ND Filter Help

Morning guys

Ive recently been trying out cheap ND filters off of Ebay to try and slow down the action during the day. However I dont know if what I am doing is correct or if the cheap filters are doing exactly what they say on the tin!
I would have thought putting an 8 stopper and 2 stopper (both screwed on)the camera it would have gave me really long exposures. The photo below was taken on Saturday and it was quite overcast. With the two ND filters on the lens (K-x & 18-55)AND a pretty dull day I would have assumed at ISO100 and F11 through to F22 the exposure would have been lenghty. The best I could get without blowing out the highlights was 1 1/2 secs at F11.




So my question is where do I come by these big stopper filters than can give me loooong exposures of 30 - 60 seconds.

I dont want to spend big money. The two filters used for this photograph were about £4 and I cant see a big degradation in IQ.

Thanks

QC

Unfortunately you may have to. A quality 10 stop ND filter will set you back about £100.00.

Welding glass, which is actually 12-14 stops, will cost less than a fiver, but the glass quality is not good and the image suffers as a result.

I suspect what you have is an ND8 & a ND2 which should give 3 stops & 1 stop respectively. (ND8 reduces the light 8 fold which is halfing it 3 times). Photographic big stopper type filters are typically ~£100 You could always try out welding glass...
V cheap, but you have to arrange your own mounting & it gives a colour cast.
Shades 8-13 are generally available, with the higher numbers blocking more. Even a shade 8 will give you a LOT more than you have here.

I bought a 52MM HAIDA Pro ND3.0 1000x off Fleabay a few months back for just over £25. I've only taken a couple of shots with it so far - definitely a 10 stopper. Possibly a *little* blue cast, otherwise looks fine.

Andrew

Even though it was overcast it was probably quite bright. 10 stops will extend exposure by a factor of 1024. The equivalent exposure time without the filters would have been about 1/640s, which may be about right, although it does seem a bit on the short side. Bear in mind filters do vary and they may not be exactly the value they say on the tin.

Dedicated 10-stop filters don't come cheap. The classic and the one a lot of people aspire to is the Lee Big Stopper. It's good but it's glass and therefore fragile. Then there are the Formatt Hitech filters. I have one of their Pro Stop 10s. It's resin and therefore less likely to break but it does have a significant blue cast. Formatt claim it's a simple matter of white balancing to remove the cast but in practice this can be hard to achieve well, which may be why shots taken with it are often converted to B&W!

If I were you I'd stick with using your filters for a while longer to see how much opportunity you get to use them. I hardly ever use the 10-stop. Personally I now find milky seas a bit passé, but they seem to be a kind of rite of passage we have to go through!

On another tack, I notice at least five small blobs in your sky. Was that spray on your filter, or does your sensor need a clean?

I have a Heliopan ND 3,0 I get about 13 seconds in midday sun at f11(ish) iso100




It wasn't an expensive filter (49mm screw on type) and I like it a lot... I like your shots better than mine though

Thanks so much guys for the advice. I will look into the heliopan. My Kx is very dirty but cleaning the sensor doesn't seem to help. is there anyone i could send it too?

Depends where you live. I've heard Advanced Camera Services in Norfolk recommended. However, if you only paid £4 for your filters you might baulk at what it costs to get a sensor professionally cleaned!

what is actually written on the filters?

nd8 and nd2
don't have them to hand to tel you what make they are

As petrochemist says, it sounds like you have a 3 stop plus a 1 stop - i.e. 4 stop total. If you've bought a 10 stop for about £4 then you've caught a bargain!

my local dealer ,Clifton Cameras, charge £45 for a wet and dry sensor clean, when i last asked how much.
the blue cast of hitech is a lot easier to remove than the magenta of cokin i have found.

Ive been talking to Calumet in Belfast and they have agreed to do it "even if it is a Pentax"

They actually asked me if it had mirror lock up capability!

is there nobody else, not sure i would trust them with a response like that.

I definitely wouldn't trust them, sounds like jessops.
Get some proper sensor cleaning swabs and do it yourself, it's not difficult, just follow the instructions to the letter.
I did my Kx without any problem