Dots, lots of 'em.

[seany65]

Not sure where to put this, but about an hour ago I was using my newly acquired Tamron 90mm f2.5 52bb to have a closer look at the insides of the the taking lens on a newly acquired Yashica D, (on which the shutter is rather inconsistent) which I thought had some fungus. Anyway when I held the 52BB at a certain angle, I could see thousands of tiny little dots that look like bubbles in water on one of the glass surfaces (possibly the front of the 2nd element of the lens, possibly further in).

I was wondering if anyone knows what these are and what their significance is?

Any help would be much appreciated.

 

[Deleted member 82967]

I know next-to-nothing about lens optics but "at a certain angle" should ring a bell for someone ...

 

[seany65]

Thanks for the reply, Ted. I took the lens back to the shop and got a refund. The dots had actually appeared in one of the photos on the listing but I either didn't notice, saw the dots but associated them with a different listing as I'd looked through about a dozen listings several times trying to decide or I thought it was reflection from the ceiling or something, lol.

 

[nikon_sam]

That Tamron lens in decent condition will not disappoint...it's one of my sharpest and a favorite for shooting flowers on the Sony a6000...

 

[raydm6]

Not sure where to put this, but about an hour ago I was using my newly acquired Tamron 90mm f2.5 52bb to have a closer look at the insides of the the taking lens on a newly acquired Yashica D, (on which the shutter is rather inconsistent) which I thought had some fungus. Anyway when I held the 52BB at a certain angle, I could see thousands of tiny little dots that look like bubbles in water on one of the glass surfaces (possibly the front of the 2nd element of the lens, possibly further in).

I was wondering if anyone knows what these are and what their significance is?

Any help would be much appreciated.

I know in the early days, lens "bubbles" were part of the manufacturing process and were to be accepted, but in later decades were mostly eliminated. Lots of discussion about this on the 'net. Some people find then endearing and that they impart character to images.

This is a quote from a 1913 Goerz Optics Catalog (p. 16):
https://www.cameraeccentric.com/static/img/pdfs/goerz_2.pdf

Air Bubbles or Bells in Lenses - Almost every modern anastigmat lens shows in some of its component parts minute air bells or bubbles. The exacting purchaser is often inclined to refuse acceptance of such lenses, believing the presence of these bubbles to be a defect. It is, however, impossible to obtain from the manufacturers of the so-called Jena glass this material entirely free from bubbles; and, furthermore, the presence of a few air bubbles does not in any way affect the work of the lens. We would be pleased to send on request a communication from the glass manufacturers on this subject. Until the manufacturers succeed in avoiding the bubbles in these special grades of optical glass, their presence is rather a guarantee of quality than otherwise.

Schott wrote a Technical Paper (2016) explaining:
Bubbles and Inclusions in Optical Glass

Introduction
Optical glass in general is nearly free of bubbles and inclusions
compared to other technical glasses due to sophisticated pro-
duction processes, which are optimized for low bubble con-
tent. Nevertheless to specify an optical glass for a desired opti-
cal component it is helpful to know the background on the
generation of bubbles and inclusions and their impact on the
application. This technical information gives an overview on
the topics involved in the selection of the right specification
for bubbles and inclusions.

Especially noted Section 3:
The Influence of Bubbles and Inclusions on Optical Application

 

[seany65]

Thanks for the info, raydm6. I don't think they were just bubbles in the glass, as there Sooooo many of them, and Tamron weren't known for bubbles in their glass.

 

[Rob-F]

Well, there must have been something there; if not bubbles, then could it have been separation between elements, or something on a surface that doesn't belong?

 

[seany65]

Well, there must have been something there; if not bubbles, then could it have been separation between elements, or something on a surface that doesn't belong?

Yes, You're right, in the reply to my email asking about it, possible fungus or something else was mentioned, (maybe separation, I don't remember) so I was told to bring it in for a refund, so I did.

