Here are a couple of picture i took with my new used Sigma 10-20. Thanks Don . If you have never shot with one ,,,pick one up it opens a whole new realm of photography Fun fun fun.
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Ultra Wide shooting requires some analysis, in my opinion.
I look for two things, initially:
- Distance to subject
- Angle of elevation
I feel that UWA is not based on how close you can get, but the actual frame you can encompass. You are looking to get a reasonably good sized subject, with definition, and the surrounding environment, to tell the story... so it is a balancing act of sorts.
The angle of elevation is what creates the major viewing distortion. The more horizontal you can make this angle, the less distortion you introduce to the shot. If you elevate, you get all sorts of flips and curls, caused by the spherical nature of this lens.
If you stay above 16mm, the lens is quite forgiving. Wider than 16mm... and you seriously have to take these into account.
The SIGMA 10-20mm f/4.5-5.6 EX DC (APS-C only), on an APS-C sensor body brings the lens to an effective focal length of 15mm-30mm. That means, until your zoom is set to 11mm... you will have a certain degree of distortion. The lens, for the most part of its zoom range, will not display a high-degree of this distortion. On the other hand, the SIGMA 12-24mm f/4-5.6 EX DG (Full Frame) lens, when mounted on a full frame body... from 12-16mm, things will appear a bit strange as you tilt the angle of the camera up and down from horizontal. Even when balance on a horizontal plane, it tends to give the image a "rounded appearance." You can fight this, somewhat, with cropping and some distortion compensation in Photoshop, but it is good to be aware that by using a little longer focal length, you can minimize it BEFORE you release the shutter.
Below: A five-shot panorama from the floor to directly overhead, using 12mm focal length on a Full Frame body. Now, this may look pretty straightforward, but it took a bit of adjustment, cropping and manipulation in PS to get it looking this sharp and straight. This image was supposed to be just a rough site-hunt shot, not mean to be used for publication... but, has wound up as such, due to discussion.
It was created from this assembled panorama: