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Contax ND

> Diane,

My ND also gets the same falling off around the edge of the photo. This seems to be a very low light problem. Not sure what is causing the problem. I have not updated my bios. Have you?

Thanks,

michael.

>
 
Diane,

A Skylight filter will add a slight pinkish warming tone. A UV / Haze filter should not. Make sure you indeed have a UV and not a Skylight. If you can get us the actual filter designation it would help. The common UV Haze filters are designated 010. The more common Skylights are usually designated 1A (or KR 1.5) and 1B.

So far the only fall-off I've experienced has been because of a normal-thickness filter on the 24-85 at the wide end. The thin filter has been fall-off free.

You may want to ascertain if the halos are at the wide end, and may be from interference through vigneting (?? - I just made that up as a possibility).

DJ
 
DJ,

The filter is an L39 (UV) MC. Is this a thin or thick filter? FYI...I took the problem shots with firmware 1.06, but have since upgraded. I am not sure if I will have the same problems in 1.07. I need to test on photos with simple backgrounds on the edges such as open sky. I did notice the vignette is visible as darkened corners in color, but these dark corners become concentrically circular halos when converted to grayscale. I'll try and post some color and B&W s&les for you to see.

Diane
 
The thickness refers to the mount. Yours is probably a normal thickness. Thin mounts are somewhat more expensive and less common. You need to specifically request it at the shop, otherwise they'll supply a normal mount. If you put them side by side, the thin mount is not as tall as the normal one. Also there may be a couple of "thin mount" variations, with the thinnest having no front thread at all (the type I got). For a B+W you're talking $100+ ... ouch.

DJ
 
> I have a thin mount UV filter on my 24-85 and have the same "fall off" problem.

michael.
 
why do you guys use UV filters anyway??? It should be a very special reason for putting another two reflective glass surfaces before your lens.
 
Irakly,

That reason is ... I tend to use my lenses in questionable environments
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.

Michael,

How bad is your fall off (in EV, 2 decimal accuracy ...) and is it only wide-open? I'll do a more explicit test. I'm sure there probably is some, I just haven't noticed. One advantage of getting old.

DJ
 
DJ
happy.gif
For this purpose I use Nikonos.
I think that this problem may be due to the fact that light must fall on a chip at 90 degree angle, which is a limitation of all digital cameras. On the other hand, I had never have a light fall off problem with ND except with 95mm B+W polarizer on 17-35, but this is understandable because the filter is for 2.8/180 Schneider Tele-Xenar.
 
Irakly,

Can you take a look at the color and B&W photo I posted entitled "Station with Halo" and let me know your thoughts on what is going on in the sky? I was using a polarizer on a 24-80 zoom at 24mm.

Diane
 
It seems to be vigneeting pretty badly. Are you sure there isn't an obstruction slightly intruding in on the corners? Did you shoot a sky without the filter?

Just about any WA lens will vignette, especially if you alter the exposure in light areas with a filter that darkens. My Super Wide lens for the X-pan requires a center filter to even out the edge balance. A lot of people that shoot Transparency film see vignetting more than those who favor neg film. Shooting Digital is like shooting transparencies.
 
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