I still struggle with reducing all of the variables that can compromise image sharpness. My goal is to have the sharpest possible image so that it will still look OK with poster-sized enlargements. And basically, I want the best quality image for the least expensive gear.
Caveat: What I consider one of my lowest quality ‘good’ images was actually selected for a digital photography magazine cover. (Yay!) I was experimenting with a generic-brand fish eye lens & due to weather conditions, I needed to set the ISO at 800 (really noisy) and the foreground flowers were still a bit blurry. I still cringe when I see the image at 100% resolution, but am so proud and amazed it was selected. So, I guess the moral of the story is that sharp images are not necessarily a requirement … but I still think it's an important long term goal.
#1 : Optimal Aperture
Suggestion: For landscape shots (where you want a large depth of field), set your aperture to f/11 and f/13.
Reason: While I would love to set my aperture to the smallest opening (ie: f/22 or more) to achieve the maximum possible depth of field, I have found that all of my lenses show drastically decreased sharpness past f/13. Since digital snaps are basically free, I’d recommend you do a test run with each of your lenses. Put your camera on a tripod & take a picture of your backyard (or something); put the camera in aperture priority mode & take an image at each aperture setting (ideally with a cable release so you have as clean/fair a comparison as possible). Zoom in to 100% and cycle through your images. Then at least you can see exactly how your lens behaves at each of the aperture settings and decide if the image quality at your aperture of interest is worth it. I was amazed how much degradation I saw in my lenses beyond f/13. Dang!
Caveat: In order to achieve a hyperfocal effect (sharp image from front to back), I have increasingly found myself taking at least two exposures, one for the foreground region and one for the background region and then combining them in post processing. This is a huge pain (hopefully I’ll get faster at it). There may be something to be said for setting your lens at f/16+, capturing the max depth of field in one shot, & moving on. After seeing how much sharper the image could be though if you maximized the capability of your lens (using f/11 or f/13), to me the extra pain in post-processing is worth it.
#2 : Mirror Lock Up
Suggestion: Enable mirror lock up when using a tripod.
Reason: When you fire off a shot, the mechanics of the mirror flipping up can cause a vibration in your camera lens and produce a blurry image. I have run comparison tests and saw a distinct improvement in image sharpness when I enable mirror lock up. You now have to click the shutter two times (using a manual cable release): the first click locks up the mirror; then pause a second; the second click takes the image, hopefully after the vibration from the mirror flip have subsided. (If you don’t have a cable release, try setting your timer to 2 seconds. You’d click once to lock up the mirror, and then the camera would take the image after the 2 second interval.)
Caveat: For handheld shots, disable mirror lock up. …Yeah, that one’s obvious, but of course, I handed my camera to a friend once while it was still in mirror lock up mode, and it caused all kind of confusion. If people are used to point and shoot cameras, they are not expecting the viewfinder to go black and appear to do nothing when they click the shutter. ;p
Alternative: In Live View mode, your camera functions with the mirror already locked up, so the problem is already solved - you only have to click the shutter once. (Live View consumes power like mad, but it is great for checking the exposure or effect of any handheld filters on the fly.)
#3 : Image Stabilization (IS) Off
Suggestion: Turn off Image Stabilization if your camera is on a tripod (for longer exposures)
Reason: Over time, the image stabilization (IS) mechanism can incrementally shift your image. If you leave IS on for your longer exposure images, when you zoom in to 100%, you will likely notice a slight duplicate image (as if you took one image on top of another, but just slightly offset). This has the effect of making the image look slightly blurry, and in any case does not maximize the potential of your gear. My camera has a ‘live view’ mode which shows basically a movie in the lcd screen of what your camera is actively seeing; in live view mode, if I leave on Image Stabilization while on a tripod, I do see the ‘stable’ image jump a few pixels every few seconds. The IS technology seems to have a threshold for keeping the image stable, but it seems to update every so often; if your image is still being exposed during one of these small ‘jumps’, it will effectively cause what looks like a double exposure in your image.
Caveat: Make sure to turn Image Stabilization back on if you take the camera off the tripod for hand held shots. (I used to inevitably mess this up one way or the other for the first round of shots. It's useful to zoom in to check your image at 100% after taking your shots to confirm the quality of your images - hopefully still giving you an opportunity to redo a shot that may have been compromised due to unintended camera modes.)
I feel a bit guilty encouraging the tips above (and more to come), because I really have found it time & effort intensive to remember and properly implement them. For the first year with my digital camera, it was almost like I needed a checklist before starting a photography shoot. I would inevitably leave at least one of my camera settings in its previous mode and mess up an hour’s worth of images before realizing my mistake. Painful, painful. I am resolved to push through the technical challenges though until the techniques are on autopilot & I can focus mainly on creativity again.
I remember my early photography days where I would hand hold all of my shots (no tripod), no special settings, and freely compose my images at any aperture available. It was wonderful for inspiration and fun, but I increasingly found that I was not happy with the technical quality of my images. I have since shifted my focus and want to achieve the highest quality to increase the options for how an image can be used. There is a definite learning curve for the techniques I now implement, but it has become more straightforward with practice. I hope you find these tips helpful!
by Laura A Knauth