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-   -   The effect of moving water (https://forums.steves-digicams.com/general-discussion-11/effect-moving-water-127148/)

Contriver Aug 8, 2007 9:53 AM

Hey guys, I took my K100D out to shoot some waterfalls (not much water flowing btw due to the lack of rain this summer). I wanted to get the effect of flowing water.

I chose an exposure setting that had a slow shutter to do this. And, then I set the aperature to a high number to compensate the incoming light. The resulting image was way too bright. Next, I locked in the ISO to 200 (the lowest this camera does), but still it was too bright. Even with the aperature as small as it could go, the images were too bright.

So, after some investigation, it turns out that a neutral density filtermay do the trick by blocking out some of the light.I remember my PS being able to get this shot to be dark enough without having to use and kind of filters.

I read somewhere that F numbers on a PS can be translated to something like 4 times that of a dSLR. So, if I am at F16 on the dSLR, its something like F4 on the PS. Thus if I am at F8 on the PS (the highest my A520 goes), it is somewhere in the ballpark of what F32 would be like on the K100D (the highest it goes to is F22).

So, to get to my question, I would just like to confirm this. Is it true that a point and shoot can capture this shot without filters while a dSLR requires a filter to block out some of the light?

Thanks!


tjsnaps Aug 8, 2007 10:18 AM

F numbers are a standard. f/8 at 1/15 and ISO 200 on a PS should give the same resaults (exposure wise) as f/8 at 1/15 and ISO 200 on a DSLR or any camera for that mater

GigaS27 Aug 8, 2007 10:23 AM

When tring to slow down shutter speed, you dont want to use the exposure setting to make it drop, because this will cause it to bring in more light which is the reason why the shutter is slower. You will need to either use aperture and use a high number, smaller opening which will casue the shutter to slow down or if avail always use S(TV) mode meaning shutter mode where you can control the shutter speep, and also adjust exposure to slow it down but not accept as much light to compensate for the longer shutter time being open.



This should correct the bright picture and also freeze the water flow.

Contriver Aug 8, 2007 10:57 AM

Thanks for the info guys. BTW, I am using full manual mode.I am controlling the shutter speed and aperture independently. I am setting it up to use a slow shutter speed and a small aperture as well as a low ISO. Yet, the resulting images still are too bright. Even at the extreme end when I set the aperture as high as it will go and then set the shutter to the fastest it will go while still making the water appear to be flowing, its too bright.

JohnG Aug 8, 2007 11:16 AM

It is absolutely possible to have this problem - especially with ISO 200 as your lowest ISO value.

There are a couple of solutions:

1. Take the shot when there is less light. If conditions are overcast there should be no problem getting extremely show shutter speeds at f22 - heck you'd have shutter speeds over a second easily.

2. A polarizer filter will reduce the amount of light coming in by up to a stop

3. As you mentioned, ND filters will also do the job.

GigaS27 Aug 8, 2007 11:20 AM

Exposure is what controls the brightess, try lowering your exposure...

Contriver Aug 8, 2007 11:44 AM

Hmm, I didn't try that. I'll keep that in mind next time. Thanks!



GigaS27 wrote:
Quote:

Exposure is what controls the brightess, try lowering your exposure...

Contriver Aug 8, 2007 11:46 AM

So, is it your experience as well that PS digicams seem to do a better job at shots like this?

JimC Aug 8, 2007 11:52 AM

GigaS27 wrote:
Quote:

Exposure is what controls the brightess, try lowering your exposure...
That's what you're doing when you change the ISO, Shutter Speed and Aperture. ;-)

The only way to make an exposure darker or brighter is to change one of those values if the lighting is the same. There is no magic feature that you use that isn't changing one of those parameters. If you're referring to Exposure Compensation, all it's doing is varying the aperture or shutter speed so that the image is exposed brighter or darker than the camera's metering would normally expose it. That does not get around the camera's limitations for the smallest aperture and lowest ISO speed you can use.

If the aperture is already stopped down to it's smallest value (higher f/stop numbers), which you don't want to do anyway for the sharpest photos; and the ISO speed is already set to it's lowest value, and the shutter speeds are still too fast when the image is exposed the way you want, use a Neutral Density Filter to block some of the light.

Or, as JohnG mentioned, a Polarizer may also get you want, depending on how bright the lighting is (depending on the way they're rotated, most will block around 2 stops of light).



Corpsy Aug 8, 2007 11:57 AM

What lens are you using? The 18-55 kit lens can go down to f/22 at 18mm, and f/40 at 55mm.


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