Was I wrong about fringing or what?

Question

See this example by teef_au: http://www.flickr.com/photos/samfeinstein/1217122341/

The pelican in the pond looks proud as a peacock in his purple vest. The fringe is pretty much at every white-dark interface - right in the center of the shot. Teef did say that this was taken with a "lens of the lesser gods." Teef, maybe you can answer this question and tell us which lens you used to create this stunning array of purple...

By the way, I'll be away from the computer until Sunday night or Monday, so don't despair if I don't respond to your answers.

Indeed, as some of my Yahoo! friends have pointed out, the fringe is everywhere in this photo. Again, go to the original size and you'll see it on the waves in the water. In fact, it does seem to be worse in the corners of the image than in the center, as far as the waves go, so we are back to the idea - not a new idea - that chromatic aberation is worse aronud the perimeter of the lens.

Craig, it's not so "funny that its a Tamron," because the problem is inherent in the lens design.

Princess, yes. Purple fringe is what it sounds like. You can see an outlilne of purple caused by a combination of things wrong with a lens and the way digital sensors deal with light. See http://www.flickr.com/photos/samfeinstein/1209211393/ for the first photo in this discussion. Since it is only steel and sky, you can pick out the purple easily if you click "All sizes" and then "Original." Better lenses and better cameras have less of a problem. Cheaper lenses and cheaper cameras have more of a problem. I'm just trying to figure out how to tame it by technique rather than throwing more money at the problem.

Answer 1

Dr I see it in the whole image, check out the waves in the background while not as severe (that what doesn't describe what i want to say! about the center of the image).

Its riddled with it that shot. Anywhere theres a highlight it seems to pop up.

Cant wait to find out the lens.

a

Answer 2

I'm going to assume that by a "lens of the lesser gods" it's meant something like a Sigma, Tamron or Tokina.

The EXIF data shows a 200mm focal length, f 5 exposure with an f 4.6 max aperture for the lens at 1/1250 sec shutter speed. The camera was set to Program and there was no exposure comp. None of the lens makers mentioned have a candidate fixed lens, so it was a zoom if made by one of them; unless they have a lens I don't know about.

None of the possible lenses by those manufacturers has a big problem with CA and where it shows up, it's when the aperture is wide open. That's the situation with this image and the CA is about what you would expect. Antoni is probably noticing this in the rest of the image, but it's not the same problem as the fringing.

On the other hand, the image is way over exposed, maybe one stop over the clipping level in the highlights. I think it was Ben that mentioned this in another question by you Sam, but with this overexposure, light is effectively pouring over into adjacent sensor elements. That's where the purple fringe is coming from in this image.

I'm surprised that nobody mentioned that it's an overexposed image. The program mode was in error. If you average just the water, it comes very close to a neutral gray reading. I'm refering to tonality, not color neutrality. For the late afternoon (early morning?) light that it seems to be, you can see that the tonality of the water is visually way off also.

Just my two cents.

Vance

Addendum: One of the these three shots shows fringing due to the highs being driven way above clipping in some specular highlights. A detail is included, showing that highlights not driven so high don't show the same fringing.

The other shots show no practical fringing in high contrast light/dark borders, but the exposures are dead on. A detail of such a boundary is included.

The lens is a Tamron 70-300 mm. That last shot of the statues is @ 200 mm, same as the subject photo.

http://picasaweb.google.com/Vance.Lear/TempFringeDemo?authkey=Gv86evrOTdQ

There are two separate problems in the photo.

Answer 3

We almost need a proper forum to carry on this conversation ...

Antoni, the Lens is a Tamron 70-300mm F4-5.6 LD with a macro switch that only works between 180 and 300 mm I think the LD is written on the lens just for laughs. I never thought this would be a great lens but I wanted it anyway because it was cheap and had the macro feature. It was purchased new via ebay and it is therefore possible that it was abused as a child. The lens looks and feels normal to use. Zoom and focus are smooth. It occasionally hunts for focus but the camera is set to spot focus.

For the shot in question, it was coupled to a D50 which was less than 6 months old at the time and suffers no known problems.

This is a truly horrible lens, whether by crappy design/build or by unique fault is not known to me and bluntly of little interest. It is also a very soft lens.

Other shots taken over water actually look quite good because of the "lovely little purple bits"

As time and weather permit I will make the effort to take some shots that lend themselves well to analysis for PF. Obviously this lens is now rarely used in favour of the 70-300 VR.

The shot shown obviously does not allow fairly for a comparison of fringe at the edge vs the center.

If anyone has other questions I can be reached via email through my profile.

Answer 4

Actually, if you look at the original, there is purple fringing all over the place, including on the head and in the water. It is just easiest to see with a vertical edge that is brightly lighted. I would suspect that it is the result of a lens with poor color alignment - maybe astigmatism - so the colors, instead of all arriving at the sensor in phase are slightly shifted for a rainbow effect.

Answer 5

funny that its a Tamron, my Tamron 28-200 does the same thiong, its a nice lightweight lens that is pretty sharp and has a great range.... its just the damn purple fringing that kills it!!

Answer 6

What a beautiful picture!! I love Pelicans!!

Answer 7

fringe- fringing= something like a fringe along an edge?

Answer 8

good luck