The Sigma 8mm f/3.5 EX DG Circular Fisheye is a wonderfully fun and interesting lens to use, producing sharp, good contrast and color balance images and as a fisheye, it does an excellent job!
First, let me get some of the usual questions out of the way. There are two types of DSLR fisheye lens, circular and diagonal both having 180 degrees of angle. The Circular type produces image well of course completely round leaving a black border around the image, while the diagonal fisheye will show the image across the sensor. Many folks ponder the question of which type of fisheye to buy If this is your first fisheye I recommend the diagonal because you will probably use it more often and the images are rectangular vice circular making blending them into your portfolios more easily without that repetitive look of a circular. However, you can crop those circular images if you are ok with the loss of image.
Sigma Build Quality: My Sigma 8mm feels solid and well made, with a firm focus ring. No complaints feel as good and any other top quality lens, and after 8 months of use no issues. This lens is in the same build class as my Nikkor 16mm fisheye, which I have had for 12 years.
Sigma Image Quality: The image quality is in the upper tier - Very Good Image Quality. The Sigma 8mm lens produces sharp images with excellent color reproduction and excellent contrast, especially if you are close in and have the sun to your back. The overall image quality depends largely on how you use the lens; the performance is best when the sun is coming from behind. I am very happy with the overall image quality and require minimal post-processing. The images produced are very good, and enjoyable to look at.
Color Fringing & Darkening: You will see some darkening around the very most outer image edge. This is not too distracting, and can easily be removed with a slight crop in, this appears as a normal anomaly due to the image being condensed at the edge. I have NOT noticed any significant color fringing even in harsh lighting conditions. Every circular fisheye I have used has the same effect some more than others, This Sigma 8mm shows minimal color fringe around the outer edge of the image.
Flares & Ghost: Chances are if the sun is out you will most likely need to deal with some spectacular flares.since the lens is 180 degrees of angle and in some situations can actually enhance the "look" of the image. The lens holds it's own in the flare department considering. The Sigma 8mm produces very little flaring. In the image to the left, you will see the sun was clearly visible but absolutely no flare was present in the lower part of the image- which I consider pretty darn good.
Focus Speed: Being such a wide lens, you do not need to worry much about how fast the lens focuses. The accuracy of the focus is very good, when used with my D4s and D810 the lens has never produced an out of focus picture - period. I use minimal focus point groups and position the focus point to what I need to be the sharpest, and the lens/camera does the rest.
My Opinion Overall: Due to the unique perspective and use of this lens I consider it excellent overall and worthy of consideration if you are looking to add unique and creative photos to your portfolio. I will not hesitate to make a recommendation for this lens if you are in the market. It is as good as any circular lens I have used.
GENERAL INFORMATION FOR THOSE CONSIDERING A FISHEYE BELOW
Fun & Creative: This is one of the more creative and is absolutely the most fun lens I use, every outing offers something waiting to be turned into circular art - you just need to see it, and with some practice, you will.
Considerations: This is a specialized lens, in general, the wider the lens the harder the lens is to use - adding the main subject becomes challenging, and the main subject may get lost somewhere in the image "where is Waldo", Move-in close is my recommendation. For a lot of people, the lens might not be worth the price considering a fisheye lens will most likely be used occasionally. If you are just starting your inventory of glass a fisheye would not be the best choice out the gate, but if you have the main staples covered - yeah!. FX vs DX although the lens will mount on a DX camera, the effect will be diminished by the crop factor and you will no longer have a circular fisheye and not even a diagonal fisheye. When used with a DX (CROP) sensor camera, the circular image will not fill the sensor since it is "round" and not rectangular - thus reducing some of those usable mega-pixels.
Top Things you need to know about a Circular Fisheye:
- Your feet/tripod/body will probably be in some of your shoots - oops
- Move-in CLOSE - closer, to obtain the best results - have the main subject up close
- It distorts, portrait lens it is not - makes people look funny, not pretty
- The sun is always your friend or foe depending on what you're trying to do
- You may not use the lens that often, making you wonder why you purchased it - then you use it and remember.
- Think creatively for best results
- Practice and Practice to "know" how to see circular - carry the lens with you and use it!!
- There is no front glass protection - Keep the cap on between shots
- Rain or Mist can wreck your shots (spots) if it is misty or rainy you will have problems.
- Small enough to carry with you all the time - have fun when you get bored with normal.
- Finally, use the subject to block that sun.... or not :)