Lens coating damage

[tim71]

I just purchased a Pentax SMC-M 40mm f/2.8 pancake lens on ebay. The lens was described as minty and in sparkling condition.

On inspection of the lens it appears that it may be less than mint condition. The second element from the front is covered in what is best described as a starfield of dust (far too many small specs to count, evenly distributed across the element). The "dust" can only be seen when illuminating the lens from behind with a torch, it is very obvious with this test and you don't have to peer into the lens to see it. Is this the first signs of the lens coating failing? I will add some photos tonight, I don't have a decent macro but it still should be able to be photographed with a nifty fity.
any thoughts would be greatly appreciated
regards,
Tim

[OzzieTraveller]

G'day Tim

This is one of those indeterminate, difficult issues
It sounds as tho it may be the start of fungal-blooming, perhaps caused by some exposure to humidity many years ago. Arguably tho, it may not matter :confused013
Take some images and blow them up as prints

You mention shining a torch...
One of the ways I have used over the years to examine a 2nd-hand lens, is to hold it upwards, diagonally to my eye, pointed towards a ceiling light. By holding it diagonally, I am not attempting to look 'thru' the lens - rather I am wanting to focus my eye on the front surface of the lens ~ and this way I can often see the years of cleaning of the lens via a series of very faint x hundreds of scratch lines around the lens edges esp, but also occasionally across the front element's face as well

Many of these lines are almost invisible when viewing the lens from the front ... one needs the ambient light coming thru the lens at an angle to the eye for them to become visible in any way

Hope this helps a bit
Regards, Phil

[tim71]

G'day Phil,

Yes I am going with the start of a fungal bloom, my old Takumar 50mf/4 macro has allowed me to peer into the lens with a bit of mangnifcation and there are "growth" rings around the specs. A real shame seeing otherwise the lens is in good condition.

I do the diagonal to the light source inspection as well, I just find shinning a torch/LED headlamp from behind gives even more detail compared to a light on the ceiling due to increased brightness so long as the lens is not swamped by light. I agree the straight thru test achieves little as even a rather dirty lens can look clean and sharp when viewed from the front.

Thanks for your reply and advice, its been very helpfull.

regards,

Tim

[ricktas]

It does look like the start of a fungal bloom. The other scenario that came to mind was salt. The lens may have been exposed to sea spray/wave etc at some time, it has dried out nicely, but the salt inside the lens has dried onto the lens elements.

Do not put this lens on your camera, do not put this lens near your other lenses. There is a risk(small) if it is fungal that any spores from fungus in this lens could infect your other gear. Fungal spores are microscopic and can transmit very easily. You may be able to get this lens professionally cleaned. You will need to tell them you suspect fungus.

[kiwi]

Id be starting a paypal claim on ebay

[OzzieTraveller]

G'day Tim

While I read Rick's post with interest - another very possible use for it would be for "soft-focus" portrait work ... I would wack a 2x on the back of it to take it to 100mm as a good f/length for portrait work

And even then - if it's not soft-focus enough, tape a piece of glad-wrap (or equiv) across the lens
Hope this helps
Regards, Phil

[tim71]

The seller is being good about things thus far, so I think I should be able to get a refund.

[tim71]

G'day Phil,

Glad wrap? I suppose its not much different to a soft focus filter.

cheers,

Tim

[tim71]

Thanks Rick,

I have placed the lens in the sick bay!

cheers,

Tim

[kiwi]

If you get a refund, and have no further use to the lens, AK and I might ask you to do some tests

[tim71]

I have posted the lens back to the seller, what sort of tests did you have in mind?

[Cage]

Bad luck with your purchase Tim.

I have this lens and it's a bloody bewdy.

I'm expecting an 'F' series 70-210 in the mail tomorrow, and I'm holding my breath hoping it has clean glass.

Hope all goes smoothly with your refund.

Cheers

Kevin

[mongo]

from the image of the lens you have posted, it does not look good.

Even if it could be cleaned, there is the expense and the strong possibility it will return later.

[tim71]

Thanks Kevin & Mongo,

the seller has been very good about it and was happy for me to return it with a full refund.

murphys has struck again and the second (Pentax A 35-70 f/4 zoom) lens I purchsed that week on ebay also has fungus (much more obvious on this lens), fortunately i asked the selller about fungus prior to bidding and he said all clear (as new/excellent condition was the description!!). He didn't have much of leg to stand on when I sent photos through of the fungus farm! Luckily he too has been good to deal with and is happy to refund.

So thus far I am only out of pocket about $20 for return postage!!...........a good excuse to buy new!!

I always pay via pay-pal as at least this provides insurance against a difficult seller who won't own their incorrect description.

cheers,
Tim

[Cage]

Hi Tim

You're not having much luck mate. Two fizzers on the trot.

I have bought heaps of lens on fleabay and so far have been lucky. I tend to only bid on items from sellers who seem to have some knowledge of photography, and avoid like the plague those who describe the lens they are selling as 'Hoya 58mm UV'. True, I've seen this happen.

On a brighter note, my 'F' series 70-210 just arrived, in it's original packing, with paperwork, and it's spotless. Luck of the draw I guess.

Hang in there mate.

Kevin

[tim71]

Thanks Kevin,

Great to hear that you have good run on fleabay! I am starting to discern a little bit better as to whether a seller knows much about photography...........the hard way I guess!! But actually these two dud lenses came from people that seemed to know a bit about photography. I had a seller recently state that they didn't even know that lenses got fungus...........no bidding on that one!

you have inspired me to have another go!

cheers,
Tim