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Had a problem today with a Sigma lens and wanted some advice. I use a
Sigma 80-400mm EX APO OS DG (Nikon fit) lens purchased in February
this year. So far it has worked well, however today I started
experiencing problems. I used the camera this morning and initially
the lens was fine, however after about an hour a number of problems
occurred. Firstly auto-focusing failed to work, the mechanism scanned
from near to infinity and back without locking onto the subject and
then at the same time I began to notice that the image in the
viewfinder was noticeably darker and a small blue circular 'blob' was
present around the centre of the view finder. The view finder image
also appeared to be a mottled blue when pointed at the clear blue sky.

I have not noticed any of these effects before and am concerned there
is a problem with the lens, however today was quite a cold day -
around 5 C in still air, but with a cold wind. Could the cold weather
have caused this problem? ...it took a time to materialise (about an
hour) and now that I have returned home and the lens is at room
temperature, the lens now appears fine.

When the problem occurred, I changed over to a Sigma 150mm macro lens
and the view finder image was perfect and noticeably brighter which is
why I believe this problem is related to the 80-400mm lens rather than
the camera.

The lens is used with a Nikon D90s camera. I tried disabling the auto
focus and image stabilising functions to see if this would make any
difference to the view finder problem. I also tried altering the focus
settings on the camera to see if this would help with the auto focus
problem. The weather conditions were cold, around 5 C in air but with
a chill wind in bright sunlight.

tia

"David" <> wrote in message
news:...
> Had a problem today with a Sigma lens and wanted some advice. I use a
> Sigma 80-400mm EX APO OS DG (Nikon fit) lens purchased in February
> this year. So far it has worked well, however today I started
> experiencing problems. I used the camera this morning and initially
> the lens was fine, however after about an hour a number of problems
> occurred. Firstly auto-focusing failed to work, the mechanism scanned
> from near to infinity and back without locking onto the subject and
> then at the same time I began to notice that the image in the
> viewfinder was noticeably darker and a small blue circular 'blob' was
> present around the centre of the view finder. The view finder image
> also appeared to be a mottled blue when pointed at the clear blue sky.
>
> I have not noticed any of these effects before and am concerned there
> is a problem with the lens, however today was quite a cold day -
> around 5 C in still air, but with a cold wind. Could the cold weather
> have caused this problem? ...it took a time to materialise (about an
> hour) and now that I have returned home and the lens is at room
> temperature, the lens now appears fine.
>
> When the problem occurred, I changed over to a Sigma 150mm macro lens
> and the view finder image was perfect and noticeably brighter which is
> why I believe this problem is related to the 80-400mm lens rather than
> the camera.
>
> The lens is used with a Nikon D90s camera. I tried disabling the auto
> focus and image stabilising functions to see if this would make any
> difference to the view finder problem. I also tried altering the focus
> settings on the camera to see if this would help with the auto focus
> problem. The weather conditions were cold, around 5 C in air but with
> a chill wind in bright sunlight.
>
> tia

Is it an SLR? if so it might be the weather I have a Nikon SLR and it wont
work below -%.
Didn`t find this out until I went away last new year, I checked it out on
the internet and apparently it is the norm. Apparently its to do with the
type of battery used.
I hope this helps if not maybe someone more knowledgeable will be along
soon.

