Dust when I look through the view finder

rgrebby

rgrebby

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Richard
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I have some specs when I look through the view finder, it doesnt matter if my lens is zoomed in or out it stays the same. If I use the little eyepiece diopter(?) it goes out of focus. I have used a blower and it doesnt seem to move at all.

could it be the other side of this class or on the mirror? I dont see the dist on pictures.


if its the mirror whats the safest way to take it off, Im not sure I want to blow in there as it might be bad.
 
I'm not a fan of rocket blowers as they can just distribute the dust elsewhere. This dust will almost certainly be on the focusing screen, and they don't appear in your pics. Personally I'd ignore them unless they're particularly bad - dust in cameras is a fact of life. Never touch the mirror anyway, as unlike conventional mirrors, the mirror coating is on the surface, and any marks, scratches or fingerprints will be there for good.

The problem is there are two sides to the focusing screen, the one you can see if you look up into the camera through the lens opening - it forms the roof of that chamber known as the mirror box. The other side is inside the prism housing where you can't get at it without removing the screen which you can do on some cameras. I'd advise caution, unless you're a very patient dexterous sort of person as it can be fiddly, and very easy to get the screen back in a worse state than it came out.

If in doubt get a pro to clean it, or just ignore it - it's only a matter time before you get some more anyway.
 
thanks for the advice, is the mirror used in taking the pictures? or just to look through the lens?
 
rgrebby said:
thanks for the advice, is the mirror used in taking the pictures? or just to look through the lens?
Click to expand...

LOL. Hell no. A DSLR is a pretty cool bit of kit - the lens is also your viewfinder. What happens when you press the shutter is...

(1) The aperture closes down to the set aperture, (It stays open until then to give you a nice bright viewfinder image. This arrangement is known as a fully automatic diaphragm.

(2) The mirror flies up and actually covers the focusing screen virtually touching it. This allows the light to go to the sensor instead of being diverted up into the viewfinder. The air it's moving when it flies up is probably responsible for a fair bit of the dust you're seeing being deposited on the screen.

(3) The shutter opens and the pic is taken.

(4) Shutter closes.

(5) Mirror comes back down.

(6) Diaphragm opens up to full aperture again.

All in a blink at that, and some camera will do all that at 10 frames a second. :eek:

EDIT.

That's a long winded way of saying - yes, the mirror is just used to give you a viewfinder image. ;)
 
Messing with focusing screens is how I got my silly forum title over on the left there...

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It's nothing to do with any hatred for Nikons. ;)
 
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