marcomarks Loc: Ft. Myers, FL

There are very few "ultra" wide angle lenses available for crop sensor cameras. Ultra is the range of 10-20mm or 8-16mm or in the micro-4/3 world it's 7-14mm

Being that I have a Sigma -16mm for my dSLR and a 7-14mm for my Olympus, I can tell you that you wouldn't be happy with an ultra wide for your landscape work. In their attempt to avoid fisheye effect these aspherical lenses have trouble with sharpness around the edges unless you keep the focal length about in the middle of the range. An ultra wide lens is a feat of engineering genius with a bunch of lens elements moving around inside to achieve that focal range but there are compromises - one of which is being a little "soft" at both ends. When I do outdoor real estate shots and the scene can be shot anywhere from 8 to 16mm, I find that 12 or 13mm is sharp around the edges but at either end the edges are just plain out of focus sometimes to the point of blurry.

If you have a very nice nifty fifty, I'd recommend you use a tripod and a panhead (it's important to calibrate the camera and lens set to the nodal point of the panhead, by the way), shoot two or three vertical shots from left to right that are 30 degrees apart, then stitch them together in post editing. This will give you an ultra wide angle end product (and more if you want to go wild) that has no fish eye effect at all, everything will be tack sharp, and you save a whole lot of money by not buying another lens.

kymarto Loc: Portland OR and Milan Italy

I have to respectfully disagree. The Sigma 8-16 is quite sharp right out to the extreme corners, and is actually sharpest at 8mm. Check the graphs at photozone.de. Of course this is not true if the sample you have has decentered elements.

marcomarks Loc: Ft. Myers, FL

Here's an example of what I'm talking about. Photo 1 was shot with the Sigma 8-16 handheld at 9mm, f/7.1 (which should be fine for everything to be in focus at such a short focal length), ISO 200, 1/500th.

You'll notice the row of flowers along the sidewalk on the bottom right and the trees and coach light on the garage along the left edge are not in focus while the "17538" above the garage door and the coach light nearer the center of the frame pretty well are in focus until you zoom in. Whether the whole photo is perfectly sharp is not the point though. It's not going to be when I'm walking around the yard hand holding the camera without a mono-pod or tripod. I'm just showing that the focus at the edges with my Sigma is worse than the focus in the center - but this is not depth of field related. I have other shots that are much worse, and I believe they were at 8mm, but I didn't want to spend an hour digging through my archives to find them.

I can now compare my Sigma 8-16 to the Panasonic G 7-14mm lens on my Olympus PEN ePL5. I didn't have anything to compare it to previous to this Spring when I got the Panasonic lens. Shot 2 that I've included is an HDR of 7 frames that came from the Olympus with Panasonic lens set at 7mm (I use 7mm almost exclusively for indoors). Notice that everything is sharp. Even the carpet in the hallway behind the chair in the bottom right has a clearly visible pattern. The tile floor on the bottom left is crisp enough to see the pores in the tile. You can zoom in and read the clock face on the shelf near the left edge.

Also, the Sigma has pretty strong vignetting of corners that I have to compensate for in LR with a vignetting compensation of 40. The Panasonic has virtually no vignetting that I can see and I don't have to compensate for it. The Sigma has slight barrel distortion at 8-10mm and the Panasonic has virtually none. I really shouldn't be talking about Panasonic G lenses here though because they are for micro-4/3 format and aren't available for a Nikon D3100.

So either my Sigma lens has crapped out (I've read of this lens "going soft" with age) and has become defective or the Sigma 8-16mm inherently isn't as sharp on the edges as it is in the center. I've also read of people who bought and received a "soft" Sigma lens, sent it back and their second one wasn't "soft."

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Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

I would send it off to Sigma - your lens is not right. There should not be that much difference between center and edges/corners.

davidheald1942 Loc: Mars (the planet)

If you want to do it right you do.
ronny

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Not really, I use everything from a 14mm to a 300mm for landscapes - my best landscape images are captured with 35-60mm in terms of natural perspective and overall "look." Ultrawides result in unsightly distortion at the edges of the frames. If I need a wider field of view, I will usually do a pano stitch, with the camera in portrait mode. If I need greater dof, I will do a focus stack, which I often combine with pano stitching to get what I want. I only use my 14-24 when I don't have enough shooting distance, and I have no other alternative, or if I am deliberately creating a perspective distortion for artistic effect.

kymarto Loc: Portland OR and Milan Italy

The rectilinear distortion of an UWA is a fact of life. It is possible to incorporate the effect to good use in landscapes, though many people don't like the effect and fewer photographers really "feel" the possibility. It almost always needs to include some foreground element that can be emphasized. Pano stitching is a good way to go to do landscapes maintaining a more "normal" object/distance relationship.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

I get that

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davidheald1942 Loc: Mars (the planet)

If you want to do it right you do. J/K just funning. I do agree with you.
ronny

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

then, :XD: