LX3 : left and right side lens softness

[longhill]

I just bought an LX3 last week,and after some pics I saw some softness on the left and right side.So today I did a test for to check how much softness was present; the test was done taking pics (raw)on a paper sticked on the wall at different focal lenght and aperture, opened with silkypix and saved as jpeg with no sharpening.Here the results:

Focal lenght 5.1mm
A=2
http://yfrog.com/0tfocal51mma2j
A=4
http://yfrog.com/10focal51mma4j
A=8
http://yfrog.com/0ufocal51mma8j

Focal lenght 9.3mm
A=2.5
http://yfrog.com/0yfocal93mma25j
A=4
http://yfrog.com/11focal93mma4j
A=8
http://yfrog.com/10focal93mma8j

Focal lenght 12.8mm
A=2.8
http://yfrog.com/95focal128mma28j
A=4.5
http://yfrog.com/0ufocal128mma45j
A=8
http://yfrog.com/0vfocal128mma8j

As you can see the sharpest is on the Focal lenght 9.3mm and A=4, but what concern me is the softness present on Focal lenght 5.1mm specially at A=2, is normal to have so much softness specially on the right side?

I noticed that also at any focal lenght and aperture is present softness on left and right side compared to the center (much less on Focal lenght 9.3mm).

I would like to know if someone did this kind of test , so I can compare with my resutls, and see if I have a faulty lens or not.
Any comments are deeply apreciated.
Thanks

 

[longhill]

No one want to discuss about this??

 

[kernow]

No one want to discuss about this??
--

There were some problems with bad lenses on early batches of this camera.
--
Oll an gwella,
Jim



[LX1]

[FZ30] * IS/L B-300 * IS/L B-Macro * Minolta No. 0, No. 1 & No. 2 * Sunpak 383 * Benbo Trekker

[L1] * Olympus 25mm 2.8 * Hexanon 40mm 1.8 * Vivitar Series 1 135mm 2.3 * Tokina 500mm 8.0 *

 

[J C Brown]

I just bought an LX3 last week,and after some pics I saw some softness on the left and right side.So today I did a test for to check how much softness was present; the test was done taking pics (raw)on a paper sticked on the wall at different focal lenght and aperture, opened with silkypix and saved as jpeg with no sharpening.Here the results:

Snip.....

As you can see the sharpest is on the Focal lenght 9.3mm and A=4, but what concern me is the softness present on Focal lenght 5.1mm specially at A=2, is normal to have so much softness specially on the right side?

I noticed that also at any focal lenght and aperture is present softness on left and right side compared to the center (much less on Focal lenght 9.3mm).

I would like to know if someone did this kind of test , so I can compare with my resutls, and see if I have a faulty lens or not.

Any comments are deeply apreciated.
Thanks

It is normal for the edges and corners of an image to be less sharp than the centre and for the difference to vary with the focal length, with the shortest focal length giving the greatest difference. The difference generally reduces as the lens is stopped down but may increase again as the aperture is further reduced towards its minimum value.

It appears to me that all of the images you refer to were shot with the camera at the same distance from the wall to which you fixed the test page. Consequently for the 5.1 mm focal length the number of pixels across the thickness of the strokes of each letter in the text will be about half the number for the 9.3 mm focal length and less than half the number for the 12.8 mm focal length.

To avoid that you should ideally adjust the distance between the camera and the test page so that the test image is the same size for each focal length. In addition before taking each shot you should tape a mirror to the wall and adjust the position of the camera so that you can see its reflected image in the viewfinder or LCD.

Assuming that the wall is flat, that will ensure that the optical axis of the lens is accurately at right angles to the test page so that both sides of the image are sharply focussed. Unfortunately depending on the design of your tripod that can be a bit tricky to do.

In the image shot at 5.1 mm the field of view is much larger than at 9.3 mm or 12.8 mm. Also in the 5.1 mm image it is clear that the lighting is not uniform across the width of the image. The background on the left hand side is darker than on the right resulting in a difference in brightness and contrast. For the longer focal lengths that difference is less so that there is less difference in the brightness and contrast between the two sides.

If you are using articial light to illuminate the test page it is best to have a lamp placed on each side of it so as to give more even illumination.

I hope that helps explain some of the differences you have observed.

Jimmy
--
J C Brown

 

[longhill]

It is normal for the edges and corners of an image to be less sharp
than the centre and for the difference to vary with the focal length,
with the shortest focal length giving the greatest difference. The
difference generally reduces as the lens is stopped down but may
increase again as the aperture is further reduced towards its minimum
value.

You right on this, but I notice a lot of people here in this forum and also on the net claim to have this camera with a very sharp lens corner to corner, I wonder if there is a sort of production "variation" or a different personal judgement on this camera.

It appears to me that all of the images you refer to were shot with
the camera at the same distance from the wall to which you fixed the
test page. Consequently for the 5.1 mm focal length the number of
pixels across the thickness of the strokes of each letter in the text
will be about half the number for the 9.3 mm focal length and less
than half the number for the 12.8 mm focal length.

you're perfectly right, 5.1mm and 9.3mm just taken at same distance and 12.8mm a little farway for focus problems.

To avoid that you should ideally adjust the distance between the
camera and the test page so that the test image is the same size for
each focal length. In addition before taking each shot you should
tape a mirror to the wall and adjust the position of the camera so
that you can see its reflected image in the viewfinder or LCD.

That's a wonderful idea, maybe I can get a more precise vertical and horizontal camera alignement.

In the image shot at 5.1 mm the field of view is much larger than at
9.3 mm or 12.8 mm. Also in the 5.1 mm image it is clear that the
lighting is not uniform across the width of the image. The background
on the left hand side is darker than on the right resulting in a
difference in brightness and contrast. For the longer focal lengths
that difference is less so that there is less difference in the
brightness and contrast between the two sides.

I tried to shoot with sunlight coming from the window but i get problem taking pics at smallest aperture, so in some pics I used the flash and in other I used a lamp, but is true every pics has brightness uniformity problems.

I hope that helps explain some of the differences you have observed.

Thank you very much for your help, I will make a second test following your suggestions.

Thanks

 

[fatman_br]

I can´t be sure, for I do not know the technical aspects involved, but for me it´s possible that the corners are out of focus in some situations, specially at wide angle, because they are farther than the centre of the image (it´s on a straight surface). I believe that a better way to test it is a curved surface, where all points of the object are at the same distance of maybe (please, help me here), the "center" of the lens or something equivalent.

For sure there are a lot of people here in this forum that can help me with this "theory"...

--
Fabio Leoni, from Brazil
My galleries:
http://picasaweb.google.com/Fabio.jose.leoni
http://www.flickr.com/photos/9741796@N05/

 

[longhill]

I can´t be sure, for I do not know the technical aspects involved,
but for me it´s possible that the corners are out of focus in some
situations, specially at wide angle, because they are farther than
the centre of the image (it´s on a straight surface). I believe that
a better way to test it is a curved surface, where all points of the
object are at the same distance of maybe (please, help me here), the
"center" of the lens or something equivalent.

I found an interesting article here in this site
http://www.photozone.de/lens-test-faq

where explain the issue that you describe as field curvature problem.Down below that page, explain how to check lens problems.
I'lll try to test this procedure later.
Thank you