Help?

[mls]

Hi,

I'm just getting into photography and I know this photo isn't very good, but

it's a good example of a repetitive problem I'm encountering on some of my

shots:

 

http://www.photo.net/photo/5685722

 

I seem to be getting some sort of linear distortion; I'm not sure what it's

technically called. On some photos it's horizontal as on this one and on

others it's vertical. I thought it was a problem with the lens but it only

shows up on some photos, is not in the same place, and in some there is direct

sunlight as there is in this example, and others are darker pictures. Has

anyone encountered this or have suggestions to prevent it?

 

Thanks!

[Mike Howard]

It is odd. What camera, lens, etc? Also, does it do this with different lenses?

[art_haykin]

Can you describe the distortion in better detail and point out where it is in the image?

 

I just don't see it.

[mls]

Sorry, I should have included that, it's just a Canon Powershot A75. No additional lens or anything like that. thanks!

[mls]

It's pointed out on here...

[brucecyr]

I don't know what they are but I wonder if you notice them at a particular zoom range, like always extended in telephoto mode or always retracted in wide-angle mode?

 

Preliminary guess (and a wild one at that) is something with either the lens or the sensor.

[charedan]

Hi Marissa,

 

Do you get this right out of the camera or after some processing with other software?

 

If right out of camera, is it in all available resolution (2048x1536, 1600x1200, 1024x768,

640x480) ?

 

Does this camera can save in tif as well as jpg? and is the problem present in tif files as

well?

 

Looks to me like a very large jpeg artifact, this is really odd!

 

Dan

[stembaughphotography]

I think, it is those pesky poltergeists playing games with unsuspecting photographers! :-)

[robert lee]

This is most likely a sensor design problem. I can only guess at the underlying issue, and it has to do with the large group of photosites at saturation, i.e., from the sun in your image. Maybe the sense amp for a row of photosites are nonlinear at cutoff.

 

Whatever the root cause, the problem should be easy to reproduce. Try shooting test images that include large, overexposed areas, maybe bare light fixtures.

 

If reproducible, about the only thing you can do is to avoid overexposure and avoid large swatches of specular highlights (or change cameras.) For what it's worth, it appears that some Nikon D200 DSLR's manifests this as well.

[mls]

I don't recall ever seeing it on shots in telephoto mode.

 

That is straight out of the camera, not from software, and appears in all resolutions. I will play around with it and see if I can save as .tif today and if it shows up there as well.

 

It shows up on some darker pictures too; I'll look for a good example.

 

Thanks!