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Lens shake?

kh1234567890
Posted 23/04/2014 - 18:03 Link
Mannesty wrote:
There is even some CA in the shot above. Open the large image and zoom in to the cut cables of the aerial. They are showing a magenta CA to the right of the cable. Similarly in the cable that extends up the left side of the mast. Not much, but it is there, and again it's showing on dark objects with a bright background.

That is purple fringing. I took out the CA. Let's not digress into PF, LoCA and all that. There is something up with the OP's lens.
Mannesty
Posted 23/04/2014 - 18:18 Link
So are you saying that your image, posted as an example, has been processed to remove CA that was evident?
Peter E Smith - flickr Photostream
kh1234567890
Posted 23/04/2014 - 18:48 Link
Mannesty wrote:
So are you saying that your image, posted as an example, has been processed to remove CA that was evident?

Yes.

Here it is with the CA left in. What is the problem ?
gwing
Posted 23/04/2014 - 23:44 Link
michaelblue wrote:
........I wonder if anyone else can replicate this with their 55-300 or is it unique to mine?

Thanks for all your comments and help so far

Maybe it's just a quirk of this lens and I'm being too 'Picky'?

If I pixel peep at a shot of mine from the weekend where I have an sunlit iron cross against white cloud background I can see purple fringing. This is I assume TCA as switching on the lens correction module in TCA only mode clears it up.

There does remain the possibility that what you are seeing is an artifact of the image processing you are running rather than the lens. Could you post the raw for your image and then we can eliminate that possibility for you?

Here's my uncorrected image with TCA still present.

Comment Image
Edited by gwing: 24/04/2014 - 00:16
michaelblue
Posted 24/04/2014 - 05:24 Link
I can't post the original Raw file as it's too large, any suggestions?
Regards,
Michael
Mannesty
Posted 24/04/2014 - 08:06 Link
Mike sent the image to me and in my opinion, it's CA, there's a very definite green tint to some edges, but not all. It seems to me that where the background is blue (sky), the foreground rock edge has a green tint and where the background is white (cloud) the edge CA appears grey.

Crop near the top of the left hand rock.

Comment Image


Crop of the top of the right hand rock.

Comment Image


Original

Comment Image
Peter E Smith - flickr Photostream
Edited by Mannesty: 24/04/2014 - 08:09
kh1234567890
Posted 24/04/2014 - 08:32 Link
It is hard to tell anything without having the full image.
gwing
Posted 24/04/2014 - 09:14 Link
michaelblue wrote:
I can't post the original Raw file as it's too large, any suggestions?

I'd try processing the raw with one of the raw development tools that does good lens aberration correction and see if that helps. For the free tools 'Raw Therapee'is recommendable and if you really want to optimise things you can attempt a custom calibration for your own lens as described at http://hugin.sourceforge.net/tutorials/tca/en.shtml.

Or just service/replace the lens if you aren't happy with the results and money is less important than time. Without the actual lens or a raw from it there isn't much more we can do to help.
Edited by gwing: 24/04/2014 - 09:16
Mannesty
Posted 24/04/2014 - 10:21 Link
kh1234567890 wrote:
It is hard to tell anything without having the full image.

I have the full image. I've shown the worst affected areas, cropped only, no other processing, and included the full image. What else would you like to see?

Take a look at the hole in the rock in the cropped image, it shows a definite green tint on about half its circumference and magenta on the rest. Do you not think this is chromatic aberration?
Peter E Smith - flickr Photostream
Edited by Mannesty: 24/04/2014 - 10:23
tyronet2000
Posted 24/04/2014 - 11:49 Link
gwing wrote:

... if you really want to optimise things you can attempt a custom calibration for your own lens as described at http://hugin.sourceforge.net/tutorials/tca/en.shtml.

Or just service/replace the lens if you aren't happy with the results and money is less important than time. Without the actual lens or a raw from it there isn't much more we can do to help.

Link doesn't work for me

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kh1234567890
Posted 24/04/2014 - 11:50 Link
Mannesty wrote:

I have the full image. I've shown the worst affected areas, cropped only, no other processing, and included the full image. What else would you like to see?

Take a look at the hole in the rock in the cropped image, it shows a definite green tint on about half its circumference and magenta on the rest. Do you not think this is chromatic aberration?

There is some CA, but also some other fault/artefact. Unless a new form of colourless CA had appeared

Pentax QA/QC on the DA55-300 is abysmal, my first example was decentered and went straight back. The one I have is better but still not perfect.
gwing
Posted 24/04/2014 - 12:23 Link
tyronet2000 wrote:
gwing wrote:

... if you really want to optimise things you can attempt a custom calibration for your own lens as described at http://hugin.sourceforge.net/tutorials/tca/en.shtml.

Or just service/replace the lens if you aren't happy with the results and money is less important than time. Without the actual lens or a raw from it there isn't much more we can do to help.

Link doesn't work for me


It didn't work for me either from the forum page. Despite being a cutnpaste of a link I tested. I'll try posting it again ...

link

That works. Actually the other one does as well if the trailing dot is removed
Edited by gwing: 24/04/2014 - 12:24
gwing
Posted 24/04/2014 - 12:26 Link
Mannesty wrote:
kh1234567890 wrote:
It is hard to tell anything without having the full image.

I have the full image. I've shown the worst affected areas, cropped only, no other processing, and included the full image. What else would you like to see?

Take a look at the hole in the rock in the cropped image, it shows a definite green tint on about half its circumference and magenta on the rest. Do you not think this is chromatic aberration?

It looks like CA to me yes. But the question then is can anything be done about it, hence the interest in trying CA correction against the raw.
Mannesty
Posted 24/04/2014 - 13:38 Link
kh1234567890 wrote:
Unless a new form of colourless CA had appeared

That's possible. Taking the hole in my first crop shot as an example where part of it shows green and the other magenta, there are also parts that are grey.

So, either the grey parts contain both green and magenta, therefore cancelling one another to produce grey, or they contain neither, leaving only the grey ghostly 'halo'.

Bearing in mind the magnification required to see it, I don't think it's such a big deal. I've seen a lot worse.
Peter E Smith - flickr Photostream
Edited by Mannesty: 24/04/2014 - 13:40
Mannesty
Posted 24/04/2014 - 13:41 Link
gwing wrote:

It looks like CA to me yes. But the question then is can anything be done about it, hence the interest in trying CA correction against the raw.

Lightroom's CA removal option removes the colour cast around the edges, but replaces it with grey.
Peter E Smith - flickr Photostream
Edited by Mannesty: 24/04/2014 - 13:41

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