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UltravioletPhotography

Finally: A Fisheye lens for UV


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I have been trying out various fisheye lens for my UV-modified cameras for years. The success has been limited as most designs are on the complex side and many elements speak against any real UV capability. The old non-retrofocus 7.5 mm f/5.6 Fisheye-Nikkor has been among the best, together with the 16/3.5 Nikkor. However, as most of my UV-capable cameras are DX format (D3200, D40xs, D200) or smaller (Panasonic GH-2), neither of these Fisheye Nikkors is perceived very "fishy" to use such a vague term.

 

Enter the Sunex 5.6 mm f/5.6 lens of Chinese origin. It is a fix focus, fixed aperture lens that captures 185 degrees on a DX camera in true fisheye fashion. The maker (www.superfisheye.com) claims a projected image circle of 14.5 mm in diameter allowing the entire circle to be shoehorned into the DX framing. I got a second-hand almost pristine sample for USD 125 thus no large loss would be suffered if the lens was bad.

 

Little is known about the optical design or coating quality, apart from a published MTF curve that looks quite good.

 

lensMTF.gif

(from Superfisheye.com)

 

The lens is heavy, but most of the heft and bulk stem from the robust adapter at the rear that comes in Nikon (F) and Canon (EF) flavours. No electronics chip is present so the camera doesn't know anything about the lens specifications unless there is a menu for non-CPU lenses present.

 

Here is the lens on a D40X (image from superfisheye.com)

 

superfisheyeNikonD40x.jpg

 

Now, have a closer look at that pack shot. The lens head is actually held in place simply by three grub screws, one of which can be seen on the photo. If these screws are undone the lens head can be extracted together with a complete M42 thread-mount. Thus it will go directly into one of those ubiquitous focusing helicoids floating around on eBay or similar sites, for attaching with focusing to say an m43 camera.

 

When used on a DSLR (DX/FX formats), no helicoid can be inserted as the rear flange to film plane distance is not long enough. However, no need to despair. Just loosen up those small screws ever so little and one now can rotate the lens head inside the M42 threads. The focusing range thus attained is not large but more than enough to give focus almost to the front element if you go all the way.

 

So what does all this mean to the UV photographer - can the lens be used for UV? Obviously any UV bandpass filtering must occur at the rear end of the lens, or inside the camera, which can be tricky but not impossible.

 

Today I availed myself of some recent nice spring weather and paid a quick visit to some road verges nearby harbouring Tussilago farfara (Colt's Foot), one of the very earliest spring plants in my neighbourhood. The lens was mounted on my Nikon D3200 (internal Baader U) and focus was set to 10 cm in front of the lens surface. I did all the shots hand-held at ISO 200-400, 1/4 to 1/8 sec, under hazy sun, which actually is a very favourable exposure compared to the UV-Nikkor and other UV specialist lenses. I must make a shoot-out some day, probably after I return from my forthcoming trip to Crete.

 

Here is the result, and the familiar UV appearance of Tussilago is quite convincing in my view.

 

TUSS_FAR_UV_Sunex_5,6mm_f5,6 fisheye lens D3200 Baader U I1704023140.jpg

 

Focus was on the flower head in the centre.

 

As the lens is pushed substantially outside its designated conjugate distances, observing some decline of the image quality is hardly surprising. However, some loss of peripheral details is acceptable given I obtained a true > 180 degree view.

 

RAW files were processed in my usual fashion by Photo Ninja. Shooting in UV triggers significant lateral CA of the blue/yellow kind, which fortunately PN deals with quite easily.

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Very nice! Good find.

 

Is this a newly manufactured lens or an old one?

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It's been out in the wild for nearly 10 years, apparently. However it obviously has flown under most radars.

 

They are sold by B+H etc. with an additional Dewarping program package for nearly USD 800.

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'Defishing' tends to be more suitable for the so-called frame-filling fisheye lenses. The maker (Sunex) claims they have an efficient dewarping ('defishing'?) software, but I couldn't download it even when I entered the required lens serial number.
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  • 1 month later...

Despite all dire weather forecasts and the occasional snowfall, spring suddenly exploded in the typical Nordic fashion: going from 2 to 20C in a day or so. Now, the birches have put on the special spring coat of blue-green delicate leaves, the birch catkins shed their voluminous pollen loads, I'm sneezing and - finally - dandelions !! First of the Taraxacum usually are the weedy species of the section Ruderalia. And some other early hardy species such as the ubiquitous Wood Anemone (Anemone nemorosa).

 

I did a 'fishy' view of these yesterday, using the SUNEX 5.6 mm f/5.6 on my Nikon D3200 (internal Baader U). In fact, all of them were made hand-held as this approach suits the 185-degree SUNEX (navigating a tripod into a position not captured by the lens is difficult, though doable). Shutter speeds around 1/15 to 1/20 sec @ISO 400 produced acceptable resemblance of sharpness and for these images sufficed well enough.

 

fishy dandelion UV E1705043304.jpg

 

Another from the same location, cropped but otherwise not geometrically altered. Plus rendered more alike the "false colour palette" Andrea and I have used for years.

 

more fishy dandelions E1705043274.jpg

 

The vast woodlands surrounding Oslo can be reached by car in a few minutes, so I powered up the little red Peugeot and moved to a good spot for Wood Anemones.

 

fishy wood anemone I1705043314.jpg

 

All of the flowers captured so far by the SUNEX have displayed their expected UV signature, thus the lens is capable of going into the [upper, presumably] UV(A) band. Compared directly against UV-specialist such as the Coastal 60/4 APO or the UV-Nikkor 105, exposure times are about 2 stops longer which in fact is very good. As I have refocused the lens off its standard setting, one can only expect sharpness to suffer yet I think the SUNEX holds up quite well nonetheless, at least when the on-axis part of the image is considered.

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