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Please help me to identify the flaw
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PostPosted: Sat Jun 19, 2010 8:07 am    Post subject: Please help me to identify the flaw Reply with quote

This is not mine lens nor my pictures but I have exactly the same lens with the same flaw:



It can be seen only when looking from the front, when looking from the rear though the lens everything is clean and clear. What is it and does it affect the IQ?


PostPosted: Sat Jun 19, 2010 11:20 am    Post subject: Reply with quote

Are you talking about the little white points inside the lens?

Well, there is a paintless body inside the lens to me. I had several zeiss and schneider lenses to ROLLEI QBM and ALL of them had this problem (not serious at all).

If you can and want to dissamble the lens, paint it with black mate paint. If you don't, give the lens to the repairman.

All seems to be OK, sure.

Good luck.

Rino.


PostPosted: Sat Jun 19, 2010 11:36 am    Post subject: Reply with quote

estudleon wrote:
Are you talking about the little white points inside the lens?

Well, there is a paintless body inside the lens to me.


I am taking about this "dust" making a complete and wide ring behind the front lens. Coud be this is a lack of paint on lens side/body, but it seems like something between the lenses. I hope this is not a separation.


PostPosted: Sat Jun 19, 2010 12:12 pm    Post subject: Reply with quote

Well, as Rino pointed out, this is only a barrel paint issue ... Nothing that can affect the IQ of the lens ...

Cheers


PostPosted: Sat Jun 19, 2010 12:13 pm    Post subject: Reply with quote

+1 what Leon said.
It doesn`t look like a separation.


PostPosted: Sat Jun 19, 2010 12:36 pm    Post subject: Fault? Reply with quote

It looks like a very good lens to me. (So don't buy on my recommendation!)

I think the only issue might be reflection of light from the dust/paint failure to the inside front lens elements and back into the sensor/film. I would estimate about 1% reflection and loss of contrast at worst? Less than the difference between mc and sc, especially in a zoom.

I bet the improvement, after painting matt, would be imperceptible?

Use it in good health!


PostPosted: Sat Jun 19, 2010 11:23 pm    Post subject: Reply with quote

I've seen this issue called "deblackening". Basically, this is paint deterioration. Glass edges are painted black to control internal flare, and sometimes the paint starts to chip off the glass. This amount of deblackening does not affect anything. I've seen far worse cases (e.g. Flektogon 50/4 is famos for this), and still no effect in the pictures.


PostPosted: Sun Jun 20, 2010 9:26 am    Post subject: Reply with quote

Thank you all!