The APO Arsat 500 5.6 lens for Pentacon Six / Kiev 60
I saw the data for this lens years ago, in some Kiev brochure, and soon felt the need to own it. I always wanted a "real" telephoto lens for 6x6...
I did own an (Meyer Orestegor) Pentacon 5.6/500, but that is a preset aperture lens, which is a little "too classic" for me...
Also, I was not very satisfied with its image quality (tested two specimens of different "generations", so it is very probably not a case of a "dog" lens...)
It just has a LOT of chromatic aberation, much "mushier" an image than the Rubinar 5.6/500 mirror lens (which is 35mm only) - in my experience, it won't really give you more detail than an CZJ 300mm Sonnar, just a bigger scale...
And last but not least, it is a HUGE sucker to lug around!
So for many years, I was out on the hunt for the Arsat 500. Finally I bought it from a guy in USA, who got it from Roskam, Holland - and so I had to pay $$$ import duties, regardless of the fact that the lens originally came from EU.... phew!
I instantly liked the tiny (well, for an Kiev telephoto, at least) lens, and how it handled.
Here is a size comparison with the Pentacon 5.6/500:
The cosmetic finish is a little rougher:
than the Pentacon:
but that is the only gripe I could have about it - but I don't really care how the lens looks like - it is much more important how the images it produces look like!
Judging by the serial number:
there weren't that many produced, that would explain why it is a bit hard to get one! Sadly, I waited so long to get one, that in the meantime film went the dinosaur way, and I use it only rarely....
The lens nicely fits both P6 and K60, and sports a stop-down lever, important for P6 users. It has internal focusing (does not get longer, when you focus close), and focuses down to 5m (1:10). It has a built-in retractable shade, and a filter diameter of 95 mm.
Here are the most important pages of the lens passport:
It seems to be an 8 elements / 6 groups design, and is said to contain "marks of optical glass with dispersion properties similar to that of optical crystals" (which I guess is Russian for "low dispersion glass", or what the Japanese would call "ED" or similar).
It is an interesting design, with all of the glass in front of the iris aperture.
Looking from behind, the glass is quite deep inside, and the lens is clearly baffled for the square format:
Shining a laser poiner into the lens, the second element seems to be made of a somewhat "foggy" glass:
I suspected that might be a property of Russian LD glass. I repeated the experiment on my modern IF-ED 80..200 2.8 Nikon zoom, and saw the same "fog" effect in Japanese glass, although less pronounced, maybe one half to one third as bright (100% subjective!!). Interestingly, the CZJ Sonnar has a "foggy" second element too, of about the same brightness as the Nikon.
For a quick and dirty sharpness test, I've put the lens on a Nikon D70, and just shot through my window. I used a sturdy tripod, and took 10 identical shots with each lens at 5.6 (arsat & pentacon), refocussing each time, and then selected the best shots, to minimize the effect of focussing errors and shake.
The shots were made raw, and "developed" exactly the same way, no sharpening.
Any color difference is due to the lenses and the change in the daylight in the cca 30 minutes between the shots.
The test scene was this: (range was cca 250m and focus was on the clock)
A crop of the clock, enlarged to 4x actual pixels looks like this -
the Arsat:
and the Pentacon:
The difference is quite startling, but one must consider two things here:
1. This is a **HUGE** enlargement (D70 pixels are 8x8um - on an 0.25mm pitch computer screen it's 125x = 2x3m from the D70 and 7x7m from the full MF!!)
2. We are comparing a modern "IF-ED" type design to an >50 years old, manually calculated design, based on WW II era types of glass...
Anyway, I was happy to see that the Arsat is easily sharp enough for use on modern electronic sensor cameras - the numbers on the clock are blurred more by the pixelation and bayer interpolation artefacts than lens aberrations. Just take a step or two back from the screen, to reduce the pixelation effect!
The virtual absence of coloration suggests it really is an apochromatic design.
Admittedly, this test only shows the center sharpness. The best test for the corners would be a nice starfield photo - I even own a polar mounted (non-motorized) telescope, which would be usable for this purpose, but manually guiding a long exposure with the required precision is HARD WORK, and that is one thing that I like to avoid, at any cost!
So I just put the lens onto one of my K60's and went around shooting. These pics have no aesthetic pretention, they are just some test shots.
Most of them aren't really revealing much about the corner sharpness, but with this kind of lens, one is inclined to make 99% of "selective focus" type pictures and only rarely an "everything sharp" one.
These were made on Ektachrome 100, and scanned with an Epson perfection 4870 Photo at 2400 PPI (10.5um pixels), no color calibration, so they are kinda bluish/purplish - that is not a fault of the lens! No processing other than "levels" adjustment was done on the pics.
This one has some detail in the corners (it was shot at f/8):
and a closeup (1:1 pixels, on an 0.25mm pitch monitor the full image would be 1.33m square) of the tree blossoms upper right corner:
with a high-mag loupe, slightly more detail can be seen on the film than on this scan - officialy this is a 4800 PPI scanner, but 2400 is realy already pushing it quite a bit! Focus was on the bridge fence, so this might not be really in perfect focus. (I guess the blossoms top right were quite close to the focus plane, but the branches in the center were definitely too close and out of focus - showing a somewhat strange "micro bokeh")
The highlights show quite a bit of chromatic abberation (blue shifted inwards), which was totally absent in the center. With a loupe on film, it does not look that bad, could be that the scanner has added some of its own...
Further enlarging to 4x actual pixels looks like this:
but keep in mind the above caveats (we are testing the scanner as much as the lens here, and focussing was not done on this part of the pic).
To conclude, I was quite satisfied with the sharpness of this lens. But what about its bokeh?
Here is a shot to evaluate the bokeh (again, at f/8)
hmmm, it is definitely not a Sonnar, but I think I can live with this. The white window frame lower right seems to show some "two line" effect, but on the other hand, the satellite dish upper left is nicely fuzzy... Distance dependent bokeh?? Will have to do more tests on this!
(Incidentally, there is a whole plethora of "Kiev trademarks" in this pic: shutter banding, mirror shadow (bottom), flocking kit peeling off (upper right side) etc :-)
General impression of the lens
This is only a preliminary essay, but overall, I would say that this is a very nice lens, if you want a "real telephoto" for the Kiev. It is quite compact for 5.6/500, has automatic diaphragm, is plenty sharp and handles well. It is a pity that it's production has practically stopped.
The viewfinder image is bright enough for focussing, the split image focusser works without problems. The upper part of the WF is dark, but that is a consequence of mirror size in the K60, and is so with all longer lenses.
Because the light rays come in rather colimated, the problems with mirror bounce shadows etc. are more pronounced. I also saw some vignetting in the corners, but don't yet know what is the cause.
In the next months, I will try to make some more and better shots with this lens and put them here.
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