NISI Filters: Help?

[Squidy]

Hi all,

I was looking to buy a Lee Big Stopper recently and was talked out of it by a salesman who advised the brand Nisi was the same quality but a bit cheaper. So, I ended up buying the NISI as others seemed to like it. It's meant to be a 10 stop filter but I'm having trouble believing that. Today it was overcast so I used it on mt 24-70 2.8 at F11 on AV and it stretched it out to 30 seconds, which was fine, but anything more than that and it won't handle it. I've read of people in low light being able to use them to exposures of a few minutes but not this time.

Any advice? Are they good or have I been had?

[NFLD Stephen]

Never heard of that brand of filter.

But a quick way to check whether it is 10 stops is to put the camera in av and see what the shutter time is without the filter then again with the filter. Then just count the stops in difference.

But really, unless you have a specific purpose it probably doesn't matter if it is exactly 10 stops. What is more important is whether there is any color cast.

Stephen

[Kayaker72]

Also never heard of the brand, but they are out there.

In terms of a "10 stop" filter, there are really a couple critical items:

1. Whether it is really 10 stops (NFL Stephens test is a good place to start, for example, a 1/1000 sec shot would be 1 sec with the filter)
2. Color cast
3. Clarity
4. Vignetting

Bryan has a good write up here comparing different filters where you can see the difference.

[DavidEccleston]

Don't most Canon cameras limit to 30 seconds, unless you use bulb mode?

[conropl]

Don't most Canon cameras limit to 30 seconds, unless you use bulb mode?

What he said.

Your camera will only let you get to a 30 sec exposure in Av mode. Need to go bulb... which also means you would need to set the exposure manually. To do so, do the following:

1. W/o the filter in place check the exposure level with your camera.
2. Each stop represents doubling your exposure one of three ways (or a combination of some or all):
   
   • Exposure time (e.g., if it was 1/30 seconds, increasing one stop would now be 1/15 sec)
   • Aperture (e.g., if the aperture was f/11, then increasing one stop would put you at f/8)
   • ISO (e.g., if ISO was at 100, then increasing one stop (doubling) would be 200)
   
   
3. Now with a 10 stop filter, you have to double your exposure time 10 times. This can get you to a pretty long exposure time if you work on exposure time only. You may want to do a combination.

Lets say your exposure w/o the filter was 1 sec, f/16, ISO 100. To get 10 stops with the 10 stop filter you could:

1. Increase the Aperture 1 stop to f/11
2. Increase the ISO 3 stops to 800
3. Increase the exposure time 6 stops to 64 sec (2, 4, 8, 16, 32, 64).

In that example you would raise the exposure 10 stops with a combination of ISO, Aperture, and Exposure time. Any combination of those three could be used.

Sorry for over explaining... but was not sure of your experience level with ND filters and setting exposures.

Pat

[Kayaker72]

BTW. This is what a nice shutter release can help a great deal with. Say if you want to do a 3 min exposure, in camera "blub" you have to hold the button down but with the shutter release (Vello Shutter boss, Canon TC-80N3, etc), all of that is programmed into the shutter release and you just press a button on the shutter release and it does everything else.

[DavidEccleston]

With the cheap Canon remote (RC-6), you can press once to start, press once to stop. You'll need a stopwatch or something, but you don't have to hold the button.

[Squidy]

Sorry, I should have clarified, I tried AV up until 30 seconds, but when I use bulb even at 38 seconds it started to become overexposed

I've got the Giga T Pro II for remote, it's pretty good so far but I only use it as a timer for bulb mode

[conropl]

If your exposure w/o filter was around 1/30 seconds, then that sounds about right. And 1/30 sounds about right for overcast day. If you want it longer... close the aperture down to f/16 or f/18 and it would have put you at more than 2 minutes.

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