Last week I had the pleasure to spend a day with a Sony A7 (thanks to Matthias Sommer!) and and bag of my favourite Rokkor lenses (and a Canon FD 2/135mm). I chose the old town of Domodossola in norther Italy for playing with theses lenses. Right away I was impressed with the detail resolution of most of these Rokkors. Most of them perform as good or better than the current professional Sony zooms (ZA 2.8/16-35mm and AL 2.8/70-200mm G).

Minolta lenses such as the MC 2.5/25mm, MC 1.8/35mm, MC 1.4/50mm, MD 2.8/85mm, MD 2.5/100mm and MC/MD 4/200mm certainly are valid alternatives to the current Sony A-Lenses. While they have to be focused manually, their focusing is much more precise than with most current Sony AF-Lenses. This can be an advantage in critical landscape and architectural work.

Due to issues with the A7, most of the excellent rangefinder wideangles from Leica and Zeiss have severe corner problems. Retrofocus lenses such as the MC 2.5/28mm, the MC 1.8/35mm or the MD 2.8/35mm have a much better corner resolution and thus are to be preferred on the A7.

The 100% crops shown here give a first impression of the performance of these lenses on the 24MP Full Frame Sony A7. All images are JPGs directly "out of cam". No postprocessing was applied - apart from cropping of course.

f=21MM

The Minolta MC Rokkor-NL 21mm 1:2.8 from 1968 was an early retrofocus superwide for SLRs (Canons FL 3.5/19mm from 1965 was the first), and it was the fastest superwide of its time (Canons FD 2.8/20mm was following in 1973). The lens always had an impeccable reputation. The lens is quite heavy, and it uses foating elements. The MC-X version shown here is from 1973.

Compared to the Sony Zeiss ZA 2.8/16-35mm (2009, see below), the 45 year old Minolta 2.8/21mm performs very well. Nevertheless these images shows the problems of superwides on high-res digital sensors. Corner performance is quite low, and we need to stop don to f11 to get a decent detail resolution. The same applies to the Minolta/Sony AF 2.8/20mm which has a slightly better detail resolution (results not shown here). 

The Minolta MC 28/21mm has a pronounced pincushion distortion, and its vignetting is more pronounced compared to the Sony Zeiss ZA 2.8/16-35mm.

The Sony Zeiss ZA 16-35mm 1:2.8 has its peak performance at f=16mm. At f=21mm we can already see the signs of degrading corner perfomance. Vignetting is weaker, and so is distortion (compared to the Minolta MC 2.8/21mm).

f=28MM

In 1968 when the Minolta MC Rokkor-SI 28mm 1:2.5 was presented it was the fastest f=28mm for SLRs. Only in 1975 Minolta (and Canon) made an even faster 2/28mm. To reduce spherical aberrations and CAs the Minolta MC 2.5/28mm uses radioactive glass (as well as the first FD 2/35mm from Canon). The radioactive thorium glass causes a pronounced yellow color cast which can be cured by UV light. 

The overall performance of the MC 2.5/28mm is quite good (and certainly better than the Sony Zeiss ZA 2.8/16-35mm at f=28mm). Wide open there is visible coma, but astigmatism is well controlled. Stopped down to f5.6 the image is nearly perfect (apart from the color cast mentioned above). At f11 there's a small increase in contrast.

The later MC 2/28mm and MC 2.8/28mm (both from 1975, not shown here) have an inferior performance, at least on 16MP APS-C sensors. Their performance on 24MP and 36MP FF sensors remains to be explored.

In 1978 both Canon and Minolta released their first superwide zoom. Canon's FD 3.5/24-35mm Aspherical (which in 1984 would become the FD 3.5/20-35mm L) was competeing with the Minolta MD 4/24-50mm shown here. Both the MD and the FD are two group zooms with twelve lenses each. Using the "two group" principle allows for much better correction of each group, and thus leads to a perfomance close to primes. The MD 4/24-50mm was quite expensive, and therefor later a MD 3.5/24-35mm (on inferior performance) was added. 

