UV protectors on lenses

Bala Variyam wrote:

> Hi,
>
> I have got a UV protector on all my lenses to protect the lens surface
> from scratches/dust/etc. Is it a best practice to remove the UV
> protector while taking a photo? I think I am noticing that the photo
> quality is considerably less with the protector (even though there are
> no scratches and not too much dust particles). What is the expert
> opinion?

No, removing it and re-installing it frequently will inevitably lead to
scratching.

Leave it in place until you replace it with a better quality filter.
Which you need to do soon if you're seeing a noticible difference in
quality when it's in place.
 >> Stay informed about: UV protectors on lenses 

In article <1128337548.864499.3970.DeleteThis@f14g2000cwb.googlegroups.com>, Hussam
<hktaha.DeleteThis@gmail.com> writes
>I agree that they aren't so necessary. It's classic product
>cross-selling.. like buying the salsa with doritos. I was always super
>extra ultra careful not to have a single spec of dust on my lenses
>thinking it made much of a difference. Then I started using a
>scratched Nikon lens (we're talking visible scratches here!) and
>results were always perfect with no noticeable effect! No one would
>ever know that the images were taken with a scratched lens.
>
>So worrying about a bit of dust or even a small scratch or two is just
>being paranoid and over protective.
>
>We are not buying better image quality when we put UV lenses, we are
>merely buying piece of mind... that's all.
>
>Sam
>
There is a world of difference between a single moderate scratch and an
overall coating of fine dust, or indeed an overall mesh of very fine
scratches. The latter, often caused by incompetent cleaning, may be
invisible to the naked eye, but reduce contrast significantly.

In answer to the original question, I have always taken the view that a
top-quality lens hood has more to offer than a protective filter in most
circumstances. It actually enhances quality by reducing flare, rather
than degrading it (however slightly); it provides better protection
against surface impacts, and is cheaper than the necessary top quality
filters if you need one for every lens. They mostly keep your fingers
off the lens glass quite well.

The exception is in circumstances where corrosive spray (such as sea
spray) is likely. Then I would use a filter, but at least I only need
one per lens filter ring size (pretty well all 77 or 72mm).

I always use the Canon bayonet fit hoods which are made of very tough
plastic and are designed specifically for each lens. I have on several
occasions had the hood bounce off a surface which could have otherwise
damaged the lens. A filter would offer poor protection in such cases.

They do though take up more room in the bag!

David
--
David Littlewood
 >> Stay informed about: UV protectors on lenses 

Hussam wrote:

> I agree that they aren't so necessary. It's classic product
> cross-selling.. like buying the salsa with doritos. I was always super
> extra ultra careful not to have a single spec of dust on my lenses
> thinking it made much of a difference. Then I started using a
> scratched Nikon lens (we're talking visible scratches here!) and
> results were always perfect with no noticeable effect! No one would
> ever know that the images were taken with a scratched lens.
>
> So worrying about a bit of dust or even a small scratch or two is just
> being paranoid and over protective.
>
> We are not buying better image quality when we put UV lenses, we are
> merely buying piece of mind... that's all.
>
> Sam
>

Of course if the previous owner of that Nikon lens had used a filter,
maybe it wouldn't have any visible scratches on the front glass.
 >> Stay informed about: UV protectors on lenses 

Bob Salomon (bob_salomon@mindspring.com) wrote in rec.photo.equipment.35mm:
> > Haven't you ever seen movies where a car with the headlights on comes
> > around the corner and you can see more than one set of headlights?
> > Jeez...get a clue?
>
> Yes and frequently that is caused by the light reflecting off of the
> lens elements themselves.

It's also frequently intentional in movies, so the fact that it exists at
all isn't proof of any "problem" with the optics.

--
Jeff Rife |
| "Resistance...is *futile*"
|
| -- Data, "Star Trek: First Contact"
 >> Stay informed about: UV protectors on lenses 

Tony Polson lays out the FUD:

> Sander Vesik <sander.TakeThisOut@haldjas.folklore.ee> wrote:
> >
> >Some 3rd party consumer lenses are AFAICT uncleanable - the coating on
> >the outside of teh front element is too soft, nd will degrade no matter
> >what you do (except not cleaing it in any way at all => always on filter
>
> Absolutely true.

