Originally posted by StringerBell When I adjust the lens so that I'm as up close as possible, the image that I'm focused on appears slightly blurry, but the environment immediately around the object will be in focus.
I assume you are too close. Sample photos would be a big help. What I suggest you do is select P mode, then Manual focus, zoom lens to 135mm, twist focus away from infinity, all the way to closest focus. Now turn on live view and focus peaking. Place camera on table or something (use 2 sec timer if camera is placed on stable surface, this helps avoid mirror slap shake for 100% sharpness), and move it closer to the subject, until focus peaking shows it as illuminated/in focus. I think that lens' minimum focus distance is around 40cm (measured from the camera sensor, so 4.5 cm behind the camera mount to the in-focus subject).
Originally posted by StringerBell (in fact, from the same distance, I'm able to focus on the same thing just fine with an iPhone camera, so I don't think I'm asking too much of this camera/lens).
Unfortunately that doesn't say much. Completely different sensor format. lens design, and so on. In fact, many phones are quite good at "near focus" because they need that feature for video conferences and selfies.
Other things to check: - make sure lens is clean, especially the back lens element (inside the lens mount). IF you decide to clean it, be careful, read up on it. But a finger print on the backside of the lens can cause blur.
- update camera firmware; probably won't do much, maybe you already have the latest version, but in the past some firmware updates included small AF optimizations.
- Macro is usually done in manual focus, not autofocus, because you always get max magnification at nearest focus. Then you just move camera forward and back to get things in focus.
- Check aperture. The closer you focus, the more shallow the DoF will be. At minimum focus, using f4 or lower f-number will have super shallow DoF, making the photo appear to be soft
- Check shutter speed. Macro magnification requires a lot of light and a very steady hand. Using a tripod or at least a stable base with 2 sec timer can dramatically improve the shots.
Originally posted by StringerBell Even after the camera focused on the background instead of my 'subject', it refused to take the picture. I had to push the button several times before it would even shoot the picture, and what I ended up with was a blurry bottle of oil.
You probably have Focus priority enabled. If you go into Menu you can switch it to Shutter priority. Once you do that, the camera will take the shot when you press the button regardless of whether the AF locked or is in motion or whatever. Focus priority is usually better for beginners, so they don't trigger the shutter too soon, before the AF completes. You can also de-couple AF and shutter button and map the AF to be another button. Lots of people do this so they can take photos without re-starting the AF action. There are threads about this (think the main one is called "perfect focus every time" or something similar)