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08-23-2009, 07:08 AM   #1
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DOF 6.5mm Opteka vs 10-17mm Pentax

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Here is a comparison between the two 180° Fisheye lenses @F8 focused @12in. Since I have a great Sigma 15mm F2.8 full frame 180° fisheye that works great as a 15mm super wide angle on Pentax DSLRs I chose the 6.5mm Opteka.






08-23-2009, 07:20 AM   #2
Ash
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Cool, now show us some of the 6.5mm captures it produces...
08-23-2009, 08:02 AM   #3
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Very Cool !

That lens looks great on that camera.

Do you know, will Rokinon be marketing it ?


wll
08-23-2009, 08:38 AM   #4
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A test shot with it.
6.5mm Opteka @F8 HDR strong 1/30 sec 100iso



08-23-2009, 08:54 AM   #5
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QuoteOriginally posted by wll Quote
That lens looks great on that camera.

Do you know, will Rokinon be marketing it ?


wll
B&H also sells the 7mm Vivitar version.
Vivitar | 7mm f/3.5 Series 1 Fisheye Manual Focus Lens | 7MMC
08-23-2009, 09:56 AM   #6
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The Rokinon version is available on eBay.
08-23-2009, 10:47 AM   #7
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QuoteOriginally posted by deadwolfbones Quote
The Rokinon version is available on eBay.
Rokinon 8mm Fisheye Lens for Pentax K-7 K2000 K200 K20D - eBay (item 350241599423 end time Sep-17-09 07:46:11 PDT)

08-23-2009, 12:09 PM   #8
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Is that the same lens as marketed by Samyang as 8mm? If so, how can it be, that different sellers give such a widely different focal length value? 6.5mm versus 7mm versus 8mm doesn't sound much, but in the ultra-wide world it is very different.

Does anybody know, what's true or whether these are different lenses?

Thanks for any insight.
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08-23-2009, 01:36 PM   #9
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Ben, because the projection Samyang used only allows an approximation of the focal length. Lenstip.pl went into an explanation of this in their review of the 8mm Samyang variety.

Samyang 8 mm f/3.5 Aspherical IF MC Fish-eye review - Introduction - Lenstip.com

That means Samyang can call it 8mm while Vivitar calls it 7mm and Opteka calls it 6.5mm. In the end it is still exactly the same lens.
08-23-2009, 01:49 PM   #10
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QuoteOriginally posted by WheresWaldo Quote
Ben, because the projection Samyang used only allows an approximation of the focal length. Lenstip.pl went into an explanation of this in their review of the 8mm Samyang variety.

Samyang 8 mm f/3.5 Aspherical IF MC Fish-eye review - Introduction - Lenstip.com

That means Samyang can call it 8mm while Vivitar calls it 7mm and Opteka calls it 6.5mm. In the end it is still exactly the same lens.
Thanks for the info. Sounds like the effective fl varies with distance from the image center - so everybody can state a correct fl... (I have to read-up more on the different projections)

Ben
08-23-2009, 01:55 PM   #11
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QuoteOriginally posted by jogiba Quote
A test shot with it.
6.5mm Opteka @F8 HDR strong 1/30 sec 100iso

Is this a crop?
08-23-2009, 02:02 PM   #12
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The Vivitar at B&H is only available in Canon, Nikon and Sony/Minolta mounts.

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08-23-2009, 03:08 PM   #13
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Since the Opteka and Rokinon are exactly the same lens, does it matter that B&H doesn't carry the Vivitar in a KA mount , besides you pay a premium for the Vivitar name when buying any of the Samyang made optics.
08-23-2009, 03:59 PM   #14
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QuoteOriginally posted by Cosmo Quote
Is this a crop?
That is the full image.
1600x1063px image
08-23-2009, 04:35 PM   #15
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How isn't it a circular image?
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