David wrote:
> Had a problem today with a Sigma lens and wanted some advice. I use a
> Sigma 80-400mm EX APO OS DG (Nikon fit) lens purchased in February
> this year. So far it has worked well, however today I started
> experiencing problems. I used the camera this morning and initially
> the lens was fine, however after about an hour a number of problems
> occurred. Firstly auto-focusing failed to work, the mechanism scanned
> from near to infinity and back without locking onto the subject and
> then at the same time I began to notice that the image in the
> viewfinder was noticeably darker and a small blue circular 'blob' was
> present around the centre of the view finder. The view finder image
> also appeared to be a mottled blue when pointed at the clear blue sky.
>
> I have not noticed any of these effects before and am concerned there
> is a problem with the lens, however today was quite a cold day -
> around 5 C in still air, but with a cold wind. Could the cold weather
> have caused this problem? ...it took a time to materialise (about an
> hour) and now that I have returned home and the lens is at room
> temperature, the lens now appears fine.
>
> When the problem occurred, I changed over to a Sigma 150mm macro lens
> and the view finder image was perfect and noticeably brighter which is
> why I believe this problem is related to the 80-400mm lens rather than
> the camera.
>
> The lens is used with a Nikon D90s camera. I tried disabling the auto
> focus and image stabilising functions to see if this would make any
> difference to the view finder problem. I also tried altering the focus
> settings on the camera to see if this would help with the auto focus
> problem. The weather conditions were cold, around 5 C in air but with
> a chill wind in bright sunlight.
>
> tia

Could it have been condensation. Not sure how well these things are
sealed. It would depend on how rapidly lens was exposed to lower
temperature.
Dave Cohen

On Sat, 22 Nov 2008 11:07:09 -0500, Dave Cohen <>
wrote:


>Could it have been condensation. Not sure how well these things are
>sealed. It would depend on how rapidly lens was exposed to lower
>temperature.
>Dave Cohen

Thanks all. Seems to be condensation...just need to figure out how to
minimise! I haven't had this lens out in very cold weather yet and it
will be a shame if I can't, I like bright Wintery scenes.

I don't see why condensation would occur under the conditions you're
describing though, as condensation typically occurs when moving your
equipment from a colder environment to a warmer, more humid one, and
the situation you've described is the opposite of that.

I've shot in those conditions with a Nikon D70 and a couple different
Sigma tele-zooms without problem, colder temperatures even.

The only time I've had a condensation problem was in summer when the
camera equipment was in a cool, air conditioned house and was brought
outside into warm, humid air, fogged up badly until the equipment warmed
up to the ambient outside temperature.

John

John D. <> wrote:
> I don't see why condensation would occur under the conditions you're
> describing though, as condensation typically occurs when moving your
> equipment from a colder environment to a warmer, more humid one, and
> the situation you've described is the opposite of that.

> I've shot in those conditions with a Nikon D70 and a couple different
> Sigma tele-zooms without problem, colder temperatures even.

> The only time I've had a condensation problem was in summer when the
> camera equipment was in a cool, air conditioned house and was brought
> outside into warm, humid air, fogged up badly until the equipment warmed
> up to the ambient outside temperature.

I wondered about that too. A possibility might be the the air inside
the camera and its zoom started out as humid indoors air which when
cooled down to the outside temperature had to precipitate the extra
water vapour somewhere. If the cooling down was fast then the glass of
the lenses might have been cooled a bit in advance of the air and thus
been one of the surfaces chosen for condensation.

--
Chris Malcolm

On 23 Nov 2008 17:55:36 GMT, Chris Malcolm <>
wrote:

>John D. <> wrote:
>> I don't see why condensation would occur under the conditions you're
>> describing though, as condensation typically occurs when moving your
>> equipment from a colder environment to a warmer, more humid one, and
>> the situation you've described is the opposite of that.
>
>> I've shot in those conditions with a Nikon D70 and a couple different
>> Sigma tele-zooms without problem, colder temperatures even.
>
>> The only time I've had a condensation problem was in summer when the
>> camera equipment was in a cool, air conditioned house and was brought
>> outside into warm, humid air, fogged up badly until the equipment warmed
>> up to the ambient outside temperature.
>
>I wondered about that too. A possibility might be the the air inside
>the camera and its zoom started out as humid indoors air which when
>cooled down to the outside temperature had to precipitate the extra
>water vapour somewhere. If the cooling down was fast then the glass of
>the lenses might have been cooled a bit in advance of the air and thus
>been one of the surfaces chosen for condensation.

It would have cooled down quickly. The lens was in a bag, then exposed
to the cold day and a bloody freezing wind. Thinking about it - the
temperature was coldest at the start of the walk, then warmed up as
the sun came up and the wind dropped.