DRebel XT, dirty sensor ? or defective ?

All the pictures recently with my new Rebel XT taken has some small round shaped darker but almost transparent cirles visible on blue backgrounds in upper left and right of all pictures (always at the exact same places) I Sent the camera for warranty repair and the three original circles are gone but a new one very similar is now present in lower center of all pictures taken since the repair (look under lowest wire in first picture, lowercenter, a bit right). What should i do ? is it dirty lens, dirty sensor ? defective sensor ? anyone had similar circled dots in pictures ? (see accompanying picture taken from blue sky). anybody has creative suggestions to solve problem ?

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The spot you are refering to looks like dust on the sensor. Try blowing it wit a blower, NOT COMPRESSED AIR,.
It may be my monitor but I am seeing what appears to be streak marks in both pictures.
Is you lens clean? Do you have a filter on the lens? Check both to make sure they are streak free.
If they are then maybe someone did a bad job at cleaning your sensor, and you should return it to have it done properly.

Does anyone else see the streaks??

Wayne

Sensor dirt. Sooner or later you'll decide going back to Canon for sensor cleaning either isn't practical or isn't economical. There are about leventy-leven skillion threads advocating various methods of sensor (sensor cover, actually, but I don't feel like typing that every time) cleaning around, all of which go into exhaustive detail, and many of which are blood-spattered. Briefly, sensor cleaning options include:
1) use a blower (Giottos Rocket Blower recommended for the devout, ordinary infant ear syringe for the casual) to blow off the dust.
2) use a clean, residue-free soft brush (with rounded bristles), carefully prepared to remove all sizing or other latent chemicals from it, to brush off the dirt. Again, there'sthe $$$ specific brush or use and prepare a makeup or similar brush.
3) Swab off the sensor using swabs and a residue-free solvent. High end solutions variously known as Pec Pads/Eclipse, Copperhill. Low end is Q-tips cotton swabs and isopropyl.
Which method to use, and which budgetting decision to apply is up to you. I use Pec Pads with Eclipse and a Giottos blower. There's a sensor cleaning thread stickied under EOS FAQ, for instance.

It's just dust on your sensor, no big deal at all.


Here's another question for ya. I've always used compressed air out of the can to clean my sensor and it's always worked perfectly, so why does everyone say not to? Is it because of the off chance that the can burps up some propellant and freezes your sensor?

That's one potential danger. Another is that it may put too much force on some of the shutter blades, and damage them.

I'll second what Jon has said on both counts. Looks like dust and something thats a fact of life and will need dealing with regularly. Not a big deal and takes seconds to deal with, for only one like this though you could just clean the image up in PS, one click and it's gone. Far as Canned air goes, keep it well away from your camera. Bigger chance of making your sensor (AA filter) even worse or as Jon said cause physical damage also.

Whats with this? I had the same problem with my xt. Long story short, I returned it because the worker clean the sensor wrong. The next Xt I got had dust on the sensor as well and I ahve yet to clean it

The dust issue is going to happen sooner or later. Its relatively easy to clean yourself using just a good quality blower bulb, less the brush. Just hold the camera downward with the shutter locked up as stated in the manual. More stubborn specks something like one the good sensor brushes will help.

That photo taken @ f/8 you'll probably never see that dust speck. And last of all a quick Clone Stamp in PS will remove it.

Dust, like other things, happens. I've not followed Olympus users' reports about how well the ultrasonic sensor shaker works at keeping dust off their sensors, but I rather suspect that performance will be, pardon the phrase, spotty. Around here, some people have more trouble with dust than others; I doubt Olympus' measures are any different. They'll only really work for dry, loose particles that a blower or brush could get off anyhow. If you normally shoot at wide apertures and/or with busy backgrounds, dust isn't going to be as much a problem for you as for someone shooting stopped down and against a solid, light background simply because it's not going to be as visible.

"a quick Clone Stamp in PS will remove it."

That is the 100% effective way to "clean" your sensor! Everytime you change your lens, you can possibly shake some dust around and it can land on the sensor. Given that, it's not too practical to send the camera back everytime it has sensor dust.

I just blow mine off the best I can and use the tried and true Clone Stamp as needed.

THanks for your input.
I thought it might be a more serious problem with sensor.
I have this thing with new stuff i buy in stores all the time: if there is one defective unit in the lot, be sure i'm the one that will happen to purchase it. That happened with my last car , my last laptop computer (many dead pixels at purchase), skis, cd player (would skip all the time from day one), previous Canon G2 camera (sensor had dead pixels at purchase) and i could continue on for hours....
Again thanks for your help.

It's not "defective" - this is normal, you may need to do it every couple of Months or so.