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insulinguy · 01-01-2012, 07:46 AM

hey all - just wondering which methods you guys use to fix barrel distortion - ive used the photoshop way but you have to crop to get rid of the background that shows after fixing the distortion. ive tried PTlens and rectfish as well - rectifsh seems to do the best job but for a $30 license fee to use it - im not entirely sold on it yet. are there other programs out there or a PS action that work with barrel distortion?? i love using the SMC DA 10-17mm but the distortion at 10mm only works on certain shots and overusing it lends itself to boredom. so any recommendations? i found the LR presets for the 10-17mm but havent been able to figure out how to get it loaded up - some help there would be appreciated too. ive seen the other threads about the presets but never found anything too specific about how to load them and use them...
i have been accepted into the fort worth main street arts festival and have several shots i want to use in my booth but feel the wonky nature of the 10-17mm isnt as marketable as i would like so i need to 'fix' some of those shots in order to feel confident in displaying them for sale. any recommendations or help is appreciated! cheers and happy new year to my fellow pentaxians!

RioRico · 01-01-2012, 08:14 AM

I use an old copy of PaintShopPro9 that includes the PTLens tools to fix minor distortion. I generally DON'T try to defish the DA10-17 @10mm because of the very problem you see. That's why I got a Tamron 10-24. The DA10-17 is splendid in very specific situations and lousy most everywhere else. If I must defish a 10mm FE shot, I'll downsample, reducing the dimensions by 50% or more. That is, print it small, and it won't look so bad.

sheld · 01-01-2012, 08:51 AM

imho, defishing the 10-17mm looks ok at 17mm, which is about like the DA15mm, but it doesn't work at 10mm to 12mm due to edge stretching causing loss of sharpness, and due to the fact that the picture composition is so much different after defishing. Sometimes defishing 14mm works, (about 12mm APS-C equivalent), but I usually prefer the fisheye version.

RioRico · 01-01-2012, 10:37 AM

Originally posted by sheld

imho, defishing the 10-17mm looks ok at 17mm, which is about like the DA15mm, but it doesn't work at 10mm to 12mm due to edge stretching causing loss of sharpness, and due to the fact that the picture composition is so much different after defishing. Sometimes defishing 14mm works, (about 12mm APS-C equivalent), but I usually prefer the fisheye version.

In terms of AOV, defishing 17mm is equivalent to about 12mm rectilinear, and defishing 10mm is about equivalent to 1mm. Huge, eh? And yes, the edge stretching is horrible, which is why I recommended downsampling / shrinking the output by at least 50% per side. Or better yet, don't defish, not unless there's a real good reason!

Kryscendo · 01-01-2012, 10:46 PM

The best way to beat the aberrations is to simply prevent them. The best way to prevent BD, CA, and other sorts of anomalies is simply get a better lens. Classic case of you get what you pay for- which is a shame because some of my favorite lenses to shoot just don't hold up against my DA*s which I frankly leave the hell alone out of the camera.

insulinguy · 01-02-2012, 10:26 PM

Originally posted by Kryscendo

The best way to beat the aberrations is to simply prevent them. The best way to prevent BD, CA, and other sorts of anomalies is simply get a better lens. Classic case of you get what you pay for- which is a shame because some of my favorite lenses to shoot just don't hold up against my DA*s which I frankly leave the hell alone out of the camera.

well - i AM using a DA lens - the 10-17mm in fact and at the price point pentax sells it for i dont really think there is a better lens in that focal length range. yes - shooting at 17mm would prevent some of the barrel distortion but why only use the 10-17 at 17mm? 10mm looks great for certain shots - my intent here is to de-fish some of the ones at 10mm so they arent quite as wonky. excuse me if im reading your post wrong but i dont see how you could tell me to get a better lens when the 10-17mm is one of the best lenses pentax makes...

RioRico · 01-03-2012, 12:30 AM

Originally posted by insulinguy

10mm looks great for certain shots - my intent here is to de-fish some of the ones at 10mm so they arent quite as wonky.

And that won't happen. A fully defished DA10-17 @10mm shot will look bad unless it's displayed very small. It's the old mapmaker's problem of projecting a 3D world onto a 2D page. Any full projection will have extreme distortion. You can crop the most-distorted edges, but that can lose 1/2 the picture; you'd get better results with a rectilinear UWA lens. Use the DA10-17 for what it is; then use a Tamron 10-24 or one of the Sigmas for what *they* are. Or show your defished 10mm FE shots at 1080i resolution.

