As a result of the recently reverberated debate on the topic “SLR vs. soap box ”and my own thoughts on this topic, I decided to purchase a“ SLR ”. It just turned out that my good friend in the States was selling his Canon Rebel XSI camera. I decided to buy this camera from him. I know him well and trust him. There are a lot of advantages to the situation: cheaper than on ebay or amazon? additional bonuses in the form of a spare battery, a couple of capacious sd-cards, the seller’s liability known to me and its accurate handling of equipment. However, in the situation of buying used "SLRs" may be present cons, about which one of my listeners kindly warned me. He wrote me a lengthy letter, in which he gave recommendations, which are better to follow when trying to purchase a used camera. With his permission, I publish it here. I hope someone else will help. Comments are welcome additions. Below is the text from the letter of Andrei Ekatov:
I would like to give a few “vital” necessary and most important tips when buying a used / ear, ie used, SLR camera and a couple of cautions when using it first.

Appearance

In fact, very banal, but in my opinion one of the most important aspects when buying a used camera is its appearance. If you see that the camera is heavily worn or there are some deep scratches on the case or, God forbid, twisted bolts, then run away! Zerkalka- the creation of a gentle and careless handling of it (falling, strikes) can knock down the fine adjustment of the focus and further affect the output, in other words, the quality of your photos

Matrix

A CMOS sensor or just a matrix is ​​the heart of your SLR camera and is an integral part of the test when buying a used, and sometimes even a new DSLR. What is the main problem with the sensor? And in comparison with simple “soap” cameras, the matrix in the mirror camera is open to the outside world and thus unprotected from dust, dirt and other “anti-particles” of the universe, which gladly settle on it and further affect the output in the form of black dots or stripes on the frame. In fact, of course, you shouldn’t worry much about this fact, as giants like Nikon and Kenon are not able to solve this problem completely, so if you buy even a completely new DSLR you can safely count on a small amount of dust on the sensor. the word “small” is important, because if you use the camera incorrectly for EVEN for a short period of time, the SLR matrix can be very quickly unrecognizable. And then another gross mistake is made, namely, an independent attempt to clean the sensor, which in 90% ends with muddy stains and scratches on the VERY sensitive top layer of the sensor and in the future they are trying to quickly “fuse” the camera, that is, to sell! This is what I want to warn you about!
To do this, always take a test picture that will show you the state of the sensor. The test algorithm is as follows:
the camera is set to “M” mode (manual)
the focus switches on the lens to manual focus mode, while the focus itself is absolutely unimportant.
Tsum of the objective gets out on a maximum. (for example, at 18-55, zum is placed on 55mm)
MOST IMPORTANT: the aperture is set as closed as possible (usually f34, f36, on some lenses a maximum of f22)
shutter speed is set to 1/50 and the built-in flash is turned on in the camera.
You are photographing a completely white sheet of paper, at a distance of about 30-40 cm so that the frame is completely white.
And then the oil painting: you open the picture and see the dust content on the sensor! For convenience, it is desirable to still play around with the levels in Photoshop, then the dust, in the form of black dots, will be seen even clearer.
Approximately, a test snapshot should look like this:
http://www.cosmetic-jerid.de/test.jpg
Such a dust content on the sensor is quite normal and it is unlikely that you will ever see it in the photo, unless of course you close the diaphragm to "crazy" values ​​like f22 and more. But this is another story ...
But if your test picture, God forbid, looks like this: www.cosmetic-jerid.de/test2.jpg , then the camera sensor is clearly “killed” and you should never buy such a DSLR!
PS You say that in my cell there is a special system for cleaning dust from the sensor and there is no point in worrying about its pollution?
Yes, I admit that the sensor cleaning system exists in almost all current SLR cameras! But, unfortunately, it is very inefficient and at most used by manufacturers only for purely commercial purposes!
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Gate

The shutter of the SLR camera is the only mechanical thing in the camera and it is he who gives her the right to be called a mirror! Like any other mechanism, the shutter is not eternal and, unfortunately, 80% of the causes of all breakdowns of SLR cameras are the shutter. The life of the camera shutter depends on the model. In budget mirrors (Canon 1000d, 350d, 450d, 500d, 550d or Nikon d3000, d5000, d90) the shutter is approximately 70 to 100 thousand shots. On more expensive models (Canon 40d, 50d, 7d, 5d or Nikon d300, d700) the shutter lives about 120-150 thousand shots. Well, at the professional, he can bend over 300t shots.
It is very important to know how many pictures have already “beaten off” the camera shutter before buying a used ear mirror. I would not recommend buying a budget DSLR with 50 thousand pictures taken, since it already has a cat in a bag disease.

Optics

It is worth paying special attention to the lenses. He can give you a lot about how the person used the camera. If the glass of the lens is incredibly smeared with fingerprints or even scratches, then the camera was clearly used carelessly and carelessly. However, a completely “licked” lens is also not very good. Continuous, endless wiping of the lens can completely remove the thin coating on the lens, which then adversely affect the quality of images. The correct objective should be moderately dusty and moderately clean. Here the golden mean is important.
In my opinion, these are the 4 most important aspects that must be observed when purchasing a used SLR camera. You can, of course, go even deeper, which, in my opinion, will ultimately completely discourage interest in buying a used SLR. Yes, and buying used goods to be 100% sure in its quality is simply impossible.
And finally, a couple of important caveats with the initial use of a SLR camera:
The change of the lens should take place quickly and, if possible, in an unspotted room. The body (camera) must be kept cut down during the change of the lens. This procedure is necessary to prevent dust from entering the sensor.
Do not just shoot the lens and admire the inside of the camera. And even more so to photograph without an objective! Again, this is due to the fact that dust can enter the sensor and in the future leave unpleasant points on the photos.
Try to handle the optics carefully! Fingerprints on the glass lens is best removed with special pencils or specials. microfiber fabrics. But you should not rub the lens on every occasion, as a little dust or prints on the front glass of the lens will not affect the quality of the photo, but the erased thin special coating on the lens will make itself felt!
Always close the lens with a protective cap after using the camera. This will prevent accidental damage or contamination of the lens.
Denis, I am always happy to help you and wish you good luck and lots of great pictures with your new SLR camera!
respectfully
Andrew