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01-23-2011, 12:31 PM   #1
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Fisheyes and 16mm?

I am wondering about the lenses such as the Pentax 16-45 f/4 which don't say fisheye. I looked at samples with this lens at 16mm. So this lens can get that wide without appearing distorted in a fisheye way? But others are 16mm but very much fisheye because people might prefer to have that distortion? I would love to save the PP work and get the one that won't distort, I don't prefer fisheye unless it's just for fun.

01-23-2011, 12:39 PM   #2
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you are on a crop sensor, 16 is more like 24mm on ff which is no where near fish eyes, 16mm fish eyes are mostly for ff camera
01-23-2011, 12:46 PM   #3
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Oh, I was wanting a lens that goes as low as possible without distorting. Or I don't mind if it distorts a bit at the end, but I know I'm getting the widest I can. So, that means this 16-45 isn't the best I can get, I need the 10-24 or so? I might get a couple primes instead but I am just trying to figure out the numbers. (Also I am curious about buying a fisheye but doing PP, to get wider than I can without PP.)
01-23-2011, 12:50 PM   #4
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QuoteOriginally posted by Kitty Quote
Oh, I was wanting a lens that goes as low as possible without distorting. Or I don't mind if it distorts a bit at the end, but I know I'm getting the widest I can. So, that means this 16-45 isn't the best I can get, I need the 10-24 or so? I might get a couple primes instead but I am just trying to figure out the numbers. (Also I am curious about buying a fisheye but doing PP, to get wider than I can without PP.)
how about this?
8mm f/3.5 Fisheye Lens: Samyang, Pro-Optic, Bower

01-23-2011, 02:08 PM   #5
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QuoteOriginally posted by clockwork247 Quote
I think Kitty wanted it without distortion...

But that is indeed a good alternative, just needs some extra processing. This guy is worth a read - Fisheye to Rectilinear Conversion - photo.net
01-23-2011, 02:12 PM   #6
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QuoteOriginally posted by Kitty Quote
Oh, I was wanting a lens that goes as low as possible without distorting.
The Pentax 12-24, Tamron 10-24 or Sigma 8-16.
01-23-2011, 03:04 PM   #7
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Fisheye lenses must be allowed to break the rules when it comes to focal length measurement. I don't know exactly why. If you look at field of view in degrees, the Pentax DA 10-17mm fisheye zoom has the same field of view at 17mm as the Pentax DA 12-24mm f4 zoom does at 12mm.

To make up for not knowing that explanation, I offer these photos. The first is with the Pentax 16-45mm zoom at 16mm. The second is with a Sigma 16mm fisheye lens meant for film use. Because I'm using it on an APSC-sized sensor, the sensor only sees the center of the lens and misses out somewhat on the fisheye effect.





The same lens used on film, with a subject that shows the distortion:


Last edited by Just1MoreDave; 01-23-2011 at 05:49 PM.
01-23-2011, 03:50 PM   #8
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The Pentax 10-17 is outstanding, because it only fisheyes at the widest end (which is spectacular), but gives you extremely decent "regular" shots at 14.

And 14 is damn, damn wide.

01-23-2011, 03:58 PM   #9
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QuoteOriginally posted by Just1MoreDave Quote
Fisheye lenses must be allowed to break the rules when it comes to focal length measurement. I don't know exactly why. If you look at field of view in degrees, the Pentax DA 10-17mm fisheye zoom has the same field of view at 17mm as the Pentax DA 12-24mm f4 zoom does at 12mm.

To make up for not knowing that explanation, I offer these photos. The first is with the Pentax 16-45mm zoom at 16mm. The second is with a Sigma 16mm fisheye lens meant for film use. Because I'm using it on an APSC-sized sensor, the sensor only sees the center of the lens and misses out somewhat on the fisheye effect.





The same lens used on film, with a sibject that shows the distortion:
They're not "breaking the rules" - they're playing by a different set of rules. There are different "projections" a lens can use, each having its unique strengths and weaknesses. Think of map projections - different types of maps use a different representation. Some keep relative sizes correct, while others keep border lines straighter. Same issue with lenses. Rectilinear lenses do a better job of keeping straight lines straight, while fisheyes using stereographic projection gives a wider view, but curves straight lines.

This explains some of it.
Fisheye lens - Wikipedia, the free encyclopedia
01-23-2011, 04:50 PM   #10
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Back to OP's question: 16-45 ain't very wide on an APS-C sensor. I've not tried any 8-16 nor 10-20 nor 12-24 nor the estimable 14 and 15's, but I currently own:

* DA10-17 fisheye zoom (and it's fishy everywhere)
* Tamron 10-24 (not fisheye, but distorting at its widest)
* Vemar 12/8 (fishy on FF; my copy is bad on APS-C)
* Zenitar 16/2.8 (fishy on FF, not so fishy on APS-C)
* DA18-55 and 18-250 (not fishy; nearly as wide as 16-45)
* Kenko (Hoya) 180 Degree Fisheye Adapter (ultra-fishy)

As mentioned, fisheyes and rectilinears use different projections. Various fisheye projections exist too, giving full-circle or various frame-filling images. Glass that's mildly fishy on APS-C, like the Zenitar-16, or the DA10-17@16mm, can be easily defished in PP without losing much IQ.