sheld · 01-03-2012, 02:37 AM

Agreed, its always better to compose and shoot with a non-fisheye, but defishing the 10-17mm can work, especially at 17mm. I used to defish more often, before I bought my DA15mm. These are from a year and a half ago, from the old city in Jerusalem, shot with the 10-17mm. At the time, I tried defishing all of the photos from that outing, but in the end, decided to stay with the non-defished versions for all of the photos. I have very accurate profiles for the 10-17mm fisheye correction correction, that I generated with ptgu 360 degree panoramas. Defishing at 10mm doesn't work that well, due to stretching and cropping, (8mm rectilinear equivalent, based on vertical FOV).. Defishing at 17mm works (15mm APSC rectilinear equivalent). Defishing at 14mm can work, (12mm APSC rectilinear equivalent). In the end, I generally prefer to use the 10-17mm without defishing. It is a good "get it all in lens", which is something that regular rectilinear wide angle lenses don't do as well. Also, the wider you go, the more the defishing changes the image to one that is sensitive to the pitch. Rectilinear ultrawides also act really wierd; and for me, the widest I like to go is my DA15mm.
- Shel

10-17mm, 17mm example

Defished 17mm example, equivalent to 15mm APS-C.

10-17mm, 14mm example

defished 14mm example, equivalent to 12mm APS-C, defished to a 3:2 aspect ratio.

10-17mm, 10mm example

defished 10mm example, equivalent to 8mm APS-C, defished to a 3:2 aspect ratio, which also crops the ultrasoft defished edges.

One more example at 10mm,

defished, this photo is probably sharp enough for the web.

RioRico · 01-03-2012, 02:08 PM

Yes, defishing works, and yes, I've defished 15-16-17mm FE shots without losing too much at the edges. But if I've defished a 180 degree FE shot and chopped it down to around 100 usable degrees, I'd have better resolution just using a 100-degree rectilinear lens, especially if the picture is to be shown fairly large. This is a case where the DA10-17 doesn't really replace a Tamron 10-24 or Sigma 10-20 -- the FE and UWA complement each other. But if the 10-17 is all you have, then run with it, and keep the prints small.

Personal note: The DA10-17 is the lens that drove me to Pentax. My original (and still most-used) kit were the DA10-17, DA18-250, and FA50/1.4. Then a zillion other lenses. But those first three plus the Tamron 10-24 and Raynox DCR-250 are my ultra-minimalist kit. And I went for the Tamron largely because I wasn't satisfied with defished shots from the DA10-17 or Zenitar 16/2.8. The Zenitar is the fastest of my wider lenses; the Tamron is the most flexible; the 10-17 is great fun but in more limited circumstances.

01-01-2012, 07:46 AM	#1
insulinguy Senior Member Join Date: Aug 2009 Location: Fort Worth, TX Photos: Gallery \| Albums Posts: 134	barrel distortion hey all - just wondering which methods you guys use to fix barrel distortion - ive used the photoshop way but you have to crop to get rid of the background that shows after fixing the distortion. ive tried PTlens and rectfish as well - rectifsh seems to do the best job but for a $30 license fee to use it - im not entirely sold on it yet. are there other programs out there or a PS action that work with barrel distortion?? i love using the SMC DA 10-17mm but the distortion at 10mm only works on certain shots and overusing it lends itself to boredom. so any recommendations? i found the LR presets for the 10-17mm but havent been able to figure out how to get it loaded up - some help there would be appreciated too. ive seen the other threads about the presets but never found anything too specific about how to load them and use them... i have been accepted into the fort worth main street arts festival and have several shots i want to use in my booth but feel the wonky nature of the 10-17mm isnt as marketable as i would like so i need to 'fix' some of those shots in order to feel confident in displaying them for sale. any recommendations or help is appreciated! cheers and happy new year to my fellow pentaxians!

01-03-2012, 02:37 AM	#8
sheld Senior Member Join Date: Apr 2010 Location: Austin, TX Photos: Albums Posts: 164	Agreed, its always better to compose and shoot with a non-fisheye, but defishing the 10-17mm can work, especially at 17mm. I used to defish more often, before I bought my DA15mm. These are from a year and a half ago, from the old city in Jerusalem, shot with the 10-17mm. At the time, I tried defishing all of the photos from that outing, but in the end, decided to stay with the non-defished versions for all of the photos. I have very accurate profiles for the 10-17mm fisheye correction correction, that I generated with ptgu 360 degree panoramas. Defishing at 10mm doesn't work that well, due to stretching and cropping, (8mm rectilinear equivalent, based on vertical FOV).. Defishing at 17mm works (15mm APSC rectilinear equivalent). Defishing at 14mm can work, (12mm APSC rectilinear equivalent). In the end, I generally prefer to use the 10-17mm without defishing. It is a good "get it all in lens", which is something that regular rectilinear wide angle lenses don't do as well. Also, the wider you go, the more the defishing changes the image to one that is sensitive to the pitch. Rectilinear ultrawides also act really wierd; and for me, the widest I like to go is my DA15mm. - Shel 10-17mm, 17mm example Defished 17mm example, equivalent to 15mm APS-C. 10-17mm, 14mm example defished 14mm example, equivalent to 12mm APS-C, defished to a 3:2 aspect ratio. 10-17mm, 10mm example defished 10mm example, equivalent to 8mm APS-C, defished to a 3:2 aspect ratio, which also crops the ultrasoft defished edges. One more example at 10mm, defished, this photo is probably sharp enough for the web. Last edited by sheld; 01-03-2012 at 07:48 AM.

