Olympus-OM
[Top] [All Lists]

[OM] Re: Learning about lenses

Subject: [OM] Re: Learning about lenses
From: Moose <olymoose@xxxxxxxxxxxxxxx>
Date: Fri, 21 Jan 2005 02:33:59 -0800
Rob Smith wrote:

>Thankyou Moose, I read your note on using later lenses.
>Do Zuiko Serial numbers run sequentially? so a larger number would be a
>later lens?
>
Yes

>I have a 50mm f1.8 which is now junk but has thrown up a couple of questions
>I would like to ask: 
>If I look very carfully at the front element and catch a very bright light
>just right I can see a couple of realy small scratches. Without carefull
>looking you would not see them.
>Would these cause problems?
>
Very unlikely. Maybe if a very bright catches one at just the imperfect 
angle, bu really not a practical problem.

>If I also look very, very carefully at an angle to the rear element under
>very bright light I can see what looks like very very fine yellowy
>condensation. It is not condensation but that is my best description. You
>cannot see it if you look at it straight on.
>The lens also looks slightly cloudy if you shine a bright light through from
>the rear and look at the front from one side. My other 50mm f1.8 does not do
>this.
>Any diagnosis?
>
What Piers said. You might keep it and use it when you want a very 
slightly softer, less contrasty image. People pay good money for filters 
to do that.

>Is it a good idea to get hoods for each of my lenses?
>
YES!  This would not have happened with a lens hood 
<http://moosemystic.net/Gallery/21__0024.jpg>. I didn't have one for 
this lens at the time, but I do now! A hand, hat, magazine, etc. can 
also be your friend., even with a hood.

>Does this reduce stray light entering from outside the lens 'cone' and does
>this help with image quality?
>
Yup

>I wish to get filters for all my lenses to protect the front elements.
>
Some people do this and others don't. The optical effect of a good one 
is generally unnoticeable. The effect of a bad one can be pretty bad. We 
had a fellow on this list who generated endless threads with complaints 
of one of his lenses, maybe a 28/2.8? He railed about how Oly could make 
such junk, how it was so much poorer than this or that other lens. Lots 
of analyses, apologias, etc. etc. were offered. One day, I had a 
thought, asked if he had a filter on it all the time and suggested he 
remove it if so. Problem solved. Suddenly the lens was just fine. Take a 
look at Gary's test of a 50/1.4 from the last, best series with and 
without a filter, especially his comments about the impossibility of 
seeing which is which with the naked eye.

I tend not to use them, but will admit they are on a couple of my most 
valuable lenses. But I take them off for pictures I really want to be at 
their best. They do add 2 more optical surfaces to generate reflections 
and it seems multi costed ones are better.

The lens hood you should have on the lens provides a lot of protection 
in itself.

>What does a UV filter do?
>Should I just get plain filters just for lens protection?
>
As Piers says, UV filters have almost no different effect on images than 
plain ones. Which also means they don't really do much for high altitude 
UV. Even Skylight filters aren't much use there. Something in the 81 
filter series is used by most high altitude photographers.

Moose



==============================================
List usage info:     http://www.zuikoholic.com
List nannies:        olympusadmin@xxxxxxxxxx
==============================================

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz