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06-16-2010, 11:00 AM   #16
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QuoteOriginally posted by Sirfishalot Quote
here's a link to someone that has created one for the DA 10-17 fisheye:

Download my Adobe Lens Profile for Pentax 10-17mm Fisheye lens Is It Work?
Nice find, works very nicely with the same lens on my K-7, at least at a first glance. (Only tried it with one image shot at 10mm, so far). Anybody know if Attila's a member of the site?

06-17-2010, 02:34 AM   #17
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A few profiles have been posted here, FYI: https://www.pentaxforums.com/forums/digital-processing-software-printing/1049...it-lenses.html

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06-17-2010, 09:37 AM   #18
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QuoteOriginally posted by Adam Quote
Excellent! We've got an outstanding question there as to which version of the 18-55 was used, but regardless this will fill another few gaps in our lens profile coverage.
06-20-2010, 06:42 AM   #19
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Hello all,

As I wrote earlier I was working on my own profile for the DA*16-50/2.8. I saw that another was posted, but I decided to post mine anyway. The simple reason being that mine has over ten times more information in it (mine is 235kb vs the other just 20kb), and as such should offer better correction?

I'm not sure about the better correction though, but perhaps my work could help us determine whether going into the detail I went into is actually worth the effort? I used focal lengths 16, 20, 28, 35, 50, apertures f/2.8 to f/22 at one stop intervals at a focus distance of about 40cm. Hence the effect of aperture on vignetting and CA should be well modelled, contrary to profiles shot at a single aperture only. Distortion quality is probably the same (though I did use 5 different focal lengths vs only 3 in the 20kb profile).

Here it is: PENTAX K-7 (smc PENTAX-DA 16-50mm F2.8 ED AL [IF] SDM) - RAW

Wim


Last edited by Ishpuini; 06-20-2010 at 06:49 AM.
06-20-2010, 12:56 PM   #20
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That's a impressive number of frames, Great work. (315 shots)


More a common note, It would be cool if it would be possible to gather a database of correction profiles with reviews here. That would help the community a lot...

that's lots of work though...

-J
06-21-2010, 04:05 AM   #21
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I know these profiles are supposed to be camera specific, but this worked great with my K2D. Much better than the manual job I was doing, so even if it isn't perfect on the K20D, it's good enough for now. Thank you for doing this.
06-21-2010, 12:57 PM   #22
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QuoteOriginally posted by GregK8 Quote
I know these profiles are supposed to be camera specific, but this worked great with my K2D. Much better than the manual job I was doing, so even if it isn't perfect on the K20D, it's good enough for now. Thank you for doing this.
Actually, they're not supposed to be camera specific. They may be, with certain lenses, but for many lenses they'll be just fine.

Consider, for example, that Adobe's own supplied profiles for Nikon shooters are all made with the Nikon D3X -- but they're not intended to be used only by D3X shooters.

It's true though that with lens / body combinations that suffer from noticeable microlens vignetting will have best results when using a profile made with the same combo (or one which uses the same sensor design).

More here:

Adobe Forums: Community lens correction works for me

06-21-2010, 01:00 PM - 1 Like   #23
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Here's one I just finished for the DA21/3.2 limited:
PENTAX K-7 (smc PENTAX-DA 21mm F3.2 AL Limited) - RAW.lcp

Focal length: 21mm
Apertures: f/3.2, f/4, f/5.6, f/8, f/11, f/16, f/22
Focus distances: 38cm, 80cm

Hope this will help someone...

Wim
06-21-2010, 01:07 PM   #24
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Ishpuini, come on, you really need to add in the different focus distances as well.. (ya know 5ft, 10ft, 15t, etc...) You really need to get those frame counts to 500-1000, even 2000 to do the job right! :-) ;-)
Just kidding! Well done, you have more patience and tenacity than I.

I'd be interested in seeing how much better your profile does than mine for CA and vignetting. I don't think much difference will be seen for distortion, but would be interesting to find if that helps.
06-21-2010, 01:30 PM   #25
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QuoteOriginally posted by amoringello Quote
Ishpuini, come on, you really need to add in the different focus distances as well.. (ya know 5ft, 10ft, 15t, etc...) You really need to get those frame counts to 500-1000, even 2000 to do the job right! :-) ;-)
Just kidding! Well done, you have more patience and tenacity than I.

I'd be interested in seeing how much better your profile does than mine for CA and vignetting. I don't think much difference will be seen for distortion, but would be interesting to find if that helps.
By no means I intended to belittle your work. I think it's very good of you to provide the profiles you posted to allow many photographers to quick start with lens corrections (I could never come up with as many doing it the way I do). And I'm sure that many will be very happy with these profiles as they are.

I had been working on my effort before you posted and as such decided to post it anyway, if only for comparison. One poster on dpreview seems to have tested both and he claims the difference is "massive" with the advantage going to my profile with more information. Not sure what that means exactly though, since I haven't tested both profiles next to each other myself. Perhaps it's just my copy of the DA*16-50 being closer to his than yours (sample variation you know), or perhaps it's the larger amount of information?

Anyway, I'm moving on to my limiteds now (starting with the wider ones). The DA15 and FA31 will probably follow (time permitting). The DA*16-50 profile will remain as it is for now...

