One of the most repeated complaints (along with the problems of exposure) for people moving from a compact digital camera to a reflex, is the lack of sharpness of their photos. And are absolutely right, the photos have really blurred out in a reflex in a compact, especially if the reflex shooting in RAW format.

Can not find a single reason for this difference, then join several aspects that influence one way or another and can appear in combination to produce images that we call "soft." These are:

Optical quality.
Even the best optics are made of interchangeable lenses , the fact is that most people start in the world with the goal reflex cheaper there, which comes in the basic kit . Without wishing to minimize these objectives , which usually have a value for money unbeatable, the truth is that it is much more difficult and expensive to make a quality optical lenses 50 mm in diameter with others of only 5 to 10 mm. Low-contrast lens and chromatic aberrations (pictured) are detrimental to the clarity, and the only solution is to make them work on your diaphragm more favorable (usually around f / 8) or, better still, changing lenses.

Depth of field.
The user of a compact is used to clear out the whole scene in 99% of the pictures. This is because the tiny size of their sensors, which makes the focal lengths used are very, very short. The vast majority of compact cameras have optical real focal length beginning at about 6 mm, which would be a fisheye on a 35mm camera. With that focus, it is the same f-stop is used, the depth of field is huge and will always do a portrait in the foreground, with mountains on the horizon and everything is clear.

In contrast, in a reflex (and especially if it's full format ) you have to know how to control the diaphragm according to the depth of field you want, so if not close enough, a scene of the scene out of focus and therefore lacking sharpness. Understand the concept of hyperfocal distance and know how to use hyperfocal tables is essential to deal with this problem.

Trepidation.
The different size of the sensors is also a matter of reflex cameras are more prone to shake, or involuntary movement of the camera visible in the image. In addition, their larger size and weight make it necessary to learn to hold steady while shooting with softness.

When the problem is the vibration there are several possible solutions, from the use of a tripod , if the reason is static until the rise of the ISO if there is no choice, through the use of stabilizers in the camera or lens and opening over the diaphragm, to let in more light. But remember that the more we open the aperture, the less depth of field and we can not focus the whole scene out.

Processing aggressive.
But surely the biggest difference is in the internal processing that make the cameras. The compact is designed to deliver finished pictures, which like the public without further complications, although they may be highly improved. SLR Instead, they tend to editable images, processed with less aggressive than allow a greater degree of post editing. For RAW files this concept comes to an end, and have not been processed at all and all work is for the photographer.

Among the processes that make the cameras are two things that affect perceived sharpness. On the one hand the application of a calibration curve (the more contrast is a clearer picture seems), and the other a very strong focus mask. So much so that some cameras will come to appreciate halos (as in the image on the right) at the edges contrasted by an excessive focus.

If I had to find a solution to the internal processing to achieve sharper JPG files in a reflex, we should experiment with the parameters of sharpness, saturation and contrast, to find values that satisfy us and not excessive.

Postprocessing.
However, none of these factors alone are important enough to make all our photos sharp decline sharply. Knowing control, with a reflex camera and some further work we can get much sharper pictures than any JPG of a compact.

Working f / 8 (or better yet, search Photozone diaphragm highest quality for our particular model of target) if possible, we ensure that we get all the juice possible from the lens, in addition to not open too, the depth of field is acceptably large. For special cases we will use the hyperfocal tables and close even the diaphragm.

Using a tripod whenever possible, help to avoid camera shake so as to be able to use very narrow aperture to maintain a low ISO to avoid noise (which also affects the sharpness).

Finally, you're the best quality, always shoot RAW. The process will take some time, but results are much better, as you will have full control of Unsharp Mask you apply in method and quantity.

In any case do not be fooled by the name, the Unsharp Mask is not going to focus on what is really out of focus, it's just a device to mitigate the effects of low sharpness caused by the low pass filter that carry all cameras.