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04-06-2012, 07:00 AM   #1
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Focal Length of 10-17 Fisheye; vs an 8-16mm

Good day everyone.

So i picked up a 12-24 about a year ago, and now I feel I want to go even wider. The Sigma 8-16mm comes to mind, immediately, but then I find out that the 10-17

1. appears rather rectilinear at 15-17mm(15mm appearing to be the limit) and
2. is, at 17mm, actually WIDER than the 12-24 is at 12mm(what?!).

So I'd like some enlightenment on this. I'm aware that the 10-17 is a fisheye. I'm NOT looking for a fisheye as i'm looking for wider angles for landscapes and interiors. However, from the (very) few shots of 17mm i've seen, i'm alright with that half-fishiness distortion, whatever you may call it.

However, if at 17mm the 10-17 is wider than the 12-24 at 12mm, how is one to have a better idea of how wide this 17mm is? It's most intriguing indeed.

04-06-2012, 07:29 AM   #2
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Good Morning,

I have both lenses and they are very complementary to each other. If you look at the diagonal field of view, each one has this field of view:
  • 10-17 -180 degrees to 100 degrees
  • 12-24 - 100 degrees to 60 degrees
Depending on the scene, the objects in the scene, your composure, along with the selected focal length, you can pretty much mitigate the fish eye effect for any of the focal lengths selected. If the objects in the frame are very square with linear lines, then the effect will be very pronounced - your eye will detect at to what they should look like and the fish eye effect can be very pronounced. On the other hand if they are "natural" with curves, etc. - think rock formations etc., then the eye really does not detect the fisheye effect at all. This lack of perception extends especially to the long end - 17mm where the fisheye effect is pretty well under control. Composition is important with the 10-17 where with a slight adjustment, in either up, down or straight on, you are able to place the "bend" at the top center or bottom. At 10mm you can have a very straight and level horizon, and if the foreground is dirt or something not straight or rectangular then you will never see the bend.

The other comparison that comes to mind is that the 10-17 when compared to the 12-24 can have a lot more contrast and the colors are a bit more vivid. The "sharpness" of the lens will appear to be different - since the field of view is so large in the 10-17, each pixel needs to capture a lot more area, as compared to the 12-24. This is not to imply that the 10-17 is soft and not sharp by any means.

Other 10-17 characteristics that you will see with use are - when compared to the 12-24, the center is pushed back into the background in order to pull more scene in from the top, bottom and the sides. This said, you can get incredibly close to very LARGE objects and still get EVERYTHING into the frame. When used in portrait orientation, check to ensure your feet or shoes are not in the frame at the bottom.

You should like the lens - its construction and build quality are outstanding. Its size compared to the 12-24 is pretty small.


Last edited by interested_observer; 04-06-2012 at 07:34 AM.
04-06-2012, 07:37 AM   #3
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Exact width (AOV) of a lens depends on the exact size of the sensor. The DA10-17 @10mm is supposedly180 degrees diagonally on nominal APS-C, which has a diagonal of 31.1mm. My K20D's sensor has a diagonal of 28.1mm so the AOV is more like 165-170 degrees. The DA10-17 @17mm defishes to about 12.5mm IIRC, which has an AOV of 101 degrees on nominal APS-C, 97 degrees on my K20D. So the DA12-24 @12mm should be a smidge wider than the DA10-17 @17mm.

[A note on defishing: When I defish any FE image, I find I must downsize the picture to retain good resolution. The defishing s-t-r-e-t-c-h-e-s portions of the image. If I shot FE at 15-17mm, I'll downsample by 30-50% or so, depending on edge detail.]

But I wonder if the different optical projection systems smudge those numbers a bit? Or if the focal lengths are completely accurate? I've read that the FA50/1.4 is actually more like 52/1.5. I'll suggest that the tolerances may overlap, that the 10-17 may actually be 9-16 and the 12-24 may be 13-25. This would account for the fisheye (long) being wider than the ultrawide (short). But I'm just speculating here.

The way to be sure, of course, is with a test. Shoot a measuring stick perpendicularly. Note the width of the captured image, and the focal-plane-to-subject distance. A wee little bit of trig will reveal the AOV of that focal length on that sensor.

