rscheffler
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Renez wrote:
@BastianK@
This is a condition called Schneideritis. It’s cosmetic and Doesn’t affect IQ.
My VM 15/4.5 III shows this too, but only as deep as the first element, from what I can tell. It appeared after it inadvertently got water in it from a leaked water bottle that was in the same non-camera bag with it (didn't have room for the VM in my camera bag that outing and had tucked it in my EDC bag). I don't recall the exact situation now, but I think water had been sitting on the front element for a bit of time before I noticed, therefore some may have seeped in at the edge of the front element. Kind of thought the lens would be toast so didn't do much about it other than let it dry out. But that was at least a few years ago and it seems to still work normally (in respect to image quality).
I had a quick look at my other Voigtlander lenses... an old 12/5.6 LTM does not show it. A fairly old 40/1.4 might, but the spots are a lot finer and appear like a metallic shimmer. It's difficult to tell though with this lens. My nearly 8 year old VM 35/1.7 also appears to show signs of this, in the manner of the 40/1.4 (very fine metallic shimmer), as deep as the first front group. The white spots in the 15/4.5 are less numerous but larger and look more like grains of sand around the edge of the front element (which it isn't - it just looks like it). A recently acquired used 28/2 v2 does not appear to show it.
It just makes me wonder if it could be a sign of moisture penetration around the edge of the optics? It only showed up in my 15 after it got wet and the 35/1.7 has been my go-to 35 for most if the time I've had it, therefore it has been used in wet conditions (rain and snow) over the years, where exposure to humidity may be a factor. The 40 I'm less sure about because I have not used it a lot even though I've had it probably at least 10 years. I bought it used (from a reputable shop), albeit at somewhat of a discount because it had a less smooth focusing ring that tended to 'squeak' at times. So I don't know it's full use history. With the 35 and 40 I only just noticed this effect now because I specifically looked for it. No idea when it may have developed in either lens. Nor can I say that I've noticed any image quality degradation.
Considering the white spots in the 25/4 you purchased appear to go pretty deep into the optics, it would make me wonder about the age of the lens and whether it has had a hard life.
Regarding the decentering/tilt: my recollection is this lens and the 21/4 have a poor reputation for consistent across frame sharpness.
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