Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
That's a case of nearsightedness, basically.
Did you assemble the new lens unit? if so, it needs reassembly after adjustment to correct the nearsightedness.
'Nearsightedness' is basically when the focal length is too small. So the reassembly of the lens must address making the focal point slightly longer.
I thought that you had assembled the lens unit yourself, and might have disturbed the optic adjustment.
Did you mount the lens unit correctly? if mounted wrongly, that could affect focal length and thus 'nearsightedness'.
If you are quite sure you mounted the new lens assembly yourself, and if it just came from the factory or the parts store... then, if the rest of your camera did not have the same problem before this, I would hazard that you might have a defective lens assembly - once again, I will mention, "nearsightedness" - or doubtfully one that simply is the wrong focal length for your exact model of camera body. What do you think?
So... I haven't quite understood the case rightly, then. What part did you put on/replace on the camera? just the sensor?
OK. Well, that assembly appears to be ... defective from Canon.
Remove it, pack it up again in its packing material, call the Canon department or vendor that you ordered it from, inform them that it is defective and you're returning it for another of the same sort, and follow their instructions on returning it (where, what address, shipping label to use, etc.)
If it is well-mounted, you didn't, I don't think.
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