What strength ND filter do I need to shoot 1/50th shutter at f1.8?

F

Filmkid2003

Well-known member
Hey everyone. I am getting ready to buy some Tiffen ND filters for my Nikon 50mm f1.8 prime lens and I was wondering if someone knows what strength ND filter I will need for a correct exposure when shooting wide open on a bright sunny day?

I also plan on buying some ND filters for my GH1 kit lens and need to know what strength filter I will need to shoot wide open at f4.0 and 1/50th shutter on a bright sunny day.

Is ther a variable ND filter that is high quality enough that it WILL NOT corrupt the image in any way whatsoever? Thanks.
 
ISO 100 on 1/50, I've usually gotten an f/22 on a bright day. So if you want to push it to f/1.8, you'd need about 7 stops of ND to open all the way. So about ND2.1, on the .1 scale.

To get f/4, you'd need two less stops, so about 5 stops of ND, or ND1.5.
 
Thanks, Barry. Do you have any experience with the Singh-Ray Vari ND filter? So far, I've read that it doesn't degrade the image at all.
 
Barry's right, of course. But just FYI, photography has something called the "Sunny 16" rule:

On a sunny day, set your aperture to f16 and shutter speed to the reciprocal of the ISO setting.

i.e. f16, 1/50 and ISO50

Of course, f16 is 6+ stops slower than f1.8 and ISO50 is a stop slower than ISO100, so 7+ stops total. And, if you want to bump up your ISO to around ISO400 (which seems to be the GH1's sweet spot: ISO320-640), you would add another 2 or so stops, for a total of ~9.

Unfortunately, I don't think the Singh-Ray goes that high. Although, you could add a polarizer into the mix, which might be good for a stop or so, depending.

HTH - Mark
 
Thanks, guys. Yeah, I read that you can now add a polarizer with the Vari ND filter without any adverse effects.
 
Barry_Green said:
Haven't used that one, no.
Click to expand...

Which ones have you used with lenses beyond 50mm? Are you satisfied with the performance? Singh Ray sounds promising and we're awaiting test results in another thread.

I sold the LCW Fader ND because it made my 70-200 unacceptably soft. (Plastic will do that.) I've been using B+W ND filters and have had to compromise with the shutter speed.

DIY may be the best bet. Which way would you go? Two CPLs (front reversed) or one CPL and front LPL?
 
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