The Rokkor Files - Ultimate Normal Lens Challenge.pdf

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24/9/2014 The Rokkor Files - Ultimate Normal Lens Challenge

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The Ultimate Normal Lens Challenge Part II - the 50mm f/1.4's

This is the second review in a series on Minolta's manual focus normal lenses, tosee the first in the series, click here .

When investing in a Minolta manual focus system one of the first lenses commonlypurchased is a 50mm f/1.4 lens. The reason for this is that it is fast, sharp, and withbrilliant contrast, while at around $50 it is about a quarter of the price you mightexpect to pay for the faster f/1.2 lens.

Due to the popularity of this speed and focal length the 50mm f/1.4 wasmanufactured for a long time, from its first introduction as an MC lens in April 1973,right through to the end of the Minolta manual focus system. The lens design wentthrough considerable changes over that period, as detailed below:

April 1973 - Introduction of the 50mm f/1.4 MC Rokkor-PG. The lens used the sameoptical formula as the 58mm f/1.2 and weighed in at a more reasonable 305gcompared to the f/1.2's 478g. It has outstanding build quality, and with its big (but notbulky) design it is an absolute pleasure to use.

August 1977 - Minolta introduced the 50mm f/1.4 MD Rokkor-X. It was the firstwholly new lens designed for the MD system, and while it retained the 7 element, 5group optical construction of the MC lens it was a more compact design, slightlyshorter and 60g lighter at 245g.

April 1979 - A new 50mm f/1.4 MD Rokkor-X lens is introduced with an opticalformula of 7 elements in 6 groups based upon that of the 50mm f/1.2 that wasintroduced in March 1978. The weight of the lens was reduced to 220g, and the filter size dropped from 55mm to 49mm

June 1981 - The existing 50mm f/1.4 lens was updated to a late MD cosmetic design(aperture ring lock, focus scale in orange not green etc.). The lens weighed an extra15g at 235g, but otherwise was unchanged from the MD Rokkor-X versionintroduced in April 1979.

(Source: Justin Bailey's "Minolta Lens Chronology"- http://www3.ns.sympatico.ca/mciepl/chronology.htm- an outstanding resource)

The lenses being evaluated in this test are examples of the first two incarnations,being the 50mm f/1.4 MC Rokkor-PG and the 50mm f/1.4 MD Rokkor-X (both with55mm filter threads). An example of the later design was unavailable for the test, butI have previously tested the 50mm f/1.4 MD and at that time I found it to be inferior tothe MC version. This finding was in line with the opinions of several other collectorsand testers, and accordingly I believe there is a consensus that the earlier designsare better performers in terms of resolution.

An important consideration to remember with these tests is that they should betreated as a guide only, and a general source of information. This is because onlyone sample of each lens was tested in this review, and there is no way for me to tellif the sample tested was indicative of the average performance of the entireproduction run. Your 50mm may perform better or worse than the ones shown here,so if this is important to you, you should consider testing your lens yourself to ensureultimate sharpness.

All tests were performed on a focus calibrated X-570, using a viewfinder magnifier


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and a tripod, and Fuji Velvia 100F fine grained slide film. The camera's self timer wasused to combat vibration. Slides taken have been scanned at 5400dpi, and focushas been individually set for each crop so as to avoid any issues with film flatness.Digital ICE and grain management has been turned off to obtain maximum possibleresolution.

50mm f/1.4 MC Rokkor-PG

vs.

50mm f/1.4 MD Rokkor-X

The resolution target used in the test - sure it's not the most interesting subject, but I find it a handy subject to enable close comparisons. The red boxes indicate the crops used in the testing

The 50mm f/1.4 MC Rokkor-PG is one of my favourite Minolta lenses, and battles itout with my 50mm f/1.2 MD Rokkor-X for time on my camera. We have already seenhow the 50mm f/1.2 performed, so I am interested to see how it compares with the

MC f/1.4. Whatever happens, one is going to be getting the lion's share of time onthe camera in future.

I am particularly interested in evaluating the bokeh of the 50mm f/1.4 MC Rokkor-PG. We saw in the f/1.2 test that the 58mm lens, while not as quite as sharp as the50mm f/1.2, had much more pleasing bokeh. With the same lens design it will beintriguing to see if the 50mm f/1.4 lenses maintain that superb out of focus rendition.

Anyway, enough preliminary discussion, and let's get down to business!


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Resolution Tests

Above we can see the performance of the two lenses from centre and corner cropsat f/1.4. Results show excellent detail given that the lenses are wide open, certainly

considerably more detail than that achieved in our last test with the f/1.2 lenses.Contrast is also noticably improved from the level recorded with the faster lenses. Itis noted that this is a challenging test target (not particularly high contrast) and thatthis crop reflects an area of less than 1mm square on the original negative. At thescreen resolution above (at standard 72dpi) the equivalent print size would be 6 feetby 9 feet. Given this the performance wide open of both of these lenses is veryimpressive.

