ND filter problem.Help needed pleeease

[joeteds]

Hello all (sorry if this thread is in the wrong section)
I got my heliopan ND filter today (ten stop) and have been testing it out in the garden. Theres a problem though, the pics come out really dark especially in the bottom half of the photo.It also looks like there is vignetting going on.Ive gone through a range of settings. I change to manual and have the biggest f number, 30 second exposure etc etc. I even kept the shutter open for 4 minutes at one point.Im off to Spain tomorrow and was hoping for some good seascapes with this filter so any help would be majorly apreciated.
Heres some examples of the problem.


071 by Joe Ted 79, on Flickr


072 by Joe Ted 79, on Flickr


082 by Joe Ted 79, on Flickr


073 by Joe Ted 79, on Flickr


080 by Joe Ted 79, on Flickr

 

[TCR4x4]

It's a 10 stop filter so you need to meter the scene without the filter, make note of the exposure settings, then add the filter and adjust 10 stops from the meter. These images are just under exposed.
Try f/11- f/16 depending how bright it is when you take the shot.

 

[woof woof]

If you're going to take seascapes and insist on using a filter maybe a graduated filter would be better to equalise the sea and sky? Even a circular poloriser. If you're going for a long exposure shot the 10 stop seems a little extreme, maybe you could grab a few less extreme ND filters and use them together if necessary.

 

[HoppyUK]

They're just under exposed. If you took the same shot without the filter, the foreground would be just as dark. If the light is already low, ie late evening, then a ten-stopper will run you into incredibly long exposures - use lower f/number, raise ISO.

The vignetting you're getting is most noticeable at very short focal lengths when the lens is viewing the scene through the filter at an angle around the edges. It is therefore thicker and more dense, hence darker. Easy enough to correct in post processing.

And make sure you cover the viewfinder during the exposure to prevent fogging through there.