Another is my Sony 1670z good? thread

Started Apr 20, 2017 | Discussions thread
rjjr Forum Pro • Posts: 14,325
Re: Another is my Sony 1670z good? thread

devinw wrote:

rjjr wrote:

devinw wrote:

The decenter doesn't look that that bad on this one.

How much de-centering is acceptable? For me any de-centering is reason enough for rejecting a lens.

I don't know if you're aware, but there are things called manufacturing tolerances.

Having had a 25 year career as a test engineer I am well aware of production tolerances.

There is no such thing as a perfect lens. EVERY lens has some amount of de centering of every element relative to the optical axis.

Any noticeable de-centering is unacceptable to me. I will not compromise on that.

The question is, is it to a point where it degrades performance. That is up to the designer to quantify and devolop a process to stay within those limits.

While true, it's up the the potential customer to decide if the de-centering is acceptable to them no matter what the manufacturer does.

As we have seen, the standard tolerances on the 1670 are probably too loose, since factory passing lenses have upset customers with their degree of soft sides.

Or perhaps it's just a poor lens design for the situation those customers want to use it for. For example, given the 16-70 FL range I'd expect to be able to use it for images from landscapes to portraits but, so far, the wide end on the lenses I've tried are not useful at all for landscapes.

In this particular case, though, I see soft soft sides at f/4 16mm, which will be due some to field curvature, but the left side "smudgy" region is maybe 15% bigger than the right. I'd say that's decent for one of these. They can get much worse. I've seen copies where the whole 1/4 of the left or right frame is blurry.

Yes, that's simply unacceptable to me. I'm certainly not going to spend any money on lenses with such built-in defects.

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