Re: How to verify a new lens
Quote:
Originally Posted by snatesan
How can I verify the lens I received is a good sample without any flaws?
Ideally, you would just throw it on a lens projector. But if you don't live next to a lens rental facility that will let you use their projector, then the next best thing is to shoot a resolution chart like the lens reviews on this site. If you don't want to shell out a bajillion dollars for a nice printed chart, you can try shooting anything with fine detail, such as a newspaper, after hours of painstaking leveling and alignment to ensure the target and sensor are perfectly parallel. Or, you could just take any old normal picture, with the understanding that all sorts of errors may creep into your test.
The easiest way is to just assume the lens is a good sample. [:D] (Works for 99% of photographers.)
Quote:
Originally Posted by snatesan
I am worried about the portion marked in the red circle. You can see some flaw there, kind of noise.
Yes, this is a flaw. It can also be called a blemish, or pimple. I hear there are some skin creams that help... [;)] Just kidding. Seriously, I don't think I see the problem ("kind of noise") you're referring to here. Does it appear in every photo at the same spot? If so, can you post a few other photos to help me understand what it is you're referring to?
Re: How to verify a new lens
www.graphics.cornell.edu/.../res-chart.html has a home-printable ISO12233 chart for download. but, uh, you need a good printer. I got a local printing house to to print one out A3, and the lines thinner than 1000lp/ph are too pixelated (from the printer) to be of any use, at 18 they just run into one blob. (but the .pdf is scaleable, you just need to find a good printer)
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For your supposed problem up there, if you want to test if there
Re: How to verify a new lens
Snatesan,
Post this and additional pictures at flickr where you can upload a decent file size plus we can click on the image and take it to the preview page with the black background and maybe see what you are seeing. The basic account is free where I find it a good place to host images.
On a side note one time I got a Sigma wide angle lens and the whole left side in a large circle was soft while the right was sharp. Bought it locally so I just returned it. I don't think I could ever get myself to buy another Sigma with the overall results that I have experienced from three different lenses.
Re: How to verify a new lens
Agree that more detail is needed in your case. A lens problem must be extraordinarily bad to show as a specific spot on an image. Look through the lens, and if there
Re: How to verify a new lens
Also would be worthwhile testing the camera with different lenses to make sure it is not a problem with the camera itself. So far, except for the lens projector, the suggestions have not allowed for a certain elimination of the lens or body as the culprit, even though the ideas have real merit of their own.
If you see the problem with the lens in question, and it goes away using your other lenses, it
Re: How to verify a new lens
Thanks guys for the advice.
I am going to test the lens as Croubie and neuroanatomist suggested and will let you know.
Meanwhile I uploaded some photos to flickr, please take a look and comment when you get a chance.
www.flickr.com/.../72157627311641695
Thanks!
Satheesh
Re: How to verify a new lens
From the flickr link:
"100% cropped image of IMG_7541. The area I am concerned is where contrast changes at the bottom of the basket which appears as noise."
I still don
Re: How to verify a new lens
Re: How to verify a new lens
I don't see any issues right off hand. What camera body are you using?
