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03-07-2016, 10:34 AM   #1
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DA 10-17 defishing?

When you defish an image from the 10-17 at 10mm how much resolution do you lose?
Also what would be the equivalent field of view from a rectilinear lens?

I don't have this lens yet, but I might do very soon...

03-07-2016, 10:46 AM   #2
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A lot of folks point out that the 10-17 is pretty close to rectilinear at 17, but fishy on the short end. The 10mm would be somewhere between 8 and 9mm when defished, but results in a very oblong result, so the calculation is not absolute. Also, with that extensive correction, the sharpness is very low at the edges and CA is emphasized. You might want to take a look at the posted Flickr photos from defished and otherwise corrected images from the lens before making a decision.

By the time you get to 14-15mm, the extent of defishing and resulting degradation is significantly lessened. If that kind of FoV is what you are after, then you might be more than satisfied. Still, if you are aiming for rectilinear for the vast majority of wider shots from the lens, other options make more sense, IMHO.
03-07-2016, 10:49 AM   #3
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If you really want a defished image, get a Sigma 8-16. Defishing a fisheye, what fun is that?

The fisheye is sold as a "fun" lens. It's for impressing your friends at parties.
03-07-2016, 10:54 AM   #4
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QuoteOriginally posted by normhead Quote
If you really want a defished image, get a Sigma 8-16. Defishing a fisheye, what fun is that?

The fisheye is sold as a "fun" lens. It's for impressing your friends at parties.
A cheap 10-17 popped up on my local classifieds and I plan to go take a look and test for issues.
Sure I'd use as a fisheye a lot of the time, but I'd want the occasional rectilinear shot
If I don't like it I could sell it here easily for what I go it as.

03-07-2016, 11:40 AM   #5
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Happy hunting!

I almost bought a 16mm full-frame fisheye with A contacts on a recent trip, and then discovered it wouldn't focus to infinity. The same lens on eek-bay is significantly more expensive than the one I handled. Hope you have better luck than I did!!
03-07-2016, 11:46 AM   #6
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I have recently bought the lens, didn't have much time to test it but i'd say that to my tastes, defishing a 17mm shot (at least with the K-3) is viable with a more than acceptable loss of resolution in the corners. That is because, as already said, at 17mm the fisheye distortion is relatively small to begin with. Unless you are shooting straigth at the facade of a building at close range, usually you can manage to somewhat "mask" the distortion or i'd better say make it as unobtrusive as possible by appropriate composition.

I've come across some people defishing shots at the shorter focal lenghts but i believe in that case the loss in resolution is too dramatic to be acceptable.

In summary i'd say it's a surprisingly versatile lens, of couse it is not wise to buy it with the intention of defishing every shot...but if you just like to have this extra possibility, in my experience the possibility is definitely there !
03-07-2016, 12:21 PM   #7
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Definitely a fun lens, great close up abilities as well. I haven't been bothered to do much in the way of defishing (embrace the fishiness), but there's a good discussion involving defishing options with examples here:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/310874-roki...omparison.html

which links to another good discussion comparing fields of view (less emphasis on defishing though):

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/235102-uwa-...omparison.html
03-07-2016, 01:09 PM   #8
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I see this discussion winding toward the UWA rectilinear aspect. A comparison of three zooms was done on the Forum, see:
DA 12-24mm vs Sigma and Tamron 10-24mm Comparison Review - Introduction | PentaxForums.com Reviews

This brings us to the high likelihood that someone will inquire about FF compatibility. The Sigma 12-24 in the comparison is FF (essentially comparable to the Sigma 8-16 for APS-c). You'll notice that the PF sample of the Sigma was good and proved excellent at controlling CA and was the clear overall winner; some other tests of the Sigma got decentered versions showing very high CA. One other aspect of the review indicated that a newer version of the Sigma lens would be coming out, but the k-mount was never released in the II version.

03-07-2016, 01:23 PM   #9
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QuoteOriginally posted by bertwert Quote
When you defish an image from the 10-17 at 10mm how much resolution do you lose?
At 10mm it gets pretty bad. There are many ways to defish. If you use the Adobe profile, then you basically end up with a crop from the centre of this :
Attached Images
View Picture EXIF
PENTAX K-7  Photo 
03-09-2016, 02:43 AM - 1 Like   #10
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It look like lightroom does a pretty bad job compared to DxO.

