Super Wide Angle Zooms

[Yagil Henkin]

If not for the fact both the reviews for the sigma were better AND cost me 100-something dollars LESS than the tamron, I would have surely went for the tamron. The only thing I don't like about the sigma is it's weight, so getting even heavier lens is out of the question.

[youpii]

I'm also interested in the Sigma 12-24 but I realized that it's not HSM in Sony mount. Is focussing accurate? And I remember about some Sigma lenses being damaged by the powerful AF of the alpha cameras.

[Dr. Harout]

...And I remember about some Sigma lenses being damaged by the powerful AF of the alpha cameras.

Or vice versa

[David Kilpatrick]

I'm also interested in the Sigma 12-24 but I realized that it's not HSM in Sony mount. Is focussing accurate? And I remember about some Sigma lenses being damaged by the powerful AF of the alpha cameras.

The 12-24mm is fine but it's worth using manual focus and setting the lens to the middle of the 'focus confirm' range for the very sharpest results - as with any ultrawide, left to the AF, it will be 'good enough' but usually at one side or the other of perfect focus.

David

[alphaomega]

I purchased the Sigma 10-20 mm for my A700/A350 and have used it for a variety of images. It does distort and I would much rather do architectural photography with my Mamiya Pro and the dedicated 50 mm T/S lens, but it is too heavy for me now and medium format shooters with tripods tend to be targeted by police and security guards here in "Gordon Brown's paradise".
When in Canada last year I used the Sigma a few times. Here is an uncorrected image and after adjustments using the PS Lens Correction Filter. I think in the circumstances the result is not bad but really I think the corner portion is too high and the building slopes too drastically towards the rear of the picture. It was difficult to get far enough away and I could not even keep the verticals straight. What do you think about the lens and the picture in general. Any ideas of what I could have done differently in order to improve?

[alphaomega]

Reference my post right above; I have never tried to post images on this Forum before and thought I should use the "Upload Attachment" facility. Clearly not as I have never seen anyone with the result I managed to achieve. Also this function shows the last upload first just to confuse everybody. The corrected image is on top instead of below as intended. Hopefully someone will take pity on me and explain how to upload pictures "properly".

[Dr. Harout]

Do you have a site where you upload your pictures regularly, e.g. flickr, smugmug, zenfolio, picassa, pbase and so forth? If yes, then open the picture you want to link, right click and (in case your using Firefox as browser) go to "copy link location, then get back to the forum, click on "Img" just above the posting window and paste the link. Et voila.

[David Kilpatrick]

Reference my post right above; I have never tried to post images on this Forum before and thought I should use the "Upload Attachment" facility. Clearly not as I have never seen anyone with the result I managed to achieve. Also this function shows the last upload first just to confuse everybody. The corrected image is on top instead of below as intended. Hopefully someone will take pity on me and explain how to upload pictures "properly".

Click the 'Place inline' option after uploading each one, and move the resulting text link to the right part of your post. You can't avoid the small thumbnails which open to your fullsize file. Use external hosting for larger images displaying directly.

David

[KevinBarrett]

I've done this with a lot of my architectural shots on a700 + Tamron 17-50/2.8, with PS 6.0. The widest angle setting on that lens has complex distortion, which complicates things, naturally, but my process is as follows:

1. Rotate image until center-most vertical elements are perfectly vertical. Yes, I know that rotation is extremely destructive, but so is the whole process, and a perfectly level image is critical.
2. Correct barrel distortion. I use whatever gets the lines straight, usually increase canvas size, then pinch by a couple of degrees.
3. Last, with a level image (true verticals in the very center), and straight but converging lines everywhere else, correct the trapezoidal distortion with Transform > Perspective.

I'd have to guess that in this case, you didn't get the image level before correcting everything else. I'm not sure what all the PS Lens Correction Filter does, but it might assume that the camera was level when the shot was taken. Other than that, it almost seems to be over-corrected, so that the walls tend to be leaning out. This may be due to correcting an non-level picture.

With your permission, I'll give it a go myself.

[youpii]

I have used all the main independent offerings - Sigma, Tamron, Tokina - including the 14mm f/2.8 Tamron, 12-24mm Sigma. The best current allround lens is the Tokina, not made in Sony mount. The least consistent for top quality corner to corner work is the new Tamron. At the moment, the Sigma is the lowest in cost and may even have HSM very soon.
David

Do you mean that the 12-24mm Sigma will be released with HSM soon? Or were you talking about another Sigma?

[David Kilpatrick]

Eventually Sigma plans to have the entire range with HSM. The question is... how long would you need to wait? It could be years.

David

[youpii]

Haha, yes. I think I'll try to grab a 2nd hand one now and see how things go later.

It would be nice to see a A-mount version of the Sigma 150/2.8 Macro, I hope it comes one day too.