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07-18-2008, 04:09 PM   #16
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QuoteOriginally posted by flifishun Quote
Is an 8mm lens usable with the K20D? I thought it had a full frame CMOS.
Short answer: 8mm is usable; examples here:
Peleng 8mm f/3.5 Fisheye

Long answer: It's common for a fisheye lens to not fill the entire frame; "usable" depends on the effect you want.

Here's what I found: the image diameter of an 8mm fisheye depends on the specific lens; for example:

- The Peleng 8mm/4.0 has an image diameter of 24mm
- The Sigma 8mm/4.0 AF EX has an image diameter of 22.04mm

(data from The Fish List - The Fish List -)


The K20D (and other pentax digitals) have a sensor of size 23.4 x 15.6mm, so the Sigma 8mm captures a full 180 degree horizontal FOV on the cropped sensor and about 127 degrees vertically. You can see many examples of this in pbase (see Heather's post).

The K20D loses about 1mm on either side of the Peleng image; I wouldn't consider this a practical disadvantage.

If you want the effect of a diagonal fisheye (180 degree diagonal FOV), you need to crop (with a possible loss in resolution relative to a 10mm APS-C diagonal fisheye). If you want the effect of a full circular fisheye, you need a smaller focal length or a bigger sensor (or film).

cheers


Last edited by troyz; 07-18-2008 at 04:14 PM.
07-19-2008, 12:54 PM   #17
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This is a picture taken with the Sigma 15mm EX:



As you can see the distortion ins not too obvious. This is at f8.
07-19-2008, 03:52 PM   #18
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I love my 10-17. For nature shots it gets a little CA ,but its a fun lens and im glad I bought it.....
07-25-2008, 06:05 AM   #19
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QuoteOriginally posted by AndrewG NY Quote
BTW, Doug, that is one of the cooler and more interesting uses for a fisheye that I've seen for a while.
Thanks! It took a lot of shooting of course, filled half a 2 Gig card following different bees around that bush to get a handful of decent shots. OK, the majority is sharp as the DOF is wide and I used a short enough exposure time, but bees, leafs and flowers were not usually in the right place. The nice backlighted transparent colors leafs was a bonus. Plan to do this again asap for any sort of flying insects. Way fun!

08-01-2008, 07:47 AM   #20
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QuoteOriginally posted by Stratman Quote
wow, a grand for that sigma fisheye, whew !!
Yes, it's very expensive, but that's because the Sigma 8mm 3.5 does an amazing job controlling PF ... particularly the infamous "ring of purple" common to cheaper fisheyes (even the older Sigma 8mm f4 suffers from the ring of purple).

I have the Sigma 8mm f4 (recent purchase) and it's a great fisheye. I had a chance to buy the DA 10-17 for almost $200 less than the Sigma 8mm but I chose the Sigma because if you're going to go with a wide fisheye you might as well go as wide as possible.

I'm sure the 8mm f3.5 is optically superior to my 8mm f4, but $400 is as much as I'm willing to drop on a fisheye lens. Yes, they're cool and help you produce awesome creative shots, but they aren't very practical and I can think of many other lenses I'd rather buy for $1,000.
08-01-2008, 08:24 AM   #21
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Having had my 10-17 for only a couple of weeks, and no other FE experience (except for the TAK 17) I am hardly qualified to say anything other than it is a fun lens! I have used it on bug close-ups and the zoom range makes it easier than a FE prime IMO.........
08-01-2008, 10:25 AM   #22
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i have
Sigma 10-20mm f/4-5.6 EX DC HSM
Pentax-DA fish-eye 10-17 mm

sigma fisheye 15 mm

the best lenses are Sigma 10-20mm f/4-5.6 EX DC HSM
you can use it for lendacape photography and panoramic photography

if you intend do make panoramic photograpy only-with sticher-Pentax-DA fish-eye 10-17 mm
is the best lenses

sigma fisheye 15 mm-i use it rarely
[url=http://www.photolight.co.il/author/3264.html
08-01-2008, 10:38 AM   #23
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QuoteOriginally posted by JJJPhoto Quote
Yes, it's very expensive, but that's because the Sigma 8mm 3.5 does an amazing job controlling PF ... particularly the infamous "ring of purple" common to cheaper fisheyes (even the older Sigma 8mm f4 suffers from the ring of purple).

I have the Sigma 8mm f4 (recent purchase) and it's a great fisheye.
...
Which flavor of the 8mm/4.0 fisheye do you have? The EX, EX DG, or one of the filtermatics?

It would be useful to compare notes (especially lateral/magnification CA adjustment and other postprocessing) here or in the Fisheye Fever thread.

08-02-2008, 05:16 AM   #24
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QuoteOriginally posted by troyz Quote
Hello all. . .

I've been thinking about getting a fisheye lens for use with a K20D; usability with film would be nice but not essential.

The leading candidate is the Pentax 10mm-17mm/3.5-4.5 fisheye zoom, but other options appear to be:

Zenitar 16mm/2.8
Peleng 8mm/3.5

and the harder to find

Sigma 16mm/2.8, 8mm/3.5 and 8mm/4
Pentax 16/2.8.

Two questions:

-- To Zenitar/Sigma/Pentax 16 owners: do you use your lens much at f/2.8-3.5 (i.e. is there a useful advantage over the 10-17 zoom for available-light work)?

-- To those familiar with the zoom and at least one prime: Do any of the primes have an advantage in resolution, contrast, or flare/ghosting resistance over the zoom?

I haven't found any hard data comparing the zoom with any of the primes (or the primes with each other) so I'd like to hear your opinions.

Thanks!
I've had both the Peleng and Zenitar FE's and I used the Z most out of the pair, but used it less and less as I found the extra FOV over my DA 16-45 not sufficient to warrant changing lenses. I found the 8mm far too much apart from fun shots. I used a loaned DA 10-17 for a few weeks and found that a much better lens than either the P or Z, it was sharper and had much better colour and flare resistance.

I subsequently sold both the FE's and never missed them, I subsequently bought a Sigma 10-20, in fact I had two, and returned both for field curvature and centricity problems as well as wierd AF issues. I also had a loan DA 12-24 at the same time as the 10-17, but in fact I rarely found I wanted much more than 14mm with a rectilinear lens apart from interiors where I sometimes think FE distrotion is prefereable to the perspective stretch you get with rectilinear wide angle lenses much beyond 14mm (i.e. a 90 deg FOV) and have since stuck with my 16-45.

When I want a wide landscape I usually take a few shots and stitch them to obtain very high resolution and detail which is what you really need in a landscape vista.

If I were to go for a wide FE lens, then the DA 10-17 is the "no brainer" solution, high IQ, well made, versatile, small and affordable. Nice one Pentax!

EDIT - Examples of a landscape vista

Here are a couple of shots taken from the same location at the same time. One with the Sigma 10-20 @ 10mm and the other a 3 image stitched pano taken with the DA 16-45. They were taken with my istD. Even resized down, the difference in IQ is readily noticable. Both were sharpened to the same degree to get the best from each.

Sigma 10-20




16-45 stitched


Last edited by Richard Day; 08-02-2008 at 06:54 AM.
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