Mod a Cokin P007 to Fit Into a Screw-in Filter




This mod is particularly useful for photographers who shoot IR.
Cokin has an IR filter, the P007. It comes as a square plastic filter and would require Cokin's adapter to be mounted.
However, the adapter would cause light leaks.
This mod shows how the Cokin filter can be cut and sanded into a circle and fitted into a screw-in filter ring.

Note: For the Cokin P series, the largest filter ring size that it can be fitted to is 77mm.

Step 1: Main Material & Tools Required

1. Screw-in filter ring (Try to use an old filter or buy a cheap UV filter).
For this mod, I'm using an old 52mm cross screen filter.

2. Cokin P series filter
For this mod, I'm using P007 IR filter.

3. Masking Tape
It'll be used to protect the Cokin filter during the cutting/sanding.
I'm using this Hunter brand. It's quite good as after removal it does not leave any adhesive residues.

4. Dremel
This is a high speed rotary tool. It'll be used for cutting and sanding the Cokin filter.
It's possible to use a saw and sandpaper, but it'll take much longer time.

5. Safety goggles and mask.
This is a must as you have to protect yourself from the plastic dust during sanding.

6. Small flat tip screw driver.

7. Water-proof sandpaper

Step 2: Remove Filter Glass From Screw-in Filter

Use a small flat tip screw driver to pry open the retainer spring on the screw-in filter.
Insert the flat tip screwdriver into the gap of the retainer spring and pry the spring out.
After separating the filter glass, retainer spring and the filter ring, keep them aside first.

Step 3: Prep Cokin Filter

Use the masking tape to tape the Cokin filter on both surfaces.
This helps to prevent scratches during the cutting and sanding process.

Step 4: Trace the Shape of the Filter Glass

Place the filter glass on the Cokin filter and trace the edge with a pencil (just do it on one side).

Step 5: Cutting Process

Use the dremel to cut as close as possible to the traced line.
Wear the safety goggles and put on the mask before using the dremel.

Step 6: Sanding Process

Use a clamp to clamp the filter element to the Cokin Filter (The picture below does not show the cut filter).
Using a Dremel sanding band, sand away the remaining plastic of the Cokin filter away.
The glass filter element will prevent you from over-sanding.
A piece of wood can be used to prevent the plastic from vibrating during the cutting/sanding process.
You might need to use sandpaper to sand the edges down to fit it into the filter ring.

Try not to over-sand till it's smaller than the original filter glass, or else light will leak through.

Step 7: Final Step!

After finishing the sanding, peel off the masking tape.
Wash the Cokin filter under a running tap.
Wipe it dry with optical cloth.
Do a fit-check. If it can't fit, use water-proof sand paper to sand the edges down.

Once the filter can be filter properly into the filter ring, install the retainer spring.
That's it!



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    18 Discussions


    10 years ago on Introduction

    ouch if i spent a bunch of money to buy a filtuer i wouldnt cut it :D BUT STILL great idea. Blehh..,.i want an ND Grad filter but i aint got 60 bucks.

    2 replies

    Reply 10 years ago on Introduction

    Hi alvincredible, if you shoot IR photos, you'd understand why this mod is impt. If you plan to use the cokin IR filter with the cokin brackets, light leak will most likely spoil the images. With this mod light leakages will not be a prob. This is considered a low-cost start for IR photography if you consider the costs of owning a Hoya R72 filter, especially the larger diameter range...


    11 months ago

    cheapest Infrared Cokin or any other square filter i've seen is about $70+

    and a 52mm screw in IR is about $10

    so I question the reasoning for doing this. I have several infrared and full spectrum cameras and many IR filters, only reason I would do this is to put a IR filter into my Canon lens to Sony body converter so I could use the Sigma 8-16mm lens which has a very convex lens. Otherwise why throw the money away?

    I got an 950nm filter of eBay for $30US that is absolutely black no visible light gets through at all and use it on a Sony DSC-F707 that has "night vision" and this is the result.

    Inst pic.jpg

    11 years ago on Introduction

    Great idea for low cost ir(or any other) hard to find filters. The Cokin adapter ring is of particlar use for smaller or odd size filters. Also, Lee Filters has polyester 87 & 87C ir filters in 3x3 and 4x4 sizes for $13.95 and $23.95 respectivly

    1 reply

    Reply 11 years ago on Introduction

    I love the b/w quality of the Lee #87. But it's quite fragile. I had used it in my Peleng 8mm fisheye lens. Very good results :)


    11 years ago on Step 7

    Great idea! For those without a mini drill or not too confident with accurate sanding, it may also be possible to glue the filter to a cokin adapter ring and trim off the outside.

    1 reply

    Reply 11 years ago on Step 7

    Just be careful to prevent light leakage. :)


    Reply 11 years ago on Introduction

    Thanks GreenDay :) Recently I bought a commercial one which could be folded flat. Didn't have space to store the DIY box. :( But the DIY is really good because of the low cost and it really works well. Cheers :)


    11 years ago on Introduction

    . Great job! Don't think I want to sacrifice any of my Cokin filters to try it, but now I know how to do it if I ever want to. Thanks. . Is water all that is required to remove masking tape residue? Or is there something special about the Hunter tape you use?

    1 reply

    Reply 11 years ago on Introduction

    Thanks NachoMahma :) I use water to wash the filter as after the cutting/sanding, there will be plastic residue/powder. It will scratch your filter when you wipe the filter using cleaning cloth. If the masking tape that you use leave sticky residue, use some olive oil and rub it in. After that give it a wash and wipe dry. Finally, use a lenspen to clean up. Cheers :)