Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

Is this fungus or glue separation?
Post new topic   Reply to topic
Home   Equipment Care and Repairs
View previous topic :: View next topic  


PostPosted: Tue Aug 25, 2009 8:13 am    Post subject: Is this fungus or glue separation? Reply with quote
Can anyone tell me if these spots is fungus or is it some sort of glue/paint separation? It only occurs on the rim where the element is glued to some black material...




And taken the front element out, photographed from the back - there appears to be a lot of dried/aged cracks in whatever the black stuff is...



PostPosted: Tue Aug 25, 2009 8:45 am    Post subject: Reply with quote
I think it is some form of oxidation of the material, causing a slight separation. If this is limited to the masked-off parts, then it should not affect the pictures.

BTW, what lens is this?


PostPosted: Tue Aug 25, 2009 8:51 am    Post subject: Reply with quote
thanks for the info Smile

Its my Sigma 16mm filtermatic fisheye:



PostPosted: Tue Aug 25, 2009 8:53 am    Post subject: Reply with quote
Do you already own it or are you planning to buy it? Any chance to test it out prior to a purchase?


PostPosted: Tue Aug 25, 2009 8:55 am    Post subject: Reply with quote
How would he have been able to take the front lens out otherwise???


PostPosted: Tue Aug 25, 2009 9:17 am    Post subject: Reply with quote
I already own it Smile


PostPosted: Tue Aug 25, 2009 9:21 am    Post subject: Reply with quote
kds315* wrote:
How would he have been able to take the front lens out otherwise???


Yes, that's a stupid question. Somehow I got the impression that it was a lens for sale. Maybe I should visit eBay less often Wink


PostPosted: Wed Nov 28, 2012 9:14 pm    Post subject: Reply with quote
it fits to the topic, so I'm digging this thread out:

is this fungus or glue??



PostPosted: Wed Nov 28, 2012 9:31 pm    Post subject: Reply with quote
Tim_Tomte wrote:
it fits to the topic, so I'm digging this thread out:

is this fungus or glue??



I`m guessing that this is neither. Most of the elements of the lens have painted rears to reduce any sort of light deformations and over many year this layer of pains simply fades/erodes/falls away and you are left with what you have hear.


PostPosted: Wed Nov 28, 2012 10:37 pm    Post subject: Reply with quote
Typically separation presents itself as a uniformly opaque and often yellowish coloured area, that starts from the edge in a continuous fashion, and expands towards the centre with an elongated roundish shape.
So, whenever you see spotted areas, whitish, and not consistent in density, and rather sparse, that should not be separation; it may not necessarily be fungus, however, although it's the most likely chance.
Fungus also often presents itself with ramification, that may be not visually identifyable at naked eye, but which usually becomes evident with a loupe.


PostPosted: Thu Nov 29, 2012 8:58 am    Post subject: Reply with quote
thank you !


PostPosted: Fri Nov 30, 2012 12:05 am    Post subject: Reply with quote
[quote="Drack"]
Tim_Tomte wrote:
it fits to the topic, so I'm digging this thread out:

is this fungus or glue??

I`m guessing that this is neither. Most of the elements of the lens have painted rears to reduce any sort of light deformations and over many year this layer of pains simply fades/erodes/falls away...



From the picture i can't understand if it's something like the so called "schneideritis" (barrel blackening that swells/flakes), or a problem with the blackening of the outer rim of the glass/glasses (negative elements, with thick rim, are painted black on the edge, to prevent unwanted reflections).
Both problems are practically irrelevant, and can be considered just an aesthetical nuisance.

Reading the posts on (most) photographic forums, i found that there is a widespread and largely unwarranted scare of separations and fungal infections.
In my own experience, those problems are quite uncommon, even in very old optics.
Being a collector of vintage large format lenses, i know a thing or two about the matter.
Separation problems are very unlikely in lenses made after the early seventies, excluding problems due to shocks or extreme overheating.
Fungii can always be cleaned, in a way or another, but the coating (or the glass itself) can be etched by acids produced by the fungal growth. A repair is economical only with super-rare lenses... if you find somebody who will re-polish and /or re-coat the offended element.
The good news: if the lenses are not exposed to dirt (with fungal spores) AND moisture (i.e. you do care a little for them), the chances of getting a fungal growth on your glasses are almost nil.
I stored all my large format lenses, including some very valuable ones, in an extremely damp cellar for nearly 20 years: no traces of fungii, just a few "lazy" shutters.

have fun

CJ


PostPosted: Thu Dec 13, 2012 8:48 am    Post subject: Reply with quote
I think Schneideritis will make MTF of the lens a bit worde because of more stray light. But this will be most likely an academic small amount of IQ that is lost.

I own a Rodenstock Rodagon 80/4 enlarger lens with delamination/separation, that is most likley from the 1980 or later.
After some research I found out that such Rodagons have this now and then. Found easily 10 internet sources:
Typical lens defects

I have a 50mm ~1.4 with delamination, don´t remember which manufacturer. But I would think it is also produced after early 1970.
On booth lenses I don´t know the history, but I remember no impact marks on the lenses.

I own a lot of lenses with fungus.
And I read a lot about lenses with fungus. For me it seems that fungus is a real problem for people living in hot humid areas. And for people who store lenses in closed bags or such long time - probably after photographing in humid enviroment. Later seems the problem here in Germany. I see a lot of lenses with fungus on flea markets. Sometimes it seems people do not reckognize fungus in their lens, some time it is hard too see, for example in wideangles or very early fungus.
Post new topic   Reply to topic
Home   Equipment Care and Repairs
Page 1 of 1