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Author Topic: Fish-Eye Lenses on MF Digital - De-Fishing  (Read 6934 times)
thsinar
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« on: December 09, 2008, 09:02:44 PM »
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I found it interesting to read recently and in another thread ("Sinar Hy6 Update - Staying with my Hy6") about the possibility to use a fish-eye lens and to de-fish the image, and would find it interesting to get more feedback from anyone using or having used this possibility in interiors or architecture, when very short focal lenses are needed.

This thread has unfortunately been closed in the meantime (http://luminous-landscape.com/forum/index.php?showtopic=30128&st=0&start=0), although there were some interesting points/questions raised and even a very promising test image from Eric W Hiss, corrected by "LensFix". Eric planed to do some more tests, especially shooting a grid to be able to calibrate the correction parameters.

I would really be interested in Eric's final findings since the shown test image is already an amazing result, IMO, especially when it takes a few seconds to apply these corrections.

Also, it would be interesting to know/show the possible loss of details and how much it can be enlarged.

Any feedback from others having experience with it would be nice.

Thanks and best regards,
Thierry
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Thierry Hagenauer
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« Reply #1 on: December 09, 2008, 10:08:36 PM »
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Quote from: thsinar
I found it interesting to read recently and in another thread ("Sinar Hy6 Update - Staying with my Hy6") about the possibility to use a fish-eye lens and to de-fish the image, and would find it interesting to get more feedback from anyone using or having used this possibility in interiors or architecture, when very short focal lenses are needed.

This thread has unfortunately been closed in the meantime (http://luminous-landscape.com/forum/index.php?showtopic=30128&st=0&start=0), although there were some interesting points/questions raised and even a very promising test image from Eric W Hiss, corrected by "LensFix". Eric planed to do some more tests, especially shooting a grid to be able to calibrate the correction parameters.

I would really be interested in Eric's final findings since the shown test image is already an amazing result, IMO, especially when it takes a few seconds to apply these corrections.

Also, it would be interesting to know/show the possible loss of details and how much it can be enlarged.

Any feedback from others having experience with it would be nice.

Thanks and best regards,
Thierry

while this is interesting Theirry, it seems to me somewhat academic -  the chances of coming across a 30 mm fisheye are slim.. I know eric
has one and there are maybe a handful around but they are very rare and out of production for a while.
It is interesting to see how far the software can correct though.
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thsinar
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« Reply #2 on: December 09, 2008, 10:15:40 PM »
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Yes Paul, you are right, but it is this "academic" approach which is of interest for me, not the commercial side.

I am much amazed what some lenses can provide in terms of image rendering, and this configuration was something I did not think about as a possibility.

Best regards,
Thierry

Quote from: paulmoorestudio
while this is interesting Theirry, it seems to me somewhat academic -  the chances of coming across a 30 mm fisheye are slim.. I know eric
has one and there are maybe a handful around but they are very rare and out of production for a while.
It is interesting to see how far the software can correct though.
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Thierry Hagenauer
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« Reply #3 on: December 09, 2008, 10:19:04 PM »
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KEH has two for sale..a CF and a CFI for "V" series.

Steve
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EricWHiss
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« Reply #4 on: December 09, 2008, 10:29:05 PM »
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Quote from: paulmoorestudio
while this is interesting Theirry, it seems to me somewhat academic -  the chances of coming across a 30 mm fisheye are slim.. I know eric
has one and there are maybe a handful around but they are very rare and out of production for a while.
It is interesting to see how far the software can correct though.


Actually due to odd luck I ended up with two and even with that in the same week after looking for a long time! Both are Rollei PQ versions.  One was near mint with box and a set of color filters so I'm keeping that copy, however as near as I can tell both had equal sharpness but the second copy has only caps and no box and a some paint chips on the barrel.   I've sent it in to Rollei Hensel for a CLA and when it comes back it will be for sale.  If anyone is interested feel free to contact me off list via PM or e-mail.


I hope to have time to shoot a grid early next week and will post my results here.  
Eric
« Last Edit: December 09, 2008, 10:33:41 PM by EricWHiss » Logged

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Jack Flesher
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« Reply #5 on: December 10, 2008, 11:51:01 AM »
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I've done some of this using the Mamiya 24 fisheye on my AFD/Phase camera, as well as quite a while back with my Canon fisheye.  My preferred software for defishing AND general lens corrections is PTLens: http://www.epaperpress.com/ptlens/index.html.  Thomas wrote this very usable GUI which uses PanoTools as the guts, and IMO it is worth about 8 times the $25 he charges for it!  I am currently using the Mac version and it runs very smoothly and fast on my system. The defish of the converted P45+ 16-bit tif (240MB total) shown below took about 15 seconds. The PTLens UI is realtime WYSIWYG as you make the adjustments and has a grid overlay for accuracy, and the final conversion maintains the original image dimensions.

