[bdery]

I am interested, though, if a lot of people like to use physical filters when capturing silky moving water... I believe in the past, I read about people suggesting using neutral density filters....but my mind could fail me....

You want a shutter speed of at least a few seconds for this, so in many cases the use of high-value ND filters is necessary. I have a ND1000 and polarizer with me when I except that long shutter speeds will be required.

[cdd29]

neutral density filters are like putting sunglasses on your camera. It reduces the amount light coming into it. Use a slower shutter speed. It's trial and error. The real trick is to not loose all of your detail in the blurred water as that often gets too overexposed (can't be helped to a point.)

[Buckeyemikie]

Most nature shooters I know-and the pros as well- simply don’t shoot moving or falling water in bright sunlight because it is very difficult if not impossible to avoid blown out highlights. Before you invest in ND filters, decide what slow shutter speed from 1/15 down to 1 sec. or so you like best. Practice on water in the shade. Using ND filters is a logistical & financial pain since our lenses have so many different diameters & Pentax is a lot better than others! Yes you can use stepup/down rings but that adds to the logistical pain too.

[MossyRocks]

I've done this a few times. As others have stated you want to have a lot of exposure time. There are various ways of getting it such as shooting in lower light situations, using the lowest ISO, stopping the lens down, using ND and/or CPL filters, multiple exposures, or a combination of those. My preferred method at this point is shooting at ISO 100, using a wide or ultra wide lens at f/8 to f/11 (to avoid diffraction), if I have a ND or CPL filter that fits the lens sticking that on, putting the camera (k-3ii) into pixel shift mode and then taking a bunch of shots (probably 60-100). For the final image I develop each pixel shift image in RawTherapee using custom pixel shift processing where I use median for moving parts and export all the images as 16 bit TIFFs. Then I align and stack the images in Hugin using the sigma clipped average for merging. With that many shots I will usually also upscale the images in RawTherapee 2x using the nearest neighbor method since with that many shots you can do a pretty good super resolution shot even off of a tripod. I actually used this method (minus the filter) for this image to smooth out the smoke from the heat plant in this image..

With using multiple exposures you still want as long of a shutter speed as you can get, but you will need to take more shots to avoid artefacts if things are moving at a moderate speed as you get some motion blur but it won't be smooth and continuous. By taking more shots you can further smooth things and using a sigma clipped average method you can toss out some of the outliers further smoothing things.

[Michael Piziak]

With linear it works not a circular filter. How do you make a circle perpendicular to a circle?

Thanks. I learned something here. Previously, I didn't know there were circular polarizers and linear polarizers. I guess only linear polarizer will gradually get darker as you turn one linear polarizer against another linear polarizer. I can tell, by experimenting with my 2 circular polarizers, that very little reduction in light occurs as I slowly spin one against the other....

[swanlefitte]

Thanks. I learned something here. Previously, I didn't know there were circular polarizers and linear polarizers. I guess only linear polarizer will gradually get darker as you turn one linear polarizer against another linear polarizer. I can tell, by experimenting with my 2 circular polarizers, that very little reduction in light occurs as I slowly spin one against the other....

Flip the one upside down and it works. A circular polarizer is a linear on top of another filter that spreads it back out.Turned around and the 2 linear are next to each other. Neat but not practical.

[Wheatfield]

One way to do it without using filters is to use Multiexposures. Take several correctly exposed pictures and blend them into one. This can be done in-camera or in software.

I read about something similar as a technique when I was shooting 4x5 film, so I decided to try it.
The correct exposure was several minutes, so I decided to get there 1/30 second at a time.
It really wasn't all that satisfactory.
I haven't tried it with digital.

My go to solution is a six stop ND filter. I've been known to stack a polarizing filter on top sometimes as well. It works as long as you have spent real money on filters, but two inexpensive ones can seriously mush out what is supposed to be sharp.

Michael, the below shot is a 28 exposure focus stack. I shot it with the 77mm lens at f/8. Each exposure was 13 seconds duration.
I used, IIRC, a 6 stop ND filter with a circular polarizer on top. I'm using Breakthrough Photography filters, which are quite good and are on the expensive side.

The water in the background was moving quite rapidly, and I knew it would turn into milk with a 13 second exposure, but the water in the foreground was relatively still, and was just sort of murky, so I decided to try to see past it.
I think it worked well enough.
If nothing else, it's just over 6 minutes of my life wasted doing something I like.

