Sensor Dust question...

Hello all,

I am brand new to the board so let me introduce myself...

I am not brand new to photography but only recently got back into it after a long hiatus. In around 1986 (?) I had a Canon AE-1 Program SLR and a few lenses, etc. I just bought a 40D and 2 lenses and have enjoyed picking photography up again.

Now for the question...

I've had my 40D about a month and have just noticed when looking through the viewfinder that there is a small black speck in the upper left corner (it is big enough to annoy me... maybe its OCD). I don't see it in most photos but have zoomed in and found it. And I have seen it using both lenses.

I used the Rocket Bulb on the sensor but that is all I am comfortabel doing. It didn't help me with this overly annoying speck.

Is there any chance this is anything other than sensor dust? Since I am not really comfortable cleaning my sensor, does anyone know any places in the New York City area that do it?

Thanks for any help guys...

Rob

If you purchased the camera new you can send it to Canon anytime during the first year for a free cleaning. I believe that it goes to Jamesburg NY which is an hour away from one of the Ellis Island ferries so you should get a really fast turn around one it. Welcome to the forum.

Whatever you are seeing through the viewfinder is not sensor dust (unless you're refering to the LCD live view then, maybe, though, I don't have experience with this). It could be something on the mirror or inside the view finder itself.

As for what you see on the images, if you only see it on some pictures when you zoom in, I wouldn't send it in for cleaning if it's only a spot or two. You will be sending it in every couple of weeks if that's the case. If it's really dirty then, yeah, get it cleaned. For the occasional spot that show's up in skys I would use spot removal in post processing software.

And if you are seeing something in the viewfinder that really stands out then you probably want to get that cleaned as well.

Hi Rob, Welcome!!...

40D is a great device.

As far as sensors are concerned, my take is to mess with them as little as possible. Specially the models with the Self-Cleaning sensor feature.

What we see through the viewfinder is routed:
viewfinder > Prism > Focusing Screen > Mirror Assembly > Rear Lens Element > Forward Lens Element.

I would clean everything except for the items in red.

The Focusing screen is actually perpendicular to the Sensor, and 45 degs from the Mirror (If you grab your camera looking into the lens mount, and turn it upside down, you should be able to see it). This is also a fairly sensitive area to clean, no wiggle room, never compressed air, and regular Q-tips are extremely discouraged in this photogs opinion. But you may want to clean it, by using a sensor swab or any such material, and apply no pressure as you clean it. Pass over it once or twice and check.

Mirror assembly? The mirror looks like a square piece of glass, and fairly simple to play around. To me, this is the easiest way to break the camera. Underneath the mirror, there is a sub-mirror (smaller version of the same) that takes care of TTL and other functions. Turns out that it is fairly easy to screw up the whole deal. Again, if you are goin to clean, just make one or two passes very softly.

Hope this information helps. If for some reason the spot shows in the photos, post an example. Otherwise, slight cleaning is the best way to go, followed by perhaps a local photo store where they may be able to profesionally clean the camera for you, ultimately with Canon, where you will shell out almost 200 bucks before they even take a glance at the camera.

NYC? There should be a photo store somewhere.

So as pointed above,

Thanks for the advice!!!