What criteria do I rate a lens?
Haptics, processing 15%
-Autofokus: Accuracy, speed, noise 15%
-Optical Imaging performance 70%
(Missing) features that can be taken from the data sheet (lack of IS, wide minimum focusing distance) are mentioned for the sake of completeness, but does not lead to a devaluation.
1.Haptik, processing:
The lens has a metal bayonet and a high-quality plastic housing. The focus ring is not running too well fed and has a certain play - not nice, but not overly tragic. The lens extends during focusing. As already mentioned in other reviews this is probably a weakness of the lens, since pressure on this tube the mechanical inner workings (also made of plastic) a load undergoes therefore order the hood and leave mounted.
The feel is overall okay. In this price range it falls on neither positive nor negative - for this reason I forgive this 3Sterne.
2.The Auto focus:
Anyone who thinks the name USM to the usual, almost silent and fast autofocus, which will be more disappointed by the motor of this lens. Although the autofocus motor does not make excessive noise, but is clearly heard. A comparison to modern micro-motors, as with the 18-55mm IS II Kit (non STM) is what speed and noise concerns mounted. Also this lens has no internal focusing, as you know it from other lenses with USM and thus changes its length. Rotate the front lens, however, does not do this, so that this would not constitute a serious limitation - it was just mentioned.
While I have written down in my last review autofocus even for his alleged imprecision, I have to correct this now. Detailed parameter studies have shown that this lens is actually focused pretty neat. It is the focal point usually already at the first attempt and does not run past him a front focus, as a long time I thought, is not available. Why I came to this fallacy, I explain below. The speed of the lens is satisfactory. For sports photography or race children perhaps it may not be enough, but this is also not the primary area of application of this lens.
Overall, I would describe the autofocus as moderate. In this price range there are more powerful lenses, yet it is reliable. So also here 3Sterne
The reason I was able to observe in this lens for a long time a constant front focus was to mishandling. Only through trials under laboratory conditions, I was able to verify that in fact no front focus occurs. The focus does not allow repositioning the shot composition after focusing more without thereby the focused spot moves out of the range of depth of field. Perspective and composition must therefore be chosen so that a focal point on the main motive is only then clear images could be reproduced reasonably reliable. Nevertheless, it is advisable to take the picture several times.
3.Optische imaging performance:
To evaluate the optical imaging performance of a lens is a very difficult matter. On the other hand it is also the most important criterion for evaluation.
Therefore now a few words in advance. Depending on the sensor type used fall various aberrations more or less significant. The images recorded by the camera pixels are not a virtual entity but meet the individual photodiodes on the sensor. Because actually have all the latest cameras from the Canon home an approximate pixel number of 20 million (+/- 10%) is the only relevant factor influencing the area on which they are distributed. So an APSC sensor has only 39% of the area of a full-frame sensor. In itself pixel count, this means an edge length of about 1.6 times less per diode than in the big cameras. This means that the influence of aberrations affecting the sharpness falls in relation to the total volume of the pixels to 60% more weight!
Thus APSC Camera delivers at the very same lens significantly stronger blurring and chromatic aberrations as a camera with full-frame sensor. Conversely, the APSC sensor trims the edges of the image, such as too small a screen for a projector aberrations that occur to the lens towards the edge (distortion, vignetting) therefore fall more in a full frame camera consequence. The sharpness of a lens can toward the edge to as full-format cameras, however, greater overall sharpness (still greater contrast and better color rendering) supply is here again simply assumed that for these effects.
From statements such as "tolerances" and "Monday specimen" I want to distance myself at this point, however, in principle, I am working full even in industrial quality assurance. Among a hundred lenses, like probably three are, which actually have significant errors. Often leaves an error on a lens really traced back only after a very long and extensive use on a cause.
As I had to admit even above themselves are errors often the user to guard against this, I once an experimental setup with a stable tripod, plenty of light and an operation of the camera on the EOS Utility software from a distance of 5 meters via laptop and using the phase autofocus ( because the Live View autofocus yes, in practice no relevance for me) used.
I tested on an APSC camera (EOS 7D)
After this basic introduction once succinctly:
Sharpness deficient usable at full aperture even in midfield and the golden section until f1,8-2. In good f4-8.
Chromatic aberrations:
Available at F1.4 already in artistic proportions, yet noticeably visible at f2. Even with f5,6-8 if you look closely in Details (reflections in the eye) clear.
CA's total can still significantly reinforce the impression of blur.
Vignetting:
Even at full aperture under normal circumstances not be recognized a Test in front of white wall I have therefore not separately performed. Vignetting can also be corrected very easily via software, however.
Distortion:
Also never noticed disturbing were corrected simply.
Exemption and depth of field:
Using Belnde f1.4 brings compared to f2 still a significant decrease in depth with it, the awards again in my opinion the image a completely different mood. Just a pity that this lens in this area provides such poor results.
I focus the eye of a model, so I do not achieve the desired focus here is the fact that the lashes to perish in a single splash of color from blur and CA's.
Overall I would give the lens for its picture quality only 2Stars since it only from aperture f2-2.8 achieves imaging performance, which afford many other lenses starting at maximum aperture. The one objective offenblendig never reached full imaging performance is me and should also be aware of each other but completely useless one objective should be offenblendig in any case.
Conclusion: on a full frame camera, which enables the same exemption already at 1 1/3 next shutter closed and this lens is already synonymous graciously responded by itself in terms of sharpness and chromatic aberrations probably give very convincing results. At one Cropkamera it bridges the gap between wonderful exemption and sufficient image quality in my opinion with nieces. A lens, which advertises a maximum aperture of f1.4 should not be usable until aperture F2.
Processing and autofocus motor are quite moderate, but inferior to other lenses selbiger price range yet.
