DIY $10 10-Stop Neutral Density (ND) Filter

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Introduction: DIY $10 10-Stop Neutral Density (ND) Filter

Most photographers at one point or another wished they had access to a ND or Neutral Density filter. But at $100 or more per filter, that might be hard for an amateur or enthusiast photographer to justify the cost. Fear no more, this guide will show you how to build your own reusable 10 stop ND filter on the cheap. If you already have a spare UV filter, then you can do this project for less than $10. That's less than $1 per stop!  Because this build is not permanent , you can use the ND filter on different lenses with different filter sizes. You can also use step down rings too if you have multiple lenses. Actual performance of this ND filter is anywhere between 10-12 stops depending on conditions, camera metering and quality of the welders glass.

A ND filter is essentially a dark piece of glass that reduces the amount of light entering the lens.  For this project, the ND filter will reduce the amount of light by 10 STOPS!  Why would anyone want to reduce the amount of light entering the camera? Well, by reducing the amount of light, we can use a slower shutter speed. This will create motion blur (great for moving water). Another popular reason for using a ND filter is to use a larger aperture, creating thinner depth of field without over exposing.  If you want to know more about ND filters, check out the Wikipedia article: http://en.wikipedia.org/wiki/Neutral_density_filter.

If you're ready, lets begin.

Things you will need:
  • Welder's Glass/Lens Green Shade #10, <$10 on Amazon
  • DSLR or camera with manual controls
  • Lens or lens adapter that accepts threaded filters
  • A spare UV filter. These are pretty cheap, sometimes free if you buy camera related items on sites such as Amazon
  • Tripod
  • Remote for your camera
  • Lens cleaning supplies
  • Black or dark electrical tape. Must be dark to prevent light leaks
  • Time
  • Working knowledge of long exposures
  • Optional: Step down rings

Step 1: Clean Your Glass

First, you need to clean the glass surfaces. Clean your spare filter. Clean your front element. And lastly, clean your welder's glass.  Also try to not damage your welder's glass packaging. You can use the packaging to store your soon to be new ND filter.  I used a Giottos Rocket Air to blow dust off everything. Then I used some lens wipe to clean off the glass surfaces.  

Step 2: Positioning Your UV Filter on the Welder's Glass

Make sure your welder's glass is clean. Center your spare UV filter on the Welder's glass. Be sure the treading side of the UV filter is not against the welder's glass.

Step 3: Securing Your UV Filter to the Welder's Glass

Now, we can secure the UV filter to the welder's glass with electrical tape.  Because the UV filter is round, use short pieces of electrical tape. Shorter pieces secure better. You can pinch the tape so its easier to apply. This is a delicate process so do not rush it. Keep the tape away from the threads of the UV filter.  The tape should only contact the non threaded edge of the UV filter and the welders glass.  Electrical tape is very strong and should be able to secure your welder's glass to your spare filter.

Tip:
For extra security, glue the UV filter to the welder's glass, then use electrical tape. I personally wouldn't do that, as I want to be able to use the welder's glass on other lenses with different filter sizes or use the welder's glass in a welding mask.  

Step 4: Finishing Touches to Your ND Filter.

With the edge of the UV filter taped to the welder's glass, your ND filter is complete. Pat yourself on the back. You've just built your own   10 stop ND filter.  You may also tape the edges of the welder's glass to prevent chipping. You are now almost ready to mount your ND filter.

Step 5: Setup Your Camera to Use the 10-Stop ND Filter

Now that your 10 Stop ND filter is complete, we can use it.  I assume you know the basics of controlling exposure on your camera.

Camera Settings
First, mount your camera to your tripod. Do not mount your ND filter yet. We need to meter the scene. Set your camera into Raw.  You can do this with JPG, but it is easier to post process with RAW. Now you can compose your scene. Focus on your subject and switch your camera into manual focus or lock your focus. You will not be able to focus with the filter on.

Metering
Now we need to meter the scene. Set your camera to Manual mode. Set your aperture and iso. Lower the iso for less noise. Perform a meter reading.  Your camera meter should tell you if you're over exposing or under exposing. Adjust your shutter speed so you get a proper exposure to your liking.  

Adjust Exposure Settings
Next, note your shutter speed.  This is your shutter speed without the ND filter.  Since the ND filter reduces the amount of light by 10 stops, you can lower the shutter speed by 10 stops too to compensate for the ND filter.  Most cameras will allow shutter speed adjustments at 1/3 stop increments. So every 3 clicks of your dial equals 1 stop.  

Bulb Mode for Long Exposures
The only problem you will run into is your shutter speed limit. Most cameras will only allow you to go down to 30 seconds for shutter speed.  If you're getting a 1/30 sec for your shutter speed without the ND filter, you will need about 32 seconds for the shutter speed to compensate for the 10 stop ND filter.  To go beyond the 30 second limit, you will need to set your camera into BULB mode. To use bulb mode, you need a remote shutter release with a timer or with a remote with the hold feature.  Nikons can also use the IR remote in bulb mode (press once to start, press again to stop).

Tip: 
You can observe your shutter speed before using the filter then calculate the appropriate shutter speed for 10 stops with a calculator too. Instructions on how to calculate shutters could be found all around the web. If you just want a handy guide for 10 stops compensation, look below. 


