How critical is dust. 20D

I got my new Canon 28-135 IS USM lens a couple of days ago and have been
testing it out. When I first got it, I looked at the lens and it looked
clean. I assumed that it was because of the good packaging. I have been
taking many photos with it and this morning, when I was taking shots of my
wife's orchids, I looked more closely and it was filthy.

I cleaned it very good and went back out and took the same shots of the same
orchids and then looked at them with PS Elements, zooming in and moving all
over the image. I had an image with dust and without on the screen together
and I couldn't see 'any' evidence of dust no matter how closely I looked.
The photos look great, both with the filthy lens and with it clean.

Maybe this was because there was such variation in color and the contrasting
shades masked any dust specks. Maybe I just don't know what to look for! I
printed one photo of each, 8 1/2 X 11, and they look almost identical. The
lighting was a little different for the two, but I can't tell which photo
was shot with the dust. By the way, it looked as if there was a tiny smear
on the lens also before I cleaned it.

Am I missing something?

Don Dunlap

Don Dunlap wrote:
I got my new Canon 28-135 IS USM lens a couple of days ago and have been
testing it out. When I first got it, I looked at the lens and it looked
clean. I assumed that it was because of the good packaging. I have been
taking many photos with it and this morning, when I was taking shots of my
wife's orchids, I looked more closely and it was filthy.

I cleaned it very good and went back out and took the same shots of the
same
orchids and then looked at them with PS Elements, zooming in and moving
all
over the image. I had an image with dust and without on the screen
together
and I couldn't see 'any' evidence of dust no matter how closely I looked.
The photos look great, both with the filthy lens and with it clean.

Maybe this was because there was such variation in color and the
contrasting
shades masked any dust specks. Maybe I just don't know what to look for!
I
printed one photo of each, 8 1/2 X 11, and they look almost identical.
The
lighting was a little different for the two, but I can't tell which photo
was shot with the dust. By the way, it looked as if there was a tiny
smear
on the lens also before I cleaned it.

Am I missing something?

Don Dunlap

First point is photography is many things. Personally I consider it an
art form and it is the final product that is important. So .... if you
can't see it, then it is not a problem.

In reality most people worry far far too much about dust on a lens.
Dust on the sensor may be a different matter. Dust, scratches and chips on
a lens seldom cause any measurable or seeable difference in the final
product.

I did say seldom, but I did not say not at all. They may make a
difference, but not what you are looking at. They will not show up as spots
on the final print. Dust on the sensor may, but not dust on the lens. On
the lens dust and un-repaired scratches or chips will cause flare. This
will reduce the contrast of the whole image. It takes a lot of them to make
a noticeable difference however. Smudges will tend to do the same and are a
little more likely to show up in an area of the image and will tend to make
the whole image a little less sharp.

Note: The best lens cleaner is clean dry air. Like from a ear syringe.

Next would include a clean soft brush (camel hair is suggested) or the
torn edge of a fresh lens issue used as a brush.

Following that would be a genital breath to dampen the lens followed by
a clean lens tissue. Note: many people like the microfiber cloths, but I
don't like them because the are seldom going to stay really clean and one
hard particle can cause damage.

Last would be the use of a commercial lens cleaning fluid and lens
tissue.

At all times it is best to use the least aggressive tool for the job.
Over the years I was in photo retail, I saw more lenses damaged by cleaning,
than by other causes. Only clean if the lens really needs cleaning. Most
of the time they don't.



--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

Don Dunlap wrote:
I got my new Canon 28-135 IS USM lens a couple of days ago and have been
testing it out. When I first got it, I looked at the lens and it looked
clean. I assumed that it was because of the good packaging. I have been
taking many photos with it and this morning, when I was taking shots of my
wife's orchids, I looked more closely and it was filthy.

I cleaned it very good and went back out and took the same shots of the
same
orchids and then looked at them with PS Elements, zooming in and moving
all
over the image. I had an image with dust and without on the screen
together
and I couldn't see 'any' evidence of dust no matter how closely I looked.
The photos look great, both with the filthy lens and with it clean.

Maybe this was because there was such variation in color and the
contrasting
shades masked any dust specks. Maybe I just don't know what to look for!
I
printed one photo of each, 8 1/2 X 11, and they look almost identical.
The
lighting was a little different for the two, but I can't tell which photo
was shot with the dust. By the way, it looked as if there was a tiny
smear
on the lens also before I cleaned it.

