B+W 10 stop ND filter? Suggestion/advice?

[Nass]

Colin, the cross is an effect of vari-ND. They're quite easy to make, just 2 different polarisers together. If you're using 2 circ put one the other way round to make it into linear. But that cross effect crops up often which is why I personally prefer the straight ND110. But YMMV =)

B&W ND110 is a good filter, but has a slight orange cast. I play with it a lot. Btw, consider using it at ISO800 with a wide aperture instead of 100 with small. Means you don't have to take ultra long exposures and regret getting that focus wrong.

I usually focus close to the horizon before putting it on, then lock it by switching over to manual. Let depth of field do the rest, even at f5.6 on a wide lens you get enough. It's a pain but a 1 minute operation, tripod up, camera in, settings to use remote control, focus, lock, filter on, expose, job done.

One tip with ND110s, think more in terms of 11 stops rather than 10. ETTR really is your friend on long exposures, go under or even marginally under and your images will be to noisy in the darks to use. So always give it a bit extra.

Yes vignetting can be a problem with stacked filters at 10mm. I buy the 'thin' versions of filters for this reason so that I can have 2 without vignetting at 10mm (ND110, CPL).

Re exposure times, I have a little moleskin book with me that I carry all my notes as I make stuff in. I also printed out from the web and sellotaped in this simple ND110 chart. Invaluable.

[Colin Southern]

Colin, the cross is an effect of vari-ND. They're quite easy to make, just 2 different polarisers together. If you're using 2 circ put one the other way round to make it into linear. But that cross effect crops up often which is why I personally prefer the straight ND110. But YMMV =)

Not sure what you mean by "the cross". Yes, essentially the Vari-ND works on polariser principles, but however they've done it, they've got the principle to work; whereas others who have tried it as you describe often report colour shifts.

B&W ND110 is a good filter, but has a slight orange cast.

I'm not sure if the filter in question is glass or resin, but resin filters typically have a different response to IR, which tends to give a cast towards red/orange.

[Colin Southern]

Hi Paul,

I have never needed to put on the hood reversed.

It's just a way to ensure I don't accidentally bump the focus when zooming or adjusting the Vari-ND. Keep in mind that when shooting into the (last) light, all this is done by feel as it's too dark to see.

Case in point - whilst taking this 12 minute shot I actually tripped over a tripod leg whilst "walking off the boredom" because I couldn't see it!

[Nass]

Yes, it's two polarisers put closely together =), By cross, look at the thing you posted here, there's an "X" overlaid, exposure-wise. The big advantage of course of those is of course that you have a lot more freedom regarding exposure times because you can mess with the NDness as such. Do you get a cast with 2 together - you're using canon right with a good inbuilt IR filter?

B&W ND110 is glass, fyi. But it's known to have an orange cast. The Hoya ND400 is supposed to have less of a colour cast but it's 9 stops rather than 10. Lee do a big stopper which is supposed to be very good, there's also one by heliopan but I know very little about it.

[Colin Southern]

Hi Paul,

By cross, look at the thing you posted here, there's an "X" overlaid, exposure-wise.

Ah - OK - I see what you mean. It only ocurs when one pushes the Vari-ND beyond 8 stops.

The big advantage of course of those is of course that you have a lot more freedom regarding exposure times because you can mess with the NDness as such.

Yes - it makes things much easier, especially when ambient light levels are changing quickly (as in sunrise/sunset) - you can even adjust it whilst the exposure is taking place

Do you get a cast with 2 together - you're using canon right with a good inbuilt IR filter?

They're made from glass, so no IR issues. I haven't noticed any colour cast.

[Nass]

fwiw, if you want to try this sort of stuff on the cheap I think welding glass was in vogue a couple a years ago. I wouldn't like to comment on the optical quality though =).