F/8 is where the 77 sings, BTW.

---

Last edited by Wheatfield; 08-23-2021 at 06:49 PM.

[MossyRocks]

The correct exposure was several minutes, so I decided to get there 1/30 second at a time.

That is why I always suggest doing lots more shots than are needed if doing the multishot method and outlier rejection (sigma clipped average) helps to remove movement artifacts further.

[Wheatfield]

That is why I always suggest doing lots more shots than are needed if doing the multishot method and outlier rejection (sigma clipped average) helps to remove movement artifacts further.

I'm not sure if you understood my post. A several minute exposure built up 1/30 second at a time is a lot of exposures.
It might work better on digital.

[SrMi]

If using the smallest shutter you will lose sharpness due to diffraction and you will make any sensor contamination more visible. Multiple exposures or ND filters are the best solutions.

[John G]

On my K3 II I've had success using the multi-exposure options in place of a neutral density filter. I simply press the shooting mode button on the back of the camera (it has an image of multiple frames and a self-timer on it). I then scroll across the top ribbon of icons until I get to 'Multi-exposure+ Continuous'. Then I select the first item 'Multi-exposure' in the sub-row and move down to select the 'Composite Mode', setting it to Average. Finally choose how many shots you want the camera to average. Something like 30 is a good starting point, but you'll probably want to experiment a bit. Of course, like using a neutral density filter to allow you to set a very slow shutter speed, the camera will need to be on a tripod to keep all the frames aligned.

[normhead]

I can do motion blur hand held at 1/6s... IBIS is a wonderful thing.

If you are in a canyon 1/20s will do.


Or even 1/4s




But for many of these I use a tripod, as a more dependable option. .5s is a little long for hand held. Also on this one, ƒ22 isn't so bad, even on APS-c. The extra DoF is often more important than the higher resolution.


In general my workflow is to set up on a tripod, take 5-10 images at each spot, at different f-stops and shutter speeds, choose the best one. It's impossible to know which you'll like best in advance.

On the tripod shots I toss 5-9 images, and keep the one I like best.

[Photos-by-Chas]

I have tried long exposures for blurring water a few times. Overall, I can agree that shutter speed is very important to get the desired effect. However throughout this discussion, only one person mentioned the use of ISO to help get proper exposure. Even on brighter days, though not bright, direct sunlight, lowering of the ISO would require longer exposures and still allow higher aperture number for deeper DOF.

[biz-engineer]

A problem I often encountered with water falls in mixed shades / sun rays, is the dynamic range. Falling water turns bright white, whereas rocks and greens are quite dark. What looks like correct exposure by the camera turns some parts of moving water burned white, I often had to exposure compensate by one or two stops to avoid clipping, with the under-exposure shifting shutter speed to higher value, going against the goal of smoothing the moving water.

[normhead]

A problem I often encountered with water falls in mixed shades / sun rays, is the dynamic range. Falling water turns bright white, whereas rocks and greens are quite dark. What looks like correct exposure by the camera turns some parts of moving water burned white, I often had to exposure compensate by one or two stops to avoid clipping, with the under-exposure shifting shutter speed to higher value, going against the goal of smoothing the moving water.

I always shoot waterfalls and sunsets with my K-1 when available, and I always bracket, thinking if worse comes to worse, I can do HDR, but I've never needed to.

---------- Post added 08-24-21 at 03:18 PM ----------

I have tried long exposures for blurring water a few times. Overall, I can agree that shutter speed is very important to get the desired effect. However throughout this discussion, only one person mentioned the use of ISO to help get proper exposure. Even on brighter days, though not bright, direct sunlight, lowering of the ISO would require longer exposures and still allow higher aperture number for deeper DOF.

Much of the time I need both low ISO and small aperture, and unless shooting birds or action, my camera always starts at 100 ISO. Max. DR is lowest possible ISO, at least on most cameras. I think I read the K-3iiI has max DR at ISO 400. Weird but not impossible. That should mean less noise at 400 ISO, also weird but not impossible. I always go for best possible image, and with my cameras, that's always lowest possible ISO. I'll risk losing images to motion blur to keep my ISO at 100 when possible.