Am I missing something?

Don Dunlap

First point is photography is many things. Personally I consider it an
art form and it is the final product that is important. So .... if you
can't see it, then it is not a problem.

In reality most people worry far far too much about dust on a lens.
Dust on the sensor may be a different matter. Dust, scratches and chips on
a lens seldom cause any measurable or seeable difference in the final
product.

I did say seldom, but I did not say not at all. They may make a
difference, but not what you are looking at. They will not show up as spots
on the final print. Dust on the sensor may, but not dust on the lens. On
the lens dust and un-repaired scratches or chips will cause flare. This
will reduce the contrast of the whole image. It takes a lot of them to make
a noticeable difference however. Smudges will tend to do the same and are a
little more likely to show up in an area of the image and will tend to make
the whole image a little less sharp.

Note: The best lens cleaner is clean dry air. Like from a ear syringe.

Next would include a clean soft brush (camel hair is suggested) or the
torn edge of a fresh lens issue used as a brush.

Following that would be a genital breath to dampen the lens followed by
a clean lens tissue. Note: many people like the microfiber cloths, but I
don't like them because the are seldom going to stay really clean and one
hard particle can cause damage.

Last would be the use of a commercial lens cleaning fluid and lens
tissue.

At all times it is best to use the least aggressive tool for the job.
Over the years I was in photo retail, I saw more lenses damaged by cleaning,
than by other causes. Only clean if the lens really needs cleaning. Most
of the time they don't.



--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

In ,
Joseph Meehan pounded out these words:

Following that would be a genital breath to dampen the lens

Keep your genital breath away from my lens. :-)

In ,
Joseph Meehan pounded out these words:

Following that would be a genital breath to dampen the lens

Keep your genital breath away from my lens. :-)

"Joseph Meehan" wrote in message
...
Don Dunlap wrote:
I got my new Canon 28-135 IS USM lens a couple of days ago and have been
testing it out. When I first got it, I looked at the lens and it looked
clean. I assumed that it was because of the good packaging. I have been
taking many photos with it and this morning, when I was taking shots of
my
wife's orchids, I looked more closely and it was filthy.

I cleaned it very good and went back out and took the same shots of the
same
orchids and then looked at them with PS Elements, zooming in and moving
all
over the image. I had an image with dust and without on the screen
together
and I couldn't see 'any' evidence of dust no matter how closely I looked.
The photos look great, both with the filthy lens and with it clean.

Maybe this was because there was such variation in color and the
contrasting
shades masked any dust specks. Maybe I just don't know what to look for!
I
printed one photo of each, 8 1/2 X 11, and they look almost identical.
The
lighting was a little different for the two, but I can't tell which photo
was shot with the dust. By the way, it looked as if there was a tiny
smear
on the lens also before I cleaned it.

Am I missing something?

Don Dunlap

First point is photography is many things. Personally I consider it an
art form and it is the final product that is important. So .... if you
can't see it, then it is not a problem.

In reality most people worry far far too much about dust on a lens.
Dust on the sensor may be a different matter. Dust, scratches and chips
on a lens seldom cause any measurable or seeable difference in the final
product.

I did say seldom, but I did not say not at all. They may make a
difference, but not what you are looking at. They will not show up as
spots on the final print. Dust on the sensor may, but not dust on the
lens. On the lens dust and un-repaired scratches or chips will cause
flare. This will reduce the contrast of the whole image. It takes a lot
of them to make a noticeable difference however. Smudges will tend to do
the same and are a little more likely to show up in an area of the image
and will tend to make the whole image a little less sharp.

Note: The best lens cleaner is clean dry air. Like from a ear
syringe.

Next would include a clean soft brush (camel hair is suggested) or the
torn edge of a fresh lens issue used as a brush.

Following that would be a genital breath to dampen the lens followed by
a clean lens tissue. Note: many people like the microfiber cloths, but I
don't like them because the are seldom going to stay really clean and one
hard particle can cause damage.

Last would be the use of a commercial lens cleaning fluid and lens
tissue.

At all times it is best to use the least aggressive tool for the job.
Over the years I was in photo retail, I saw more lenses damaged by
cleaning,
than by other causes. Only clean if the lens really needs cleaning. Most
of the time they don't.



--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math


Good information. It seems to support what I am seeing. I have a very soft
brush with a bulb at the end for blowing stuff off the lens. It was part of
a kit I got with a camera purchase about 15 years ago. I keep it in a small
bag and it seems to clean the dust specks off very well.

