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Reviews, Tests, Comparisons of Lenses

Cooke Triplet, Tessar and Planar: E. Ludwig Meritar 50mm f/2.9, Industar-61 L/Z 50mm f/2.8 and Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3).

Lenses:

Industar-61 L/Z 50 mm f/ 2.8   (view specifications)

Nikon Micro Nikkor-P.C 55 mm f/ 3.5 non-Ai   (view specifications)

E. Ludwig Meritar 50 mm f/ 2.9   (view specifications)

Introduction:

During this test we will compare three relatively “slow” ~50mm prime lenses: E. Ludwig Meritar 50mm f/2.9 from Germany, Industar-61 L/Z 50mm f/2.8 from USSR and Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) from Japan. These lenses have very simple but interesting classical optical formulas: Cooke Triplet (three lens elements in three groups), Tessar (four lens elements in three groups), and the five-lens Planar (exact name - Xenotar - five lens elements in four groups). You can learn more here: Fast Normal Photographic Lens Historic Line Up Stangrit This review will include not only a trivial comparison of the sharpness, but also the analysis (of course within homemade possibility) of the optical aberration of the lenses.
 

All these lenses were made almost within a decade around 1965-1977. However, the difference in their appearance, workmanship, ease of usage and image quality would judge on a qualitative leap in photo lens designing and manufacturing, that occurred in the 70 years of the last century. So:
 

Lenses that will be discussed:
E. Ludwig Meritar 50mm f/2.9 normal, prime, manual focus, kit lens for 35mm SLR Exakta (Germany) cameras. The lens-to-camera mount is M42 screw.  It is using the Cooke Triplet optical formula (three lens elements in three groups). To obtain the maximum relative aperture of f2.9 this lens supposes to be made of special sort of the glass (most likely lanthanum). The lens is made in the late 60-ies of XX century. The aperture system has five rounded blades. There is Anti-reflective coating.

 

Industar-61 L/Z 50mm f/2.8 normal, prime, manual focus lens for 35mm SLR Zenit (USSR) cameras. The lens-to-camera mount is M42 screw.  It is using the Tessar optical formula (four lenses in three groups). The lens was designed with the usage of lanthanum glass in the 60-ies of the XX century, which allowed maximum relative aperture of f2.8. This particular lens is made in 1978. It has six blades of the aperture. In the range of f5.6-f11 aperture forms a hole of six-pointed star shape. It is likely to have single-layer anti-reflective coating.
 

Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) normal, prime, manual focus macro-lens for 35mm SLR Nikon (Japan) cameras with Nikon F bayonet.  It’s using Planar five lenses optical formula, also known as Xenotar (five elements in four groups). Nikon began producing lenses with such a formula during early 60-ies of XX century. The lens is made in about 1975-77. The aperture system has six non-rounded blades.  There is multilayer anti-reflective coating.


Group photo and Optical formulas:


 

Parameters for compaison:

Design and usability.
Sharpness of images in the center and at the edge of the frame for a short distance (~ 1.0m)
Sharpness of images in the center and at the edge of the frame for a long distance (~ 150m) Aberrations:
 - Spherical aberration
 - Coma / Astigmatism
 - Longitudinal Chromatic aberration
 - Lateral Chromatic Aberration
A pointed source of light in the background and circles of confusion (bokeh)
Vignetting(the light fall off in the corners of the frame)



Technical Notes:

Camera Sony NEX-6 was used for the comparison. So all conclusions are related to APS-C sensor with a size of 23.6mm x 15.7mm. In case of usage of smaller (Micro4/3) or larger (Full Frame) sensor sizes corner effects (such as coma, for example) would be noticeably different.
Because the concept of "comparison" is only applicable to the measurable parameters, this review was based on as much as possible “technical measurable capability”. Art capabilities of lenses were not taken into consideration.


Design and usability.

E. Ludwig Meritar 50mm f/2.9 provides mixed feeling: on the one hand - it has well built quality, all-metal aluminum case. On the other hand - a sensation of somefrailness.

Usability is poor. The aperture ring can be easily confused with focus ring. Both rings are thin, not comfortable.

Industar-61 L/Z 50mm f/2.8 is made very solidly, with no exceptions.
From the usability point of view this is one of the most pleasant lenses. Focusing ring is very wide and well built. An aperture ring is small enough and prevents accidental change of the setting.


Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3), the lens has traditional Japanese manufacturer quality.
In terms of usability it has one drawback - the aperture ring is located too close to the camera (adapter), and often it is very difficult to locate it. In addition, it can be easily confused with a "fake" ring, which placed just a few millimeters up front of the aperture ring.

 

In addition it should be noted: for all three lenses front lens element is recessed dip into the rim (Nikon - more, Meritar - less), allowing their usage without hood. In this regard, no additional testing for flare prone was conducted.


Sharpness of images in the center and at the edge of the frame for a short distance (~ 1.0m)


Conditions: artificial lighting, ISO400, automatic white balance, Sony NEX-6, a tripod, a two second delay before the shutter release.
A standard test format ... was used. Distance from the model was chosen so that the model covers the entire plane of the frame.For the analysis, two models were used: in the center and at the edge of the frame. Click on the picture to see full size.

