Available? Adobe lens profile for manual Samyang 8mm fisheye lens + Canon full-frame?

[l_d_allan]

Is anyone aware of an Adobe lens profile for the combination of a manual Samyang 8mm fisheye + Canon full frame (such as 5dm2)? Anyone made one that they are satisfied with?

 

As noted from experts in the forum, PTGui works better to leave "Distortion Correction" and "Vignetting Correction" unchecked in ACR/LR when generating tif/jpg's for PTGui.

 

However, it seems like it would be worth having a camera+lens profile for the "Chromatic Correction" capability. Correct? My impression is that fisheyes typically have significant CA. Also correct?

 

My experience was that the 14mm profile was difficult to make because of the ultra FOV, but it does seems to work well. I would think the fisheye would be very difficult to make a lens profile for, at least to get correct. I'd think you would need several huge prints, and a huge wall. I haven't attempted to make such a profile.

 

I have seen a profile available via Adobe for the combination of the Canon 7d (1.6 crop factor) + 8mm, but iirc, it didn't work all that well with my 8mm fisheye + T3i (same sensor in Rebel body).

 

TMI?

My understanding is that such a profile for pretty much any Canon full-frame would work at least reasonably well with other full-frames ... 5dm2, 5dm2, 6d, 1D#, etc, regardless of resolution. Or not? Does resolution matter? Most of the Canon full-frames from the past 5 years have similar resolution ... 18 to 22 mpx.

 

[Erik Krause]

Am 08.05.2013 14:41, schrieb l_d_allan:
> Is anyone aware of an Adobe lens profile for the combination of a manual
> Samyang 8mm fisheye + Canon full frame (such as 5dm2)? Anyone made one that
> they are satisfied with?

You don't mention which version of ACR you use. However, you don't need
any profile in ACR 6.7 and 7. Just check "Remove Chromatic Abbereation"
on Lens Corrections tab (on Profile sub-tab in ACR 6.7). In ACR 7
eventually adjust Purple Amount and Purple Hue (and/or Green Amount and
Green Hue) if you want purple (and/or green) fringes removed. In ACR 6.7
this is isn't available. Instead choose type of Defringe on the Manual
sub-tab.

The results are superior to any other CA reduction tool I saw.

--
Erik Krause
http://www.erik-krause.de

[Michel Thoby]

Hi Erik,

Le 9 mai 2013 à 11:54, Erik Krause a écrit :

You don't mention which version of ACR you use. However, you don't need any profile in ACR 6.7 and 7.

Just check "Remove Chromatic Abbereation" on Lens Corrections tab (on Profile sub-tab in ACR 6.7). In ACR 7 eventually adjust Purple Amount and Purple Hue (and/or Green Amount and Green Hue) if you want purple (and/or green) fringes removed. In ACR 6.7 this is isn't available. Instead choose type of Defringe on the Manual sub-tab.The results are superior to any other CA reduction tool I saw.

I use LightRoom 4.4 (I did not upgrade from PS CS4) and I confirm the same observation when using the same (CA removal) engine as ACR7. Unbelievable how good this tool is, really...

Michel

[l_d_allan]

Using LR4.#, which is more or less equivalent to ACR 7.#

 

Thanks for the assistance. However, I'm unclear what you mean by "eventually adjust". I infer this means to manually adjust the CA for images. Individually? 

 

So suppose I take 20 sets of HDR panos at the museum this morning with the fisheye, during the two hours they opened the doors early for me. At four images per 360 degrees, that's 12 images per HDR pano, and 240 total images. Do I individually (eventually?) adjust each image.

 

My understanding of the automatic-from-profile-CA that I made for the Samyang 14mm was the targets had prominent black bars that were specifically designed to have CA happen, especially along the outer parts of the lens. The software improved the CA present in the test image target. These corrections are then assumed to be advantageous to apply to all other images.

 

Or not?

[Erik Krause]

Am 09.05.2013 14:40, schrieb l_d_allan:
> Thanks for the assistance. However, I'm unclear what you mean by
> "eventually adjust". I infer this means to manually adjust the CA for
> images. Individually?

No. This applies to purple (or green) fringes removal. Since those
fringes are not produced by the lens but by the camera, you should be
fine to adjust it once and save it as a preset.

CA varies according to focus distance and (partly) aperture value. Hence
I see not much benefit in a profile especially for a lens which reports
neither focus distance nor aperture. Automatic CA correction was the
best thing Adobe ever added to ACR and it didn't fail in any one image I
processed since, been it from my frequently used Zenitar 16mm fisheye
(which is difficult to correct perfectly, since it's CA is non-linear),
the Samyang 8mm, the Peleng 8mm and any Canon lens I own.

You need lens profiles for anything else, but not for images you want to
stitch in PTGui. They would be needed to correct lens distortion, but
that does PTGui better and directly from the images.

Try it to believe.

[Karmadillo]

For my Sanyang 14mm fisheye (on full-frame camera) the lens quality was such that I didn't have visible CA.

I hope this is the case with your 8mm lens too.

Having no CA was wonderful because I could process TIFF files directly in PTGui which would handle Vignetting and Distortion Correction well. This made for a faster workflow than other lenses.

The latest (CS6) version of Photoshop/ACR does a good job automatically detecting and removing CA without having a lens profile to help it.