Nine arguments in favor of manual focusing:
Doing macro-shooting lens it is usually located very close to subject. And consequently the auto-focus mechanism can precisely find out not always that place which is important for you in macro-shooting. And depth of sharpness sometimes so is small that can to be displaced from simple trembling of hands.
I think, not one even the modern ultrasonic auto- focusing motor can't compete to you if it is question of shootings of races especially when cars are carried by by you with a speed more than 200 km/h
3. Old lenses
Once a choice variant between automatic and manual focus wasn't in general. If you want to use some of fine old lenses, you can find out that they don't have automatic ability of focusing or that they aren't compatible to your system of auto-focus.
4. Weak illumination
For an auto-focus sensor control – weak illumination serious enough test. Even to fast lenses with big светосилой can have hardly in a dark room as for example in church or a cave.
5. Washing out
By means of manual focusing you have art control of a picture, and by means of it to create special effects размытости. By means of auto-focus such it is often impossible to execute.
Probably all asked a question how to shoot such picture of the nature where accurate rocks on near front, and an accurate water smooth surface in the distance are visible also.
7. Shooting of fireworks and the star sky
For shootings of the sky and fireworks – the main thing that it is necessary to make, establish the chamber in a manual mode and to concentrate on infinity. It is truth! Look many training courses – speak about the same!
8. Shooting with conducting
If you know a route of your object, you can establish the focus center in position through which will take place object. Actually when the object to appear in the center of your focus, you should accompany it turning the chamber behind it, during this moment and to do a picture. The dynamical photo as a result should turn out.
9. Lens Babies
Lensbabies (ссылко) are created more for an entertainment. They give good effect of the small center of focusing. Lensbabies do it in the presence of flexible fastening which allows a lens to bend every which way.
Earlier I so suffered with an auto focus... Now victory!