SD9 UV / haze-2a filter test (1)

Started Aug 12, 2003 | Discussions thread
OP Yi Ding Senior Member • Posts: 1,371
sorry, the test photos are here:

ding1 wrote:

There hasn't been any sunny day in Columbus since I received my
50mm lens and the haze-2a filter for it, so I only did some
preliminary tests.

In the first row, gray reference was picked on the gray card.
Although the lighting condition of the sky is not really the same
as that of the card, I think the use of a gray card is valid,
because the sky is usually only the background of a photo and we
want the white balance to be optimized for the main objects. The
real sky color in my impression was somewhere between the UV filter
image and the haze-2a filter image (maybe closer to the latter, but
I'm not very sure). It seems that the haze-2a filter, which looks
a little yellowish, cuts off some visible shortwave blue. The sky
color in the first two images are vivid and pleasing, just like the
effect of a polarizer! If the sky was indeed deeply blue, then it
would probably appear unnatural in the first two images.

The lamp in second row used a blue-coated bulb that was supposed to
give out some UV light. They were all with auto white balance;
choosing the gray reference on the white wall doesn't noticably
change the color. There is not much difference between the image
with and without the UV filter, while the haze-2a filter really did
a good job. What I saw with my eye was nearly the same as the
third image.

The most significant benefit of the haze-2a filter is that it
suppresses haze and purple fringes very effectively. This is
evident in the third row (cloud picked as white reference). The
haze-2a filter also made the image a little warmer and the green
color more vivid.

In summary, it seems the X3 sensor in SD9 does intensify the blue
color of the sky, which sometimes is a good thing. The haze-2a
filter probably reduces the sky color, but this is very easy to
adjust on the computer (for example, using the magic wand tool in
photoshop to select the sky). Overall, the use of a haze-2a filter
on SD9 seems to be pretty advantageous. However, why didn't Sigma
use haze-2a filter glass to make the dust protector? Is there any
other major disadvantage of the haze-2a filter? I'll do more
tests, but any input will be greatly appreciated.


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