question on purple fringing

Hello,

I was just wondering, are wide angle lens very prone to purple fringing? I just got a 24-70 yesterday and there are shots were purple fringing was noticeable. I had to use f5.6 up to make it acceptable. any other techniques to minimoze them?

thanks,
Randal

The purple fringing you refer to is called chromatic aberation and is more prevalent with some lenses than others. What make of lens were you using? If it was the one in your avatar, that surprises me, as that looks like a Canon L

Can you post a picture illustrating the problem please?

thanks for the quick reply. i'm having CA problems with the sigma 24-70 F2.8 EX DG. CA is worst at the wide end at F2.8, at F5.6, CA has almost disappeared. i'v also experience this with the 18-55 kit lens. so i'm not sure if the 24-70 i have has problems or is it just that wide lens are very prone to CA.

i'm at work right now so can't post a sample picture. i'll try to post some as soon as I get home.

thanks,

It still surprises me, as I've read many good comments about the Sigma 24-70 but never anything about it producing CA.

Dave Condyc is a big fan of that lens, so if nobody else satisfactorily answers your query, you could try sending him a PM.

I've seen some CA with mine from time to time, but since I shoot in RAW and process in ACR, I just adjust the CA reduction slider and it magically goes away.

I've seem it a little on my 24-70L (Canon) wide open, with very high contrast edges (white a little blown out). No lens is perfect. Some are just less imperfect than others.

W

ok, looks like mine has no problem at all. i was just making sure, since I got mine used for a really, really low price low price.

by the way, this lens (sigma 24-70 f2.8) is big and heavy. it attracts attention especially with the hood attached.

anyway, thanks for the time.

I've never seen CA on my copy but maybe I haven't used the exact configuration, lens and environment mix related, that may produce it. It's a very good lens.

Under the right (wrong) lighting conditions any lense will show this. Some are worse than others. Even very expensive refractor (lense) type telescopes will show a wee bit of color fringing on bright objects. I can get this using my Canon 100-400, Canon 300L F/4 depending on the sun's angle when shooting little birds in the tree branches on bright sunny days. Strangely enough my Sigma 600 Cat will show the odd color (CA) variations due to the the front lens.

Software can correct this or try to lower the F stop. Filters can work but are very pricey.

Chris. Spratt
Victoria, BC

My Tamron 17-35 f2.8-4 suffers in extreme contrast situations. It might not always be purple though, mine is blue
Photoshop works wonders with it though.

Are you sure it's CA? For what it's worth, alot of people confuse colour fringing with chromatic aberation not knowing that they are two completely seperate things, caused by different circumstances. "CA from hard contrast" usually isn't CA at all but is caused by how the photo sensor deals with overexposure next to dark borders. I would think a higher end lense like that wouldn't show much CA considering my cheap 28-105 3.5-4.5 and 50mm 1.8 both show no CA, ever.

I'll try to post some sample pics later. I also have the 50mm 1.8 and I didn't have issues with CA with it either. that's why it really bugged me when i saw those purple shades from the images taken with the sigma 24-70.

thanks,