Wim
06-21-2010, 01:36 PM   #26
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Oh, no offense taken! I apologize if it came across that way. My comments were totally in jest.
Except that I do respect the amount of tedious work you had to go through to get these done.

I am truly interested to find out what difference all that extra work has to offer.
I will probably see if I can compare both next time I have a need to make fixes. (which for me seems pretty rare, thus I suppose also explains my lack of motivation for creating a better profile. :-) )
06-23-2010, 05:50 AM   #27
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QuoteOriginally posted by Ishpuini Quote
Here's one I just finished for the DA21/3.2 limited:
PENTAX K-7 (smc PENTAX-DA 21mm F3.2 AL Limited) - RAW.lcp

Focal length: 21mm
Apertures: f/3.2, f/4, f/5.6, f/8, f/11, f/16, f/22
Focus distances: 38cm, 80cm
I had a look into the profile. It is an XML file readable in any text editor.

It contains 14 (2x7) settings as to be expected.

Each setting is to correct 3 artifacts: distortion, CA, vignetting.

distortion and CA are corrected together by undistort & scale each color channel separetely. The global scaling parameter is named "FocalLengthX/Y", the undistort parameters "RadialDistortParam1/2/3" (2 and 3 being zero). The four parameter formula generally is a third-order polynomial in relative radial distance r, which returns a factor to scale r with.

vignetting is corrected using the average (luminance) scaling and parameters "VignetteModelParam1/2/3".

That's it.


Now comes my question:

The settings do contain the lens alignment error too ("ImageX/YCenter"). And Ishpuini lens has about 2.5% misalignment which is probably a good value (the center is shifted to the lower left). An alternate explaination would be that the K-7 sensor isn't exactly aligned with the optical axis. The deviation corresponds to about 50 pixels. A distance easily travelled by the SR mechanism. So, with SR, the lens is never aligned anyway ... But even w/o SR, does the K-7 lock the sensor at exactly the same position for every camera?

So, does it make sense to use the alignment measure for other samples of a lens? Or would it be better to edit the lcp file and reset these values to 0.5? Or to the "SR locking value" of one own's K-7? And does it matter at all?

Last edited by falconeye; 06-23-2010 at 05:59 AM.
06-23-2010, 02:08 PM   #28
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Good questions, Falk.
QuoteOriginally posted by falconeye Quote
So, does it make sense to use the alignment measure for other samples of a lens?
In general, the answer should be "yes". Otherwise it wouldn't make sense for Adobe/Sigma to provide ready-made lens profiles.

QuoteOriginally posted by falconeye Quote
Or would it be better to edit the lcp file and reset these values to 0.5? Or to the "SR locking value" of one own's K-7? And does it matter at all?
If the answer to the last question is "no" then the other questions go away. It should be easy to answer the last question by doing a correction with the original profile and a modified one respectively and then comparing the images.

I've just ordered LR3 so won't be able to do that test right now.
06-23-2010, 04:02 PM   #29
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QuoteOriginally posted by falconeye Quote
The deviation corresponds to about 50 pixels. A distance easily travelled by the SR mechanism. So, with SR, the lens is never aligned anyway ... But even w/o SR, does the K-7 lock the sensor at exactly the same position for every camera?
The answer when using a tripod (ie. shooting with SR "disabled") would have to be yes, the image sensor is centered -- otherwise the available range of compensation adjustment wouldn't be the same every time, as it'd depend on where the starting point was.

Obviously it's important for folks making the profiles to remember to disable SR (use self-timer with MLU).
06-24-2010, 04:47 AM   #30
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QuoteOriginally posted by knoxploration Quote
the image sensor is centered -- otherwise the available range of compensation adjustment wouldn't be the same every time, as it'd depend on where the starting point was.
Theoretically yes. But the compensation range is about 400 pixels (2mm), the "misalignment" as stored in the profile is about 50 pixels only. So, if the manufacturing sensor centering calibration allows for +/- 50 tolerance, SR and the compensation mechanism would still work good enough.

I am not convinced that manufacturing tolerance is much less, like +/- 10 pixels. Otherwise, I wouldn't be able to understand that quite a few K-7 have been shipped where the horizon wasn't calibrated properly.

And IF tolerances are in the +/- 50 tolerance range, one should probably edit the profile made for another camera and lens.

In order to find that out, we have to look into profiles for different cameras and watch the alignment values. Preferrably for an identical lens, shared between owners of several bodies.


UPDATE:
I looked into some other profiles. E.g., for Ishpuini's camera, the values are all over the place. So, it is lens specific really, not camera-specific. I looked into other people's profiles as well. At 16mm focal length, the value generally seems to be 0.5 exactly. At larger focal lengths larger than 20mm, it starts to deviate. The deviations can reach 10% (0.55 rather than 0.50). So, the interesting test would be two have an identical body/lens combo with 2 bodies and 2 lenses. And measure both possible combinations of body+lens.

But first, let's see if the difference is noticeable and if LR doesn't do this all by itself. After all, a profile contains an author's name. BTW, when editing the file, the file length shouldn't be altered. At the end, there is a white space padding section.

Last edited by falconeye; 06-24-2010 at 05:22 AM.
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