Below is a quick example I shot in my atrium yesterday and just got around to processing today, so please excuse the uninteresting (and poorly lit) image as it is just for example purposes, containing lots of depth and lines to show how the image is affected.  As you can see, the process is very viable.  HOWEVER, lens anomalies will show up, especially in the corners where the pixels get stretched -- so minor CA can get significant in the corners.  You lose about 10% of your focal length to the rectilinearization after the crop as well, but it is a cheap way to get a real wide shot if you only need them occasionally, and of course you get dual-duty from the fisheye lens to boot.  In this example, the 24 fish turns into about a 26mm final, but frankly needs to be cropped in to about a 30mm FoV before the corners equal the Mamiya 28's performance.

The 30 Zeiss fish for the Hassy/Rollei may be significantly better than the Mamiya lens though, and given it's longer probably has less aberrations, so might be a good alternative to the widest rectilinear lens for your systems as you'll likely end up around a net of 34mm FoV or so.  

At the end of the day, I am of the belief you are probably better served with a dedicated rectilinear 24 to 35 if you shoot wide a significant amount of the time, and of course here the digital-specific lenses from Schneider and Rodenstack will no doubt deliver a significantly superior result, but of course the cost of the added body and back adapter comes into play...






Cheers,
« Last Edit: December 10, 2008, 12:53:38 PM by Jack Flesher » Logged

carstenw
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« Reply #6 on: December 10, 2008, 12:29:09 PM »
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Does anyone have experience with the Arsat 30mm fisheye used in this manner?
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thsinar
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« Reply #7 on: December 10, 2008, 08:05:50 PM »
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Thanks Jack, for the test, the information and your time.

best regards,
Thierry

Quote from: Jack Flesher
I've done some of this using the Mamiya 24 fisheye on my AFD/Phase camera, as well as quite a while back with my Canon fisheye.  My preferred software for defishing AND general lens corrections is PTLens: http://www.epaperpress.com/ptlens/index.html.  Thomas wrote this very usable GUI which uses PanoTools as the guts, and IMO it is worth about 8 times the $25 he charges for it!  I am currently using the Mac version and it runs very smoothly and fast on my system. The defish of the converted P45+ 16-bit tif (240MB total) shown below took about 15 seconds. The PTLens UI is realtime WYSIWYG as you make the adjustments and has a grid overlay for accuracy, and the final conversion maintains the original image dimensions.

Below is a quick example I shot in my atrium yesterday and just got around to processing today, so please excuse the uninteresting (and poorly lit) image as it is just for example purposes, containing lots of depth and lines to show how the image is affected.  As you can see, the process is very viable.  HOWEVER, lens anomalies will show up, especially in the corners where the pixels get stretched -- so minor CA can get significant in the corners.  You lose about 10% of your focal length to the rectilinearization after the crop as well, but it is a cheap way to get a real wide shot if you only need them occasionally, and of course you get dual-duty from the fisheye lens to boot.  In this example, the 24 fish turns into about a 26mm final, but frankly needs to be cropped in to about a 30mm FoV before the corners equal the Mamiya 28's performance.

The 30 Zeiss fish for the Hassy/Rollei may be significantly better than the Mamiya lens though, and given it's longer probably has less aberrations, so might be a good alternative to the widest rectilinear lens for your systems as you'll likely end up around a net of 34mm FoV or so.  

At the end of the day, I am of the belief you are probably better served with a dedicated rectilinear 24 to 35 if you shoot wide a significant amount of the time, and of course here the digital-specific lenses from Schneider and Rodenstack will no doubt deliver a significantly superior result, but of course the cost of the added body and back adapter comes into play...

Cheers,
« Last Edit: December 10, 2008, 08:06:12 PM by thsinar » Logged

Thierry Hagenauer
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« Reply #8 on: December 10, 2008, 08:40:57 PM »
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Quote from: EricWHiss
Actually due to odd luck I ended up with two and even with that in the same week after looking for a long time! Both are Rollei PQ versions.  One was near mint with box and a set of color filters so I'm keeping that copy, however as near as I can tell both had equal sharpness but the second copy has only caps and no box and a some paint chips on the barrel.   I've sent it in to Rollei Hensel for a CLA and when it comes back it will be for sale.  If anyone is interested feel free to contact me off list via PM or e-mail.