I tend to use the Zenitar 16/2.8 indoors because it's noticeably faster than my other glass in that neighborhood. I use the DA10-17 if I want widest FOV and/or strange angles and curves. I use my new T10-24 for wide FOV with least distortion (although mine is a little soft in one corner -- I may go for a replacement). I need to adjust the Vemar 12/8 a bit -- more on that another time. And I use the Kenko 180 on a 35-70 or 28-80 zoom, with full-circle at around 35-40mm and frame-filling from around 60-80mm -- that's a good test-bed for projections, although it's soft around the edges.

Options for wide shots depend on 1) how wide? and 2) how distorted? and 3) how much money? Aw hell, it's only money, eh? Grows on shrubs, eh?
01-23-2011, 08:43 PM   #11
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I like to put this up in appropriate threads. I only wish I had done the 10-17 at 10mm...

01-23-2011, 09:20 PM   #12
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I've been testing the 10-17. It's very fishy at 10. Generally, I'm not pleased with the quality overall. For a zoom, I believe the Sigma 10-20 is best. For a prime, the DA 15 Limited is the best lens I've ever used or owned. It's coated in magic. Very little bending, which is only noticable if you get a verticle object on the far edges.
I still want a fisheye and will probably get a Bower 10mm or 8mm at half the price.
01-24-2011, 03:19 AM   #13
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Most of the options mentioned seem great but too expensive for me. The only affordable one seems to be the Pentax 10-17 and then it could use defishing in PP most of the time. I'll probably wait and try to get a good deal on a 10-24 someday, as it's not that much more expensive, and I like it going higher b/c my main lens is 28-75.

I wish there were more primes that were cheap, even if they are older MF. I don't see any in the database below 17mm that are reasonably priced, they seem to cost almost as much as the 10-17.

So, for a related question, since I can't afford the wideangle yet (and might buy another lens, like a 75-200, first) -- would it look good to stitch 2 or 3 pics together in CS3? For example, if I was trying to shoot that same Century21 building with my 28-75mm lens. Would my end result be nearly the same, better, worse than shooting at 10mm, 12mm, 14mm, 16mm? I am guessing I'd get the other kind of distortion which is sort of like reverse of fisheye distortion? Especially the higher number I am using so shooting at 28mm is worse than if I had a 24mm or 17mm to shoot with?

Last edited by Kitty; 01-24-2011 at 03:24 AM.
01-24-2011, 08:39 AM   #14
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Y'no Kitty, you keep asking us about another bit of kit. If you have a camera and a lens I'd go out and take pictures until I find the kit is stopping me 'create my vision'. Now having had SLR cameras before (both film and digital) that meant I came to the K7 with a good idea what extras I needed, beyond memory cards and a spare battery that is. In fact I had some of them - I didn't sell them with the E510.

But so far as I know you've not got an SLR background. Maybe a lot of playing before you buy lots of extras might be worthwhile?
01-24-2011, 09:18 AM   #15
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QuoteOriginally posted by Kitty Quote
Most of the options mentioned seem great but too expensive for me. The only affordable one seems to be the Pentax 10-17 and then it could use defishing in PP most of the time. I'll probably wait and try to get a good deal on a 10-24 someday, as it's not that much more expensive, and I like it going higher b/c my main lens is 28-75.

I wish there were more primes that were cheap, even if they are older MF. I don't see any in the database below 17mm that are reasonably priced, they seem to cost almost as much as the 10-17.

So, for a related question, since I can't afford the wideangle yet (and might buy another lens, like a 75-200, first) -- would it look good to stitch 2 or 3 pics together in CS3? For example, if I was trying to shoot that same Century21 building with my 28-75mm lens. Would my end result be nearly the same, better, worse than shooting at 10mm, 12mm, 14mm, 16mm? I am guessing I'd get the other kind of distortion which is sort of like reverse of fisheye distortion? Especially the higher number I am using so shooting at 28mm is worse than if I had a 24mm or 17mm to shoot with?
Stitching workds great. I've attached an example - this is a panorama I shot with an old 28mm prime. The one issue with stitching is you're limited to rather static objects - you can't have objects moving from frame to frame.
RE this pic - I could have included another row of the rocks close - that would have given it a more normal aspect ratio.

You also get a bit of perspective distortion (it looks a little curved...) unless you shoot off an L bracket. The image above suffers from this - there was no bend in that river when I shot it. They make special brackets that mount in the tripod to let you rotate around the lens' front element, rather than the camera axis.

Jumping back to your original question a bit - what is your goal for this lens?
What shots do you want to take that you've been unable to get?


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