You say, "from the (very) few shots of 17mm i've seen, i'm alright with that half-fishiness distortion". If so, you might consider the Zenitar-K2 16/2.8 (the K2 means it's in PK-M mount). I find images from the DA10-17 @16mm indistinguishable from the Zenitar, except that the DA is f/4.5 there and the Zen is f/2.8. The Zen is still my favorite for dim tight spaces -- that extra 1.3 f-stops makes a difference.
04-06-2012, 07:47 AM   #4
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I just happened to have picked one of these up a few days ago (the DA 10-17) and I'm having a lot of fun playing around with it, though I haven't been anywhere yet to shoot an actual decent subject. I'm thinking it might be the only wide angle I'll need, (I've said that sort of thing before, tho.) since it morphs from a fisheye to a lot less "fishy-ness" from 15-17mm. Nice versatility. And the build quality is superb.

04-06-2012, 08:07 AM   #5
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A while ago, I actually went out and measured the side to side, top to bottom observed field of view (as opposed to the diagonal)........ also here are some shots using the 10-17 where the fisheye effect is pretty flat...
04-06-2012, 08:18 AM   #6
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QuoteOriginally posted by interested_observer Quote
also here are some shots using the 10-17 where the fisheye effect is pretty flat
Those are GREAT shots! Love the color & perspective.
04-07-2012, 10:55 PM   #7
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QuoteOriginally posted by interested_observer Quote
Depending on the scene, the objects in the scene, your composure, along with the selected focal length, you can pretty much mitigate the fish eye effect for any of the focal lengths selected. If the objects in the frame are very square with linear lines, then the effect will be very pronounced - your eye will detect at to what they should look like and the fish eye effect can be very pronounced. On the other hand if they are "natural" with curves, etc. - think rock formations etc., then the eye really does not detect the fisheye effect at all. This lack of perception extends especially to the long end - 17mm where the fisheye effect is pretty well under control. Composition is important with the 10-17 where with a slight adjustment, in either up, down or straight on, you are able to place the "bend" at the top center or bottom. At 10mm you can have a very straight and level horizon, and if the foreground is dirt or something not straight or rectangular then you will never see the bend.
I took these images the other evening and thought I would put the link here. You can see how the Fish Eye effect comes into play when you have a combination of the strong geometric patterns against something a bit softer - in terms of curves, all in the same frame. Also, something that is LARGE, where you need to tip the lens up in order to pull it all in, which plays havoc with the lines below - especially the horizon.... On the other hand it really gives you a wide perspective.
04-07-2012, 11:26 PM   #8
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The 10-17 is never rectilinear.



04-08-2012, 05:09 AM   #9
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You need to remember that a fisheye generally has 180 degree field of view corner to corner, but if you "defish" the lens the useable rectilinear portion of the image is no whe near as wide.

If you want really wide, fet the sigma 8-16. I use a 10-20 myself and it is at 10mm 60% of the time
04-08-2012, 05:52 AM   #10
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I always wants to try the sigma 8-16 but i always feel i can use my fisheye instead.
04-08-2012, 07:10 PM   #11
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A few years back when I was going to Cambodia I was trying to keep my kit small, I had the Sigma 12-24 as well as the FA17-28 fisheye zoom, and as you say at 17mm the fisheye has the same FoV as the 12mm, I chose to take the Pentax 17-28 because it was about a 1/3 of the size, but after looking at my pics when I got home, I wish I had taken a diagonally corrected lens as trying to defish and crop and correct 1000 pics is just not practical.
04-08-2012, 09:24 PM   #12
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QuoteOriginally posted by cmohr Quote
A few years back when I was going to Cambodia I was trying to keep my kit small, I had the Sigma 12-24 as well as the FA17-28 fisheye zoom, and as you say at 17mm the fisheye has the same FoV as the 12mm, I chose to take the Pentax 17-28 because it was about a 1/3 of the size, but after looking at my pics when I got home, I wish I had taken a diagonally corrected lens as trying to defish and crop and correct 1000 pics is just not practical.
You kept your kit too small! Fisheye zooms really are specialized, not general-purpose lenses. That's why my bag always contains the DA10-17, Tamron 10-24, and DA18-250, as well as a fast prime or two. (And a couple wee tiny slow ultralight primes.) There are times the DA10-17 is absolutely necessary, but many more situations that call for the T10-24. I do my best to avoid defishing.
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