Scratched mirror?

[braticus]

After having used my camera in some crappy weather last week, and changing the lens several times, I noticed things looked a bit foggy through the viewfinder. After pulling the lens off and inspecting the mirror it looked like it was a bit dirty. I took a qtip, breathed on the mirror, and gently cleaned the mirror. After another inspection it looks like there is now a small scratch on the mirror. Now when looking through the viewfinder I can see a small brown dot.

I'm afraid to do anything more at this point. Are these mirrors that fragile that a qtip would scratch it? I wouldn't have thought it would be an issue at all. I'm not sure how else I could have cleaned it up, since it wasn't dust or particulates that was the issue.

 

[aardvark7]

If you have scratched your mirror it would not have been the Q tip but rather a piece of grit that was already on the mirror. Unfortunately, Q tips are relatively hard over a small area so may have pressed the grit firmly against the mirror during cleaning and so caused the scratch.

Also, because of the nature of camera optics, the silvering is at the front of the mirror, not the back, as in an ordinary looking glass. This makes them much more fragile so should only be cleaned carefully with one of the advised methods, such as a brush or blower bulb.

As to whether it has an effect will depend on where is the damage. It will have absolutely no effect on the photograph because the mirror flips up and has no part in the capture, but if it is in line with a focus or exposure sensor it could affect these. Only precise testing will determine this.

My advice is to take a card full of shots and judge the results. Any problems and you will need to have it repaired, but this is relatively straightforward and should not be hugely expensive, though not particularly cheap, either.

p.s. Of course, there may be no scratch at all but merely some stubborn dirt. Do, though, proceed with caution. I hope this proves to be the case.

 

[victor beato]

be patient, got to read the whole article--you'll learn how to clean your sensor, as well. http://www.tribcsp.com/~sigma2/SensorDust01.html

 

[braticus]

Ya, it's definitely not coming through on the shots I've taken. So, it seems I probably messed up the mirror a bit. It's small and off to the side, so I can live with it, albeit I'm still a bit mad at myself. Although, like I said, it wasn't dust or particles but was more like dirty condensation that dried up, so blowing it out got me nowhere (forgot to mention I tried that first). I wasn't sure of how else to get it clean but to come in contact with it using somthing soft.

Lesson learned I guess. Next time I'll deal with the other effect and then take it to a professional when it gets bad enough.

Thanks guys

 

[braticus]

So, I couldn't get it out of my head, even though I said I could live with it, hehe. And I may have got ahead of myself as well.

I brought it into my lab and checked the mirror with my scope and found that there was in fact, no scratch.

After looking at every possible thing I could to see why there is a clearly visable brown speck, it seems like a particle may have made it behind the focusing screen?

Has anyone ever heard of this? Obviously, I can't clean it without removing it or using some high velocity compressed air from my lab to maybe blow it out; but, there's no way I'll play with removing the screen or have it removed for something that's more asthetic than anything. I'm not sure if using high psi to blow it out is smart either.

 

[aardvark7]

Many cameras have replaceable focus screens, for different applications and preferences, and it is a relatively simple matter to change.

It would be best to see if you can obtain the relevant manuals or ask on the particular forum relating to the brand of camera you have.

I have a KM7D which can be fitted with a third party screen containing split and microprism focus, as opposed to the standard ground glass. Cleaning would be straightforward during such an exercise.