Getting to the right shutter speed

Hi excuse what I'm sure is a simple question. I wanted to capture a long exposure using a 10 stop ND. The clouds weren't moving that fast so I wanted an exposure of at least a minute. Using one of the calculation apps, I knew that I needed the speed to be 1/15 to get to 1 min 10 stops down. My ISO was at L and I was using a middleish aperture. No matter what I did I could not get the exposure right in the viewfinder. The reason for the confusion was that I was sure that I saw a video of someone using a 1/15 shutter speed in bright sunshine and I don't think he was using any filters (prior to applying the 10 stop) to get to that. What am I missing?

When you say ISO was set for "L", numerically what does that mean?

That is a key part of the calculation and you have to be specific in your setting; eg - 50, 100, 200, etc.

IainUK wrote in post #18331953
Hi excuse what I'm sure is a simple question. I wanted to capture a long exposure using a 10 stop ND. The clouds weren't moving that fast so I wanted an exposure of at least a minute. Using one of the calculation apps, I knew that I needed the speed to be 1/15 to get to 1 min 10 stops down. My ISO was at L and I was using a middleish aperture. No matter what I did I could not get the exposure right in the viewfinder. The reason for the confusion was that I was sure that I saw a video of someone using a 1/15 shutter speed in bright sunshine and I don't think he was using any filters (prior to applying the 10 stop) to get to that. What am I missing?

Did you have the camera set to BULB to take the shot?

sapearl wrote in post #18331956
When you say ISO was set for "L", numerically what does that mean?

That is a key part of the calculation and you have to be specific in your setting; eg - 50, 100, 200, etc.

ISO 50

Could you also, please, be more specific than "middleish" aperture? Were you at f/8? f/11? The person in the video you saw may have been at f/16 or f/22.

You've learned one of the surprising lessons in photography. A 10 stop ND filter in bright sunlight is not enough to get really long shutter speeds.

If you start with the Sunny 16 rule it tells you that you need 1/ISO at f16 in bright sunlight so for you (I think L is usually ISO 50) that would be 1/50 shutter speed at f16 to start which is past mid-aperture to me.

But anyway, the shutter speed it is about 2 stops away from your starting goal of 1/15 shutter speed. You could get to 1/15 by closing down your lens two more stops to, if your lens has it, f32. That is not a mid-aperture but would have gotten you very close to the correct exposure.

For mid-day sun you might consider either a 14 stop ND filter or combining your 10 stop filter with a polarizing filter with to get 12 stops of ND.

IainUK wrote in post #18331953
No matter what I did I could not get the exposure right in the viewfinder.

Don't know what you mean by that, but when you stick a ten stop ND filter on the front of a lens the viewfinder will go dark.

What do you mean by "get the exposure right in the viewfinder"? If you're in bright/direct sunlight, you're always going to have your meter showing overexposure at a 1/15 shutter speed; that's just too much light. You would have to put the filter in place in order to get a proper exposure to meter. As others mentioned, depending on specific conditions, you may need to stack another filter to get the result you want. Several manufacturers are now offering 6-stop filters for just that purpose, to supplement their 10-stop ones.

Am I the only one that noticed that the OP said . . . "I wanted to capture a long exposure using a 10 stop ND. The clouds weren't moving that fast so I wanted an exposure of at least a minute." That would be fun .

Hello, apologies for the lack of detail. I use using 70-200mm f2.8. The was shot at f8, ISO 50. Although this was less then a minute, I used Bulb in the end.
I was metering before I put the 10 stop on John

Why did you put the filter on John. Goes on the lens. ߘ

IainUK wrote in post #18332038
Hello, apologies for the lack of detail. I use using 70-200mm f2.8. The was shot at f8, ISO 50. Although this was less then a minute, I used Bulb in the end.
I was metering before I put the 10 stop on John

Hosted photo: posted by IainUK in
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forum: General Photography Talk

So is this taken with or without the 10 stop filter?

That appears to be with the filter on.

If you wanted to get a 1 minute exposure, you would've had to have stopped down to f/16.

It was with the filter on...