Based upon my review of the images from which these crops were taken I concludethat at f/1.4 the 50mm MC is noticably sharper than the MD in the centre, but that thegap between the lenses has narrowed at the corners and both are very similar at thispoint. Corner performance is actually very impressive, and contrast remains good,

despite light falloff (discussed later).It is my opinion, based upon the above results, that both lenses are fully useableeven for work requiring relatively fine detail at f/1.4. This is an outstanding result anda tribute to the quality of the 30 year old design.

The shot below was taken with the 50mm f/1.4 MC Rokkor-PG at f/1.4 in order tominimise the depth of field. The bokeh exhibited in this shot is gorgeous, and it isquite probably my favourite shot taken in 2004.


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Owning a 50mm that is sharp enough to generate these results at f/1.4 opens up some amazing photographic possibilities. Low light photography can be fully explored, and the use of wider apertures to

deliberately reduce the depth of field can be undertaken with confidence.


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At f/2 the MD lens has improved markedly to catch up to and even possibly surpassthe MC version. The MC lens has naturally also improved, and in fact both lensesdeliver excellent resolution at f/2. The double lines of some of the highways arevisible in the crops from both lenses, but possibly slightly more clearly in the MD

version.. When you consider that these lines are approximately 0.5mm apart on theoriginal poster that is a quite incredible result.

The corner sharpness of the two lenses appears to be very similar at f/2. Overall, Ifeel that at f/2 the MD lens has very fractionally outperformed the MC lens, but thedifference between the two lenses is very difficult to pick even at a 100% crop at5400 dpi. Certainly there would be no way to split the two lenses based upon prints,even with very big enlargements.


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At f/4 the MD version holds its marginal lead in centre sharpness, and cornersremain too close to call. Contrast has also improved with both lenses. These areamazing optics.


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At f/8 the 50mm f/1.4 MC Rokkor-PG has caught up to and possibly marginallysurpassed the 50mm f/1.4 MD Rokkor-X in terms of centre resolution. Both lensesrecord excellent corner sharpness. This is the best aperture tested in terms of sharpness for both lenses, but the difference between the results at f/4 and f/8 isvery small. Certainly either of these lenses could be used for images where criticalsharpness was a priority from f/4 and above.

Resolution Summary

Based upon the crops above and my reviews of the full images I conclude that thetwo lenses are very similar in terms of performance, and are difficult to differentiatebetween. Possibly the MC was the better performer at f/1.4, but at f/2 and f/4 the MDmarginally outclasssed its earlier counterpart. By f/8 the MC was once again slightlybetter. I believe that the performance of both was so close as to render it impossibleto say that one was better than the other.

Lets examine some other aspects of the lens' performance to determine if these willhelp us separate them in terms of performance.

Lens Bokeh

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 lenseswere tested wide open at f/1.4, and again at f/4, what I would consider to be anormal portrait aperture when photographing in daylight.


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The 50mm f/1.4 MD Rokkor-X shows neutral bokehand the areas without sharp highlights do show a

very nice blur.

The 50mm f/1.4 MC Rokkor-PG shows results possibly not quite as good as those achieved by the

MD version, but still OK.

In terms of bokeh both lenses do a good job, but not up to the level of the 58mmf/1.2 tested previously. This is to be expected given its faster aperture and longer focal length both work together to increase background separation. A cursorycomparison to the 50mm f/1.2 MD Rokkor-X shows both lenses exhibit similar bokehto that lens, however close up review of the highlights does show a very slight

brighter band around the extremity of each out of focus highlight. A closeup of theindividual highlights is shown below:

The background blur of the 50mm f/1.4 MD Rokkor- X is not bad, but i t is not up to the level of either of

the f/1.2 lenses (as would be expected).

The 50mm f/1.4 MC Rokkor-PG surprisingly performed slightly poorer than the MD version at this test, albeit the differences were very minor..

Both lenses show some evidence of this ring, but clearly the 50mm f/1.4 MD Rokkor-X has slightly better performance in this respect. It should be noted that the testabove is an extreme one with literally hundreds of highlight spots, and hugetransitions in contrast. Normal use would see a much nicer blur.

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


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At f/4 with the MD the background highlights haveblurred together nicely.

The hexagon shapes of the MC's highlights areslightly more defined, but the blur is still very nice.

