Using ND Filters

[ElizabethAtkinson]

I went for a nice trip to the beach yesterday and used my Cokin ND filters and the end result was absolute trash. Obviously I am doing something drastically wrong and I'm annoyed that it was the perfect chance to have a play with the filters but couldn't figure out what I was doing wrong, and yet I won't have the opportunity to go the beach again for a while.

Anyhow, what I did was to meter with the filter(s) in place and take the shots (alternating between ND8 and ND8+ND4 together) - the end results was every shot was highly over exposed.

I googled the process, and became even more confused. A lot of sites state to meter before you put the filter on and then put it on, keeping the metered settings and just shoot. Another site said you need to meter first, put the filter on and then adjust the speed to compensate for the size of the ND filter (totally lost me).

Can someone please explain the correct process to follow when using an ND filter so my next trip to the beach won't be such a catastrophe. My graduated ND filters are 2, 4, 8 and I am waiting for my Hoya ND400 to arrive.

Many thanks,
Liz

[William]

Hi Liz, Are we talking this kind of ND grad filters, The ones that have a holder like this http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/filter/Cokin-Systems.html or the round screw on type ?

[ElizabethAtkinson]

Yes, that's them - they are the filters that slot in to the holder, HOWEVER the ND400 is a screw on filter.

Thanks, looking forward to your response. regards.

[old dog]

hi there Liz. I`ve found that my camera will still focus with the ND400 on but not in poor light. Usually 9 times out of ten it will. I always shoot in manual with it on and find that if I give it 1 to 2 stops overexposure when adjusting the speed dial I get it right more often than not...and if you shoot in raw then it is more forgiving still. Anyway just experiment and you will get it right pretty quickly. If say you figure out that you need 2 full stops of overexposure everytime then you can set the exposure compensation meter to plus two and then use aperture priority. It`s a fun filter so enjoy. I too want the grads in the slot in setup...so one day I`ll get them.

[William]

I dont know what mode you were shooting in (Manual or Auto) But IMO you need to shoot Manual, Just set your desired f stop, and ISO and adjust the shutter speed to get the right exposure with the filters on ( Keep on checking the LCD screen), Of cause you will need a tripod in low light , I always set focus and shutter speed with the filters fitted , You can drive yourself crazy with mathematical equations metering without filters and trying to get the right filter for the job The more dynamic range the stronger the filtration, I use 5 stops at Sunrise and maybe just two stops in the day to cut down bright clouds , Not very technical , But it works , After a little while you will know just by looking what filter to use for a certain situation :) Hope this helped a little , Have a play

[ricktas]

I would say learn to use the histogram on your camera LCD. If your first photo is over-exposed and the image on the LCD and the histogram confirms this, then adjust your settings to a faster shutter speed.

Learning how to use your histogram : http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

What settings did you use?

[ElizabethAtkinson]

93196
:lol: Here is one of many of the photos and the details are :-


File Info 1
File: EMA_1069.NEF
Date Created: 9/16/2012 6:13:31 PM
Date Modified: 9/15/2012 11:21:38 AM
File Size: 16.1 MB
Image Size: L (4928 x 3264)
File Info 2
Date Shot: 9/15/2012 11:21:33.50
Time Zone and Date: UTC+10, DST:OFF
Image Quality: Lossless Compressed RAW (14-bit)
Artist:
Copyright:
Image Comment:
Camera Info
Device: Nikon D7000
Lens: VR 18-200mm F/3.5-5.6G
Focal Length: 50mm
Focus Mode: AF-S
AF-Area Mode: Single
VR: OFF
AF Fine Tune: OFF
Exposure
Aperture: F/32
Shutter Speed: 4s
Exposure Mode: Shutter Priority
Exposure Comp.: 0EV
Exposure Tuning:
Metering: Center-Weighted
ISO Sensitivity: ISO 100
Flash
Device:
Image Settings
White Balance: Direct sunlight, 0, 0
Color Space: sRGB
High ISO NR: OFF
Long Exposure NR: OFF
Active D-Lighting: OFF
Image Authentication:
Vignette Control:
Auto Distortion Control: OFF
Picture Control
Picture Control: [SD] STANDARD
Base: [SD] STANDARD
Quick Adjust: -
Sharpening: 6
Contrast: +1
Brightness: 0
Saturation: +1
Hue: 0

[William]

f32 worries me , f11 to f16 maybe , Still should have, With Grads fitted given you the soft water look you were maybe after for the time of day , 6.13pm , You could always make it a high contrast mono like this :)

[I @ M]

Something is RADICALLY WRONG here.

