d7100 newbie: Photos not sharp enough. My fault or camer fault?

Started Aug 8, 2013 | Questions thread
bflood Senior Member • Posts: 1,410
Re: d7100 newbie: Photos not sharp enough. My fault or camer fault?

It looks like camera movement to me. The whey image clearly show this movement, but with a 1/8 sec shutter speed this is to be expected.

The intended focus point may have been the BMW insignia, but the actual focus is behind that. The red flower is sharpest along the edge closest to the camera, probably not the spot you intended. As you point out for the last one, the focus is best on the flower in front of your target. The actual focus is not consistently left, right, closer, or farther, and this indicates to me that the aim of the camera is changing in the time between you decided the focus point is located where you want it, and when the shutter actually fires. Using f1.8 with its minimal depth of field means that there's essentially no tolerance for even small changes in the aim of the lens. Making sure you are actually focusing on the object you want becomes even more critical with longer lenses.

If you have a tripod, a simple test can tell a lot.  Raise the ISO to 800-1600 (a little noise in some test images won't affect the results of a focus test) and set a shutter speed as high as your lighting will allow (1/500 or better). Use your f1.8 setting - closing the aperture down can mask some inaccuracy in focusing. If you don't have a remote shutter device, use the self timer to make your shots - this will give you the best setup for eliminating camera shake from your test.  Use a small, detailed target  - I recommend a printed page of text because it's easy to judge the sharpness and the location of the sharpest area. Shoot at an angle to the paper so that each line of text is at a different distance from the camera, and underline one word in the center of the page that you will use to focus on.

Obviously, take care in aiming the camera to get the focus "spot" on your target, and lock the tripod without moving the aim off-target.  Use the half-press on the shutter release to focus, and then take the shot using the self timer. Do a few of these shots, refocusing each time.  Once you've got several shots, take the camera off the tripod and disable the self timer (turn the camera off and back on should do it), and take the same shot hand-held a few times.

Then have a look at the images. The tripod-mounted shots will show you what the camera/lens can do, and the hand held shots will show you what you can do (at the moment - skill grows with practice - you can quote me on that).

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