blue shadow around whites

[kevin_t3]

this is a probably a basic question... but.

 

a lot of my digitally acquired pics seem to have a blue shadow around

white/bright portions of pictures. i realize some small amount of shadow is

expected but this is easily visible with little or no 'zoom'.

 

i don't know how/why it is getting created, nor do i know how to remove it..

help!

 

 

thanks kt<div></div>

[ellis_vener_photography]

which camera? looks like you've got fringing from seriously over exposed whites?

[kevin_t3]

it is a nikon d50 with a nikon 150?-300 zoom

[don_e]

What Ellis said. The highlights are blown out. Unless this was a raw capture, I do not think you can correct it. Even if there is raw data, it may not be correctable.

 

 

--

 

Don E

[dan_linne1]

Looks like Chromatic Aberration to me. That's why I don't use zooms. CS2 has a fix for it under Filters-Distort-Lens Correction.

[leicaglow]

It's called "purple fringing". As mentioned, it's usually around high contrast areas, like white shirts, flowers, etc. It happened on my equipment with older lenses, but after upgrading to newer Nikkors, I don't have the problem.

 

Do a search on the net for this term and you'll get lots of info. Here's an article that says how to remove it (I haven't read the article, but I know it's not easy to do): http://www.pcworld.idg.com.au/index.php/id;154451015;fp;2;fpid;1585691688

[kevin_t3]

what i am hearing is the problem is two fold.. the first, it seems, is to try to avoid the high contrast situations. the second is a possible lens problem.

 

the first seems like the most difficult to solve, as anyone who wears a white shirt is going to create the situation.

 

the second i can try as i also have a high quality nikkor 50mm lense to attempt this with.

 

i do still have the image in raw format, i can certainly try jue/saturation trick the article mentioned.

 

 

if these conclusions are wrong please correct me. if not thanks for all the input.

 

 

kt

[roger_smith4]

Solution A (overexposure) watch your histogram and don't be afraid to dial in -1/2 exposure compensation to preseve the highligh details.

Solution B (purple fringing)- get a better quality lens

Solution C (defects in pictures you have shot)- do a search for "purple fringing action" or "chromatic aberration action" and remove this in photoshop

[steve_dunn2]

<p>If it's lateral chromatic aberration, it can (at least mostly) be fixed in software. PTLens can fix it; ACR (in the full Photoshop product, not in Elements) can fix it when converting RAW files; I believe DXO can fix it; there are probably other solutions. Lateral chromatic aberration shows up with complementary colours on high-contrast edges; if (say) it's blue on a high-contrast edge facing away from the centre of the image, then it would be yellow on a high-contrast edge facing towards the centre of the image.</p>

 

<p>If you see blue or purple on all high-contrast edges, no matter which way they're facing relative to the centre of the image, it's not lateral CA.</p>

 

<p>Using a prime does not necessarily eliminate CA, though in general zoom lenses often suffer from more CA than primes do.</p>

[steve_bingham]

Yep, it's CA. Sometimes expressed as "purple fringing". It is usually found along contrasting borders. It is also more prevalent the farther you go away from the center of the picture.

 

This is caused by a few factors:

1- Quality of the lens. The cheaper the lens, the higher likelihood of fringing.

2- It tends to show up more in wide angle portion of the lens.

3- It is accentuated by shooting JPG rather than raw (JPG artifacts accentuate the fringing).

 

The good news is that it can usually be mostly corrected in raw conversion (ACR and others).

[steve_bingham]

Kevin,

 

In PS CS2 convert the raw file using Adobe Camera Raw (ACR). Click on the Lens tab in the ACR window. Zoom in and adjust the Blue/Yellow fringe (CA). Quick and easy. No need to fuss with other methods.

[kevin_t3]

with respect to the chromatic abberation of the lens. this shot was taken full unzoom. since i was too lazy to change the lense for this shot, i stood back 25 feet to take it.

 

does the CA artifacts tend to show up when a zoom lens when it is at its min/max settings? or one or the other? or lens dependant?

 

thanks again for all the wonderful input.

 

kevin