If the exif detail is reliable then there is a BIG problem with either the camera or the lens but most likely it lies with the metered area for the shot.
Taking the photo in shutter priority is not a huge sin in itself if all the points of the exposure triangle line up and according to the exif data they do so there should be no reason to over expose the shot that badly other than if your choice of metering area made the camera expose incorrectly.
You have not reached the minimum aperture of the lens at the shutter speed chosen so therefore the camera is metering at a level that it thinks is correct. If you are metering on an inappropriate area to bring the darker areas to a correct exposure level and ignoring the brighter parts of the scene and then recomposing and taking the shot then it is entirely possible that the result that you have is quite correct and entirely operator error.

[ricktas]

OK. so if they all came out like this, you need to reduce the exposure, so leave the ISO at 100, and the f stop at 32 and reduce the shutter time. If 4 seconds over-exposes your photo, halve it to 2 seconds. Then judge again as to how the exposure went (using your LCD and the histogram), and keep adjusting the shutter speed till you get a good result. You are the photographer, you need to control your tools to get the result you want. Do not expect the camera to do it for you!

[arthurking83]

f32 worries me , f11 to f16 maybe , Still should have, With Grads fitted given you the soft water look you were maybe after for the time of day , 6.13pm , You could always make it a high contrast mono like this :)

I was thinking .. geebus! .. at 6PM and with 5 stops of ND, a 4sec exposure at f/32 should have turned out close to black!
But the issue is that it was basically midday when the image was actually shot(according to exif data) .. the image may have been edited (and hence recreated at 6:13PM tho).

Too bright in the day for only 5stops of ND I reckon, if a very slow shutter was required(was it sunny?) at the time yesterday .. it was in Melbourne.

With using ND filters, I reckon what you should do is the meter with no filters and then add your exposure difference method.(using manual as William said).

So, depending on how the camera is set up. If it's set up to adjust exposure by 1/3 per click stop, you can set exposure without the filters mounted so that the meter reading look like

ˑ ˑ | ˑ ˑ

and then when you place the ND's in front of the lens, you would then see that exposure (according to the meter reading) will look more like this:

i i |..i..i

ie indicating that it's going to underexpose by -2Ev or more(technically it should be by about 5 stops.
(with ISO and aperture being constant) what you now need to do, rotate the shutter control dial 15 times or clicks(assuming 1/3 exposure increments) to the left, so that the meter indicator looks like the initial example again(if neutral is what you want it to be .. or give it a touch of underexposure to be sure.

ie. -2/3Ev underexposure will have the meter indicator look like this:

ˑ ˑ |..ˑ ˑ

I reckon the filters made the meter system go all haywire(it shouldn't have, but there's no reason not for it not too).

I use grad filters all the time and usually take meter readings from the filtered part of the scene for confirmation of exposure balance. While it's not foolproof, I can't ever recall that I've seen it this far off course.

So, how to correct for it next time ....

1. get more ND filtration
2. stay longer or come later
3. choose a day when the water is more rough/choppy/faster moving
4. find a lens that stops down beyond f/32!
5. shoot faster(shutter speed) and hope that PS can process the water to look milky :p


... Oh! and one other thing. In your camera's menu system is a noise reduction feature for long exposures. It's actually better to leave this set to On!
I think it may be called LNR(Long exposure NR). Anyhow, best set to enabled.

[ElizabethAtkinson]

I'm re-reading through your posts now as there is so much info to take in, but the time of the photo isn't correct. It was probably around 11am (6pm is when I resized the photo to post it here)

[arthurking83]

..... It was probably around 11am (6pm is when I resized the photo to post it here)

Yep! that's what I said(I think .. I'm sure) .. it was probably too bright on the day for a 4sec exposure at those settings.

Another issue that may have transpired as a result of your camera setting: As you set the camera to Shutter priority, the camera will then adjust aperture value to bring the exposure value to your requirement.
If the lens's aperture value can't be set appropriately then you will get an exposure anomaly.

As an example of that in action: You set your shutter speed to 4s. The camera's meter is reading the scene brightness and determines that the correct aperture (at ISO100) is f/36. You lens only stops down to f/32 ... exposure will be too bright. How you can visualise this before it happens is via the meter indicator in the viewfinder(my picture of the i's and .'s up above.
Unless you understand photography in general and your camera's sensor perfectly, I recommend that you try using Aperture priority as the main semi-auto mode for landscapes, or use Manual know when and by how much to compensate exposure, and watch the meter indicator.
(my personal preference is for Aperture priority for 99.9% of my uses .. but occasionally I switch to Manual mode).

