How to check the lens?
The quality of lenses usually varies greatly from model to model. At the same time, digital cameras are more demanding on the characteristics of optics than shooting on film. But sometimes it is extremely difficult to choose a suitable specimen so that it does not have a back focus, is sharp enough and without blurry edges. Usually novice photographers are not always afford to buy a new lens, there is an alternative here - buying a lens at a thrift shop. But how to check the lens in this case, and what to look for, especially when buying a new optics? There are a number of characteristics by which one can determine a serviceable and high-quality optical instrument.
Begin to check the lens must be with an external examination, which is especially important when buying a used lens. This is the most basic indicator, especially if you are thinking about how to check the lens. In the store, be sure to ask to take the device in hand to better consider it.
- The presence of scuffs and scratches.If there are scratches on the lens terminals, this means that the lens has already been put on the camera at least once. The magnitude of these scratches can even indirectly judge the frequency of use of the lens.
- Inspect the terminals. After all, even clean terminals without scratches still do not say anything, because the lens could never be removed from the camera, especially if it is the only one. Therefore, you need to look for scuffs and scratches on the zoom rings and the bayonet.
- The presence of traces of impact or fall. It is necessary to find out, also, whether the lens was dropped. To do this, check whether there are traces of a fall on the body, for example, dents of metal parts, cracks on plastic parts, etc. The fall causes the optical elements to move, and this makes the lens defective. If you shake the lens slightly, the lenses should not make a clicking sound. In some models, there may be a slight metallic noise that usually produces an auto-focus drive.
- Find out if the lens is not handed over for repair. This is also a very important step in how to check the lens when purchasing. Since scratches on the lens screws indicate that the lens was taken apart.Repair service is not terrible, but amateur could repair optics. Inspect the need to also screws, if their slots are torn and bent, then this characterizes the unqualified repair.
- You need to inspect the glass for the presence of chips and scratches. If you bring the lens close to the desk lamp, you can close, then inside you can see dust, bubbles, villi, etc. To get a better view of it all, you should position the lens at a light angle at an angle so that a dark background appears behind the lens. If the number of tiny bubbles and dust is small, then this is considered acceptable.
- The presence of bubbles and scratches on the front lens will have almost no effect on the quality of the images, but this can have a psychological effect on you, especially when buying expensive optics. Scratches and bubbles on the back of the lens are a really bad indicator. It is worth remembering that the large proximity of defects to the matrix increases the influence of these defects on the quality of images.
The work mechanisms of the lens
The second most important stage of how to check the lens before buying is to check the operation of electronics and lens mechanisms.
- Zoom rings and focusing must necessarily rotate smoothly, without characteristic squeaks and stickings, but at the same time, it is not very free so that the focus does not get lost. Extend the retractable part of the lens until it stops and shake it slightly - the play should be minimal.
- If you direct the lens vertically up and down, respectively, then the movable optical unit from the selected position should not be displaced by its gravity. Some models have a special retainer to prevent this.
- It is worth paying attention to the bayonet, because the mounted lens must be firmly fixed on the camera, without strong backlash.
- It is also necessary to check the operation of electronics. Especially check the operation of autofocus in manual and automatic modes.
- Check the performance of the diaphragm. To do this, you need to view the depth of field, using the preview button.
- Check the operation of the flash, especially for lenses that indicate the focal length of the camera. The subject must be equally illuminated by flash at any distance.
- The lens is better to check on the camera on which you plan to install it. Sincesometimes the lens may not fit, and an error will be displayed when the camera is turned on.
Now you know how to check the lens. This will allow you to achieve great shots. We wish you good luck!