I hope to have time to shoot a grid early next week and will post my results here.  
Eric

well I guess there are more than a handful - eric has both hands full.
I remember about 10 years ago when all the art directors were looking for that big-head little-feet look, I had kurland in nyc send me out one he had for rental - amazing piece of glass on that.    
it is amazing what the computer can straighten.  
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stefan marquardt
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« Reply #9 on: December 11, 2008, 02:08:22 AM »
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Quote from: carstenw
Does anyone have experience with the Arsat 30mm fisheye used in this manner?


hi, carsten,

the 30mm arsat is an incredible good value lens (for the little money it costs).
I use mine (not that often) on a mamiya zd for exterior architecture shoots.  I find it sometimes easier to defish an image from this lens and end up with perfect straight lines, than to correct an normal wide lens that has complex distortion, like the 45mm pentax 67. just depends on the subject.
the arsat is quite sharp. even very sharp in the center. (sharper than my 35mm mamiya). towards the very edges it gets softer , but you usually loose the edges anyway, when you defish the image. It shows some CA but that is easy to correct in LR.


stefan
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stefan marquardt
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carstenw
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« Reply #10 on: December 11, 2008, 03:47:26 AM »
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Quote from: stefan marquardt
the 30mm arsat is an incredible good value lens (for the little money it costs).
I use mine (not that often) on a mamiya zd for exterior architecture shoots.  I find it sometimes easier to defish an image from this lens and end up with perfect straight lines, than to correct an normal wide lens that has complex distortion, like the 45mm pentax 67. just depends on the subject.
the arsat is quite sharp. even very sharp in the center. (sharper than my 35mm mamiya). towards the very edges it gets softer , but you usually loose the edges anyway, when you defish the image. It shows some CA but that is easy to correct in LR.

Thanks Stefan, I look forward to trying it out on my Contax 645.
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EricWHiss
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« Reply #11 on: December 11, 2008, 09:40:05 AM »
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Quote from: carstenw
Does anyone have experience with the Arsat 30mm fisheye used in this manner?

Hi Carsten,
I think I saw a comparison on the arsat vs. the zeiss distagon on line with photos somewhere.  You could see a difference with the zeiss being a bit better but it wasn't a huge difference. Sorry don't have a link, but I think you'll find it if you do a search.
Eric

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Morgan_Moore
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« Reply #12 on: December 11, 2008, 11:59:44 AM »
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Those interested in this concept may also be aware that there is or was the mamiya 24mm fish lens (manual) - I used to defish on my kodak proback

I think it is indeed simpler to correct a pure fish lense than a badly corrected mustash lense (say my nikkor 20-35 which is a nightmare)

As a manufacturer, sinar for example, stuck with a lack of wide on their mirrored offering, once one is happy with the concept of digital only lenses I think that fisheye and the relevant checkbox on the software is well worth investigating

I wonder if one could make a defishing finder or at least the relevant 'barrel' viewfinder mask to make the viewing experience more pleasurable or at least intergrate instant de-fish into the live view software

Once one is pure digital in both aquisition (live view) and output (the file) who actually cares what shape the lens is projecting onto the sensor - hasselblad have realised this some time ago - the realisation that enabled them to create the 28 at such 'reasonable' cost and pull off stunts like the TS adapter

S
« Last Edit: December 11, 2008, 12:02:17 PM by Morgan_Moore » Logged

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« Reply #13 on: December 11, 2008, 12:40:00 PM »
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Quote from: Morgan_Moore
As a manufacturer, sinar for example, stuck with a lack of wide on their mirrored offering, once one is happy with the concept of digital only lenses I think that fisheye and the relevant checkbox on the software is well worth investigating

S

That's a great idea, Sam.
Eric

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« Reply #14 on: December 11, 2008, 12:48:54 PM »
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Quote from: EricWHiss
That's a great idea, Sam.
Eric

Checkbox - I meant Exif data of course - no action by the user

S
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carstenw
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« Reply #15 on: December 11, 2008, 04:37:03 PM »
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Eric, if you mean the 35mm f/3.5 Zeiss Distagon, then I have picked that up too, so I should be able to compare them (once I scrape together the money for a back). I hope the Arsat isn't that good
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« Reply #16 on: December 11, 2008, 07:13:23 PM »
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I had the 24mm Mamiya fish eye before for this purpose, but it wasn't very sharp, even at f11 or f16, so I sold it.
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brianc1959
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« Reply #17 on: January 03, 2009, 07:30:16 PM »
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Quote from: rueyloon
I had the 24mm Mamiya fish eye before for this purpose, but it wasn't very sharp, even at f11 or f16, so I sold it.

Panoscan is now selling a 22.5mm fisheye that has dramatically improved performance relative to the 24mm Mamiya:

http://www.panoscan.com/22mm.html
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« Reply #18 on: January 05, 2009, 02:24:06 AM »
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Hi Thierry,

I sold my Mamiya 24mm fisheye. When I had ZD I used it and tried some de-fishing. It also gave a nice very modest fisheye effect on a 48x36mm sensor. Now I use Leaf Aptus 65 (44x33mm sensor) and Mamiya 28mm as widest. I found the Mamiya 24mm was too soft for the Aptus 65 sensor while for the larger area and 22MP ZD it was fine.

If I would like wider now I can simply stitch two images from panning the camera on the tripod. Likewise I can get similar effect as a mild fisheye by also distorting it in Photoshop...  

Regards
Anders
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