 

The center of the frame

 

The edge of the frame.

Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) has visible advantage at aperture f3.5 in the center and at the edge of the frame. It shows excellent sharpness, which increases up to f5.6 aperture and remains constant up to f16.
Industar-61 L/Z 50mm f/2.8 in this test also showed a very good result, though somewhat inferior to Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3).
E. Ludwig Meritar 50mm f/2.9. It looks like a clear example of the benefits of the "new" optical formulas with respect to the "old" optical formulas. The result at an open wide aperture in the center of the frame can be called mediocre, and at the edge of the frame - just a disaster. When you stop the aperture down sharpness improved moderately and reaches its peak around the values ​​of f8-f11.


Sharpness in the center and at the edge of the frame in the far field (150m)
 


 

The result of this test is mostly identical to the result of the test in the near field. Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) shows the best result, Industar-61 L/Z50mm f/2.8 - the middle, and E. Ludwig Meritar 50mm f/2.9 - acceptable in the center and poor at the edge of the frame.
 

Aberrations: spherical aberration.
To analyze spherical aberration the pictures of the pointed source of the light at a distance of 2.5-3.0m were taken. The distance to the light source was chosen based on the diameter of the circles of confusion. They have to be the same when lens focused toward infinity (rear focus) and when lens focused toward near field (front focus).

Analysis of illumination uniformity of the circles of confusion focused toward infinity (rear focus) and focused toward near field (front focus) allows us to estimate the degree of corrections of the spherical aberration.
Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) shows excellent results – both circles are very similar and very even illuminated. Analysis of circles of confusion for Industar-61 L/Z50mm f/2.8 and E. Ludwig Meritar 50mm f/2.9 indicates the presence of spherical aberration . And E. Ludwig Meritar 50mm f/2.9 shows higher degree of it. As a result - the worse sharpness in the center of the frame.


Aberrations: Coma / Astigmatism.
To analyze the Coma / Astigmatism the pictures of pointed source of the light placed in the corner of the frame at distance of 6-7 meters were taken. For easer comparison, the images of pointed source of the light in the center of the frame (the ideal case) also were shown during the test.

First, the good thing: Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) – based on a homemade test this lens shows almost no coma and no astigmatism.Just the perfect lens!

Industar-61 L/Z50mm f/2.8 shows a small presence of coma, which disappears if stop the aperture down to f5.6. There is no Astigmatism.

In opposite E. Ludwig Meritar 50mm f/2.9 shows a lot of coma and astigmatism. When stop the aperture down to f5.6 the coma disappears and astigmatism becomes more visible. Thus, both coma and astigmatism cause so mediocre sharpness results of this lens at the corner of the frame. Moreover, these phenomena (especially astigmatism) will be even more noticeable when using sensors larger than the APS-C format.
 

The Longitudinal / Lateral chromatic aberrations

The result of this test is simple - neither longitudinal or lateral chromatic aberrations observed on these lenses. And in general, there are no chromatic aberrations in these lenses should be. Chromatic aberrations are more pronounced for fast lenses (with maximum relative aperture below f2.0), which is not the case.


Background blur (Boke)

This test had some difficulties due to the difference in the Minimal Focusing Distance (MFD). E. Ludwig Meritar 50mm f/2.9 has MFD 0.7m there was difficult to get "perfect" circles of confusion.
A stop down aperture at the Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) drives circles of confusion to become a "standard" nut-shape.
At E. Ludwig Meritar 50mm f/2.9 only five aperture blades along with great corner rounding produce  smooth pentagons which  look very interesting. At the edge of the frame circles of confusion transforms into ovals, so it has possibility for background torsion effect.
The designers of the Industar-61 L/Z50mm f/2.8 aperture went exactly the opposite way. The sharper - the better. The six-ray star bokeh is an Industar-61 L/Z 50mm f/2.8 trademark.

 

General observation - bokeh is a matter of taste, and there is no disputing about tastes

 

 

 

 

 

 

Vignetting(the light fall off in the corners of the frame)
It was difficult to detect vignetting on these lenses, so the Photoshop option was applied in - (posterizing level 4)

 

Difficult to say anything specific. For Nikon, vignetting can be seen more, and at f5.6 the difference disappears.


Conclusions:
There will be very short conclusions. If you need a lens for macro, close-up or landscape photography - Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) will be one of the best options. Moreover, the lack of autofocus can be considered as an advantage.
Industar-61 L/Z 50mm f/2.8 owners (which still do not have Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3)) should not be disappointed - good lens for little money.
E. Ludwig Meritar 50mm f/2.9 lens can surely bring happiness to fans of "art" photography. Does someone have already tried to shoot vintage video with this lens???

Pictures gallery made by these lenses:

Industar-61 L/Z 50mm f2.8

Nikon Micro Nikkor 55 mm f/ 3.5 non-Ai

Author: YuriS 13.07.2013 14:31:49
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