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Canon D60 (10D) + Sigma 8 mm Fish Eye for Panoramas Part 2 Technical Data
by Hans Nyberg

Sigma 8 mm Fish Eye Sharpness

The image below can be downloaded in the original as it comes from the camera.

Download file 2.9 mb

This is the largest resolution 2048x3072 Filesize 18 mb Best Jpg compression.

Exposure F9.5 1/250 200 asa, Parameter is set to Low Contrast

You can also see a sharpness test with different Fstops , scroll down.


click here
to see the image corrected for light fall and with shadows lightnend
Back
The image to the left is the one used in the panorama. As you can see it is much brighter

Actually it is only 1/2 F:stop lighter exposed. Exposure was F 9.5 1/125 200 asa. I would have prefered that it had been as the above image. The blue house is almost totally washed out.

The shadow areas in the above image is very easy to correct with a curve in Photoshop. This is the main problem with digital. If you expose as the camera tells you, you get blown out highlights. I have now started using raw files and I expose for the highlights. To get the shadows is easy.

Another reason why the blue house is better on the above image is that you have a light fall to the edges. You need to make a selection with a feather to lightnen the peripheral areas. The light fall does not show very good on the above image.
I have found a better image which you can see here

To se the above image corrected both for shadows and for light fall click on the link below the large image above.

The Sigma has some color aberration in the peripheral parts about the same area as the light fall. This can be corrected with Panotools but I also found that Quantum Mechanics a filter to reduce noise can do it.

Below is before and after Quantum Mechanics. You have to be carefull not to apply to much . It also reduces colors. Look at the red shirt to the left.

You can get almost same result with following method.
Make an action with this.
Choose the red and blue channel. Select all. Choose Transform-Scale and set to 99,9 percent in both width and height.

Or select only the green channel and transform to 100,1 percent.

BEST RESULT IS IF YOU HAVE ADDED EXTRA CANVAS FIRST SO THAT YOU HAVE A FULL CIRCLE AND THE TRANSFORMATION IS THE SAME IN BOTH DIREECTIONS.

Below is sharpness at different F-stops. Even at full opening it is reasonably sharp.
The normal setting for the camera + Photoshop Unsharp mask 180 - 0.5 -1 has been used.
Original files where raw files and they have been saved with Jpeg 80 % compression.
Periferral
Center
F 11 and 16 are exactly as F8. At 22 and 32 you get a softer image. I do not know why they made it possible to stop down to 32. Usually you only have that option on Teles.