How to check used lens before purchase?
All problems when choosing used lenses come down to one thing: they used a lens. This means that they were photographed a lot, put and removed from the camera, stored somewhere, fell in the rain with it, twisted the zoom a lot and often, wiped the lenses … How to choose a used item lens and do not mess around? What to look for when buying? How to identify dead glass? After a thorough article about the best DSLR for a beginner and a story about which first lens to buy in addition to a whale, I was bombarded with questions about lenses, and after a while I finally decided to write the corresponding article. It laid out the main problems that arise when choosing a used one. lenses, and tried to tell how not to encounter them.
1 Main problems b.u. lenses
1.1 Missing hoods / hoods
1.2 Worn anti-reflective coating
1.3 Fingerprints on the lenses of the lens
1.4 Dust on lenses
1.5 General lens wear from normal use
1.6 Lens mechanical damage
The main problems b.u. lenses
Missing covers / hoods
Before inspection B. at. look at the lens on the Internet to see if it comes with a lens hood. If it does, then ask the seller for it.
The absence of a hood is not a decisive factor in itself, but it is very difficult and often expensive to find a hood for expensive models, so the absence of this device is a great reason to bargain.
As for the caps, any lens sold should always have 2 caps, one front and one back. It is generally impossible to buy a lens without a back cover, you can bargain for the front one (if the lens has an antireflection coating on it and there are no fingerprints, otherwise you should not buy glass). In addition, remember: caps of large diameter and non-standard sizes (62, 68, 77, 82 mm) can be difficult to find. Most likely, you have to order them on ebay or elsewhere. And if you buy a lens of third companies (Tokina, Sigma, Tamron and so on), then with a high probability you will not be able to find a cap on it with the name of the company you need. You will have to buy either a cover without an inscription, or with the model of your camera.
If the lens was stored without covers, then it is almost 100% likely that it will damage the antireflection coating, there will be a lot of micro scratches on the rear lens (which is sooooo bad), the mechanisms will be full of dust, which will then migrate into the camera shaft and inside the lens .
Worn backlight coating
The first problem, it’s the main one. On the glasses of any more or less modern lens there is an antireflective coating that makes the image sharper, eliminates chromatic aberration and coma, eliminates hares and glare, and, as a result, allows the lens to focus faster. On examination, used the lens should be very careful about this.
How to check the antireflection coating? Take the lens, rotate it with the front lens to the light and look at the reflections that arise in it. You will see rainbow highlights, most often purple. Sometimes there are green ones, but the most important thing is that with a slight rotation of the lens you should see that these glare are uniform on the entire plane of the front lens.
If you see irregularities in the reflection, the glare is interrupted or changes color stepwise in different parts of the lens, then there are problems with the antireflection coating. Visually, it looks like a wiped, untidy glass. Most often, the center of the lens suffers.
Fingerprints on the lenses of the lens
Also, fingerprints may be visible on the antireflective coating: salts and fats contained on the hands, in some cases, can react with the antireflection coating, and then the imprint remains on the lens forever. If, when examining the lens, you find fingerprints or handprints on the lenses, you should be wary: firstly, the device was not handled carefully, and secondly, most likely, you will never be able to wipe them off (I guarantee that the seller tried to do this, But could not).
Fingerprints also degrade picture quality, reduce contrast, sharpness, and generally.
When inspecting the lens in the light, pay attention to the amount of dust. The presence of several dust particles outside on the front and rear lenses is not a terrible symptom. Dust may appear on the lenses, this is the norm. You can immediately blow off dust particles with a pear at the seller. No need to go in there with a brush, so as not to irritate the seller and not give him reason for speculation. Take care of this later.
Dust on the outside of the front lens has virtually no effect on the image until you start taking pictures in bright backlighting. Once the sun or other bright sources of light fall into the frame, each speck of dust begins to glare. At a minimum, this leads to a loss of contrast, and as a maximum to its complete absence, the inability to focus on a sunny day, ugly glare and hares when bright light sources get into the frame.