Fungoid M-100/4 macro

Hi Guys,
I am contemplating one of these rather nice little lenses on an auction.
One can't have enough macro lenses don't you think ?
The mushroom is in inside the back element.
I'm wondering if there are any specific issues with getting into the back ?
Read a few threads but nothing referring to this lens.
Any clues appreciated
Pete

Super Takumar 50/4, FA50/2.8, FA100/2.8, Tamron SP90/2.5 (2 versions)

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K-1 K-01 Q-7
some len

Close to the Edge
Down by the River

Thisl link will provide some reviews of the lens itself (not cleaning info).

I have the same lens in Pentax K: very nice , however, only goes to 1:2 magnification.

Link: http://www.pentaxforums.com/lensreviews/SMC-Pentax-M-100mm-F4-Macro-Lens.html

Thanks Mate,
Yep I saw the reviews there
I don't mind the 1:2, its the closer focus than my little K 105/2.8 that I fancy.
cheers
Pete

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K-1 K-01 Q-7
some len

Close to the Edge
Down by the River

The lens is quite a simple 5/3 arrangement (see here) so I'd imagine it's fairly straightforward to dismantle. The problem would be if the fungus is between the 4th and 5th elements as they're a cemented pair - not a job I'd undertake to be honest.

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Joining the Q

In my experience the fungus isn't generally between two cemented together elements - it usually seems to form either on the inside of the front or rear elements or on the front element of the rear element group (presumably as damp can get to here quite easily due to the gaps for the aperture lever). That's true of 50mm primes and a 28-50mm zoom I've dealt with anyway, I've never had a 100mm macro so I'm not sure if it's built in the same way.

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Matt

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.

Thanks Hefty1,
Yes fungus inside the layers would be pretty terminal...
The guys saying it is on the outside but who knows
cheers
Pete

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K-1 K-01 Q-7
some len

Close to the Edge
Down by the River

I let it go
went for equivalent of 43 quid
Pete

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K-1 K-01 Q-7
some len

Close to the Edge
Down by the River

I'd probably have had a bid for that much - I don't know what lens prices are like in NZ but a good M 100mm f4 Macro usually goes for around the £100 mark here.

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Matt

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.

The earlier 100mm f/4 macros are known to have problems with the cement becoming cloudy between the elements.

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

What do you count as an "earlier" 100mm f4 macro lens - they were around a long time before the M series?

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Best regards, John

As I understand it the M series version was a simple renaming of the K series? I'm not sure how much was carried over from the Takumar, and there's a fair chance Pentax changed the composition of the glue at some point.

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Matt

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.

I'm not sure of the exact models, but Google throws up quite a bit of info if you just put in Pentax 100mm macro cement elements

This link might work

This one discusses a possible repair

http://www.mail-archive.com/pdml@pdml.net/msg06623.html

Sorry that last link has to be pasted into the browser.

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

yes it was possible cement issues that I thought might spoil any bargain
Pete

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K-1 K-01 Q-7
some len

Close to the Edge
Down by the River