[bwDraco]

When it comes to vignetting, the Pentax 18-135mm is at its worst near 100mm. In fact, I've identified mechanical vignetting most pronounced at 100mm when the lens is at or near minimum focusing distance. In other words, the extreme corners of the image literally fall outside of the image circle and become totally black. This phenomenon is most evident when the lens is stopped down to f/16 or further and is only exacerbated by the Shake Reduction system, which can take parts of the image further outside the image circle.

What are your thoughts on this issue? Can you reproduce it? If so, do you find it a serious problem?

—DragonLord

[crewl1]

Do you have a sample you could show?
I use my 18-135 a lot but never really paid attention to this issue.

[starjedi]

When it comes to vignetting, the Pentax 18-135mm is at its worst near 100mm. In fact, I've identified mechanical vignetting most pronounced at 100mm when the lens is at or near minimum focusing distance. In other words, the extreme corners of the image literally fall outside of the image circle and become totally black. This phenomenon is most evident when the lens is stopped down to f/16 or further and is only exacerbated by the Shake Reduction system, which can take parts of the image further outside the image circle.

What are your thoughts on this issue? Can you reproduce it? If so, do you find it a serious problem?

—DragonLord

Do you have a sample shot? I never took down to F10 at 100mm for this lens...

[bwDraco]

As requested:

Pentax K-5 with DA 18-135mm @ 100mm. Av, 1/80s f/16 ISO 3200. Manually focused to minimum focusing distance.


—DragonLord

[UncleVanya]

Decentered? I notice the effect is not symmetrical.

[bwDraco]

Decentered? I notice the effect is not symmetrical.

Play in the zoom cams is to blame to some extent, but the SR system is what makes this effect most visible. The lens was serviced for decentering in the past.

—DragonLord

[crewl1]

Ok I see it now. With mine the vignetting is a little less severe than yours and approximately even in all corners.

I don't see the effect at normal focus ranges, as I don't use the 18-135 as a macro so that is probably why I never noticed it.

I have other lenses that I use for close focus so in my view it is not something to be concerned about, but if it is so for you then I understand.

The 18-135 is a very useful lens for me.

[RGlasel]

I have exactly one (1) photo with this lens at exactly 100mm and f16 and only 3 photos at f11, but focus wasn't at or near the minimum distance. No vignetting at all in any of the corners on those 4 photos. I took a quick look at any pictures at 100mm or longer, and while I did see some mild vignetting in the corners of a few pictures, it was only when the lens was wide open (well, wide open for the 18-135) and it wasn't at the minimum focus distance either. If I was trying to use this lens as a pseudo macro, the limitation you found would be a problem, but I use a 90mm 1:1 macro for those situations. Then the problem is the lens barrel blocking the light source.

Edit: I see crewl1 made the same point, but posted it two minutes earlier.

[VisualDarkness]

Well, some Sony lenses are like that throughout the zoomrange, at any aperture and even with software compensation!

[macTak]

I have a hard time believing that the lens is in spec like that (though I don't have one to compare). Is it always the top corners (in which case I would think it decentering or an optical alignment issue) or depending on the shot (i.e. where SR goes) is is sometimes in the bottom corners?

[UncleVanya]

How was your subject lit?

[MPrince]

I just tested my 18-135 lens with the K-3. Vignetting was present in all four corners, was roughly uniform in extent and degree, and was far less severe both in extent and degree of vignetting than in DragonLord's example. It is present with or without the lens hood. I did not test with SR turned off (it was hard enough under the lighting conditions to get a non-blurry image with SR). Vignetting was present at f16, f8, and f5.6 and was most pronounced at f16. Shooting conditions were natural window light on an overcast day.

[PabloFP]

I've just tested mine, there is no vignetting. Perhaps u have a bad copy, As someone suggested above it seems to be descentered

[crewl1]

I've just tested mine, there is no vignetting. Perhaps u have a bad copy, As someone suggested above it seems to be descentered

I'm surprised you don't have the dark corners.
Did you use closest focus with same settings?
I only see it with mine focused right up at a few inches from the target.

I would be surprised if your lens is different in design as I consider mine to be a good example otherwise.

[Glen]

My 18-135 has more vignetting than any other lens I've owned, but it's not nearly as bad as you describe. Do you have a particularly thick filter on it? The vignetting is nothing that Lightroom can't fix quickly and isn't always noticeable but I've never narrowed it down to the situations where it's most noticeable.