Thin blue-ish outline around objects.. what is it? how to fix?

[chrisblau]

Hey all - I've just gotten into some more serious photography. I'm using a Canon XSi and an 18-200mm lens by Tamron (no IS, couldnt afford it).

My problem is when I shoot (often outdoor shots) there is a thin blueish glow/outline around objects, often when the object is darker than the background.

What is it? Is it a symptom of a bad lens? Is there an easy way to take it out in post?

thanks much!

Chris

 

[hulk]

Not sure, but it might be chromatic abberation.
Check out the pics in the article to compare.

 

[Goontz]

Post some examples, it'll be easier for us to see what you're talking about and offer help.

 

[musicaleCA]

Sounds exactly like chromatic aberration, and the lens you are using is prone to it. Avoid high-contrast situations, as CA is generated when an edge is extremely highly contrasting. CA can be removed in post, but it will always result in a loss of sharpness around these edges.

 

[KmH]

It is a lens quality issue.

I think it's more commonly known as Purple-Fringing and it can be mitigated in post processing with Photoshop.

Google to find many, many tutorials out there about fixing it.

 

[chrisblau]

Thank you all so much for the quick replies!

Yes - I do think its a CA problem. I did a quick search and found a short how to video about removing it, real straight forward stuff (especially if you're shooting in RAW). is the link.

I'm a college kid so I didn't have a ton of money to spend on a lens and I wanted a lens that would give me a lot of possibilities (hence the 18-200). I'm thinking of getting a straight 50mm lens or something like that for indoor/museum use.. any suggestions? Minimum CA stuff, hopefully, and IS would be nice.. for a Canon body.

Thanks again!

 

[stierzy34]

I'm in college too and know all too well about the money issues! I actually picked up a 50mm f1.8 for very cheap. I love it!

 

[musicaleCA]

A 50mm prime doesn't really need IS. All of the ones in Canon's current line-up are very fast, an even on a crop body it's not a very long focal length to deal with.

 

[Village Idiot]

It is a lens quality issue.

I think it's more commonly known as Purple-Fringing and it can be mitigated in post processing with Photoshop.

Google to find many, many tutorials out there about fixing it.

Everyone I know commonly refers to it by CA, it's actual name.

 

[musicaleCA]

Actually, purple fringing, while sometimes caused for the same reasons as CA, can also be caused by lens flare, and a score of other reasons. Purple fringing and CA are subtly different.