As you re read my post, have camera in hand and play with it so that you understand the meter indicator 100%.
Set it up on your computer table and have the ND filter handy. Set camera to manual, and exposure to neutral. Place an ND filter in front of the lens, and watch the meter indicator bars light up to the right of -0-(or the central point). This means that you will under expose the scene. All you need do now is to rotate the command dial(shutter dial) to the left.

How many Ev steps is the camera set to for each dial click stop? The options should be 1/3, 1/2 and 1 stop increments.

[ricktas]

Also remember that you do not need water to practice your long exposures. A nice windy day with blue sky and mottled cloud can produce some amazing swept-cloud results when taken early or late in the day with ND filters on.

Would I be right in saying you do not have a good grasp of how ISO/Aperture/Shutter Speed combine, and how to use them depending on the amount of light available, and the result you want?

I think you need to get back to the basics of these three camera functions and get a good understanding of how they interact, and then you will know what adding an ND does and how to compensate for it, using adjustments to these three camera settings.

[ElizabethAtkinson]

OK, analysing what I possibly did wrong I came up with the following :-

given it was a sunny day, the shutter speed was too long for the conditions. I had it at 4 seconds because I wanted the "milky" appearance

perhaps I should have used matrix metering rather than centre weighted

the water wasn't really choppy so overall I should have picked a better day/time of day


I thought I had a pretty good understanding of the exposure triangle, and generally shoot in either manual or aperature (however, using shutter for sports photos), but using a filter is a totally new adventure to me.

Thanks all for your responses, I will try again

- - - Updated - - -

Thanks for this detailed reply (and your later response too) which I intend to digest but WOW, it sounds so complicated/involved. Perhaps I don't know as much about photography as I thought, and I have been doing it on-and-off for years (well, with film at least).

[arthurking83]

...... I had it at 4 seconds because I wanted the "milky" appearance

perhaps I should have used matrix metering rather than centre weighted

the water wasn't really choppy so overall I should have picked a better day/time of day


.....

Once again , I don't think you're fully understanding what the issue may really be here.
(ok, without actually being there at the time of the shoot, it's hard to be 100% certain .. but I think I'm 99% certain about this).

The issue isn't about metering. The metering is going to give you a particular level of exposure, that's for sure, but only if the camera's parameters can set themselves to do so.

So, as already said, by using Shutter priority, this forces the camera to alter either aperture or ISO to maintain a predefined level of exposure.

if the camera required an aperture of f/64(at ISO100) to achieve the desired exposure level(as set by the metering), then the minimum available aperture of the lens is where it all fell into a heap for ya.

The camera simply couldn't provide the necessary hardware level variables to maintain a shutter speed of 4sec.

This is why it was mentioned that Aperture priority would have been the better shooting mode to use, where you set the aperture you prefer to use, and the camera then sets the necessary shutter speed.

If you wanted a shutter speed of 4s (to achieve this milky water look), and you could only see 1/20s through the viewfinder than you automagically know that you need a smaller aperture, and if this bottoms out then you needed more ND filtering ..... or if that wasn't available, then you needed less light. .... etc, etc.

I don't think that you "don't know as much about photography as you think" !! From your replies, it seems you just have less understanding about which 'mode' is best for a specific purpose(which encompasses the hardware aspects of photography).
That is, had you realised that the aperture was minimum'ed out and that ISO was base'd out, and that you only had shutter speed to play with, then your only choice would be to adjust shutter speed to effect a 'correct' exposure.
In many ways this is the extreme opposite of what many new to photography folk find out about their kit lenses, where they want more aperture but can't get it from a kit lens. You wanted less aperture from your lens(because you were shooting in shutter priority!!) but (possibly) couldn't get it.

... it's all about (knowing) the hardware!

People always go on and on about using Manual mode.
I find it tedious at best, to use M mode .. except for specific purposes!!.
For the vast majority of my landscaping needs Aperture priority is the best mode to use, in 99% of the conditions I've found myself in.
When I get myself a full frame .. eg. D800 .. camera one day soon, I reckon that figure will rise to 99.9%.

(just so that you know why I sometimes don't use Aperture priority mode)
When the camera is set up and your eye is not up against the viewfinder, using Aperture priority is fraught with the possibility that stray light enters through the viewfinder and confuses the metering system into thinking that there is more light than there really is. So your exposure can be affected.(D800, D700 and the D2/3/4 series of pro camera bodies all have a viewfinder curtain to prevent this happening.

