Silly point - mirror dust does it effect sensor and image

[cedartraveller]

I orderd eclipse fluid and sensor swabs drom warehouse express tp clean some dirt on my sensor, however this might sound silly, if there is dust on the mirror does this effect the image or the mirror is for the viewfinder only.

 

[Doug Kerr]

Hi, traveller,

I orderd eclipse fluid and sensor swabs drom warehouse express tp
clean some dirt on my sensor, however this might sound silly, if
there is dust on the mirror does this effect the image or the
mirror is for the viewfinder only.

The reflex mirror is only in the optical path to the viewfinder and (insofar as its tranmisissive aspect) the path to the autofocus detectors. The secondary mirror is only in the path to the autofocus detectors.

In any event, dust particles on the reflex mirror rarely even show up in the finder view, as they are not at a focus of the optical system. The result is that their effect in blocking light is spread out over an area of the image much larger than their size, and thus the effect of this blockage is greatly "diluted" (as with dust particles on one's eyeglasses).

Certainly, if the reflex mirror became seriously dirty, we might expect some deleterious effect on the finder image.

Best regards,

Doug

Visit The Pumpkin, a library of my technical articles on photography, optics, and other topics:

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[Petteri Sulonen]

...the mirror is extremely sensitive to damage, so don't touch it.

Petteri
--
Me on photography: [ http://www.prime-junta.tk/ ]
Me on politics: [ http://p-on-p.blogspot.com/ ]

 

[cedartraveller]

So, if there is dust on the mirror, which i am not going to touch, will that effect the output being the image.

In summary as I understand it the mirror is for focusing and the view finder and has no impact on image output or quality.

 

[RDKirk]

Theoretically, if the mirror got dirty enough, it could affect autofocusing and metering, but I have 25-year-old SLRs that aren't that dirty.

Don't do anything more than blow at the mirror gently--not with a Rocket blower, even.

--
RDKirk
'TANSTAAFL: The only unbreakable rule in photography.'

 

[jackkurtz]

Dust and crud on the mirror will not appear on the photo. But, once the dust and crud is on the mirror, it is a short trip from the mirror to the sensor. So you want to keep the mirror as clean as possible.

jack

--
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