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09-15-2012, 01:12 PM   #16
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I wonder why they opted for a f2.8 instead of a f4 with this lens. Yes you lose a stop, but really who would want to use a lens this wide at f2.8?? I would trade the extra stop for a smaller package. But yes this is very intriguing, a lens that pentax should've done a while ago.

09-15-2012, 02:01 PM   #17
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The only 8mm (sometimes called 7mm) I know of is sold under Bower, Rokunar, Samyang, or Vivitar brands and is a fish-eye, not rectilinear. The Pentax zoom that goes to 10mm is also a fish eye at that focal length, so does not qualify as an alternative to the Samyang 10mm, but both the 10-20 and 8-16 Sigma zooms are near rectilinear, allowing the barrel distortion at the wide end.
09-15-2012, 02:10 PM   #18
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There is also an 8mm Peleng lens that works for Pentax, but it is also a fisheye.
Why 2.8 instead of 4.0? Well, it could be useful in some situations, wide angles are not only used for bright sunny landscapes after all. Also, most lenses are not great wide open and this would mean at f4, the lens should control its aberrations well.
09-15-2012, 02:20 PM   #19
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QuoteOriginally posted by Na Horuk Quote
There is also an 8mm Peleng lens that works for Pentax, but it is also a fisheye.
Why 2.8 instead of 4.0? Well, it could be useful in some situations, wide angles are not only used for bright sunny landscapes after all. Also, most lenses are not great wide open and this would mean at f4, the lens should control its aberrations well.
I wonder if the Peleng is also the same lens as the Bower-Rokunar etc. I've never heard of the Peleng brand.

09-15-2012, 02:23 PM   #20
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QuoteOriginally posted by 24X36NOW Quote
Widest rectilinear PRIME lens. The widest APS-C rectilinear wide angle is still the Sigma 8-16.
+1
Heck that front element looks vulnerable, at least the sigma keeps the hood mounted
09-15-2012, 02:43 PM   #21
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QuoteOriginally posted by WPRESTO Quote
I wonder if the Peleng is also the same lens as the Bower-Rokunar etc. I've never heard of the Peleng brand.
Peleng was Belorusian and the company was Belomo. The 8mm is a circular FE. It projects a 24mm circle on a 24x36mm frame.

Home - Peleng 8mm f/3.5 Circular Fisheye Lens for Canon, Nikon, Olympus

Last edited by Blue; 09-15-2012 at 07:18 PM.
09-15-2012, 02:53 PM   #22
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QuoteOriginally posted by cali92rs Quote
I wonder why they opted for a f2.8 instead of a f4 with this lens. Yes you lose a stop, but really who would want to use a lens this wide at f2.8?? I would trade the extra stop for a smaller package. But yes this is very intriguing, a lens that pentax should've done a while ago.
+1 on all fronts.
09-15-2012, 03:38 PM   #23
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Original Poster
QuoteOriginally posted by cali92rs Quote
I wonder why they opted for a f2.8 instead of a f4 with this lens. Yes you lose a stop, but really who would want to use a lens this wide at f2.8?? I would trade the extra stop for a smaller package. But yes this is very intriguing, a lens that pentax should've done a while ago.
Low light shots. People do take cityscapes for example at night.

QuoteOriginally posted by WPRESTO Quote
I wonder if the Peleng is also the same lens as the Bower-Rokunar etc. I've never heard of the Peleng brand.
No, Peleng is Russian and is completely different in it's optics from the Samyang.


Last edited by Blue; 09-15-2012 at 07:18 PM.
09-15-2012, 03:57 PM   #24
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QuoteOriginally posted by Docrwm Quote
Peleng is Russian.
It's from Belarus.

See

About www.Peleng8.com | buy it now - Peleng 8mm f/3.5 Circular Fisheye Lens for Canon, Nikon, Olympus
09-15-2012, 04:02 PM   #25
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QuoteOriginally posted by cali92rs Quote
I wonder why they opted for a f2.8 instead of a f4 with this lens.
In addition to the reason Doc mentioned, see post #13.

Diffraction may be starting to degrade the image at f/4,
like it does with the 8.5/1.9 on the Q
according to Photozone's tests:

Pentax-01 Standard Prime 8.5mm f/1.9 (Pentax Q) - Review / Lens Test - Analysis
09-15-2012, 04:13 PM   #26
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QuoteOriginally posted by lytrytyr Quote
In addition to the reason Doc mentioned, see post #13.

Diffraction may be starting to degrade the image at f/4,
like it does with the 8.5/1.9 on the Q
according to Photozone's tests:

Pentax-01 Standard Prime 8.5mm f/1.9 (Pentax Q) - Review / Lens Test - Analysis

You cant compare a Q lens to one designed for much larger format...the larger the format, the larger the f number it will begin to show the effects of diffraction. No lens designed for APS -C is going to show diffraction at f4 beyond a very negligible amount
09-15-2012, 04:16 PM   #27
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QuoteOriginally posted by Docrwm Quote
Low light shots. People do take cityscapes for example at night
Yea, you could, although I would still prefer the smaller package. Personally, if I was doing a night city scape it would be at f8 and on a tripod.
09-15-2012, 06:19 PM   #28
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QuoteOriginally posted by cali92rs Quote
You cant compare a Q lens to one designed for much larger format...the larger the format, the larger the f number it will begin to show the effects of diffraction.
You could compare the Q 8.5/1.9 and the Samyang 10/2.8 adapted to the Q.
Diffraction effects ultimately depend on the size of the aperture blades' opening.
What you are describing is more a function of different "equivalent" focal lengths,
and different enlargement ratios for a given print size.

QuoteOriginally posted by cali92rs Quote
No lens designed for APS -C is going to show diffraction at f4 beyond a very negligible amount
Look at the Photozone test of the Sigma 8-16 at 8mm:
Sigma AF 8-16mm f/4.5-5.6 DC HSM (DX) - Review / Lab Test Report - Analysis
Diffraction is already degrading the central image noticeably between f/4.5 and f/5.6,
from 2850 to 2675 lw/ph on APS-C (16MP).

Last edited by lytrytyr; 09-15-2012 at 06:25 PM.
09-15-2012, 06:36 PM   #29
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QuoteOriginally posted by cali92rs Quote
No lens designed for APS -C . . .
Interestingly enough, the Polish site
Samyang 10 mm 1:2.8 ED AS UMC CS - Optyczne.pl
mentions the Samyang 10/2.8 as becoming available for "Cztery Trzecie," Four Thirds.
I don't know how reliable their information is,
although Samyang does have a base in Poland.
09-15-2012, 09:23 PM   #30
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I'll stick with my Tamron 10-24. I like autofocus.
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