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06-03-2018, 09:04 PM   #1
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Grand Lens Test 5: The Arsat 30mm Fisheye

Series Contents

Okay, I'm going off the reservation for this one, partly because I promised it in another thread.

Pentax makes one medium-format fisheye, a 35mm full-frame fisheye for the Pentax 67. I have used that lens extensively, but I can also attest that it suffers from significant lateral chromatic aberration that has to be corrected. But at least it can be corrected. I made this photo using that lens, on an island off Cape Cod where I put together a photo book several years ago:


Bigelow Point in the Round, 2012
Kodak Ektar, Pentax 6x7, SMC Takumar 35mm Fisheye.

But 35mm is a bit long for a fisheye on 645, and especially for cropped 645. So, I decided to adapt my Arsat 30mm fisheye to the 645z to see if it would perform better. TLDR: It does.

Quick history for those who don't know it: After WWII, as "reparations", the Soviet government cleaned out the Zeiss factory in Jena of some of its tooling, materials, and knowhow, and pushed it over to the Arsenal factory in Kiev, Ukraine. They particularly took the machinery for making Contax cameras, which were "duplicated" in Kiev, giving evidence to the fact that it ain't just the tools that make the camera. But the Soviets also set up an optical factory at Arsenal, and nobody can claim the Soviets didn't know how to design optics. Starting in the 70's, they created two new cameras: The Salyut, later known as the Kiev 88, which was a re-creation of the old Hasselblad 1600f, which, unlike later 'blads like the 500 and 501, used a focal-plane shutter. The other camera they made was the Kiev 6C, later known as the Kiev 60. This was a simplification of the Praktisix, which was later known as the Pentacon Six. Both adopted the Praktica-style SLR format, which was as much as any the successor to the Exakta camera, and the forerunner of Japaneses SLR's. (We should remember that Pentax bought what became its brand name from Pentacon). These are the cameras that established the horizontal-travel SLR format that became the de facto standard for small-format SLRs. So, there were three competing form factors for professional cameras in medium format at the time: The box SLR (Hasselblad, preceded by the original Exakta 66), the twin-lens reflex (Rolleiflex), and the horizontal travel SLR (Pentacon Six, which followed the Exakta Kine model--essentially the modern SLR form factor, and a fully integrated version of a Leica with a Visoflex). The SLR's of the late 50's and later emerged from these, including all the Japanese SLR's. Among professional medium-format cameras, most makers followed the first two form factors. Mamiya started with a 6x6 TLR, but later made box SLR's in 6x7 and 645. Bronica and Kowa made box SLR's. Norita was the exception--during the 60's, they made horizontal-travel SLR's like the Pentacon, but they didn't last. And then Pentax took that form factor to the highest form it ever achieved in medium format: The Pentax 6x7 and its successors.

Back to the Soviets: They wanted a cheap version of the Pentacon Six for internal use that could use the same lenses, and this became the Kiev 60. But they also made their own line of lenses for it, and the optics were usually available in both the Pentacon Six mount and the Kiev 88 mount. The Pentacon Six mount is a breech-lock mount, with the lock ring on the camera. One aligns the pin at the top, inserts the lens, and turns the ring to clamp it down. The Kiev 88 mount is a partial-screw mount similar to (but not the same as) the original Hasselblad mount.

Adapters for Pentacon Six lenses for use on Pentax 645 cameras are made by Hartblei, which is a coalition of ex-Arsenal employees, and by Arax, which is a (maybe) different coalition of ex-Arsenal employees. I have owned one of these adapters for years, so that I could use the incomparable Carl Zeiss Jena Sonnar 180mm f/2.8 lens on my 645NII, as a portrait lens. That lens is, for me, the absolute gold standard for creamy bokeh.

I've owned this Arsat Fisheye for nearly 20 years, and used it extensively on my Kiev 60's, Exakta 66, and Kiev 88cm. Believe me, it's much happier on a Pentax.

A fisheye lens makes a round image of a diameter a little less than three times its focal length. So, a 30mm fisheye provides a 180-degree field of view across the corners of the 6x6 frame, which is 80mm. A 180-degree full-frame fisheye for the 645z would need to be about 20mm in focal length, but none are made. Nevertheless, a fisheye a bit longer than that still provides an extraordinary sweeping view. Note that it is not necessary for a fisheye to be all that fishy. For subjects where straight lines can cross through the center, or where forms are round instead of rectilinear, the fisheye can actually be less distorted looking than a rectilinear lens.

