ND Filter

Hi guys
some realy interesting stuff on here and some fantastic pictures
i have a problem
I would like to try flowing water and waterfall shots so I got an ND filter Xcsource variable nd2 to 400
just tried it at home and setting at max I get purple haze (Hendrix would be happy ) in blotches
if I take it back a little seems ok
exposure was about 60 sec f11 35mm with the 18-105
Was only a tenner so do we think it's poor quality or just try it at a less than max setting and for a tenner see what I get ?

Maybe post an image so we can try to help?

Yeah, pics would help. It's possible you might have a light leak somewhere. I've had that before when not covering the viewfinder and oddly enough when I stacked filters and not screwed on well.

Variable ND's are pretty much just paired polarizers, and most that I've found work OK up to about 6 stops and after that you get hot spots throughout. The cost of one that really works is generally so high that it's cheaper for me to carry an ND400 and a 2 and 3 stop.

First one filter set at max f8 45 sec 18mm
Second f13 62sec 26mm filter taken back I assume a couple of stops no info on
Hand held

That's pretty typical of what I've found with variable ND's past 6 stops or so. I went through 3 of them before giving up. Some folks here have some that seem to work past that, but if you want 9 or 10 stops then get a dedicated filter.

Well that pretty much solved that
would you go for a 400 with maybe an nd2 on top
or is it ok to stack maybe two or three lesser ones
and what is the equation for stacking eg nd2 plus nd4 what does that give me hope you don't say 6 or 8

Skwaz said:

.........just tried it at home and setting at max I get purple haze (Hendrix would be happy ) in blotches .....

Click to expand...

Are you covering up the viewfinder? If not, light can and will spill in, bounce around, and can end up on the sensor. If your camera doesn't have a VF shutter (that's pretty much a top-end body feature), your camera should have come with a little plastic cover (Part no DK-5, I think) that covers the viewfinder.

Would you like to give me a run down on a typically waterfall setup
is it focus and meter before filters go on or is there a short cut

Thanx for your interest Sparky
no I didn't cover eyepiece but tried several times and all the ones set at max had the haze the ones at just less than max regardless of exp times were ok

Skwaz said:

Thanx for your interest Sparky
no I didn't cover eyepiece but tried several times and all the ones set at max had the haze the ones at just less than max regardless of exp times were ok

Click to expand...

That could be simply due to the shortened exposure time when you 'dial down' the filter. You're changing the exposure based on it and how much light comes through the lens, but you're not changing how much light comes in through the viewfinder. When you dial the filter up towards 'max', you're cutting down the light coming through the lens and adjusting the exposure accordingly. But you're not reducing the amount of light spilling in through the VF, so a longer shutter time will cause it to expose more light.

An easy way to test for this is to set the camera up, and take a long exposure with the lens cap on. If you get a black image with splotches, it's light coming from the VF.

Skwaz said:

Would you like to give me a run down on a typically waterfall setup
is it focus and meter before filters go on or is there a short cut

Click to expand...

If you going 10 stops or indeed any number of stops where there isn't enough light to meter properly then do everything before putting the filter on.

Use live view, zoom in and use manual focus. Meter your shot(keep it to the right for more information) add your ND filter and calculate the metering time.

Use se a remote or time delay in camera.

Skwaz said:

Well that pretty much solved that
would you go for a 400 with maybe an nd2 on top
or is it ok to stack maybe two or three lesser ones
and what is the equation for stacking eg nd2 plus nd4 what does that give me hope you don't say 6 or 8

Click to expand...

I have an ND400 in my bag, and ND 2, 4 & 8 on my shelf (1, 2 & 3 stops). If I think I'll have a need to stack there's a good chance I'll only throw the 3 stop in my bag as I've rarely run into a situation where I wanted something more restrictive. I don't like stacking more than 2 pieces of glass, particularly on a bright day when the chances for light reflecting between the two is increased.

And good call from Sparky on the covering of the eyepiece. With any kind of long exposure in a lit environment you run the risk of light leak, so either use the plastic cover, or lay a piece of cloth over the top of the eyepiece before depressing the shutter - just make sure that it won't catch any breeze that might be there and cause camera movement. I'll often just hold a hat over it without touching the camera.

I have one of the variable ND filters. You just can't use them at maximum, and that is that
So I invested in an ND400. I don't think I have used the variable filter since I got it. I generally find that works well for 15sec or more exposures, and if I need just 1 or 2 secs in most situations my polariser gives enough effect. Most of my long exp shots are done is shaded areas tho so that may not work given your situation