Complete bullshit. Modern optics (for the last N decades, N ~= 5) have
received coatings that are as hard as (if not harder) than the
underlying glass.

Polson, why lie like this? The truth is _much_ more interesting.
(Speaking of truth, maybe you can, finally, identify that issue of
Paris Match that bears your image on the cover?)
 >> Stay informed about: UV protectors on lenses 

In rec.photo.equipment.35mm David Littlewood <david.DeleteThis@nospam.demon.co.uk> wrote:
> There is a world of difference between a single moderate scratch and an
> overall coating of fine dust, or indeed an overall mesh of very fine
> scratches. The latter, often caused by incompetent cleaning, may be
> invisible to the naked eye, but reduce contrast significantly.

Some 3rd party consumer lenses are AFAICT uncleanable - the coating on
the outside of teh front element is too soft, nd will degrade no matter
what you do (except not cleaing it in any way at all => always on filter

>
> David

--
Sander

+++ Out of cheese error +++
 >> Stay informed about: UV protectors on lenses 

David Littlewood <david.TakeThisOut@nospam.demon.co.uk> wrote:

> A technique regularly used in slide duplication - and occasionally used
> in normal film photography - achieves the goal you describe. This is to
> give a brief pre-exposure (of a fraction of the main exposure) to even
> white light, which lower contrast considerably.
>
> It would be quite feasible to do this in a digital camera using a small
> internally-directed flash.

I don't think it would have the same effect on digital. The point behind
doing it with film is to lift the "base" of the exposure above the toe of
the film's response curve. The sensor, having a linear response, would
not benefit in the same way.

--
Jeremy | jeremy.TakeThisOut@exit109.com
 >> Stay informed about: UV protectors on lenses 

In article <1128352344.823863 DeleteThis @haldjas.folklore.ee>, Sander Vesik
<sander DeleteThis @haldjas.folklore.ee> writes
>In rec.photo.equipment.35mm David Littlewood <david DeleteThis @nospam.demon.co.uk> wrote:
>> There is a world of difference between a single moderate scratch and an
>> overall coating of fine dust, or indeed an overall mesh of very fine
>> scratches. The latter, often caused by incompetent cleaning, may be
>> invisible to the naked eye, but reduce contrast significantly.
>
>Some 3rd party consumer lenses are AFAICT uncleanable - the coating on
>the outside of teh front element is too soft, nd will degrade no matter
>what you do (except not cleaing it in any way at all => always on filter
>
Interesting - do you have any documented data on this, or is it a
personal observation? The range of coating materials available is not
large, and one would expect the top coating layer to be similar in most
cases - and of a hardness similar to the glass used. However, I do
accept that differences in the quality of the actual coating method may
be relevant.

David
--
David Littlewood
 >> Stay informed about: UV protectors on lenses 

In article <11k2u70jns0f444.RemoveThis@corp.supernews.com>, Jeremy Nixon
<jeremy.RemoveThis@exit109.com> writes
>David Littlewood <david.RemoveThis@nospam.demon.co.uk> wrote:
>
>> A technique regularly used in slide duplication - and occasionally used
>> in normal film photography - achieves the goal you describe. This is to
>> give a brief pre-exposure (of a fraction of the main exposure) to even
>> white light, which lower contrast considerably.
>>
>> It would be quite feasible to do this in a digital camera using a small
>> internally-directed flash.
>
>I don't think it would have the same effect on digital. The point behind
>doing it with film is to lift the "base" of the exposure above the toe of
>the film's response curve. The sensor, having a linear response, would
>not benefit in the same way.
>
You are of course right about the effect on film. However, I'm not so
sure about the part where you say the sensor has a linear response. It's
probably true (I'm not in a position to argue) but is it the right
question? Surely the point is that the overall system sensor ->
amplifier -> A to D -> whatever, is restrained logarithmically.