I did use the 'Lens Cleaning Fluid' that came in the kit and the Lens
Cleaning Tissue to clean off the smear. Everything looks pristine now, and
I think that I can mainly keep it that way using just the brush.

Thanks
Don Dunlap

"Joseph Meehan" wrote in message
...
Don Dunlap wrote:
I got my new Canon 28-135 IS USM lens a couple of days ago and have been
testing it out. When I first got it, I looked at the lens and it looked
clean. I assumed that it was because of the good packaging. I have been
taking many photos with it and this morning, when I was taking shots of
my
wife's orchids, I looked more closely and it was filthy.

I cleaned it very good and went back out and took the same shots of the
same
orchids and then looked at them with PS Elements, zooming in and moving
all
over the image. I had an image with dust and without on the screen
together
and I couldn't see 'any' evidence of dust no matter how closely I looked.
The photos look great, both with the filthy lens and with it clean.

Maybe this was because there was such variation in color and the
contrasting
shades masked any dust specks. Maybe I just don't know what to look for!
I
printed one photo of each, 8 1/2 X 11, and they look almost identical.
The
lighting was a little different for the two, but I can't tell which photo
was shot with the dust. By the way, it looked as if there was a tiny
smear
on the lens also before I cleaned it.

Am I missing something?

Don Dunlap

First point is photography is many things. Personally I consider it an
art form and it is the final product that is important. So .... if you
can't see it, then it is not a problem.

In reality most people worry far far too much about dust on a lens.
Dust on the sensor may be a different matter. Dust, scratches and chips
on a lens seldom cause any measurable or seeable difference in the final
product.

I did say seldom, but I did not say not at all. They may make a
difference, but not what you are looking at. They will not show up as
spots on the final print. Dust on the sensor may, but not dust on the
lens. On the lens dust and un-repaired scratches or chips will cause
flare. This will reduce the contrast of the whole image. It takes a lot
of them to make a noticeable difference however. Smudges will tend to do
the same and are a little more likely to show up in an area of the image
and will tend to make the whole image a little less sharp.

Note: The best lens cleaner is clean dry air. Like from a ear
syringe.

Next would include a clean soft brush (camel hair is suggested) or the
torn edge of a fresh lens issue used as a brush.

Following that would be a genital breath to dampen the lens followed by
a clean lens tissue. Note: many people like the microfiber cloths, but I
don't like them because the are seldom going to stay really clean and one
hard particle can cause damage.

Last would be the use of a commercial lens cleaning fluid and lens
tissue.

At all times it is best to use the least aggressive tool for the job.
Over the years I was in photo retail, I saw more lenses damaged by
cleaning,
than by other causes. Only clean if the lens really needs cleaning. Most
of the time they don't.



--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math


Good information. It seems to support what I am seeing. I have a very soft
brush with a bulb at the end for blowing stuff off the lens. It was part of
a kit I got with a camera purchase about 15 years ago. I keep it in a small
bag and it seems to clean the dust specks off very well.

I did use the 'Lens Cleaning Fluid' that came in the kit and the Lens
Cleaning Tissue to clean off the smear. Everything looks pristine now, and
I think that I can mainly keep it that way using just the brush.

Thanks
Don Dunlap

The very critical area are at any points along the path that are in focus.
The lens unit is designed so that no surfaces are in focus. The critical
point is the surface of the CCD block. This is equivalent to the focal plain
of the camera.

Light has a characteristic of going around objects. The effect of the object
is depended on its distance in relation to the focal point, and the
wavelength of the light.

If you have small dust particles on a lens that is being used for normal
picture taking, this will have no visible effect, unless they are very sever
in quantity, or large in size.

Obstructions, if severe enough, on the lens surface would show up as an
effect of softening the resolution in the resulting picture at near, and at
its location.

A scratch on a lens would be a little different. Under some conditions this
would show up as a flaring or softening in the resulting picture. If the
scratch is very small, it may not be visible under most shooting conditions.
The flare can show as a sort of aberration effect in the picture, or cause
bright points of light to show up as having blurred lines off of it. The
effect would be something like a bad star filter, but only at the location
where the scratch is.

If there is a defect in the coating on the lens surface, this can show as a
discoloration, or a flaring effect, depending on how the light is hitting
the surface of the lens.

