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07-07-2008, 10:32 AM   #16
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Are you sure about your FOV numbers? The seem a little wide to me. Are you giving full frame FOV or APS-c sensor FOV? I get 90 degrees from my 14mm on a DSLR.


QuoteOriginally posted by vanchaz2002 Quote
You are looking for rectilinear lens shorter than 16mm, which leads to FOV of around 110 degree. There are a few options available including the already mention DA lenses.

Tamron has 14mm one covers 115 degree. Pentax has K18 covers 100 degree. Tamron one is fairly expensive and K18 is MF, hard to find, and relative expensive.
Zeiss has its new distagon in 18mm fits Pentax. It covers FOV of 99 degree. Sigma also has a relative cheaper 14mm but not sure it come with Pentax mount.

Basically, rectilinear lens are hard to build, especially over FOV of 100 degree. Said such, ultra-wide rectilinear is most likely an exotic and luxurious option.

So what left for budget hunter is using a fisheye lens and covert the image in computer. I believe Photoshop has plug-in that can do the job. Internet has enough information of fish-eye to rectilinear conversion.

Hope that helps, good luck on lens hunting.


07-07-2008, 10:55 AM   #17
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You could be right on your numbers. My calculation is on full frame.

For digital camera with 1.5 crop factor:

14mm is around 90 degree
15mm --> 87'
16mm --> 84'
17mm --> 81'
18mm --> 77'

Thanks for bring that out.
07-07-2008, 01:48 PM   #18
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QuoteOriginally posted by Light_Horseman Quote
I'm hoping the greater forum knowledge can help me find a good ultra-wide prime lens. I'm looking for something 16mm or less focal length and not a fish-eye.

I would love a Pentax 15mm rectilinear but they are hard to find and very expensive, so I'm looking for an alternative. I'm not particular about brand or speed, just as long as it is decent quality.

So what are my options and what should I look for.


I have a Sigma 14mm 2.8 that I would consider selling as I don't use it enough to warrant keeping....I tend to shoot more towards the long end. If you think that that would suit your needs PM me .


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