UWA for UV-A

[StephanN]

Recently I found two new UWA-toys on EBay, which I hoped to give at least some response in UV-A:

• Asahi Takumar Fish-Eye, 17mm f/11
  
• Soligor 17mm f/3.5
  

I sort of remember reading something about the Takumar around here, but not about the Soligor.

 

So, I took them to my favourite cemetary to take some shots. I also took along the Soligor 21mm f/3.8 as a comparison, now that Ulf has tested the Bushnell-variant. The cameras was the Canon 6D, internal XNite-330C, bayer-filter removed.

 

The first two are with the Soligor 21, the first with the S8612 and the second without. The reason for this double-photo is that while I'm sure that one can tinker around to put filters on the UWA-lenses, a fish-eye is always tricky, and the Soligor 17 does sport a filter thread, but also a fixed hood, so one would need the filter in the right size and nimble fingers, neither of which I own. So I wanted to see how much of a difference the filter makes with this subject.

 

Soligor 21, at f/3.8, ISO100, 1.6s, with S8612:

 

Soligor 21, at f/3.8, ISO100, 1.3s, without S8612 (of course there is some difference, but not that much):

 

Takumar 17mm, at f/32, ISO100, 30s:

 

Soligor 17mm, at f/8, ISO100, 6s:

 

Both appear to have a response similar to the Soligor 21

 

The Soligor 17, even though it's not yet quite a fish-eye, does exhibit mighty strong distortions, I've tried a few shots at f/16, and even those are bizarre. I can imagine that when shooting a city skyline from quite some distance the effect might be less dramatic, but as a usable supplement of the Soligor 21 for closer-range shots it's a washout. Of course, if the subject lends itself to it, the results might be "interesting", i.e. "artsy"

 

All the following are with the Soligor 17, the first two at f/3.5 and the last three at f/16:

 

 

 

 

 

[colinbm]

They & the images are looking good.

[dabateman]

I might be confused by your test.

You camera has a fixed UV filter, but does leak a little IR.

So the only way to compare is with exposure settings. Were the 17mm lenses faster or slower than the 21mm lens?

Listing the ISO, F stop and shutter speed for each photo would be helpful for comparison.

 

But it does look like your having fun.

To answer the general question I should post about the Sigma 10-20mm f4/5.6 lens soon as I get some good images. My copy in EF mount has a UV cut off at 378nm. Making useful for ultra wide UV. I bought it for reverse mounting macro. So its also a 9x to 10x macro lens with a Meike reverse macro adapter. So I can get some crazy autofocus and in camera focus stacking with Olympus hacked cameras using it.

[StephanN]

I might be confused by your test.

So the only way to compare is with exposure settings. Were the 17mm lenses faster or slower than the 21mm lens?

Listing the ISO, F stop and shutter speed for each photo would be helpful for comparison.

 

Apologies, I had intended to list the data for each photo, but after listing f-stop I forgot to put the others, probably too tired. Fixed it in the original post.

[StephanN]

To answer the general question I should post about the Sigma 10-20mm f4/5.6 lens soon as I get some good images. My copy in EF mount has a UV cut off at 378nm. Making useful for ultra wide UV..

 

Please do. I'm intending to test the Canon EF 16-35, and one or two other lenses as well, and post the results here.

[aphalo]

How does the Soligor 17 mm perform in visible light? Is performance any better? Could this be just a bad/"damaged" copy?

[StephanN]

How does the Soligor 17 mm perform in visible light? Is performance any better? Could this be just a bad/"damaged" copy?

 

Performance in VIS is very good, also in IR. So it would appear that this lens was not designed with UV in mind. There are some examples to be found on the web, e.g. this one: .

 

I have seen photos of a lens very similar, labelled Vivitar 17mm f/3.5. There are quite a few variants out there, mine looks like this one here: https://www.ebay.com/itm/Soligor-Wide-Auto-Wide-Auto-17mm-f-3-5-5-6-Lens/254872807806?hash=item3b579a697e:g:0KMAAOSw-IlgL1B3 , just that the rear part underneath the aperture ring is painted black.

[OlDoinyo]

These images look very odd: the image quality seems to go to hell very suddenly toward the sides of the frame; there is no gradual transition. The boundary where it happens appears straight rather than circular, and I don't see the same thing to the same extent toward the top or bottom of the frame. I am unsure what effect could even produce such a pattern.

 

I believe the Vivitar you mentioned may be a rebadged Tokina.

[StephanN]

These images look very odd: the image quality seems to go to hell very suddenly toward the sides of the frame; there is no gradual transition. The boundary where it happens appears straight rather than circular, and I don't see the same thing to the same extent toward the top or bottom of the frame.

 

The reason for the distortion being not that bad at the top and bottom may simply be a question of geometry. These edges are closer to the centre, of course, and if I take the last photo and do a quadratic crop of the centre, the four corners look about equally bad.

 

[StephanN]

I believe the Vivitar you mentioned may be a rebadged Tokina.

 

According to this, Spiratone 18mm, Sigma 18mm, Tokina 17mm, Soligor 17mm, Asanuma 17mm, are all the same lens (probably all of them made by Tolina, apart from the Sigma) : http://makingnottaking.blogspot.com/2009/09/spiratone-18mm-f35-wide-angle.html . There is even a link to a test of the Spiratone-variant.

[OlDoinyo]

The four edges of that crop do not look alike: compare the middle on either side (bad) with the middle top and bottom (much better.) This is not a pattern I would expect from chromatic aberration; however, I wonder if UV focus shift could possibly create some kind of focal plane curvature in the lateral direction. That does not explain the anisotropy of the effect, though.