P3D Re: Importance of lens coatings

["K.Morcus" <k.morcus@xxxxxx>]

Eric Goldstein wrote:
> 
> Dr. George A. Themelis wrote:
> 
> > I am surprised you removed any coating in the first place... I clean
> > lenses all the time and never had a problem.  Are you sure you removed
> > coating and not "blue dirt" or something?
> 
> It is relatively easy to abrade early lens coatings, either through use
> of too strong a solvant, too abrasive a tissue or too much pressure
> applied during cleaning. If this were not the case, so many classic
> cameras would not suffer from so-called "cleaning marks" which are more
> the norm than the exception. Look at your old cameras carefully and I
> wouldn't be surprised if you don't see some coating wear.
> 
> But as I said, I too doubt that one cleaning removed all or even most of
> the front surface coating...
> 
> > The lenshood will cut off stray light but how is the filter going to help?
> > Does it help to put a coated filter over uncoated lenses?
> 
> Sorry to be unclear here. You're correct... a filter isn't going to
> help, coated or otherwise. It is the excellent lens hoods which comes
> with this set which will be of benefit in this regard...
> 
> Eric G.
Many thanks for the reactions on my question. It is wonderful to receive
so much support. I appreciate that very very much.

After having read the reaction of Dr.T. (Sorry that I am not able to
quote from his message) I began to think over his words concerning a
possible other reason why the cotton buds became blue. Suddenly I
remembered that I had  used several days ago a black writing marker (one
uses them for writing on plastic sheets for the overhead-projector) in
order to make  2 tiny scratches on the front lens rings less visible.
The marker was of the "non-permanent" type, so the ink was solvable in
water. But the ink was black not blue. I immediately took the marker
and  diluted a tiny bit of the black ink with a cotton bud, result:
BLUE!!
So, that was quite a relief.

Thanks again!

Best wishes,
Klaas


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