Normal Exposure = With ND Filter
1/1000 =  1
1/500 = 2 
1/250 = 4 
1/125 = 8 
1/60 = 16
1/30 = 32
1/15 = 64
1/8 = 2 min
1/4 = 4 min
1/2 = 8 min
1 = 16 min
2 = 32 min

Step 6: Taking the Shot

Without Remote
Set your shutter speed to compensate the 10 stops of light reduction. Screw on your ND filter. Press the shutter button. To reduce vibrations, you can use your in camera self timer to trigger the shutter.

With Remote
If you are using a wired remote release with a timer, set your remote for the appropriate time  length the shutter will be open for. Now attach the ND filter.  Trigger your shutter with your remote and set the hold. If you are using a manual remote without a timer, use a stopwatch or a timer to keep track of how long your shutter should be open for. Once the time has passed. Your remote with a timer should close the shutter. If youre using a manual remote, release the hold to close the shutter. If you're using an IR remote like Nikon's, one press to open the shutter. Then press again to close the shutter.

If your photos are coming out dark, use a slightly longer exposure. But following the chart should give you an exposure thats not dark. Welder's glass is not designed to be exactly 10 stop ND filter. Thus, sometimes you might need to use a longer exposure than what the calculated times "should" be. You can also use a different shade of welder's glass if you do not need 10+ stops.

Tips:
You might consider closing or covering your eye piece to prevent light leaks.
To speed up this process, turn of the noise reduction. 
You might see hot spots in your photos if you are doing really long exposures, or repeated long exposures. This is your camera sensor overheating. Some cameras will warn you when your sensor is overheating.
Remotes work differently on each camera. See your camera's user guide for instructions.

Step 7: Conclusion

There you go! You've just built and used a 10 stop ND filter.  Load up your raw image in your favorite photo editing software and start processing it like any photo you would take.  Most likely you will need to tweak the white balance and tint. Since the welder's glass is slightly green, you will need to compensate this green tint.  The sample photo I took uses the ND filter for a motion blur effect. Because the shutter speed was so slow, the cars on the bridge were blurred and appeared to have vanished.

Thats it! Now go out there and be creative with a ND filter. There are tons of resources on the web regarding the use of ND filters and how to build filters out of different types of glass. Enjoy!

Tip:
You can use step down ring adapters and attach it to other lenses instead of re-taping a another filter onto the welder's glass.
Don't trash the packaging of your welder's glass. You can reuse it for storage of your new ND filter.
You might get more lens flare than usual as the welder's glass is not coated.
Want to use the ND filter on another lens? Just remove the tape!
Depending on the type of Welder's glass you buy, you might be able to make a 15 Stop ND filter.
Crank up the ISO to use a faster shutter speed.

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41 Comments

That's a polycarbonate lens, and they scratch too easily. A glass lens from a goggle would work fine!

A good job indeed.Thanks for helping poor photographers to save money.

Instead of a calculator, android user can get an app called ND Filter Timer.

A wonderful app to have.

I like this instructable, but I just wanted to say that its a little confusing to call it a "neutral density" filter if it has a green hue. Neutral density means that the filter affects all wavelengths equally, therefore, every color equally.

Thanks for posting it!

thanks for the comment. you're correct on how a ND filter is suppose to work. however, some of commercial ND filters esp ones over 9 or 10 stops will also have a noticeable color cast. In practice, most ND filters cannot reduce all wavelengths equally. its just some filters are not as noticeable as others.

I have tryed this welding glass myself, first problem was getting the glass cut into a circle to match with a 58mm adjustment ring, so called into a glass company that makes stained glass windows, they cut two welding glass filters to near enough a perfect fit for the 58mm ring in just a few minutes and never even charged me. attached them to the rings with a black sealant, a 8 shade witch works out as a 10 stop, and a 10 shade witch is a 12.48 stop. then to get rid of the green colour cast i made a custom white balance with a white card, when i took the shot i opened it in raw file in photoshop cs6, ( for this to work right you have to open it in raw file ) and with the white balance eyedrop tool i just clicked it on the skyline of the photo, the green colour cast was gone, then it was just a mater of messing around with the sliders to get the right colour balance and temperature. so at the end of the day the only money i was out was, £2.80p for two welding glass filters and around £3.00 for the adjustment ring. so i now have two filters for long exposure, a 10 stop and a 12.48 stop for just £5.80p

So I created my ND filter using the welder's glass/lens shade green #10, but my pictures are coming out highly saturated in green. Have I missed a step in this process? If so, how can I correct it?! Thanks in advance for the help.

P.S. Here are the items I used: shade green #10 glass, Tiffen UV protection filter to attach my welder's glass to, and electrical tape.

See step 7:

"Most likely you will need to tweak the white balance and tint. Since the welder's glass is slightly green, you will need to compensate this green tint."

Just open your photo in your favorite photo editor (Photoshop, Paint.net, GIMP, etc) and you can reduce the amount of "green" in the photo.

This is a fantastic Idea! I glued my welders glass to a cokin adapter (the screw in part that attaches to the lens) I got on ebay for less than $2... It will be nice to have a removable ones as well to use on my other lenses!

It might be easier to use cokin adapters and tape the glass to that. It's flat around the edges, so the taping would probably be easier... I'll have to get another glass and try it!

sounds good!

cokin adapter should work well.