I fancy an ND for fairly long exposures in daylight. I'm looking at either a 1.8 or a 3.0. The problem is I use a point and shoot (Fuji Finepix s7000) where the maximum shutter speed is 15 seconds. How do i work out how long an exposure I would be likely to need with each filter? I don't want to buy one and find out 15 seconds isn't long enough in most conditions.
ND 1.8 or 3.0? limited shutter speed
- Thread starter The Matt
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Ok I think I'm getting this.
The 1.8 and 3.0 have a 6 & 10 stop/EV reduction respectively. To get the same amount of light with the filter on (assuming a fixed aperture) I need to double the exposure time for every 1 stop the filter removes.
So for a shot that needs f8, 1/90th without the filter, I multiply that by 2 to the power of 6 to get an exposure of ~0.7 seconds for the 1.8, and by 2 to the power of 10 for the 3.0, which gives an exposure time of ~11.4 seconds.
Is that right? Please stop me if I'm missing the point completely here!
The 1.8 and 3.0 have a 6 & 10 stop/EV reduction respectively. To get the same amount of light with the filter on (assuming a fixed aperture) I need to double the exposure time for every 1 stop the filter removes.
So for a shot that needs f8, 1/90th without the filter, I multiply that by 2 to the power of 6 to get an exposure of ~0.7 seconds for the 1.8, and by 2 to the power of 10 for the 3.0, which gives an exposure time of ~11.4 seconds.
Is that right? Please stop me if I'm missing the point completely here!
Claire
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Don't get me to explain it, I just whack on the filter and hope for the best. 
But at f/22 on a bright sunny day I can get 30 seconds with a 10 stop filter (3.0).
So what is the smallest f-stop on your camera? Seeing as it won't go down to f/22, maybe the 3.0 will give a longer exposure?
But at f/22 on a bright sunny day I can get 30 seconds with a 10 stop filter (3.0).So what is the smallest f-stop on your camera? Seeing as it won't go down to f/22, maybe the 3.0 will give a longer exposure?
My range is f2.8-f8 and my lowest iso is 200 (and preferred iso, as things get noisy if I increase).
I suspect the 3.0 is that I want, but don't want to get it and then find that at f8 or similar needs a much longer exposure than I can do
You have some greatt long exposure shots on your flickr by the way Claire
I suspect the 3.0 is that I want, but don't want to get it and then find that at f8 or similar needs a much longer exposure than I can do
You have some greatt long exposure shots on your flickr by the way Claire
Claire
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I see what you mean. But I think it should be fine, 'cos if 15 seconds isn't long enough, you just have to open up the aperture a bit.
If you wait 'til tomorrow (when it's light) and put your camera to f/8 and ISO 200, and see what shutter speed it's saying. Then look at this table and you should see how many stops you need to take off: http://www.flickr.com/photos/tomasradzevicius/2267881902/
Thanks BTW!
If you wait 'til tomorrow (when it's light) and put your camera to f/8 and ISO 200, and see what shutter speed it's saying. Then look at this table and you should see how many stops you need to take off: http://www.flickr.com/photos/tomasradzevicius/2267881902/
Thanks BTW!