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Author Topic: Lense Profile Sigma Art 50mm  (Read 6560 times)

orc73

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Lense Profile Sigma Art 50mm
« on: August 06, 2015, 08:18:05 am »

Hello

I don't see a lense profile for the 50mm Sigma Art.
This is quite disappointing, this lense is the best AF 50mm lense for Canon now and 50mm is kind of a workhorse focal length.
Many of the Canon lenses are not on the level of current 5dsr cameras, Sigma is one of the important players for that field.

Is there a way I can get that profile or is there an easy way around it?

best regards
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Bart_van_der_Wolf

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Re: Lense Profile Sigma Art 50mm
« Reply #1 on: August 06, 2015, 08:27:47 am »

I don't see a lense profile for the 50mm Sigma Art.

Hi,

What do you expect the lens profile to do?

Cheers,
Bart
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David Grover / Capture One

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Re: Lense Profile Sigma Art 50mm
« Reply #2 on: August 06, 2015, 11:51:02 am »

Sigma 1.4 HSM  for canon is in the list.

But Bart is right.  With that lens probably not much to correct!
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David Grover
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orc73

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Re: Lense Profile Sigma Art 50mm
« Reply #3 on: August 06, 2015, 12:51:41 pm »

ok you got a point, probably not much to correct on that lense.
But still the listed lense profile is not the new "Art" lense, but the ex dg hsm.
I run the latest trial version to see if it's something for my new canon 5dsr, files are rendered much better then LR.

It will be more of an issue with  all the sigma art the 24mm, the 35mm and the 24-35mm.
At least one of them I will plan to buy in near future, they are better then the canon ones, and the 5dsr needs good lenses.

In general I expect to correct distortion, vignetting, CA.
I know this can be corrected manualy, I would really prefer to have a profile, it's a standard.

I come from Hasselblad, and I can tell this company does a really good job on their (own!) lense profiles (in phocus).
I'm sure p1 is doing the same for their MF systems.
Also most Canon lenses are in, so why not put the best lenses the system has to offer? ;)
« Last Edit: August 06, 2015, 12:58:40 pm by orc73 »
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orc73

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Re: Lense Profile Sigma Art 50mm
« Reply #4 on: August 06, 2015, 12:56:28 pm »

And I wonder what this would be: http://www.lensrentals.com/blog/2015/07/a-quick-look-at-the-new-sigma-24-35-f2-art
"There's good news for you who are disappointed now: Computer image analysis (like Imatest and DxO) don't show astigmatism directly so this lens will probably look better with those test results than it does on the optical bench."
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David Grover / Capture One

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Re: Lense Profile Sigma Art 50mm
« Reply #5 on: August 06, 2015, 03:06:23 pm »

You're right.. I sped read the lens!

By the way.. you can do a bespoke CA analysis of any lens in Capture One (even if it has been profiled)

Next to the chromatic aberration checkbox, click the box with three dots and then 'Analyse'.  You can do this on a batch of images too.

D
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David Grover
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brandon

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Re: Lense Profile Sigma Art 50mm
« Reply #6 on: August 07, 2015, 03:22:35 am »

You're right.. I sped read the lens!

By the way.. you can do a bespoke CA analysis of any lens in Capture One (even if it has been profiled)

Next to the chromatic aberration checkbox, click the box with three dots and then 'Analyse'.  You can do this on a batch of images too.

D

Hi David, I find with Fuji XPro1 files (and maybe there are other examples) that I cant analyse for CA. I can use the manufacturer's profile with or without CA box ticked but "analyse" is greyed out, or choose eg generic pofile (or others) but the analyse is still greyed out from the 3 dots box. Am I doing something wrong there?
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David Grover / Capture One

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Re: Lense Profile Sigma Art 50mm
« Reply #7 on: August 07, 2015, 05:31:15 am »

Hi Brandon,

No, its because of the XTRANS format.  The CA analysis is based on bayer pattern.

David
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David Grover
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orc73

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Re: Lense Profile Sigma Art 50mm
« Reply #8 on: August 07, 2015, 05:34:36 am »

what is going on in the sharpness falloff slider? is that usefull if  I have to use a generic profile?
Also is the generic profile recommended to fix distortion/vignetting or should in that case a different tool be prefered after the raw convertion?
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Bart_van_der_Wolf

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Re: Lense Profile Sigma Art 50mm
« Reply #9 on: August 07, 2015, 06:37:47 am »

what is going on in the sharpness falloff slider? is that usefull if  I have to use a generic profile?

Hi,

When you use Capture One sharpening (and do not disable sharpening in the export recipe), the fall-off of sharpness towards the corners, can be compensated with that slider. Sharpness fall-off towards the corners is present in virtually all lenses.

Quote
Also is the generic profile recommended to fix distortion/vignetting or should in that case a different tool be prefered after the raw convertion?

A generic profile can be made to correct many things at the same time, but is still generic. A specific lens may need a bit more (or less) correction, or if no profile exists, and those sliders will allow to correct that. However, do understand that all distortion corrections will mean that the image will be (counter-)distorted and thus resampled, which will cause variable sharpness at the pixel level in the entire image. Suppose a 1 pixel wide line, e.g. a hair, is moved and falls exactly between 2 new pixel positions, it will potentially be rendered as a 2 pixel wide line at half the brightness.

Distortion correction at the same image pixel size, is always a compromise. When shooting architecture it may be more important to keep straight lines straight, than suffering a bit of resolution loss. Shooting large, and down-sampling after distortion correction is a better solution, if possible.

Ideally, the distortion correction would be done at the Raw conversion level, before or as a part of demosaicing, just like Chromatic Aberration correction is best done then, but I'm not sure if Capture One does that.

Cheers,
Bart
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