I'm starting to do more macro work with my 5D, in which high
F-stops are common. At high F-stops, dust becomes more in
focus, while at lower F-stops is not visible (below F11-16).
Here is a macro shot I made yesterday at F32 using 180mm
macro plus 1.4x converter. Notice the dust on the right.

http://www.airsprite.net/OM/dust_MG_3717.jpg
100% crop of right side:
http://www.airsprite.net/OM/dustcrop_MG_3717.jpg

This dust is not affected by using a CO2 duster, so I'm
beginning to wonder if the origin of the dust is from the
camera itself, such as lubricants. The visible dust website
http://www.visibledust.com/nature_of_dust.html
mentions the possibility of metal or lubricants from the
camera itself.

I'm wondering if this becomes more of an issue the more
the camera is used. Not that the small size of the particles
become nearly invisible at F8 and below, so may not be
noticed much by many photographers. Only when high
F-stops are used does it become a problem. I have not
used a visible-dust brush, but only a PecPad and my own
plastic utensil (made from stiff bubble pack plastic) and
a couple of drops of methanol to clean this.

I'm open to suggestions on how to deal with this problem.
I'm beginning to think the 5D is not the ideal camera for
macro work, and that a 20D or 30D would be a better
choice.

WayneS

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