I strongly suggest to people to get a good quality UV filter for every lens
that they have. These are very cheap in relation to the cost of having a
front element changed. The filter will not cause any visible degradradation
the quality of the results, and will offer an excellent protection for the
front element. Once I put one of these on to the lens, I never remove it,
unless the front element must be cleaned. If I want to use a polarizer, I
will screw it on top of the UV filter. I have done many tests, and have
never seen any difference between with, and without the UV filter.

--

Jerry G.
======


"Don Dunlap" wrote in message
news:3bc8$41a0a993$452343d7$9179@allthenewsgroups. com...
I got my new Canon 28-135 IS USM lens a couple of days ago and have been
testing it out. When I first got it, I looked at the lens and it looked
clean. I assumed that it was because of the good packaging. I have been
taking many photos with it and this morning, when I was taking shots of my
wife's orchids, I looked more closely and it was filthy.

I cleaned it very good and went back out and took the same shots of the
same orchids and then looked at them with PS Elements, zooming in and
moving all over the image. I had an image with dust and without on the
screen together and I couldn't see 'any' evidence of dust no matter how
closely I looked. The photos look great, both with the filthy lens and
with it clean.

Maybe this was because there was such variation in color and the
contrasting shades masked any dust specks. Maybe I just don't know what
to look for! I printed one photo of each, 8 1/2 X 11, and they look
almost identical. The lighting was a little different for the two, but I
can't tell which photo was shot with the dust. By the way, it looked as
if there was a tiny smear on the lens also before I cleaned it.

Am I missing something?

Don Dunlap

The very critical area are at any points along the path that are in focus.
The lens unit is designed so that no surfaces are in focus. The critical
point is the surface of the CCD block. This is equivalent to the focal plain
of the camera.

Light has a characteristic of going around objects. The effect of the object
is depended on its distance in relation to the focal point, and the
wavelength of the light.

If you have small dust particles on a lens that is being used for normal
picture taking, this will have no visible effect, unless they are very sever
in quantity, or large in size.

Obstructions, if severe enough, on the lens surface would show up as an
effect of softening the resolution in the resulting picture at near, and at
its location.

A scratch on a lens would be a little different. Under some conditions this
would show up as a flaring or softening in the resulting picture. If the
scratch is very small, it may not be visible under most shooting conditions.
The flare can show as a sort of aberration effect in the picture, or cause
bright points of light to show up as having blurred lines off of it. The
effect would be something like a bad star filter, but only at the location
where the scratch is.

If there is a defect in the coating on the lens surface, this can show as a
discoloration, or a flaring effect, depending on how the light is hitting
the surface of the lens.

I strongly suggest to people to get a good quality UV filter for every lens
that they have. These are very cheap in relation to the cost of having a
front element changed. The filter will not cause any visible degradradation
the quality of the results, and will offer an excellent protection for the
front element. Once I put one of these on to the lens, I never remove it,
unless the front element must be cleaned. If I want to use a polarizer, I
will screw it on top of the UV filter. I have done many tests, and have
never seen any difference between with, and without the UV filter.

--

Jerry G.
======


"Don Dunlap" wrote in message
news:3bc8$41a0a993$452343d7$9179@allthenewsgroups. com...
I got my new Canon 28-135 IS USM lens a couple of days ago and have been
testing it out. When I first got it, I looked at the lens and it looked
clean. I assumed that it was because of the good packaging. I have been
taking many photos with it and this morning, when I was taking shots of my
wife's orchids, I looked more closely and it was filthy.

I cleaned it very good and went back out and took the same shots of the
same orchids and then looked at them with PS Elements, zooming in and
moving all over the image. I had an image with dust and without on the
screen together and I couldn't see 'any' evidence of dust no matter how
closely I looked. The photos look great, both with the filthy lens and
with it clean.

Maybe this was because there was such variation in color and the
contrasting shades masked any dust specks. Maybe I just don't know what
to look for! I printed one photo of each, 8 1/2 X 11, and they look
almost identical. The lighting was a little different for the two, but I
can't tell which photo was shot with the dust. By the way, it looked as
if there was a tiny smear on the lens also before I cleaned it.

Am I missing something?

Don Dunlap

Bob Hatch wrote:
In ,
Joseph Meehan pounded out these words:

Following that would be a genital breath to dampen the lens

Keep your genital breath away from my lens. :-)

And keep my stuff away from your genitals!