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    4. Dandelion from series “Tom Thumb in the flowers world”. Camera lens is placed in two centimeters from the flower pith. This allowed us to hide behind it the disk of declining sun. Macro lenses of small digital cameras have considerably higher depth resolution than standard lenses of reflex cameras. Camera Model Name - Nikon coolpix 5000. Sensitivity 100 ACA. Exposure 1/250 sec. Aperture Value - 7,6.
    5. At the mode of closed aperture all lenses work properly. You can distinguish acutance of an expensive lens from a cheep one only by peculiar blur of defocused parts of the picture.
Having chosen a camera lens beforehand, you can go to the shop to make a test shooting. You should enlist the permit of the seller. If he is against the trial, it’s better to find another shop. To perform the test, you need a newspaper with a lot of text throughout the page. Draw a cross with a pen in the middle of the page. It’s necessary to make two shots. Put the newspaper on the floor. Fix the camera on a save stand and point it at the newspaper at an angle of forty five degrees. Point acutance at the cross and open aperture in full. In most specialized Moscow shops the salesmen reluctantly consent to insert the card of your camera into the card reader of their computer. But it’s difficult to estimate the quality of lens on a LCD monitor. You have to go home and use standard electron-beam monitor. After 100% enlargement of the image you can see where your device has depicted the acutest letters. If the best acutance is obtained exactly on the cross, this means that your camera and lens function properly. If acutance is dislocated from the cross you have to bring the optic system to a workshop for adjustment. Then make 200% enlargement of the picture and examine it carefully. High-quality lens makes borders of letters contrast, without any blur. There shouldn’t be any coloured halos around the letters. Blue and red chromatic aberrations happen mostly. Let’s assume that the test satisfies you. Then look at the shots of the second test that you make in the shop as well. It is the same newspaper which is now shot directly. This time you must make two takes: the first one with open aperture, second – at aperture value 8. The point is that at this aperture value you can estimate the best properties of your lens and compare them with the worst properties. Direct shot allows estimate not only ability of the optics to depict small objects in the middle of the shot where camera lenses usually function properly. Optics blurs at the borders of shot as a rule. Examine attentively letters at the image periphery; compare them with the letters in the middle of the image. Having done this you can make an impartial decision whether to buy the lens or not.
    Acute camera lens is only a part of eternal struggle for acutance. Amateur and professional photographers prefer mostly reflex cameras that allow controlling the image directly through the lens. The image first falls to the mirror that lies at an angle of forty five degrees on the way of light towards the matrix. Then it comes through special pentahedral prism to video selector ocular. A photographer can see it here. At the time of shooting the mirror goes up quickly, the shutter acts, the picture remains in the memory of matrix or film, and the mirror swiftly goes down. It’s an excellent mechanism! But it has one annoying quality. When the mirror rises and falls, it shakes the whole camera. As a result vibrations appear that reduce considerably acutance of image. Producers of professional press cameras increase weight of cameras intentionally in order to reduce influence of mirror blows on special damping mechanism. Expensive cameras have special mode of prior mirror rise. At this mode the mirror rises several seconds before the shutter release. After the camera and stand have settled down, photographer pushes start button second time. Shutter blinds don’t have significant influence on the image acutance. However, if your camera doesn’t have mechanism of prior aperture rising, don’t be distressed, buy stable stand and hang any heavy object on it before an important shooting when you need maximum acutance. You may use, for example, your coffer with accessory lenses or a plastic sachet with roadside stones. This simple trick exerts legs of the stand and minimizes microvibration. But victory over vibration doesn’t mean total defeat of blur. Present-day photographers have one more technique in reserve that is called sharp. This word has come into Russian along with Photoshop; it is a direct loan translation of a filter name “sharpen” that considerably enhances outline acutance of digital pictures. It’s obvious that film techniques couldn’t apply such means. In precomputer times even a slightly blur negative meant total fiasco. Mighty Photoshop appearance makes correction of pictures possible. I’m not going to describe in details all means of acutance improvement this time. There are lots of such techniques, so this is a theme for special articles. Nevertheless it is important to know methods of digital acutance improvement.
   1. Total increase of acutance all over the shot. At this the whole shot undergoes the effect of unsharp mask or sharpen filter. It is a crude technique. It can result in emergence of typical unsightly regular grains as well as black and white outlines at the borders of objects (See photo 5).