Sonntag, 10. Mai 2015

The Carl Zeiss Tessar 50mm f/2.8 - what a nice Bokeh!

Sony a7 with CZ 50mm at f/2.8 near minimum focus distance
First the good news: This I will conclude the series of articles about the relatively inexpensive standard lenses. Sure, I could also use the Leica Summicron or Mitakon 50mm f / 0.95 to write an article, but who should pay me the expensive lenses?
The Tessar from Zeiss is relatively faint. The lens and its optical calculation are quite old and are originally from the year 1902. At that time, in the very first versions with an initial aperture of 6.3. The optical design is very simple and virtually free of astigmatism and field-curvature. The name and the Tessar optical calculation were patented by the company Zeiss. After the patent protection had expired have all the major manufacturers (such as Leica, Minox, Voigtländer or Pentax) built such Tessars.
The sharpness of the recalculations from the thirties was incredible and the Tessar was one of the most popular lenses in the normal range was until then replaced by the 50mm f / 1.8.
My copy comes according to his serial-number from the years 1967 to 1970. These are the so-called Zebra version, that is the aperture and focus ring in the changes are striped black and aluminium color. It has four lenses into three groups. The filter diameter is 49mm. The minimum focus distance is very good with 35 centimeters. The focusing ring moves smoothly, the focusing path is pleasantly long and suitable for accurate focus. The bezel of aperture snaps accurately and clearly audible. You can use the lens after some practice without eye contact.

There are on the used market an incredible number of different versions of this Tessars, but is common to all the letter "T" in the name, which stands for Tessar. Many versions are equipped with M42 thread. You can easily use the lens with an adapter on Micro Four Third, Sony E-mount or other bayonets.
In the period 1965-1980 there was due to a patent dispute to the name "Zeiss" between the companies Zeiss Oberkochen and Zeiss Jena. The negotiated compromise was that wore the lenses produced in East Germany only the inscription "from Jena". The addition "Zeiss" was omitted.
The Tessar is very sharp at maximum aperture in the center, the edge drop to the corner is moderate. From Aperture 5.6, the entire image from one to the other corner is razor sharp. Even at full aperture, the contrast is very good, but sometimes show slight blur effects. The Bokeh is very creamy and quiet. This blurring of the background is the real highlight of the lens. Photos are also in backlight and sidelight pleasant to the viewer.
One note: you should the exposure on the camera with this lens on about provide  - 0.3 to -0.6 EV, as Tessar overexpose usually something.

Sony a7 with CZ 50mm at f/2.8
Sony a7 with CZ 50mm at f/5.6
Sony a7 with CZ 50mm at f/2.8
So if you do not mind the lack of light intensity, gets to the Tessar a very good standard lens for almost any occasion. Prices for used lenses begin- depending on the condition- on EBay anywhere from five Euros and level out in general at twenty Euros.
Since you can not complain. This value for money is unbeatable one.

Sony a7 with CZ 50mm at f/2.8 nearby the minimum focus distance 
Sony a7 with CZ 50mm at f/4.0
Sony a7 with CZ 50mm at f/2.8

Sonntag, 3. Mai 2015

For bargain hunters on full frame: the Tokina RMC 24mm f/2.8

Sony a7 with Tokina RMC 24mm at f/4.0
If you wanna make  a really steal for your new full frame Sony a7(s//r/II), you must snatch this little cheapy gem. 
The essential technical data I have already put together in a post of 16 June-2013. Look at here. At that time I was only my little Sony NEX-3N available, so I was able to test the optical quality this wide-angle lens only on an APS-C sensor. For several months I have been photographing with the Sony a7, a camera with a so-called full-frame sensor. This corresponds to the classic film format of 24 x 36 mm. Now is a lens as the Tokina with its 24mm focal length a real wide angle. On the one hand quite pleasant, especially in indoor shots. On the other hand is now also the typical optical errors of a wide-angle lens.
First, the barrel distortion at the edges may be mentioned. I use such an old jar on a modern camera, then optical errors are corrected course not inside the camera. Correction requires electronic exchange of data and it can with a purely mechanical functioning lens in this case not be taken for granted. The adapter between lens and camera costs a little light intensity (scattered light losses during radiation passage), but separates the more reliable the camera and lens from each other.
For modern lenses (eg. from the Canon EF-S or AF-S Nikon series), there are now adapter with electronic data transmission, but these are very expensive and usually provided with additional corrective lenses, which further reduces the light output.

Sony a7 with Tokina RMC 24mm at f/4.0
The edges are not only distorted, but at the same time show themselves to intense contrast lines strong purple and blue fringing. Taken to the raw data format such disturbances for example in Adobe Lightroom must be removed with one click, but in jpegs they represent a permanent nuisance.
So at this point a specific recommendation as experience in recent years with many old and ancient lenses: you photograph please in raw data format. Optical corrections must be made easier here.

The Tokina was already on the APS-C format relatively sensitive to backlight. On full frame this phenomenon is still much more pronounced. Sometimes already extends slightly laterally incident light to the photo completely get rid of contrast and color. The pictures are without a lens hood just rubbish. Here two typical example for side light.

Sony a7 with Tokina RMC 24mm at f/5.6 
Sony a7 with Tokina RMC 24mm at f/2.8
The sharpness is very good at such a lens with medium light intensity even at full aperture. Of course, only in the center to about two-thirds of the exposed area to the screen. The corners at f 2.8 and 3.2 rather soft. Little bit stopping down to 3.5 to 4.0 to the rescue, the photos are from now until the final image edges sharp. The effective aperture is reached somewhere between 5.6 and 8, then blurring caused by the strong light scattering of small apertures.

Sony a7 with Tokina RMC 24mm at f/4.0
Sony a7 with Tokina RMC 24mm at f/4.0
Sony a7 with Tokina RMC at f/4.0
Overall, my conclusion is confirmed from the first review two years ago: this lens is given the required use price between thirty and sixty euros not only a bright bargain, but also a wonderful alternative to very expensive lenses from Zeiss and Sony, which currently are offered on the market: FE 16-35 mm f/4.0 ZA OSS, FE 24-240 mm f/3.5-6.3 OSS or FE 24-70 mm f/4.0 ZA OSS. Here are the best prices starting at one thousand euros. 

I expect in the next few days at last the new Sony FE 28mm f/2.0 to test it on the a7. The first reviews on the net, in particular by Phillip Reeve promise a real optical highlight. Let's see how this is reflected in practice.

Sony a7 with Tokina RMC 24mm at f/4.0
Sony a7 with Tokina RMC 24mm f/2.8 
Sony a7 with Tokina RMC 24mm at f/4.0
Sony a7 with Tokina RMC 24mm  at f/4.0