Little Black Dot On Pix

Archived from groups: rec.photo.digital (More info?)

Logan Spitznauer <mjdr10a@prodigy.net> wrote:
: I have a Sigma SD-9 which has a little black dot in the lower right hand
: side of 99% of my pictures. Sometimes it's sharp, sometimes it's subdued.
: Could I have burned it? Is there a tiny nick or foreign object on the
: lens/mirror/cmos?

: What do you suggest I do to troubleshoot this?

It may be a spot of dust on one of the lens elements in your camera lens.
Probably on the front element. If this is a zoom lens, changes from wide
to tele would explain why it is sharp in some images while it is out of
focus on others.

I would think that if there was a flaw or speck of dirt anywhere after the
lens it would remain at the same focus and location all the time. You
mentioned it's stable in location so it must not be on a rotating/moving
lens element. But since it goes in and out of focus, it must be on a
moving element. And it is possible for a spot on the front of a macro
would be in or near enough to the Depth-of-field envelope to be in focus
or nearly so. While when the lens is at a long telephoto length, it would
blur, possibly all the way out to invisibility.

The solution would depend on where it is. Cleaning the front of the front
element may get the pesky speck. And if that doesn't work, try doing the
same to the rear most lens element. But if neither work, you should take
the camera and lens to a reputable dealer/repairer. Don't try to
disassemble the lens to "get that pesky dust blot" yourself. It would be
very likely you would never be able to get it back together again.

JMHO

Randy

==========
Randy Berbaum
Champaign, IL

Archived from groups: rec.photo.digital (More info?)

"Logan Spitznauer" <mjdr10a@prodigy.net> wrote in message
news:8t54e.3284$k57.2869@fed1read07...
>I have a Sigma SD-9 which has a little black dot in the lower right hand
>side of 99% of my pictures. Sometimes it's sharp, sometimes it's subdued.
>Could I have burned it? Is there a tiny nick or foreign object on the
>lens/mirror/cmos?
>
> What do you suggest I do to troubleshoot this?

If the spot appears in every photo regardless of which lens you are using
than it is probably dust on your sensor. This is normal for a DSLR and easy
to clean. The SD9 manual has instructions on how to clean the sensor,
including removing the dust protector, it's very easy to do. I clean my SD9
sensor with a 100% nylon foundation makeup brush, it cost only $ 9.99 US
which is a lot less for the same brushes from VisibleDust. You simply blast
a bit of air on the brush from a can of compressed air (this gives the nylon
a static charge) and then wipe it across the sensor. It will pick the dust
off of the sensor.

Archived from groups: rec.photo.digital (More info?)

> I have a Sigma SD-9 which has a little black dot in the lower right
> hand side of 99% of my pictures

Dust on the sensor.

> Sometimes it's sharp, sometimes it's subdued.

Because of different apertures. Shoot wide open and you likely won't
see it, shoot stopped down to f/22, especially with a light subject,
and you'll see it.

>What do you suggest I do to troubleshoot this?

Shoot a white subject at f/22 and look at the file at 100%. Then read
up on cleaning the sensor.