There is
no optical difference between the two lenses - the changes are cosmetic in nature. Specifically, the ring on which the focal lengths are printed is now black instead of silver, the font used for the lens name is different, some text has been placed in different positions on the lens ("Image Stabilizer" was moved), and the registration mark (the white square used to align the lens to the mount) is now just painted on vs. being moulded and painted. These were the same cosmetic changes made to the EF-S 18-55mm f/3.5-5.6 IS when it was 'updated' to the MkII verison.
all i was told from canon is that they reworked the optics for better IQ and that they are sorry but could not get me more infos about what exactly was reworked.
it should also have a faster CPU for faster autofocus and better IS.
Gothmoth, I believe that you were given misinformation about the reworking of the optics for better IQ. The optics are identical in both versions. At least, Canon made no official statement to the contrary, and the size, weight, number of elements and groups, and most importantly, the MTF curves, are identical (well, the MTF curves are not
exactly - if you compare the Canon pages for the
MkI vs.
MkII, the 55mm MTF on one is identical to the 250mm MTF on the other, and vice versa - but, that must be a website error). The fact that you see no IQ difference between the two versions is certainly consistent with the fact that they have identical optical construction and MTF curves...
Regarding the supposed 'better IS', when they released the EF-S 18-55mm f/3.5-5.6 IS II, Canon explicitly
stated, "
The version II of this lens includes new IS algorithms to distinguish between normal photographing and when the camera is panning to automatically provide the optimal level of image-shake correction." Canon made no such statement about the EF-S 55-250 f/4-5.6 IS II. Since the certainly aren't shy about publicizing improvements, the inference is that there is nothing cahnged for the IS algorightms of the 55-250mm MkII.
but it could also be possible, that they just made the manufacturing process cheaper
That's the bottom line. From a consumer standpoint, there is no difference at all in the 55-250mm MkI vs. MkII, and only a very minor electronic difference specific to the panning mode IS for the 18-55mm MkI vs. MkII. But from a corporate perspective, the changes to these lenses result in a small savings on the unit production costs for these two lenses. Given that Canon makes more of these two lenses than any others (and those two plus the 50mm f/1.8 II almost certainly account for more units sold than than all other Canon lenses combined!), even a small reduction in the unit production cost translates to a
significant increase in profit.
