Dust, fungus, or normal?

[Csacwp]

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When I look with a flashlight at the rear elements of larger M lenses (75mm Summilux, 90mm Apo Summicron, etc.) I always see lots of little white specks, especially around the periphery of glass.  Even new lenses have these specks.  They aren't visible without the flashlight or direct sunlight being shined on the element at an angle.  Are these normal marks or dust, or is it fungus?  Is it possible that a brand new 90 Apo would have fungus or dust like this?  I may be freaking out over nothing... I know the flashlight test isn't for the faint of heart.

[pico]

You are freaking out for nothing. Enjoy your lenses.

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[Csacwp]

You can see some of the specks at the uppermost side of the rear element in this photo.  There are far more of them in person, and they are more visible.  They look kind of like dust but they don't come off with a microfiber cloth or blower.  I suppose they could be under the element.  Just got worried that they were fungus... the lens was sold by the Leica Shop in Austria as being in near-mint condition with no optical issues, and I figure they know what they are doing when they inspect a lens.

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Edited September 22, 2017 by Csacwp

[adan]

Make sure you do the "flashlight test" the right way around - put the flashlight BEHIND the lens to transilluminate the inside from the back.

 

http://www.kenrockwell.com/leica/images/50mm-f2-summitar/IMG_0657-haze-0600.jpg

 

https://1.img-dpreview.com/files/p/TS560x560~forums/55459363/fb617e52ff7a4be58109e13ae659ea75

 

As to dust vs. fungus - fungus will usually have at least some kind of "biological, petri-dish" appearance. A spot with a halo of new growth, fractal patterns, non-random spacing, "threads or fibers", etc. Fungus is microscopic cells - you need a significant "colony" (with the structures and outliers of any colony - e.g. a human town) for it to be visible to the eye at all.

 

Randomly-spaced solid-looking "chunks" will almost always be dust.

 

One key advantage of the "reverse-lighting" flashlight test is that you can pull out a loupe (or another lens from your bag - a 35 or 50 is an ideal loupe) to examine the specks from the front at 8-10x magnification, which can help with diagnosis.

 

As to dust in new lenses - "new" means never used. Once a lens has been out in the environment, being focused back and forth (thus changing the internal volume and pumping air in and out, "inhaling" and "exhaling"), dust can immediately start to find its way in.

Edited September 22, 2017 by adan

[M9reno]

Look here for some examples, and you probably won't be in too much doubt as to whether it applies to your lens:

 

http://www.4photos.de/camera-diy/Lens-Fungus.html

[pico]

Randomly-spaced solid-looking "chunks" will almost always be dust.

 

If you have lots of money you can have the dust extracted and do a DNA test to see if it belongs to a Leica employee (a lot of dust is skin sloughing). I was stunned to see many of them working without body suits, face masks, goggles, gloves and hair covers. Gosh! Four specs of dust in a lens! I'm gonna talk to my friend Chicken Little!

Edited September 22, 2017 by pico

[adan]

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Well, one can get fungus that is smaller and more dust-like in appearance, at least to the naked eye. Which is where using a magnifier can help.

 

http://forum.mflenses.com/userpix/943_IMG_8769_1.jpg

[pico]

Well, one can get fungus that is smaller and more dust-like in appearance, at least to the naked eye. Which is where using a magnifier can help.

 

http://forum.mflenses.com/userpix/943_IMG_8769_1.jpg

 

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[Ko.Fe.]

It could be dust in new lenses. At least, I read about reported. In old time lenses it was bubbles as well.

On photo provided it is impossible to see anything. Lens must be checked with light source behind and it must be played little bit to have inner part of optics reviled. You could also get x10, x20 loupe and see it very close.

[Mute-on]

I bought a brand new, sealed in the outer grey box, Leica 28 Elmarit ASPH in April. It has at least 3 specs of visible dust. I didn't use a flashlight.

 

Images using the lens are astounding.

 

Dust is normal. Enjoy your "new" lens

[jmahto]

https://www.lensrentals.com/blog/2008/10/front-element-scratches/

[luigi bertolotti]

Lenses aren't made to work only into surgery rooms ... and dust on glass is a lot less annoying than dust on sensor, nowadays...

 

Some time ago I had my Elmarit 28mm first type CLAed .. when I got it from the lab, it was FANTASTICALLY clean... I made 5 or 6 pics (at home, inside and garden)to verify the work, and from then it stood, both caps on, at home into a shelf : 1,5 years about passed... it HAS some dust inside...

Edited September 23, 2017 by luigi bertolotti

[chasdfg]

When I look with a flashlight at the rear elements of larger M lenses (75mm Summilux, 90mm Apo Summicron, etc.) I always see lots of little white specks, especially around the periphery of glass.  Even new lenses have these specks.  They aren't visible without the flashlight or direct sunlight being shined on the element at an angle.  Are these normal marks or dust, or is it fungus?  Is it possible that a brand new 90 Apo would have fungus or dust like this?  I may be freaking out over nothing... I know the flashlight test isn't for the faint of heart.

 

I'm pretty sure it isn't fungus. As for whether it's dust or not, if new lenses have them then I'm sure there's nothing to worry about. I've never seen these specks you describe of on my lenses, though we could be looking at different things. 

 

I'm very meticulous when buying lenses both new and second hand. This said, I've bought a lens from Leica Shop with a cleaning swirl on one of the inner elements (not a cleaning mark, just residue) which used to bother me. I have another lens which has 2 small scratches on the front element. However, they work as they should and once I'm out and about shooting with them all is forgotten. It's an old cliche, but just bring your gear out to shoot. You'll remember why you bought those lenses in the first place. Mechanical issues can always be fixed, glass can be cleaned and polished - it's a matter of cost and some time down the road you can always send them for a check and service.

Edited September 23, 2017 by chasdfg