mammothz Member  146 posts Joined Apr 2008 More info | Jul 16, 2008 17:35 | #1 As can be seen in this foto... theres a purp edge around the white tie... wat would be the course of this is it the lens ?... this was taken with a 400D and a brand new 28mm F/1.8 with a Hoya 99% trans uv filter  HOSTED PHOTO please log in to view hosted photos in full size. MammothZ - [400D+Grip+430EX II]
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Hermeto Cream of the Crop  6,674 posts Likes: 2 Joined Oct 2005 Location: Toronto, Canada More info | Jul 16, 2008 17:50 | #2  Permanent banPurple Fringing - a known issue with 28mm f/1.8 lens. What we see depends mainly on what we look for.
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Jul 16, 2008 19:04 | #3 IC.. thanx... dam i wish i know about this before buying it... this was taken at f/2.2... i thought would be high enough MammothZ - [400D+Grip+430EX II]
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Hermeto Cream of the Crop 6,674 posts Likes: 2 Joined Oct 2005 Location: Toronto, Canada More info | Permanent ban One of my biggest disappointments in the Canon EF 28mm f/1.8 USM Lens is the very obvious CA (Chromatic Aberration) it exhibits at wide apertures. Proneness to flare is another notable negative characteristic. Otherwise, image distortion is low and colors are good. http://www.the-digital-picture.com …-1.8-USM-Lens-Review.aspx Chromatic Aberrations (CAs) CAs (visible as color shadows at harsh contrast transitions) can reach an average CA pixel width of more than 2 pixels at the image borders - a very weak performance here. CAs can be reduced and usually even eliminated via imaging tools but a fix-focals should definitely perform better than that. Verdict Generally the verdict for the Canon EF 28mm f/1.8 USM cannot be better than for its Sigma counterpart - high center performance but substantially worse borders. This is more so disappointing because this full frame lens was tested on an APS-C DSLR. The sweet spot effect has a positive effect on vignetting which is nothing to worry about. The distortion figures are pretty low but chromatic aberrations are hefty comparable to ultra-wide zoom lenses. So in total the lens may be good but we expect more from a fix-focal lens even though the design of a large aperture lens with a moderate pricing was certainly far from being simple. What we see depends mainly on what we look for.
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paulp Member 94 posts Joined Jun 2005 Location: Brisbane, Queensland Australia More info | Jul 17, 2008 00:24 | #5 It would really bug me having this happening to my new lense 450D, Canon 17-40mm f/4 L, Canon 50mm f/1.8 , Canon 18-55 IS , Canon 55-250 IS
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RiffRaff Goldmember  1,111 posts Likes: 1 Joined Mar 2007 Location: Austin, Texas, USA More info | Jul 17, 2008 01:37 | #6 mammothz wrote in post #5924571  IC.. thanx... dam i wish i know about this before buying it... paulp wrote in post #5926451 It would really bug me having this happening to my new lense Purple fringing can happen with any lens. It happens more often with certain lenses, and at larger apertures. Any technical lens review you look at (e.g. Photozone.de or SlrGear.com) will show graphs for chromatic aberration. In fact, from the SlrGear.com review for the 28mm f/1.8: Shawn McHorse - Shawn.McHorse.com
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Jul 17, 2008 01:53 | #7 yes... i did more research... also because it is a wide lens,.. has more effects because of that. but u gain a really good quility image with low distortion and at a higher F stop, i can lower the CA... and try not to use "wide open" in bright light situation, use a lower F in a lower light situation which wont have so much problem with CA in lower light Riff Raff wrote in post #5926728 Purple fringing can happen with any lens. It happens more often with certain lenses, and at larger apertures. Any technical lens review you look at (e.g. Photozone.de or SlrGear.com) will show graphs for chromatic aberration. In fact, from the SlrGear.com review for the 28mm f/1.8: "Like the 28mm f/2.8 though, this lens' weak point is chromatic aberration, and again is higher on a subframe body like the 20D with its smaller pixels than it is on a full-frame camera with larger pixels, like the EOS-5D. The chromatic aberration curve of this lens is similar to that of the 28-f/2.8, but is slightly higher throughout the aperture range." So it is a weak point for that particular lens. But consider that the cost of the better lenses around that focal length (i.e. 24mm f/1.4L and 35mm f/1.4L) is more than double. You can't have everything. MammothZ - [400D+Grip+430EX II]
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