 

[seany65]

Hmmm, I get the impression that the "fungus or something else" may have been an erroneous opinion of the person who replied to me and told me to take it in for a refund, as I now see that the shop is reselling it as having no fungus or haze etc. I'll try and add one of the photos in the listing. In the pic you can see the "dots", and even though the shop now seems to think nothing of them, I'm not going to re-buy it, just in case they're wrong.

 

[santino]

It does not look like „normal“ bubbles. It does not seem to be seperation and fungus. Maybe outgasing of lubricants or moisture that create this little bubbles. I guess it is not so easy to open and clean such a lens. I‘d stay away from it unless you get a really good deal.

 

[seany65]

I did have it, but took it back because in the reply to the email I sent, I was told to take it back for a refund. Now they've re-listed the lens with the same photos and don't mention the "bubbles", so I presume there's been a mistake in using these photos for a different example or other, (more senior?), members of staff don't consider them a problem.

 

[Sonnar Brian]

Hmmm, I get the impression that the "fungus or something else" may have been an erroneous opinion of the person who replied to me and told me to take it in for a refund, as I now see that the shop is reselling it as having no fungus or haze etc. I'll try and add one of the photos in the listing. In the pic you can see the "dots", and even though the shop now seems to think nothing of them, I'm not going to re-buy it, just in case they're wrong.

The person that told you to get a refund gave you good advice. If there is a camera shop that has staff that does not consider this to be a problem: do not buy from them again. What else that is wrong with a camera or lens do they overlook.

This might be dried moisture, like what forms on the inside of a car windows. It will reduce contrast. It will cause flare. It needs to be opened up, and the Haze cleaned out. It does affect the image. I've cleaned many lenses with internal haze like this, usually moisture gets on the surface of the lens and dries.

 

[tobymars]

Could be deposit of aerosolized lubricant on one of the glass surfaces

 

[seany65]

Thank you Sonnar and toby for the further replies.

I accidentally found the shop's reply to my question about it and the writer told me:

"...Sadly it looks like fungus or a coating break down internally. Please return it for a full refund."

Yet they relisted it without mentioning that and it sold.

I'd been going to that shop for many years, (mostly for window shopping) and I knew the man that had the business before they took over, he was known a s Knobby. I'd bought from them and sold to them for some of that time and was mostly happy with it all.
A short time after returning the 90mm lens, I bought a Mamiya-Sekor C S 45mm lens from them which seemed to be as good as I could wish for, but it couldn't focus on the houses opposite mine in the square where I live, let alone focus on infinity. So I took it in and they tried it on my M645 1000S (which I'd bought from them) and they tried it on an M645 Super. The particular staff member (they have about half a dozen), agreed that it did have a "slight problem" which "could be dealt with by stopping down a bit but it's not the same as it being 'right' "so he gave me refund and said they'd send it to a tech who'd take either 4-8 or 6-8 weeks. I left Neutral feedback as it had been described as "Mechanical-10" which I thought was incorrect because of its focusing problem, I did mention various positive things. They asked me to change it to Positive, but I politely (yes, I was actually polite) refused as I no longer had the lens because there was an actual problem with it. A short while later (I'm sure it was less than 4 weeks) they relisted it without mentioning the problem. I messaged them three times asking if they minded if I bought it from the again, and asking if the tech had actually fixed it (I'd been told a few months earlier that techs don't like working on lenses in reply to a question I asked about a Tamron 105mm lens they had for spares - I'd wondered if I'd bought it a tech would be able to use it to fix MY Tamron 105mm lens), but I didn't get an answer. You'd think they'd be honest and tell me to "bog off" or something. I'm beginning to wonder if the 45mm lens did work properly on the M645 Super and that my M645 1000S somehow has trouble focusing with wide-angle lenses? I have 80mm and 150mm lenses. I've seen other 45mm lenses for sale in the UK, but the listings all say "No Returns".