For example, if the main exposure is 1 shadow and 100 highlight, this is
a ratio of 100:1. If an additional exposure of 10 is given overall, this
becomes 11 shadow, 110 highlight, i.e. a ratio of 10:1

Simple (and exaggerated) example, I know, but it raises (ahem) the
question of whether it would indeed allow a reduction in dynamic range
in a case where the dynamic range of the result of the main exposure
alone was excessive. Obviously the post-exposure processing would need
to be capable of dealing with this - by turning down the amplification
to suit, perhaps.

David
--
David Littlewood
 >> Stay informed about: UV protectors on lenses 

In article <1128275926.160808.271310 RemoveThis @g14g2000cwa.googlegroups.com>,
"Bala Variyam" <bala.variyam RemoveThis @gmail.com> wrote:

> Hi,
>
> I have got a UV protector on all my lenses to protect the lens surface
> from scratches/dust/etc. Is it a best practice to remove the UV
> protector while taking a photo? I think I am noticing that the photo
> quality is considerably less with the protector (even though there are
> no scratches and not too much dust particles). What is the expert
> opinion?
>
Any extra glass between the lens and subject will alter quality -
InfraRed filters and the like are a necessary evil.
Make it a habit the affix the lens cap as often as possible.
 >> Stay informed about: UV protectors on lenses 

On Mon, 03 Oct 2005 10:50:18 -0400, Bob Salomon
<bob_salomon.DeleteThis@mindspring.com> wrote:

>In article <031020050641372363%rag@nospam.techline.com>,
> Randall Ainsworth <rag.DeleteThis@nospam.techline.com> wrote:
>
>> In article <bob_salomon-2AB3C7.09234003102005.DeleteThis@news.isp.giganews.com>,
>> Bob Salomon <bob_salomon.DeleteThis@mindspring.com> wrote:
>>
>> > What filter?
>> > Whose filter?
>> > Multi-coated on both sides filter?
>> > Solid glass filter?
>> > Sandwiched filter?
>> > Uncoated filter?
>> > Single coated filter?
>> >
>> > Where was the light?
>> > Would there have been a reflection without the light coming from that
>> > direction?
>> > Was the unwanted reflection caused by a poor filter, a non-multi coated
>> > lens or the angle of the light?
>> > With or without an effective hood like a compendium?
>> >
>> > What did the reflection look like?
>>
>> Haven't you ever seen movies where a car with the headlights on comes
>> around the corner and you can see more than one set of headlights?
>> Jeez...get a clue?
>
>Yes and frequently that is caused by the light reflecting off of the
>lens elements themselves.

I've seen examples of filters clearly causing unwanted reflections.
Part of it is the fact they are flat and have two parallel surfaces,
which is one reason why Canon was/did make meniscus filters, filters
with parallel but curve surfaces. If you point a camera anywhere near
the sun or an incadescent light, I don't care how good the coatings
are, even if they are phased-matched multicoatings with 99.9%
reflectivity, you can still get unwanted reflections.
-Rich
 >> Stay informed about: UV protectors on lenses 

Sander Vesik <sander.DeleteThis@haldjas.folklore.ee> wrote:
>
>Some 3rd party consumer lenses are AFAICT uncleanable - the coating on
>the outside of teh front element is too soft, nd will degrade no matter
>what you do (except not cleaing it in any way at all => always on filter


Absolutely true. And it isn't just consumer lenses. Look at the
number of good quality lenses sold on eBay with "coating marks".

By no means all of these marks were caused by cleaning that was too
vigorous or too frequent.
 >> Stay informed about: UV protectors on lenses 

"Ray Fischer" <rfischer.DeleteThis@bolt.sonic.net> wrote in message
news:dhqhgi$h0k$1@bolt.sonic.net...
> John H. Holliday <nospam@okcorral> wrote:
> >"Ray Fischer" <rfischer.DeleteThis@bolt.sonic.net> wrote in message
>
> >> One simple test for quality is to shine a light at the filter and look
> >> at the reflection. If the relfleciton is the same color as the light
> >> then it's a lower-quality filter. If it's dark and blue/green then
> >> it's a better filter.
> >
> >Silliest thing I ever heard...
>
> Don't mock what you are incapable of understanding, fool. Filters
> with anti-reflection coatings are almost always of better quality.

You are very right to say this.
 >> Stay informed about: UV protectors on lenses