two from the 50mm at f/1.2.

As can be seen, both lenses exhibit significant falloff at f/1.2 when using slide film. As discussed above, this falloff will be less noticeable, but still apparent when using negative film. When seen side by side the falloff seems particularly significant, but when seen in terms of the full image it is lessened to a degree by the distance between the crops. For example, refer to the crop below of the full image from the 58mm f/1.2.

At f/4 the falloff is virtually eliminated on both lenses. The level apparent on the 50mm f/1.2 is negligible, and would not even be noticed when shooting a broad expanse of a solid colour. The falloff recorded bythe 58mm is slightly higher, but also would be effectively invisible in any print. To see the evidence of this, refer the crop below, again from the 58mm, but at f/4.

The two f/1.2 normal lens designs produced by Minolta, while each a very nice lens, perform quite differently. Based upon the above, I feel that they best fit two different roles.

The 58mm f/1.2 is not as sharp as the 50mm f/1.2, but exhibits the best bokeh of the two lenses. I feel that if you a seeking a fast normal lens primarily for portraiture then the 58mm f/1.2 is the best choice. The smooth buttery bokeh together with a very slightly softer image will enable lovely portraits, and the extra 8mm of focal length will also help to compress features for a more flattering image.

If, on the other hand you are looking for a gerneral purpose super-fast normal lens then the 50mm f/1.2 Rokkor-X appears the best choice. For travel and landscape photography the higher resolution and lower falloff will be beneficial, and the wider field of view adds flexibility. However, whichever you choose to purchase you will be buying a lens of the highest quality, and which I guarantee you will enjoy using. Until you have shot with a lens of f/1.4 or faster you simply won't appreciate how great it is to have a super-bright viewfinder image that snaps into focus, making manual focusing a breeze even in really low light.

Now just to show where the super-fast normal lenses truly excel, here are a couple of shots from my first night in New York that didn't make it to the American Journey travel journal. This bar was so dark that even I could have met a girl, and yet the 50mm f/1.2 was easy to focus, and still hand-holdable.