Ultra Wide Angle Lenses

I often find it necessary to take pictures indoors and get the most coverage possible in a small room. My kit lens will only go down to 18 mm, which on a 2/3 frame DSLR is not an extreme wide angle.

Because I used a Fuji s7000 for several years, I solved this problem with a wide angle attachment. The first one I got from eBay and it was a disappointment. It was the Bower lens shown below.

  It comes in two parts, a main objective strongly negative lens made of low dispersion glass, and a strongly positive lens, made of ordinary flint glass. In fact, the second lens can be used by itself as a macro lens, but since it is not achromatic, the results are disappointing. I think I paid more than $50.

So I bought a better wide angle lens to use instead of the Bower. This lens (Raynox DCR-5000) is basically the same idea but without the macro. You need to use with your main lens in macro mode. When I switched to a DSLR, I found that I had to use a macro with the DCR-5000 in order to focus the image. I got the DCR-5000 used for about $50.

I was much more satisfied with this lens, but eventually, I decided to get a fisheye lens that was not an attachment, but a stand alone lens. I got the Rokinon manual fisheye for that. If you know how to use a manual lens, then this may be what you are looking for. It is about $300.

Results

Canon kit lens set to 18mm.

This is the Bower lens attached on top the Canon 18 mm lens. I stepped in closer to keep the field of view about the same. The effective focal length of this combination is about 12 mm. I stopped down to f/16, which REALLY improved the performance. I regret doing that now because it is not a fair comparison. So I re-did the photo at f/6.3. That appears below.

The Bower lens at f/6.3 With this setting, it is more apparent that there is not only chromatic aberration, but there is a lot of image blurring near the edges of the frame.

This is the DCR-5000 used with at f/4. The much wider aperture is closer to the way you might be tempted to use the lens, so the results are more typical.

If you wish to stop down to f/16, this is what you'll get.

With a little help from Panotools (_red= 1.008, d_green=1.003, d_blue =1.00) we get something with fairly low chromatic aberration, though the image gets really soft in the corners.

Finally the 8mm Rokinon used at f/5. The effective focal length is 8 mm. You should be able to tell from the perspective on the pots in the upper corners that the lens is a much wider angle than the attachments above. It should also be immediately obvious that the lens has much less chromatic aberration than the attachments. The large amount of barrel distortion is characteristic of fisheye lenses.

Canon 18mm lens	Canon 18 mm + Bower f/16
Canon 18 mm + Bower f/6.3	Canon + DCR-5000 f/4
Canon + DCR-5000 f/16	Canon + DCR-5000 f/16 With Panotools adjustment Considering Panotools is free and the DCR-5000 is $50 instead of $300, this might be an acceptable approach for you.
Rokinon f/5

This is a Rokinon shot of some landscaping working being done, capturing the entire back corner of the lot quite well.