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What does bloom and fungus look like?

selectcase
Posted 19/05/2004 - 00:59 Link
Hi

I have decided to purchase some fixed focal length lenses for my mz5

cna anyone tell me what fungus and bloom look like so i know what to avoid, for example one Tamron lens I have appears to have "small bubbles" or someting on one of the interior lenses, its not dust but I have not got any good clear results with this lens.

Any advice on what to look for when purchasing lenses would be appriciated, I have allready learnt that non genuine lenses and 2x converters appear to be a wase of money if you want really sharp pictures!!
Kim C
Posted 24/05/2004 - 12:26 Link
Hi,
Fungus is like a kind of mould. Depennding on how severe it is, it can be just a very small patch or lots of very fine filaments trcing along the lens. "Bloom" I believe is a general degradation of the coating. Some people claim a small amount of fungus especially off centre has no effect. I don't believe that. I wouldn't touch an optically damaged lens even if it was very cheap. If it has any fungus, it is likely to grow and even if a technician tries to clean it, it is likely to have damaged to coating as it feeds off it. At best, it is going to affect the flare resistance of the lens and is also likely to affect the sharpness. In the same way, I wouldn't accept a lens with a build up of dust in it. It won't grow but will have the same effect. Besides which, there are plenty of "clean" lenses out there.

Before you buy, make sure the diapraghm is fully opem and have a careful look through the lens both ways. If there are any signs of dust, muck or growth in the lens, reject it. Close the diapraghm, and check that the mechnism is free and that the iris coses sharply and reopens almost insantaneously. Finally check the lens on a body and make sure it focuses to infinity. I have come across a couple which didn't.

Hope this helps
Kim
selectcase
Posted 24/05/2004 - 13:11 Link
Thabnks for the advice, greatly appriciated

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