Hello,
My camera EOS 70D is suddenly not focusing 
I do not know why: I have not dropped it, gottenn anything on the lens, the lens is clean.....It took good pictures for the first time and I tried taking the recent ones at the same distance. I tried to put the setting on close up but it will still not focus.
The lens I am using is the Ultrasonic macro 1.5m/4.9f 70-300mm. my subject is Lake Superior Agates ...this is one of the first I took:
" The lens I am using is the Ultrasonic macro 1.5m/4.9f 70-300mm."
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The "MACRO" text that you see printed on the side of your lens is simply stating the MFD, Minimum Focusing Distance. It is saying that you need to be a minimum of 1.5 meters, or 4.9 feet, from your subject for the lens to focus.
If your subject is inside of that minimum distance, the lens cannot focus on the subject. Your posted shots may be inside of that distance. It doesn't matter if your lens is in AF or MF mode. The lens cannot focus inside of the MFD. Macro lenses are specialized lenses that are designed to have short focusing distances, and do not need to have very long focal lengths, either. The typical focal length for a macro lens is 100mm. They come shorter and longer, but not by very much.
This shot was taken with an EF 100mm f/2.8L IS USM macro lens. Lots of light helps to improve sharpness because you can reduce the ISO, hopefully to ISO 100, and still maintain a fast shutter speed.
There are ways to cheat, though. You can use closeup filters, which have lens elements, which means they will have an impact on image quality, They can only take away from it, not add to it.
You can also use extension tubes. These are simply hollow rings that sit between the lens and the camera. The physics behind them means the MFD will be reduced by a factor related to the focal length of the lens, and the extended distance in millimeters of the extension tube. Basically, the more focal length you have, the more you need to "extend" the lens away from the camera.
I would recommend taking shots like the one you posted from a tripod, to reduce any camera motion blur. You can use the rear LCD screen to focus in Live View mode, which also allows you magnify the image to help achieve fine focus. The above shot was handheld, but taken in very bright sunlight with a fast shutter speed.
And, then there is depth of field, which becomes very short at such close focusing distances. A plate of rocks may not be fully captured in focus when the lens is very close to the subject. I think I can see the effects of DOF in your posted shot.