[William W]

If I understand the situation correctly:


you are at the Beach on a Sunny mid-day
you have Two Graduated Neutral Density Filters, they being an ND8 an ND4.(ND8 provides 3 Stops attenuation and ND4 provides 2 Stops)



you want to use 4s as the Shutter Speed
your minimum available aperture is F/32
your minimum available ISO is ISO 100


With those filters and that shooting scenario, you will ONLY be able to get to a shutter speed of about 1/4s AND there will still be areas of the image overexposed, where the graduation of the ND filters is the weakest.

An ND400 provides about 8⅓ Stops of attenuation and with that filter, for the same shooting scenario, you will just be able to get to a shutter speed of around the 4 seconds you seek.

When using an ND400, I find framing the scene and focussing the scene easier to do before I place the Filter on the Lens.

WW

[Jad]

If you want to do long exposures of the range of 3 to 6 minutes during sunny conditions, you will need a solid ND filter (or two stacked) of at least -10 to -15 stops of light (buy filters bigger than your lens filter size). Set your ISO to the lowest setting and stop down your lens all the way. You will want to meter and focus in the manual mode before putting on the filters ( I have set my camera to focus with the AF lock button on the back instead of the shutter release button). Once you have focused and metered put your camera to "B", bulb mode, before making the long exposure (be certain to check the f-stop setting is correct in bulb mode). I always use mirror lockup with a cable release. Another tip for making images you want in black and white, is to set your cameras "picture style" to black and white so your LCD screen is viewed in black and white, (YOU MUST EXPOSE IN RAW IN THIS MODE). This is very helpful when in the field to make a assessment of the image. Here is a long exposure chart you can use to help guide you. I have created a small cheat sheet I carry in my camera bag of my standard four or five exposures I normally deal with when making a long exposure. To use this chart, first determine how many stops your ND filter is. Example, say your ND filter is -10 stop. First meter with your camera (without the filter on), and lets say your meter reading is 1/30. Locate the 1/30 on the chart. Now look at the far left side and find 10 in f-stop reduction column and follow the line back to the column under 1/30. The correct exposure for your -10 ND filter will be 30s. These settings are just guide lines to get in close to the proper exposure. The thing to remember with long exposures are, the only difference between a 3 min. and a 6 min. exposure is one f-stop of light. There is a lot of room for exposure error and still be able to render a usable image. Good luck. PS, the chart is not loading. I will try to edit

[Jad]

EDIT bad IMG used...
http://www.ausphotography.net.au/forum/webkit-fake-url://0047A123-FD52-4E81-8471-0E5AAB510234/image.tiff

[Geoff Port]

Isn't this just the most fantastic site for photographers. So much great advice.

[Mark L]

Thanks for the detailed explanation John.
And the link still doesn't work!

[Jad]

I have tried several times to post the long exposure chart, but it just won't post for some reason.

[ricktas]

I have tried several times to post the long exposure chart, but it just won't post for some reason.

Cause you are using the wrong like - your post above (post 19 in this thread) shows the reason, it has 'webkit-fake-url' in the middle of the image link. It is not a valid link.

Also note that as you have only 19 posts you are not allowed to post links to anything other than your own photos at this time. read the site rules (rules 3-7)

[freelancer]

Ive given those super dark ND filters a go, found that the live view simulator in M mode really good for getting things right. A hand held meter also came in handy.
Jon

[basketballfreak6]

hi Elizabeth, noticed you were shooting in shutter priority mode also using centre weighted average so my guess is the fact that you were on an auto exposure mode the camera metered for the foreground which would be a lot darker than the sky therefore the whole image was overexposed

what you should do is expose manually also consider getting set of grad nd filters and in the case of sunset reverse grad work even better (only singh ray makes them as far as i am aware and they are expensive as hell, about to plonk cash down for one myself) to balance out sky and foreground

just remember the camera does not really know how you want to exposure the scene, learn to expose manually and when you need to exposure compensate and everything will become clear, chasing middle of the meter often will not give you the correct exposure pending on metering mode and what you are metering off

for example this shot i took few days ago

http://farm4.staticflickr.com/3822/9997465325_cf1285ea02_b.jpg (http://www.flickr.com/photos/basketballfreak6/9997465325/)
birthday sunset @Moogerah (http://www.flickr.com/photos/basketballfreak6/9997465325/) by basketballfreak6 (http://www.flickr.com/people/basketballfreak6/), on Flickr

i had a lee 3 stop soft grad nd (darker on the top, lighter on the bottom) to balance out foreground with light in the sky stacked with a 6 stop nd and exposed manually (came to 3 mins exposure)

especially in this case during sunset towards last light sun drops very quickly so light changes in that 3 mins so i had to actually guesstimate the exposure a bit

hope that made sense