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01-01-2012, 08:14 AM	#2
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	I use an old copy of PaintShopPro9 that includes the PTLens tools to fix minor distortion. I generally DON'T try to defish the DA10-17 @10mm because of the very problem you see. That's why I got a Tamron 10-24. The DA10-17 is splendid in very specific situations and lousy most everywhere else. If I must defish a 10mm FE shot, I'll downsample, reducing the dimensions by 50% or more. That is, print it small, and it won't look so bad.

01-01-2012, 08:51 AM	#3
sheld Senior Member Join Date: Apr 2010 Location: Austin, TX Photos: Albums Posts: 164	imho, defishing the 10-17mm looks ok at 17mm, which is about like the DA15mm, but it doesn't work at 10mm to 12mm due to edge stretching causing loss of sharpness, and due to the fact that the picture composition is so much different after defishing. Sometimes defishing 14mm works, (about 12mm APS-C equivalent), but I usually prefer the fisheye version.

01-01-2012, 10:37 AM	#4
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by sheld imho, defishing the 10-17mm looks ok at 17mm, which is about like the DA15mm, but it doesn't work at 10mm to 12mm due to edge stretching causing loss of sharpness, and due to the fact that the picture composition is so much different after defishing. Sometimes defishing 14mm works, (about 12mm APS-C equivalent), but I usually prefer the fisheye version. In terms of AOV, defishing 17mm is equivalent to about 12mm rectilinear, and defishing 10mm is about equivalent to 1mm. Huge, eh? And yes, the edge stretching is horrible, which is why I recommended downsampling / shrinking the output by at least 50% per side. Or better yet, don't defish, not unless there's a real good reason!

01-01-2012, 10:46 PM	#5
Kryscendo Senior Member Join Date: Sep 2011 Posts: 222	The best way to beat the aberrations is to simply prevent them. The best way to prevent BD, CA, and other sorts of anomalies is simply get a better lens. Classic case of you get what you pay for- which is a shame because some of my favorite lenses to shoot just don't hold up against my DA*s which I frankly leave the hell alone out of the camera.

01-02-2012, 10:26 PM	#6
insulinguy Senior Member Join Date: Aug 2009 Location: Fort Worth, TX Photos: Gallery \| Albums Posts: 134 Original Poster	Originally posted by Kryscendo The best way to beat the aberrations is to simply prevent them. The best way to prevent BD, CA, and other sorts of anomalies is simply get a better lens. Classic case of you get what you pay for- which is a shame because some of my favorite lenses to shoot just don't hold up against my DA*s which I frankly leave the hell alone out of the camera. well - i AM using a DA lens - the 10-17mm in fact and at the price point pentax sells it for i dont really think there is a better lens in that focal length range. yes - shooting at 17mm would prevent some of the barrel distortion but why only use the 10-17 at 17mm? 10mm looks great for certain shots - my intent here is to de-fish some of the ones at 10mm so they arent quite as wonky. excuse me if im reading your post wrong but i dont see how you could tell me to get a better lens when the 10-17mm is one of the best lenses pentax makes...

01-03-2012, 12:30 AM	#7
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by insulinguy 10mm looks great for certain shots - my intent here is to de-fish some of the ones at 10mm so they arent quite as wonky. And that won't happen. A fully defished DA10-17 @10mm shot will look bad unless it's displayed very small. It's the old mapmaker's problem of projecting a 3D world onto a 2D page. Any full projection will have extreme distortion. You can crop the most-distorted edges, but that can lose 1/2 the picture; you'd get better results with a rectilinear UWA lens. Use the DA10-17 for what it is; then use a Tamron 10-24 or one of the Sigmas for what they are. Or show your defished 10mm FE shots at 1080i resolution.

01-03-2012, 02:08 PM	#9
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Yes, defishing works, and yes, I've defished 15-16-17mm FE shots without losing too much at the edges. But if I've defished a 180 degree FE shot and chopped it down to around 100 usable degrees, I'd have better resolution just using a 100-degree rectilinear lens, especially if the picture is to be shown fairly large. This is a case where the DA10-17 doesn't really replace a Tamron 10-24 or Sigma 10-20 -- the FE and UWA complement each other. But if the 10-17 is all you have, then run with it, and keep the prints small. Personal note: The DA10-17 is the lens that drove me to Pentax. My original (and still most-used) kit were the DA10-17, DA18-250, and FA50/1.4. Then a zillion other lenses. But those first three plus the Tamron 10-24 and Raynox DCR-250 are my ultra-minimalist kit. And I went for the Tamron largely because I wasn't satisfied with defished shots from the DA10-17 or Zenitar 16/2.8. The Zenitar is the fastest of my wider lenses; the Tamron is the most flexible; the 10-17 is great fun but in more limited circumstances.