Can you post a sample of one of your shots. Here is a photo taken with a Rebel T5.
[EDIT] This image was taken using a UV filter, and a custom white balance. The custom WB was actually a happy accident. I had been taken night photos of street life earlier in the evening, and was using a custom WB to compensate for those orange mercury vapor street lights.
I began shooting pictures of the moon, and never changed the WB setting. I looked at my results after a couple of shots, and saw that all of my moons pictures that I had taken were blue. I reset WB to AUTO and took some more shots with the same shot settings as before. The blue pictures turned out looking sharper for some reason.
You should probably post one of your images.
If you are focusing manually, the camera is on a tripod, and you're taking care to make sure nothing is shaking the camera when you take the exposure, then it's likely that you are simply missing focus.
If you use the viewfinder to focus then you'd need to take care that you've accurately focused the diopter adjustment (the tiny wheel in the corner of the viewfinder). If you ignore what you see through the lens (it's best to just point the camera at a plain white wall ... or plain blue sky... etc.) and then adjust that wheel until the array of focus boxes that you see etched on the viewfinder are tack-sharp then you've adjusted the viewfinder for YOUR eyes (someone else would need to re-adjust it for their eyes since everybodies' eyes will be different.) Now that the diopter is adjusted to your eyes, you can trust the focus that you see through the viewfinder.
If you use the liveview (my preferred method for astrophotography subjects) then focus in live-view, then magnify the live-view to the 10x and refine the focus again.
Usually focusing on the moon isn't that difficult (focusing on a planet is much harder). If I really want pinpoint focus then I use a pinpoint source. E.g. if you can point the camera at a bright star (because in astrophotography, if anything in space is focused... then everything in space is focused.) If I take photos of a planet, I never focus on the planet (too many things can make me *think* I've nailed focus when, in fact, it's soft) Instead I focus on a star and then move the camera back to the planet (or in your case... the moon.)
There is one other possibility... and that's the quality that astronomers refer to as "seeing" conditions. The atmosphere acts like a lens and, if the atmosphere isn't stable then it will distort objects. Our brains are pretty good at working things out and ignoring the distortions to a degree, but a still camera can't do that.
If you were to imagine a coin in the bottom of a pool and there are no waves in the pool then you can probably see the coin quite easily. Use something to magnify your view such as a long lens, binoculars, etc. and you might even be able to read the date on that coin. But now imagine someone starts making a bunch of waves. You'll still the coin, but it will distort and there's not a chance that you'll be able to read the date. That's "seeing" conditions.
Here's a video to describe the effect (I made this a few years ago ... I have a video camera attached to the observatory telescope (this scope happens to be a Celestron C14 and it has a 3900mm focal length -- so we are REALLY magnifying things). This video camera isn't digital... it only puts out a video signal intended to connect to an NTSC video monitor (hence I had to record the image displayed on the monitor using my phone). But you can clearly see the moon "wobble" through the atmospheric distortions as though we're trying to look at the moon through water.
If you are within 200 miles of a warm front, cold front, or the jet stream then the upper atmosphere is probably turbulant and seeing conditions are degraded.
To get around this problem, astrophotographers will resort to using "stacking" techniques. They shoot video -- perhaps somewhere between 30 seconds and 1 minute's worth. They stacking software (e.g. Registax or AutoStakkert -- both are free) then uses the video frames. You search for a couple of of the clearer frames and the software searches for similar frames -- and rejects the rest. It processes those frames to try to create a final image which is sharper than any single frame.
And then there's the exposure...
Use ISO 100, f/11, 1/100th sec and you if you focus, you'll nail it.
You can use "equivalent" exposures (e.g. if you want to go a stop faster on ISO and then halve the shutter speed, for example.)
The exposure is set based on following the "Loony 11 Rule" (I swear I did not make that up). The rule is named becasue if you use f/11 then the shutter speed is always the inverse of the ISO setting. So at ISO 100 you use 1/100th sec. At ISO 200 you use 1/200th, etc.) You said you used f/7 which is about 1.3 stops faster and that means for your moon shot you would need a shutter speed of about 1/250th (you didn't post your shot but I'm guessing it was just a bit over-exposed.)
Here's an example from one of my old posts.
In this shot my camera is attached to the back of a 540mm telescope AND there's a 2x doubler on it so you should basically think of this being shot through something just slightly longer than a 1000mm lens (don't worry that you don't see this much detail in your shot.)
