A lense question

[Seb]

Hello,

Here is as shot taken last week end with my Nikon D70 and Tamron 28-75mm XR Di lense.

48mm 13sec f/10 iso 250

There is nothing much to say about the picture itself but I have noticed some light reflection (flare? lack of coating?) arround the lamp posts on the bridge. Notice that in the center the light arround the lamp post appears to be normal. Moving to the left there is what I might call flare going on the left side of the light. The effect get stronger on the extreme left. The same thing appears (inverted) on the right side.

Is this usual or not?

Any comments/thougths are welcome

regards

Seb

[Trevor Ash]

Interesting observation. I don't have an answer but I bet some optics gurus will. I suppose the question can be rephrased to "Is it normal that lens flare is more noticeable on the outer edges of a photo?" OR, "Do different coordinates in a lens produce different lens flare characteristics?"

I looked things up a bit and found this link:
http://medfmt.8k.com/mf/flare.html

An interesting quote from it and I've bolded the important part:
"Artistic Flare
The source of the reflections of bright light sources such as the sun or street lights at night should now be obvious. These bright light sources are reflecting off the glass elements (and other internal parts of the lens, including perhaps shiny lens mounts (see Kiev-88 notes). The bright reflected patterns can be used artistically. Most viewers are used to seeing them in various television and other movie situations too. This source of flare can be controlled in part by stopping down, and by changing angles or use of lens hoods and other efforts."

Ah yes, have you noticed before how moving the camera left to right affects lens flare? This would seem to support the idea that the direction light enters into the lens (and what it reacts to/bounces off of) affects the flare characteristics.

Based on this; I might answer my rephrased questions like:

"Is it normal that lens flare is more noticeable on the outer edges of a photo?"

Yes, but it doesn't mean that it's always the outer edges that will have more lens flare. It could be that the center of the frame produces more flare with the same high intensity object than the edges.

"Do different coordinates in a lens produce different lens flare characteristics?"

Yes, but it's not a single factor (x,y coordinate) that determines the flare characteristics. There are more things involved including the angle of light, internal lens elements, intensity of light, coating imperfections, etc.

THESE ARE JUST THEORIES of mine based on a few minutes of reading.

[another view]

Perfectly normal, I've seen this with different lenses that I have. I do think it looks different on digital than film though. Usually on film you'd get a flare like that to happen when you stop the lens down all the way but I've shot evening shots like this at middle apertures on digital and it still happens. The reflectance of the sensor is different than film; one of the reasons that the first digital TTL flashes didn't work too well. Here's one I shot last fall.

[Seb]

Hey guys,

Thanks a lot for your imput. Sincerly, I appreciate it.

To Trevor Ash: The link you provided is highly interesting. I havent taken the time to go through the entire page but I'll do it for sure. You bring interesting points too. They make sense to me.

To Another View: It's good to know that my lense most likely isnt faulty. It's still quite new to me and I tend to get obsessed about my gears lol. Thank you for sharing one of your pictures as an example. Frankly, the dof and the sharpness impress me.

best regards

Seb