Sigma Lente EX DC HSM f/2.8 de 4,5mm para SLR Digital da Canon USA

Comments about Sigma 4.5mm f/2.8 EX DC HSM Lens for Canon Digital SLR:

I wanted a full round fisheye for my Canon 7D, and this is the only one I could find. It seems well made and I'm content with it, though there were issues. Specifically, the 7D was unable to get correct autofocus. After an autofocus, if I turn on Live View and zoom in, the focus can be seen to be blurry. A Live View autofocus will correct it. I wrote to Canon and they said it was probably the lens since it wasn't made by them and I had no trouble with other Canon lenses. I wrote to Sigma and they said it might be an adjustment problem and I could send them the lens for calibration. [...]The second lens has the exact same behavior.Canon says the Sigma lens must not use their autofocus signals correctly, and the lens was probably designed before the 7D was sold. But my Canon 40D body has the same problem. It seems likely the camera's focus sensors have trouble with the extreme wide angle of a full round fisheye. Live View uses contrast comparison on the image sensor instead of the usual focus sensors. Since this works fine, I'm content to use the lens this way. My application is round landscapes and QTVR panoramas; working in Live View for this lens is okay. It's pretty amazing how the stitching software can take three round fisheyes and produce an undistorted 360 degree panorama. The extreme field of view captures the zenith and the nadir. If you just wanted a very wide angle, you'd probably get better results with a rectangular fisheye that used the whole frame (like the Sigma 8mm). But if you want a full round, this is the only way I found to get it on an APS-C sensor. When the images are blown up they're not tack sharp, which you might expect in a lens at this cost. But this is a special type of image and, as I said, I'm content.[...]

Comments about Sigma 4.5mm f/2.8 EX DC HSM Lens for Canon Digital SLR:

I have been shooting sport photos for a while now and was looking for something new to spice up the images. I wasn't sure how I could use the fisheye but now I have had a chance to use it... wow. I can get some excellent images from a perspective I have never used before. It has taken me a bit of practice and it has been worth every second. I love this lens.

Comments about Sigma 4.5mm f/2.8 EX DC HSM Lens for Canon Digital SLR:

Great lens for outdoor and even interior/architecture. This is a really fun lens especially on portrait.

Comments about Sigma 4.5mm f/2.8 EX DC HSM Lens for Canon Digital SLR:

for special architectural effects when capturing a large building. Try composing the frame with an image in the foreground and use the sloping background to enhance the theme. For instance, using a fisheye lens when shooting a tulip field in Holland adds interest when foreground flowers feature prominently and a quaint windmill farm frames the background.