Any ideas what is causing this defect?

[beyond rational]

Every time I take a photo with a long[ish] exposure this "strain" becomes visible, the degree of visibilty increasing with exposure time, what is it and what causes it? I'm going to take the camera into Jessops but would like some idea of what i'm describing to them if possible. cheers

[olf]

Dust on the sensor or lens?

[robdickinson]

Most likely dust on the sensor, take a lonf exp of a sheet of paper at the highest fstop & see what turns up.

Could be on the lens, could be fungus or something if the lens is old.

[beyond rational]

The mark appears on the white paper lense is clean - though this is not a DSLR, so dust on the sensor/something inside the lense, is that likely? i guess it is possible, i can't see what else it could be ???

[robdickinson]

How old is the camera?

sure jessops will be able to have it cleaned anyhow.

[beyond rational]

about 9 months, so still under warrenty and has damage protection cover as well, I guess its probably best to let them worry about it, I'm just interested as to what it could be and to be more informed before I contact them

[Graham@Reading]

That's too big for a dust bunny, digital OR film.

If it were digital, I'd suggest a grease mark on the sensor, but on a film SLR...I've no idea.

[beyond rational]

Sorry, wasn't very clear in my previous post, it is a digital, just not a DSLR, (fuji S9500) - "prosumer" big lense jobbie

[robdickinson]

And therefore smaller sensor is more affected by dust if/when it gets in there, also may be on any piece of glass in the assembly or the sensor & not in focus.

[GetCarter]

it's dust. honest.

[Graham@Reading]

I've changed my mind - it's dust.

Ahem.

[beyond rational]

Those that guessed dust on the ccd get a gold star

Sent to Fuji friday, back this morning at 7am!