Lens or Sensor?

Ok, so I recently purchased a 50d and I have been shooting the last few days quite a bit. I have been messing around with settings and getting a feel for things. I noticed something very annoying when I put the pictures on the computer last night and this evening. When I shoot at higher aperture i.e. 20 on up little dots appear in the photos. (see pic below) The more I edit some of the pictures the more the dots appear. But this is what confuses me, these dots only appear when I shoot on high aperture. Anything 8 and below there are no sign of the dots at all. Is this the lens that the person gave me with the camera or is it the sensor in the camera. The lens is a 18-55mm. I'm going to be very irritated if it is indeed the sensor and I have to pay to get it fixed. What do you guys think?

Simply "sensor snot" (dust) which is always more pronounced at smaller apertures...

Take it somewhere for a sensor cleaning (usually $25-35 USD) or else bone up on how to clean it yourself via Rocket Blower, Sensor Kleen Pen or else a wet system like Copper Hill.

They could be dust on the sensor, which can sometimes be removed with a squeeze bulb. The procedure for raising the mirror for cleaning with the bulb is in the manual. If you do this, don't put the tip of the bulb any further into the front of the camera than the lens mount, in case the mirror returns to its normal resting position.

Your sensor needs cleaning, that's dust.

You could also examine your motives for using such small apertures. Diffraction softening starts to kick in at around f/11 to f/16 on APS-C, and for most purposes sufficient depth of field can be achieved without going smaller.

W Vee wrote in post #13923027
If you do this, don't put the tip of the bulb any further into the front of the camera than the lens mount, in case the mirror returns to its normal resting position.

Have I missed something? How is this going to clean the sensor filter surface? The sensor is a long way from the lens mount.

Lowner wrote in post #13923153
Have I missed something? How is this going to clean the sensor filter surface? The sensor is a long way from the lens mount.

You don't want the shutter closing on the tip of your rocket blower...

I've heard the same warning but only in conjunction with any worries that you don't have enough battery to ensure the shutter stays open and the mirror stays up.

FlyingPhotog wrote in post #13923163
You don't want the shutter closing on the tip of your rocket blower...

I've heard the same warning but only in conjunction with any worries that you don't have enough battery to ensure the shutter stays open and the mirror stays up.

J,

Yes, Of course. But the cleaning setting in the camera menu should (provided theres enough oomph in the batteries) prevent that. I use canned air and get the nozzle as close as I dare to the filter surface while carefully avoiding touching anything.

After all, if it needs to be followed up with a brush or even a wet clean, then this HAS to be right in there.

Lowner wrote in post #13923461
J,

Yes, Of course. But the cleaning setting in the camera menu should (provided theres enough oomph in the batteries) prevent that. I use canned air and get the nozzle as close as I dare to the filter surface while carefully avoiding touching anything.

After all, if it needs to be followed up with a brush or even a wet clean, then this HAS to be right in there.

Uh, oh! Duck! You're gonna get it now! The villagers are grabbing pitchforks and lighting torches!

(I use canned air too.)

Roush611 wrote in post #13923017
What do you guys think?

Welcome to POTN!

As you've learned already, it's junk on your sensor.

Here's a good introduction to sensor cleaning: http://cleaningdigital​cameras.com/

And here's a good tutorial: http://www.copperhilli​mages.com/index.php?pr​=tutorials

I use the Copperhill kit for wet cleaning, as do lots of other POTNers.

-js

Canned air eh? From purists I know that's a no no but how does it work? Should be fine as long as you are not too close to the sensor and don't go all out right?

I use sensor swabs if the rocket air won't get it.

Get some good glass for that thing, 17-55 if your pockets are deep or the 17-85 / 15-85 if you need some reach. 50d is a great camera.

Roush611 wrote in post #13927544
Canned air eh? From purists I know that's a no no but how does it work? Should be fine as long as you are not too close to the sensor and don't go all out right?

Air + can + pressure

It's ok as long as you don't tilt the can and shoot out the liquid. It's also not good to have massive or long bursts of air because it can and will blow dust into places you will have a hard/impossible time of removing.

I personally never us it as I think it has too much pressure and too high a risk for what a simple blower can accomplish.

Roush611 wrote in post #13927544
Canned air eh? From purists I know that's a no no but how does it work? Should be fine as long as you are not too close to the sensor and don't go all out right?

It needs care I admit, but really its not as difficult as its said to be.

I always carefully blow out moisture where the can may have been lying on its side in storage, then make very sure I stand it on a flat horizontal surface and gently press it down while I'm using it to make sure it stays there (tilting the can is the big no-no). Then use short bursts, not long ones. This is to prevent the air cooling and forming ice crystals as these definitely will not do the sensor cover any good at all!

Its highly effective. Simply because the air speed is far higher than any hand blower will achieve. I use one of those expensive spinning brush things, but a good quality (& clean!) artists sable brush static charged with the canned air would probably be as good, if not better and cheaper.

Number Six: Not the pitchforks and flaming torches yet?

Lowner wrote in post #13928001
Number Six: Not the pitchforks and flaming torches yet?

They'll be here, don't worry.

One additional advantage of canned air: you can aim it accurately. Try aiming a bulb blower while squeezing it - it jumps all over the place.

If using a rocket blower, it's a good idea to put the camera on a tripod so you can use both hands on the blower.

-js