new 40D, but oh ffs....

KaraSchaeffer · #1 10-28-2007, 01:14 AM

I think I have a speck of dirt in my viewfinder
It shows up through the viewfinder but not on the shots, and the lens is clear.

It's really irritating. Any ideas on how to get rid?

Josh_Hawkins · #2 10-28-2007, 02:19 AM

It's probably on the focusing screen. Remove the focusing screen and clean, be careful, everything in the mirror box including the focusing screen can scratch pretty easily.

KaraSchaeffer · #3 10-29-2007, 04:47 AM

thanks Josh - I tried something else first in the end as I am too much of a wuss to try something damaging - I took off the lens leaving the mirror exposed, pointed the exposed area to the floor, went into the camera menu and choose the "clean sensor" option, heard the mirror flap, put the lens back on and....

no more annoying spot in viewfinder. cool

one happy camper

GOOD option!

Noel_Carboni · #4 10-30-2007, 07:35 AM

I think you're not normally expected to clean the sensor that way, Kara. The sensor cleaning option is so you can swing the mirror, open the shutter and scrub the sensor with a brillo pad as needed.

What I'd do in the future if you see this happen again is to pull off the lens, leave the mirror and shutter where they are, and use a puffer bulb to puff some air up into the top area of the camera, where the focusing screen is (do not blow air from your mouth). I'd suggest canned air, but you have to be very careful because it can shoot liquid or just blow too hard, so do that at your own risk.

-Noel

Ronald Garrett · #5 10-30-2007, 07:50 AM

I've noticed that my focusing screen is kind of a matt finish, with a slight pebbley texture. I understand that is normal? I don't notice it unless concentrating on it instead of the subject. Thought this might be the opportunity to ask and make sure.

KaraSchaeffer · #6 10-31-2007, 04:50 AM

might be normal - but I dont see that on mine.

Noel - I'm sure my way wasnt the "preferred" way

but hey, it works & isnt scary! To be fair, I never once got a speck of dust in my sensor on my 10D as far as I could see (& yes I would inspect @ 100% most of my photos to make sure).

Noel_Carboni · #7 11-01-2007, 08:07 PM

Well, I just mentioned that because swinging the mirror out of the way and opening the shutter really has nothing to do with a speck of dust on your focusing screen. If it was going to fall out, it should be able to fall out with the shutter closed just as well, and you don't risk getting additional dust on the main sensor. Put another way, the focusing screen is exposed the the environment whenever the lens is off the body. The sensor is only exposed when the shutter is open.

And yes, Ron, the focusing screen is supposed to be rough. It's a bit like a back projection screen for a slide projector or projection TV.

-Noel

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