what causes this?

i was experimenting with some long exposures using an nd3.0 filter, and every image has this light steak on the bottom third of the image. Only the long exposures, between 15 and 30 seconds, have this, all normal exposure images are fine. Ive never really tried this before, am i doing doing something wrong? i have attached an image, straight out of camera.

Are you covering the viewfinder when doing these ? If not you risk light entering.

Regards
George

I agree with George - for long exposures with a ND filter, you will need to cover the viewfinder. When I did this without covering the viewfinder, I didn't get the streak effect - but got the washed out look across the frame

Thanks George, I didnt....is that what it is?

Most likely yes. Try with the viewfinder cover that comes with the camera (did with k5 and above)

Regards

George

Definitely, you need to cover the viewfinder on long exposures in daylight.

Yep, when doing long exposures during the day, you have to cover the viewfinder, otherwise you get light leaks that look like this.

If you don't have the correct cover then just place a piece of black cloth over the back of the camera. It's easier and less fiddley.
CHEERS Vic.

thanks for all the replies.....very helpful.
my camera (k3) did come with a viewfinder cover, but i thought it was just to protect it!!
looking at it, it looks like i would have to remove the viewfinder eyepiece rubber to use it, which seems a bit of a clart on. Bit of black cloth (thanks Vic) sounds like a good idea....or may try a bit blu tac.
i will try again next time im up the caravan....

It's the bit of plastic the rubber is attached to that slides up and off. Don't try pulling the rubber or you may tear it. Comes off quite easily , get my thumb nail under it (just above lcd) and pull upwards. The cover then just slides on.

Regards
George

The eyecup is a stiff article to remove. I always carry a push-on lens cap that hangs quite happily over the viewfinder and does the job a treat