Alert! Oil mark Found on Lens!

[POSTI-Tuomo]

Discovered this nasty on my dear Tamron f3.5 35-70! Is this a cause for concern? I have no idea where the mark came from. It is just behind the front element, so disassembly would be needed to mend it. I possess no such skills, and the lens cost me about 45 euros. Doesn't seem sensible to have it fixed by a pro...

When looked through the viewfinder, it doesn't show, though. But clarity of the VF isn't all that impressive so can't judge if it has an effect on final images or not. I examined some negatives taken with that lens, no discernable errors there. But I fear prints may reveal a horrid truth about it...

Oil on a coated lens element can't be good anyway, I think. Can oil corrode that sweet coating? Am I better off to just use this lens until it doesn't produce decent images or should I try fixing it?

 

[KoNickon]

Tuomo, zoom lenses are a lot more complicated than something like a Tessar in Leica screw mount, so I would be very reluctant to take it apart without a pretty clear idea of what does what. I'm guessing that if you remove the ring with the lens name and information on it (using some sort of friction device) you may then be able to get at the front element -- I see slots for a spanner wrench. But who knows just what unscrewing that will do? Will it remove the front element, or a front lens group that will require further disassembly?

If you can get a copy of a service manual for the lens, or at least an exploded version, that would be most helpful.

But I think if it were me, I would resist the temptation to take it apart, and just keep using the lens. I bet you will notice no degradation in image quality. I do not know about whether the oil will damage the lens coating. I hope someone else can help with that.

 

[POSTI-Tuomo]

Tuomo, zoom lenses are a lot more complicated than something like a Tessar in Leica screw mount, so I would be very reluctant to take it apart without a pretty clear idea of what does what.

Words of wisdom there, mate. I must resist the urge! I was struggling with the J-8, will not touch this!

Hmph. Maybe I'll rack this one up for 'experience'. I suppose it won't have too much of an effect on final pictures. Or at least I hope so. Maybe odd flaring here and there, but nothing more. It's good that the oil has leaked from the side and not directly onto the mid-area.

 

[KoNickon]

Was the lens stored a) on its side, b) in an excessively warm spot, or c) both? Neither practice is a good idea, but usually this results in oil on the aperture blades, not on the glass. As you say, a lesson learned (but it may have happened anyway). Keep using the lens and don't worry about it too much!

 

[POSTI-Tuomo]

It has been pretty much attached to my Fujica all the time I've had it... It is a semi-recent purchase, so I don't really know. Got if off eBay. It may have been there at the time of purchase, but I noticed it only recently, about 2 weeks ago. May as well have appeared during the time it has been in my possession...

Bah.

I'll keep shooting! That's what I do best. Best to leave tinkering to gearheads.

Thanks for the advice and insight.

 

[POSTI-Tuomo]

I just did a 24-48 Tamron. Just under the outer element will be at least two more glass elements. It may appear to be just under the front glass, but it is doubtful.

How much do you have experience in fixing lenses?