I didn't use it much yet, go it no long again, but anyway, in attachement, here a few fish/defished picture at respectively 17, 13 and 10mm. You just need to click to enable/disable distorsion tab and select to not keep aspect ratio.

Basically, only the corners are lost, but the aspect ratio of the picture change: it goes from 3:2 to 1.9, so between 16:9 and 2:1

Last edited by Nicolas06; 01-31-2017 at 02:03 PM.
03-09-2016, 02:52 AM   #11
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And for the picture quality, here a few crops (from the 13mm picture, f/5.6) from border/center as normal fish or defished:

Count theses are actual K3 crops, so that's 1/6 of the picture in both direction, quite an enlargement.

I'd say even not difished, the corners are never that sharp, It get worse defished. It is good enough if there no important subject on it, if you want something like a landscape that would need the thing to be quite sharp, it could be interresting to crop a bit.

I still think you'd as much usable/sharp enough picture with the 10-17 that goes up to 180 (diagonal) while the 8-16 is twice as expensive and go only up to 120 (diagonal).

Don't get me wrong, the 8-16 is sharper, even maybe on center. But the 10-17 while not extremely sharp, is sharp enough for reasonably sized prints. Full screen on my computer (22" screen) it look nice.

You should get it for the fish eye, the size/weight/build quality with an option for a medium quality rectilinear that likely get you up to 8-12 field of view once cropped to remove the weak borders.

Reality is depending of the subject, either a fish, either a rectilinear would do a better job... And in DxO at least, you have a cursor to choose how much you correct the distorsion. You are not limited to fish or completely defished. I get lightroom the same.

Last edited by Nicolas06; 01-31-2017 at 02:03 PM.
03-09-2016, 03:29 AM   #12
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Why defish? No point having the fisheye if you want to defish I reckon. Embrace it and learn to work with it, if it doesn't suit your shooting style, sell it and move on. Mine, I love it, it barely leaves my camera.
03-09-2016, 04:05 AM   #13
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QuoteOriginally posted by Grippy Quote
Why defish? No point having the fisheye if you want to defish I reckon. Embrace it and learn to work with it, if it doesn't suit your shooting style, sell it and move on. Mine, I love it, it barely leaves my camera.
Why not defish? No point having a defish feature in lightroom, DxO and other and never use it!

I only defished here to illutrate the things of what possible as I used the DA15 that day for rectilinear shots, but not everybody has a DA15 + a DA10-17...

Not to say you should buy a fish to defish, but for the case of bertwert, he can get it for 180$, CAD I think. At that price there normaly no possible way to get any kind of UWA. A DA15 is $300 used and a 8-16 even more than that maybre 450$. The 10-17 also quite small (yeah the DA15 too) and a zoom.

So even for defished pictures, that's a better offering, because there no competition. Plus you don't have to defish all the time, plus defished picture will still offer a wider angle of view than most rectilinear UWA.

While people with the money for it and wanting rectilinear perspective rendering should avoid fisheyes, as long as you don't ask for the lens more than it can provide, you can get lot of things done with it.

There also many cases where you may want something in between, not full fish rendering, not fully defished and that 10-17 excel at it with its zoom feature. This zoom is one of the Pentax unique lenses and an interresting compromize.
03-09-2016, 04:44 AM   #14
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I've happily owned the DA 10-17 for many years. I originally bought it for a great price from a forum member who thought he could get acceptable results by defishing in PP. Most of the time, it just looks weird and you end up cropping so much, you could have used the wide end of the kit lens. The 10-17 is awesome as it is! Rather than defish, learn to use it creatively. On occasion, I do end up doing a tight crop, but that is a result of having the lens on the camera when it wasn't quite the proper tool but I didn't have time to change it.
03-09-2016, 04:54 AM - 1 Like   #15
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I had both for a while, and I sold the Sigma.

For a start, even when defished, the DA10-17 @ 10mm is *wider* than the Sigma @ 8mm, and the corners are comparable (and the flare is better)

Plus it's smaller, and a real fisheye when you want it, and its a Pentax


Man cave 10mm FE corrected


Man cave 8mm

Last edited by Sandy Hancock; 03-09-2016 at 05:00 AM.
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