At f4 and f5.6 the MD 4/24-50mm has slightly more detail resolution than the Sony Zeiss ZA 2.8/16-35mm (see below), but CAs are more obvious as well. While the overall performance is certainly not bad, one might prefer the MC 2.5/28mm for demanding work.

f=35MM

The Minolta MC Rokkor-HH 35mm 1:1.8 was presented at Photokina 1968 (as well as the MC 2.8/21mm and the MC 2.5/28mm shown above).Its performance on the 24MP FF sensor of the A7 is excellent, and much better than both modern Zeiss lenses (ZA 2.8/16-35mm and ZM 2.8/35mm). Details on the performance of various 35mm lenses can be found here.

The Sony Zeiss ZA 2.8/16-35mm at f=35mm on the Sony A900 (RAW data converted using Raw Therapee 4.1)

f=85MM and f=100MM

The Minolta MD Rokkor 85mm 1:2 always was considered as "incredibly sharp". The small an lightweight lens was introduced in 1978 as a successor to the MC/MD 1.7/85mm. It performs perfectly, even at f2.0.

Another one of those little Minolta gems that are waiting for the upcoming 50MP+ FF sensors ...

The Minolta MD Rokkor 100mm 1:2.5 was originally presented in 1968, and it had a strong competitor: Nikons legendary 2.5/105mm Nikkor, which was based on Berteles equally legendary Zeiss Sonnar 2/85mm. The MD 2.5/100mm shown here has a slightly adapted optical formula (one lens doublet of the MC 2.5/100mm was replaced by a single lens from new optical glass).

Its performance on the 24MP FF sensor is very good, but the lens seems to have a slightly reduced detail resolution at f2.5. There are some CAs as well.

At f5.6 and f11 the lens clearly outperforms the 24MP sensor.

f=135MM

The MC/MD Tele Rokkor 135mm 1:2.8 in its four lens model (presented 1975 as a successor to the six lens MC 2.8/135mm) generally is considered the best 2.8/135mm from Minolta. The lens doesn't perform as perfectly any more as the previous MD 2/85mm and MD 2.5/100mm. With increasing focal length also the color aberrations are more difficult to correct. Minolta was using a large, heavy and expensive LD ("low dispersion") glass element on its 2.8/135mm [4/4]. Nevertheless some remaining CA are evident. Longitudinal CAs (LoCAs) result in "purple fringing" at f2.8, and some lateral CAs are visible in the corners.

At f5.6 the LoCAs are gone, and corner details have slightly improved. But only at f11 the lens really really performs well over the entire image field. However, the current Sony Zeiss ZA 1.8/135mm is clearly better in almos all respects (apart from weight): It has a much better detail resolution and no CAs at all (images shown here).

Canons FD 135mm 1:2 from 1980 seems to a have slightly less detail resolution in the center and better corner performance (note that here f2, f2.8 and f5.6 are shown, while above at the Minolta MC 2.8/135mm we see the apertures f2.8, f5.6 and f11).

At f2 there are slight problems with image quality, but the lens performs remarkably well given the large aperture. At f2.8 we see a small decrease in center resolution, probably due to resitual spherical aberrations (and related focus shift). At f5.6 the lens is close to perfection - we have cleary a better detail resolution and less CAs compared to the Minolta MD 2.8/135mm.

f=200MM

The Minolta MC Tele Rokkor 200mm 1:4 is an excellent lens. Given tha fact that color aberrations (CAs) are much more difficult to correct at f=200mm, its detail resolution wide open is quite remarkable. Apart from some purple fringing at f4, the overall performance wide open is the same as f8 or f11.

f=300MM

The Minolta MD Tele Rokkor 300mm 1:4.5 IF was the successor of the much more bulky MC 300mm 1:4.5 from 1969. The MD 4.5/300mm has internal focusing, and low dispersion (LD) glass is used. For its focal length it is lightweight (710 g) and quite small. Focusing is smooth and easy, but not as precise as with earlier the non-IF versions.

At f4.5 the detail resolution in the image center is very good, and purple fringing (LoCAs) is well controlled. However, the corners there are strong CAs. Surprisingly, the image quality in the field and in the corners decreases when stopping down. This behaviour is quite unusual, and up to now I have no explanation for it. From the recorded EXIF data (shutter speed) however it is clear that the phenomenon is real.

More recent 300mm lenses such as the Minolta AF 2.8/300mm APO G and 4/300mm APO G or the Sony AL 2.8/300mm G SSM have a clearly superior detailresolution and much less CAs.