At 05:31 PM 4/14/2006, Wayne S wrote:
>Ok, here is an update of dust correlated with F stop with 5D.
>After several cleanings with PecPad wrapped on credit card
>cut to size, there were a few spots that refuse to change.
>Here are some 100% crops around those spots:
>
>http://www.airsprite.net/5D_dust/dust_32.jpg F32
>http://www.airsprite.net/5D_dust/dust_22.jpg F22
>http://www.airsprite.net/5D_dust/dust_16.jpg F16
>http://www.airsprite.net/5D_dust/dust_11.jpg F11
>http://www.airsprite.net/5D_dust/dust_8.jpg F8
>http://www.airsprite.net/5D_dust/dust_5_6.jpg F5.6
>
>You can see that the spot is evident at F16, starts to disappear
>at F11 and nearly invisible at F8. I did not enhance the contrast.
>
>Almost all the spots could be cleaned with PecPad plus
>alcohol, except a few.
Hi Wayne,
I missed your first message that described using a CO2 blower to
clean the sensor but if it's something like canned air you've got a
lot more nerve than me. Well, I guess you do anyway. Just the
thought of sticking a cut down credit card into the sensor chamber
makes rabbits run over my grave, even if the card is covered with a
PecPad. :-)
Also, it might be interesting to run some tests to see what effect
diffraction is having on your shots at f32 as compared to something
like f11. I know you're trying to increase your depth of field but
some sources that I've read claim that, with the 5D, diffraction will
start reducing image sharpness at between f11 & f16. I also seem
to remember reading somewhere that as the reproduction ratio starts
approaching 1:1 the effects of diffraction are multiplied such that
the reduction in sharpness at f32 would be similar to that at f64 and
normal focusing distances. Anyway, I'm just wondering if what you're
gaining shooting at f32 is being offset by losses in sharpness due to
diffraction.
Later,
Johnny
__________________________
Johnny Johnson
Cleveland, GA
mailto:jjohnso4@xxxxxxxxxx
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