Here's my test scene wtih the (already wide) 35mm FA lens, just for comparison:


And here is the same scene on a much duller day with the Arsat Fisheye:


Clearly, the Arsat pulls in a lot more of the scene.

Here's a 1:1 crop from the center at f/3.5:


So, wide open is for composing and focusing, because even in the center, it's a little soft and suffers from significant flare that reduces contrast. Also, the camera struggles to fine the right exposure with this lens wide open--the result was about a stop underexposed. (I placed the camera in Av mode, with the lens stopped down).

Here's a 1:1 crop of the center at f/11:


That's a lot better. This image shows no sharpening, but when sharpened, this image would became pretty crisp. And remember that this is a pretty tiny portion of the center of an image that would be 7 feet wide at the 100 pixels/inch most people have on their screens.

With ultra-wides, the corners really tell the story. Here's the upper right corner, at 1:1 and f/3.5:


The color fringing is pretty bad--lots of lateral chromatic aberration (but not as much as with the Takumar Fisheye--trust me). This is easy to fix in software, as shown below:

Photoshop might do a bit better job of repairing the lateral color--this is what I could do as a non-expert with DXO Mark Photolab, which I'm just learning to use. Remember, this is the corner at f/3.5.

Let's look at the lower right corner, which is much closer to the camera than the focus point, at f/3.5:

It's either out of focus or the corner performance is limited at f/3.5.

This corner at f/11 looks a lot sharper:


I corrected for lateral color in the above, but as you can see, the software occasionally misses some.

Is this usable? Yes, for smaller prints. But let's see if we can sharpen it up enough to be usable:


That helps, but this would not meet my definition of endless detail in a 7-foot wide print. But it does for smaller prints.

The bottom line is that I would not expect a $200 lens from the Soviet bloc to out-do something really expensive from Japan or West Germany. But I think it will meet my definition of endlessly sharp in a 16x20 print, which is the biggest print I can make.

But there simply is no alternative, so I work as carefully as I can and just limit how big a print I can make.

Rick "not bad for a couple of C-notes" Denney


Last edited by rdenney; 06-30-2018 at 12:11 AM.
06-03-2018, 09:49 PM   #2
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Rick,
Thanks for posting the test! I'm looking forward to having mine back from repair/adjustment. Buying this lens new from the Ukraine it is definitely more than a couple of C notes.

Phil
06-03-2018, 10:59 PM   #3
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"New" is a fuzzy concept. Arsenal hasn't made these for very many years. Arax is selling refurbished models that they multicoat for about $400, but I see them used for a couple of c-notes often enough.

But they are a bargain at either price, and give good results when used carefully.

I bought mine new in the late 90's (it was made in '97), and mine is multicoated.

Rick "who knew a network of suppliers in those days" Denney
06-04-2018, 06:25 PM   #4
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QuoteOriginally posted by rdenney Quote
"New" is a fuzzy concept. Arsenal hasn't made these for very many years. Arax is selling refurbished models that they multicoat for about $400, but I see them used for a couple of c-notes often enough.
That explains why the case has a rather aged dusty look to it.

06-15-2018, 10:00 AM   #5
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Hi Rick, thanks for posting these and the comments about the 6x7 35mm FE. You are of course right about the 35mm FE CA - I acquired one a few weeks ago but haven't had chance to use it before now. That said, until I started to look at your 100% crops and comments about them, I'd probably would have sided on these being 'acceptable compromises' for lenses of this type. Obviously straight lines are going to highlight it more than more random patterns. Centre sharpness looks good though, at least considering the wide angle of view and therefore the minuscule size of objects in the frame. Keeping the camera level and choosing suitable subject & framing goes quite far in hiding the 'fishy-ness' - leaving it looking like it was shot on rectilinear lens with some barrel-distortion towards the edges (similar to my Pentax-M 28mm f/2.8).

I haven't had results back from the lab from the P6x7 yet, but if the CA gets as progressively worse towards the edges of the 6x7 frame as much as it does on the D, I might have to rethink my acceptable print sizing (I'm sure chromes would look great - at least until you get the loupe out).

Thanks again for being dedicated enough to run and comment on these tests.

John.
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