The bokeh of both lenses appears good, but the 50mm f/1.4 MD Rokkor-X stilldefinitely has an advantage. The highlights show slightly less definition, providing amarginally smoother background in areas of very high pinpoint highlights.

Bokeh Summary

Based upon my review I would expect either lens to perform well in terms of out of focus blur in normal use, with the MD lens possibly marginally edging out the MC(albeit the differences are quite minor). The images above are designed to show alens' flaws, and as a result you may conclude that these lenses are poorer performers with respect to bokeh. Disabuse yourself of this notion, as it is patentlynot the case. A quick review of the photograph shown previously of the plantdemonstrates that the MC lens has outstanding out of focus rendition, and basedupon our tests the performance of the MD would even be slightly better. Either of these lenses would make an outstanding performer when it comes to bokeh, butcertainly still the 58mm f/1.2 reigns supreme.

Light Falloff One of the issues when shooting with faster lenses is the natural light falloff thatoccures 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 withblue skies or light coloured walls etc, it manifests as a darkening of the frame at thecorners.

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 inthe 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 signof a lens that handles this well is when this falloff is gone after closing down a stopor two. Lets see how the two Minolta 50mm f/1.4 lenses handle falloff.

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


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The image to the right shows two sets of crops.The top two are from the 50mm MD at f/1.4, thebottom two from the 50mm MC at f/1.4.

As can be seen, both lenses exhibit significantfalloff at f/1.4 when using slide film. As discussedabove, this falloff will be less noticeable, but stillapparent when using negative film. When seenside by side the falloff seems particularlysignificant, but when seen in terms of the fullimage it is lessened to a degree by the distancebetween the crops. For example, refer to the cropbelow of the full image from the 58mm f/1.4.

At f/2 both lenses record a significantimprovement in falloff. At this level the falloff would likely be not noticeable in a photographunless the shot included a significant expanse of solid colour, such as a blue sky. I can see no

real difference between the performance of bothlenses.


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At f/4 the falloff is virtually eliminated on bothlenses, and would not be noticed when shootinga broad expanse of a solid colour, even on slidefilm. Refer to the image below showing thesample area at f/4, and it can be clearly seenthat for all intents and purposes falloff iseliminated at f/4.

As is evident above, the slight difference in the white crops seen when they are sideby side is simply not visible when looking at a full image taken at f/4.

Falloff Summary

Both lenses record significant falloff at f/1.4 that would be apparent on prints or slides.By f/2 this falloff has been significantly reduced, and by f/4 it is all but gone. Basedupon the results detailed above I conclude that both lenses are essentially identical intheir performance in this respect.

Summary The two 50mm f/1.4 lenses tested are outstanding optics, and performed brilliantly for what are still very fast lenses. Central and corner sharpness were outstanding fromboth lenses, and perfectly usable for full frame critical sharpness applications fromf/4. For portraiture and general use these lenses can be used wide open at f/1.4without hesitation, bearing in mind of course the light falloff that is evident at larger apertures.

The performance of both lenses was superior wide open than that recorded by thef/1.2 lenses at f/2, and in fact across the board, at all apertures the f/1.4 lenses


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outperformed the f/1.2 lenses in terms of resolution and contrast.

In terms of bokeh the 50mm f/1.4 MD Rokkor-X performed marginally better in our tests, but I would question whether anyone would be able to pick the difference in aphotograph, even at larger print sizes. In general use both lenses produce a lovelyblurred out of focus rendition, enabling the photographer to concentrate the viewer'sattention on his subject.

Overall I rate the 50mm f/1.4 MC Rokkor-PG and the 50mm f/1.4 MD Rokkor-X as

equally as good as each other. The MC had a very slight resolution advantage at f/1.4in our test, and the MD had very slightly better bokeh in our examination of thisaspect of lens performance. These differences are, however, so minor that they couldsimply reflect sample variation, and accordingly I would consider that the owner of either of these lenses has every reason to be pleased, and no reason to covet theother version.

A useful test would have been to also consider the 58mm f/1.4 MC Rokkor. Producedprior to April 1973, the 58mm f/1.4 has an avid following who swear by itsperformance. It is made from six elements in 5 groups (similar to the later 50mm f/1.7lenses). I find it difficult to imagine that its resolution would be up to that of the later 50mms, and certainly it strikes me that Minolta would have been unlikely to produce a

more expensive 7 element design to replace it unless this also brought with itimproved performance.

Well there it is, my review of the f/1.4 normal lenses. Still to come are the reviews of the slower normal lenses, comprising the 50mm f/1.7, f/2 and the 45mm f/2. I amintrigued to discover if there will be a hidden gem amongst these cheap lenses.

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The Rokkor Files - Ultimate Normal Lens Challenge.pdf

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